Brain Structure-Function PDF

Brain Structure-Function relationship LG1) How do dissociation logic lesion studies work? The study of the link between cognitive process and speciﬁc brain areas by studying individuals with brain lesions Using lesion studies and dissociation logic, scientists can map brain functions and better understand the organization of cognitive processes Insights help in development of targeted treatments and rehabilitation strategies for brain injuries Single Dissociation: Shows one function is a:ected, while a related function is not Double Dissociation: Conﬁrms two functions are independent by showing each can be impaired alone è Stronger evidence; conﬁrms clear independence, by showing that each function can be e?ected separately, proving they rely on di?erent brain systems > Single Dissociation alone might be unclear whether the two functions are truly separate or if one is just “harder” to disrupt LG2) What are the di:erent brain regions and their functions? Cerebellum (“little brain”): Contains more than half of the brains neurons è Around 69 billion out of the 89 billion we have Essential for smooth and precise motor control Helps with coordinating and regulating various functions, especially those related to balance and movement è If damaged your movements will become uncoordinated and halting Hemisphere: Separates the brain in two halves Although functions in each brain are almost the same the hemispheric lateralization suggests some functions are more dominant in one hemisphere than the other Brainstem: Consist of three parts: 1. Midbrain o Parts of the midbrain are involved in pain modulation o Plays a role in processing auditory and visual information and in orienting reﬂexes 2. Pons (latin:bridge) o Main connection between brain and cerebellum o Important for some eye movement, movements of the face o Modulate arousal and pain 3. Medulla o Essential for life o Houses cell bodies of many of the 12 cranial nerves, providing sensory and motor innervations to o Controls vital functions: Heart rate, blood pressure, respiration (breathing), arousal The 4 Lobes: Frontal Lobe: 1. Prefrontal Cortex: Executive functions, decision-making, emotional regulation 2. Primary Motor Cortex: Voluntary movement control 3. Premotor Cortex: Movement planning and coordination 4. Broca´s Area: Language production 5. Supplementary Motor Area: Movement initiation and coordination 6. Orbitofrontal Cortex: Risk assessment, decision-making, and social behavior 7. Frontal Eye Fields: Eye movement control and visual attention Parietal: Receive and interpret signals 1. Primary Somatosensory Cortex: Touch, temperature, and pain 2. Somatosensory Association Cortex: Interpretation of sensory input, hand-eye coordination 3. Superior Parietal Lobule: Spatial awareness, body position 4. Inferior Parietal Lobule: Integrates sensory info for complex tasks like language and math Temporal: 1. Primary Auditory Cortex: Sound processing 2. Wernicke’s Area: Language comprehension 3. Hippocampus: Memory formation 4. Amygdala: Emotional processing 5. Fusiform Gyrus: Facial and object recognition Occipital: 1. Primary Visual Cortex (V1): Basic visual processing 2. Visual Association Areas: Complex visual interpretation 3. Dorsal/Ventral Pathways: Location/motion (dorsal) and object recognition (ventral) Unitsensory cortex Multisensory cortex The Diencephalon: 1.Thalamus Divided into two parts – one on left hemisphere one on right Both parts are connected by a bridge of gray matter called massa intermedia receives sensory information from the body and directs it to the appropriate regions of the cerebral cortex for further processing (except for some olfactory inputs) plays a role in coordinating motor signals between the cerebral cortex and other parts of the brain involved in regulating the sleep-wake cycle and levels of consciousness è helps modulate the brain’s alertness and attention levels by controlling the ﬂow of sensory information during sleep 2. Hypothalamus maintains internal balance by regulating body temperature, hunger, thirst, and ﬂuid balance monitors blood parameters and initiates responses to keep these parameters within narrow limits Through its connection to the pituitary gland it releases and regulates hormones that inﬂuence growth, stress responses, reproduction, and metabolism plays a role in emotional responses, as it is connected to the limbic system LG3) What are the names of the a:ected areas and their functions? Phineas Gage: a?ected area: Ventromedial – ventromedial prefrontal cortex - located in the frontal lobe Function: - helps process and regulate emotions in response to social interactions, contributing to socially appropriate behavior, empathy, and moral judgment - crucial for decision-making processes - essential for understanding reward value and risk assessment - supports moral judgment by helping individuals understand the social implications of actions and behaviors - self-referential thinking, such as reﬂecting on one’s own beliefs, past experiences, and sense of identity - supports the ability to suppress impulsive reactions in favor of more considered, adaptive responses “Tan”: A?ected area: Broca´s Area Located in the frontal lobe on the part of the left hemisphere Function: Language Production HM A?ected area: medial temporal lobe – hippocampus Function: Memory formation LG4) Two di:erent examples of brain damage and their e:ects Lobotomy: Lesional surgery on the brain -> Now-Obsolete-Surgical procedure ( surgical procedure is no longer used) Developed by António Egas Moniz in 1936 Mostly performed in 1930s-1950s Severing connections between prefrontal cortex and deeper brain areas ( like the thalamus and limbic system, which are involved in emotion ) Goal: To reduce symptoms of mental illnesses, especially extreme mood swings, hallucinations and aggression 1. Prefrontal Lobotomy (Standard): Small holes were drilled into the skull on the sides or top, then a surgical tool was used to cut brain tissue 2. Transorbital Lobotomy (Ice-Pick Lobotomy): Long, thin instrument (looked like an ice-pick) was inserted through the eye socket -> pushed up to the frontal lobe -> moved around to damage the neural pathways ->this method was quicker and often done with minimal anesthesia Result: - Personality Change: Patients could become apathetic, lose interest in life or become indi?erent - Loss of Cognitive Abilities: Decision-making, social skills and emotional expression were often impaired - Physical Side E:ects: Some patients experienced seizures, incontinence ( lack of control over urination) or other physical issues due to brain damage Split Brain: Sometimes done to treat severe epilepsy Corpus Callosotomy: Severing of the corpus callosum ( bundle of nerve ﬁbers that connects the brain´s two hemispheres ) This e?ectively isolates the two hemispheres preventing them from communicating with each other Procedure limits seizure activity to one hemisphere, making it more manageable EOects of a Split Brain: splits visual perception, but does not create two independent conscious perceivers within one brain - Functions remain with a split brain, but each hemisphere can only process information from the side of the body they control directly o information presented to one side of the body or one visual ﬁeld may only be processed by the opposite hemisphere o For example: if an object is shown to the left visual field, it is processed by the right hemisphere. Since the right hemisphere lacks direct language capabilities, the patient may not be able to name the object, even though they can draw or recognize it by touch. -> each hemisphere can process information independently but only the left hemisphere can express it verbally - Split-brain studies have provided valuable insights into lateralization of brain function - describes how specific functions are localized to either the left or right hemisphere of the brain LG5) Example of a single and double dissociation Single Dissociation: Double Dissociation: Episodic memory vs. procedural memory Hippocampus vs basal ganglia, cerebellum Cognitive control 1. Explain the case of Phineas Gage (what was the actual explanation) 1848: survived a massive injury by an iron rod (6 kg, 1.09 m in length, maximum diameter 31.75 mm, 6 mm at the tip) which went through his left cheek and head caused by an accidental explosion Early Reconstructions: Bigelow (1850): - Drilled a whole through a “ordinary skull” to enlarging it until the iron rod would ﬁts through to simulate gages lesion - Could not recreate gages lesion, since his was smaller Damasio (1994): - Reconstructed how the rod went through gages skull with a 3D computer- generated “standard skull” - Concluded rod exited gages skull on the right side - suggesting it passed through the sagittal sinus superior (SSS) along with the prefrontal area, orbitofrontal cortex, and anterior part of the cingulate gyrus bilaterally New Insights Gages medical records didn´t match with the previous studies didn´t match Findings: - brain injury was limited to the left frontal lobe - did not involve the ventricular system - Only the medial and lateral orbitofrontal and dorsolateral prefrontal areas of the left frontal lobe were directly impacted by the incident (areas associated with decision-making and impulse control - Injury aRected approximately 11% of his white matter and 4% of his grey matter è Relatively low percentage of damaged suggest that crucial parts of the brain and pathways stayed in tact - Recovery: - (changes in behavior my be a bit exaggerated) Gage later on adapted and worked successfully as a stagecoach driver in Chile 2. What is cognitive control? also known as executive function ð Refers to a set of psychological processes enabling goal-oriented behavior ð Allows individuals to use their perception, knowledge, and objectives to inﬂuence their choices and action eJectively Key characteristics: Goal-Oriented Behavior: Cognitive control provides the mechanism by which goals shape § Maintaining focus on relevant information § Inhibiting distractions or irrelevant stimuli § Monitoring process towards goal § Flexibly shifting between sub-goals if needed Dependence on Working Memory: connecting perception, long-term memory, and action to facilitate decision- making and goal-directed behavior Neurological Basis: § Prefrontal cortex plays a crucial role, particularly in accessing and maintaining active representations of information § Dorsolateral Prefrontal Cortex (DLPFC): Implements top-down control by managing attention, planning, and working memory § Anterior Cingulate Cortex (ACC): Acts as a monitoring system, detecting conﬂicts or errors and signaling the need for increased control Conﬂict detection & Regulation: § When competing or mutually exclusive representations (e.g., actions or thoughts) arise, the ACC identiﬁes the conﬂict § In response, areas like the DLPFC are activated to reduce the conﬂict and optimize performance 3. Examples of cognitive control 1. Stroop Task 2. Action Inhibition Task: Description: Participants are required to stop a pre-planned action, when a stop-signal is presented Role of Cognitive Control: task tests the ability to halt automatic responses, demonstrating inhibition Brain Activity: § right inferior frontal gyrus (IFG) plays a key role in initiating inhibitory control 3. N-Back Task: Description: Participants are shown diRerent stimulus in a sequence, their task is to identify the earlier presented stimuli N Role of Cognitive Control: § Requires maintaining task-relevant information (working memory). § Involves ignoring irrelevant stimuli and updating memory representations Brain Activity: § Dorsolateral Prefrontal Cortex (DLPFC) is heavily involved, showing heightened activity when task diRiculty increases 4. Decision Making and Value Assessment: Description: Evaluating the trade-oRs between immediate and delayed rewards, such as choosing between a smaller, immediate reward or a larger, delayed one Role of Cognitive Control: Involves suppressing impulsive decisions in favor of long-term goals Brain Activity: § The orbitofrontal cortex (OFC) encodes the value of options § The lateral prefrontal cortex (LPFC) interacts with the OFC to prioritize long-term over short-term reward 5. Dynamic Filtering Task: Description: Tasks requiring selective attention to relevant information while ignoring irrelevant data Role of Cognitive Control: Filtering irrelevant stimuli and maintaining focus on relevant cues Brain Activity: § The lateral prefrontal cortex ( LPFC) facilitates dynamic ﬁltering, enhancing the activation of task-relevant representations while suppressing irrelevant ones 6. Multitasking: Example: Managing unrelated goals, such as driving while conversing Role of Cognitive Control: ERiciently switching attention between tasks and maintaining priorities Experimental Insights: Experienced multitaskers, such as avid video game players, often perform better due to strengthened cognitive control networks 4. The Prefrontal Cortex’s role in cognitive control Two Prefrontal control systems First: LPFC, OFC, and FP, supports goal-oriented behavior constitute a working memory system that recruits and selects task- relevant information. planning; simulating consequences; and initiating, inhibiting, and shifting behavior Second: MFC guiding and monitoring behaviour works in tandem with the rest of the prefrontal cortex, monitoring ongoing activity to modulate the degree of cognitive control needed to keep behaviour in line with current goals. 5. Can brain lesions cause personality changes? Personality refers to the unique set of characteristics, patterns of thinking, feeling, and behaving that distinguish one individual from another. It encompasses a person’s consistent traits, emotional responses, attitudes, and behaviors over time and across different situations. Personality is shaped by a combination of biological factors (such as genetics), environmental influences (like upbringing and experiences), and social interactions. It is often studied through theories like the Big Five personality traits (openness, conscientiousness, extraversion, agreeableness, neuroticism) or psychoanalytic, humanistic, and behavioral perspectives. EZects of frontal lobe lesions in patients: Perseveration→ Patients that persist in a response even after being told that it is incorrect Apathetic Distractible impulsive unable to make decisions Unable to plan actions Unable to understand the consequences of their actions Unable to organise and segregate the timing of events in memory Unable to remember the source of their memories Unable to follow rules. disregard social conventions unable to complete a plan socially inappropriate disinhibition syndrome -> damage to ventral and medial portions of the frontal lobe -> normal cognitive functions, perform normally on laboratory tests of response selection and working memory -> symptoms: constant movement which is not channeled toward productive activities, euphoric or manic with abnormal sense of humor, fail to respond to social cues 6. How does the Stroop task work? (role, conditions, etc) The Stroop task involves naming the ink colour of a word. In congruent conditions, the word and ink colour match (e.g., “RED” in red ink), while in incongruent conditions, they differ (e.g., “RED” in blue ink). Naming the ink colour in incongruent conditions requires more cognitive control to overcome the automatic tendency to read the word. The task is used to study conflict monitoring and cognitive control processes. Monitoring, inhibition and shifting rules is needed ACC detects conflict, DLPFC resolves if by enhancing attention to the relevant stimulus dimension (color) ACC -> detects errors and monitors conflicts DLPFC -> prioritizes the instructed task over the automatic task 7. Which brain areas are involved in cognitive control? primary motor cortex secondary motor cortex (lateral premotor cortex, supplementary motor area) prefrontal cortex (PFC) lateral prefrontal cortex (LPFC), frontal pole (FP), orbitofrontal cortex (OFC), medial frontal cortex (MFC)) 8. Try to understand what the diagram means. Colored error lines -> feedback loops ACC plays important role to detect conflict -> when it detects mismatch it signals the need for increased control -> DLPFC resolves the conflict Memory I LG1) What is the di.erence between working-memory and short-term memory? How does it work? Working memory like a subset of short-term memory where we mentally manipulate information Phonological Loop: deals with spoken and written material 1. Phonological Store (inner ear) processes speech perception and stores spoken words we hear for 1-2 seconds 2. Articulatory control process (inner voice) processes speech production, and rehearses and stores verbal information from the phonological store As long as we keep repeating it, we can retain the information in working memory Visuospatial Sketch ( inner eye): stores and processes information in a visual or spatial form -> used for navigation Executive Control: the boss of working memory manages attention and coordinates phonological loop and visuospatial sketch è Combines information from those two systems while also drawing information from the long-term memory enables the working memory system to selectively attend to some stimuli and ignore others Episodic Bu>er: acts as a “backup” store which communicates with both long-term memory and the components of working memory integrates more complex, multimodal information, resembling short ﬁlm clips Short-term memory Working memory Lasting time Seconds - minutes About 30 secs (without repetition ) capacity 7 +/- 2 Elements Suggested more limited than short-term function To store information To store and process information system Uniform-system Multi-component-system LG2) What are di.erent memorisation techniques? Chunking: technique to bypass limitation (7 +/- 2 elements) by grouping information into larger, meaningful units example: instead of remembering a whole phone number, categorizing it into pairs of numbers Repetition: fundamental technique where information is reviewd repeatedly to keep it active in short-term memory & promote its transfer to long-term memory phonological loop maintains speech-based information through internal repetition Elaboration: information is linked to existing knowledge structures and embedded in a broader context instead of simply memorizing facts, one attempts to understand them, make connections to other concepts and ﬁnd example Mnemonic Devices (eselsbrücken): usage of images, rhymes, stories or other associations to make information more memorable Retrieval Practice: involves actively recalling information from memory rather than passively reviewing it è strengthens memory traces and makes it easier to retireve the information in the future Contextual Cues: hippocampus binds events, time and place contextual cues can improve memory by mimicking the environment or state during learning Sleep: supports memory consolidation critical for memory formation, as information gathered during the day is processed and stored in long-term memory during sleep LG3) What are the neural correlations of retaining information? (Brain activity) The Medial Temporal Lobe: Hippocampus: plays a critical role in forming new declarative memories, i.e., memories we can consciously retrieve and verbalize Studies on patients with amnesia, such as the famous case of patient H.M., have shown that damage to the hippocampus results in severe impairments in forming new declarative memories, while other memory types may remain intact Consolidation: medial temporal lobe is critical for consolidation, the process of transferring new memories from a transient short-term state to more stable long-term storage standard consolidation theory posits that the hippocampus plays a temporary role and that memories are eventually stored in the neocortex. multiple-trace theory suggests that the hippocampus remains involved in retrieving episodic memories even after they have been consolidated rength of synaptic connections between neurons is increased through repeated stimulation. LTP is considered a cellular mechanism underlying learning and memory. NMDA Receptors: NMDA receptors, a type of glutamate receptor, play a critical role in initiating LTP. Synaptic Changes: Long-term memories may require substantial changes in the nervous system that can be directly observed. These include forming new synapses, eliminating old ones, and reorganizing synaptic connections. LG4) Why is the retaining of information limited in time and amount? Short-Term Memory (STM) and Working Memory: Limited Capacity: 7 ± 2 items means that only a ﬁnite amount of information can be held in STM at a given time. Decay: Information in STM rapidly decays if it is not actively rehearsed or processed This explains why we often forget information we have just seen or heard shortly afterward Interference: New information can displace older information in STM, leading to interference explains why it can be challenging to remember something when simultaneously confronted with additional information Long-Term Memory (LTM): Consolidation (festigung): Transferring information from STM to LTM is a complex process that requires time and resources Not all information in STM is consolidated and stored in LTM Interference: Interference also occurs in LTM when similar pieces of information compete with one another explains why it can be di]icult to recall speciﬁc details when you have had many similar experiences. Synaptic Plasticity: Storing information in LTM relies on synaptic plasticity ( =the ability of synapses to strengthen or weaken in response to experiences) Over time, these changes can diminish or be overwritten by new experiences. Additional Factors: Aging: Cognitive abilities, including memory performance, often decline with age è can be attributed to age-related changes in the brain, such as the loss of neurons and synaptic connections. Emotions: Strong emotions can impact memory formation both positively and negatively è Stress and anxiety can impair memory performance, while positive emotions may enhance consolidation Sleep: During sleep, the brain processes information and stores it in LTM Sleep deprivation can impair memory formation LG5)What is the part of the brain responsible for short-term memory? Not a single part of the brain that is exclusively responsible for short-term memory è But prefrontal cortex plays a central role The prefrontal Cortex: Studies on humans and animals indicate that activity in the prefrontal cortex increases during tasks requiring working memory Studies on humans and animals have shown that lesions in this area impair the working memory Patient H.M., who had his medial temporal lobe removed, retained normal working memory, suggesting that his prefrontal cortex remained intact Studies suggest that phonological working memory tasks primarily activate the left ventrolateral prefrontal cortex, while spatial working memory tasks tend to show bilateral (=two-sided) activation Lesions and Deﬁcits: Lesions in the left supramarginal gyrus (Brodmann Area 40) lead to deﬁcits in phonological working memory damage to the parieto-occipital region of both hemispheres a]ects visuospatial short-term memory. Recent research has identiﬁed additional brain regions potentially involved in short-term memory, such as the parietal lobe and the cerebellum LG6) Explain the monkey experiment Cue phase: 1) Cue is presented on the screen at a speciﬁc location 2) Monkey observes the position of the cue in his peripheral vision 3) Neural activity spikes brieﬂy in brain areas responsible for processing visual stimulus and encoding its location ( V1 & dorsal stream) (called phasic activtiy) Delay phase 1) The cue disappears & monkey has to maintain the location of the cue in his working memory 2) Sustained (anhaltend) neural activity in brain regions responsible for working memory, such as the prefrontal cortex ( called tonic activity) 3) Activity stays high until stimuli is presented, then working memory doesn´t need to hold onto the location of cue Response phase: 1) Stimuli & arrow appear on the screen, ending the delay phase + ﬁxation point vanishes 2) Neural activity spikes again due to the response of the monkey to the stimuli Memory II LG1) How is long-term memory organized? What are the di.erent types of long-term memory? Organization LTM: Medial Temporal Lobe Memory System: includes the hippocampus, amygdala, and surrounding parahippocampal, entorhinal, and perirhinal cortical areas o Hippocampus: plays a critical role in linking relationships between di>erent types of information, which is essential for episodic memories, such as time, place, and the people involved o Perirhinal cortex: is involved in familiarity-based recognition, while the hippocampus and posterior parahippocampal cortex support source- based recognition (episodic memory) o Studies of amnesic patients like H.M. show that the medial temporal lobe is necessary for forming new long-term memories but not for short-term memory or the formation and retrieval of new procedural long-term memories Neocortex: the brain's outer layer, is where long-term memories are ultimately stored Storage tends to occur in cortical areas where the information was ﬁrst processed and held in short-term memory è For instance, the visual cortex is critical for visual object recognition Frontal Lobe: is involved in various aspects of memory, including working memory processes, encoding episodic information, and organizing the retrieval of information from long-term memory Parietal Lobe: The parietal lobe also plays a role in encoding and retrieving memories, particularly episodic or context-rich memories The retrosplenial cortex (RSC) within the parietal lobe appears critical for retrieving contextual information. Types of LTM 1. Declarative Memory § Declarative memory refers to memory for facts and events that we can consciously access and verbalize § It is also called explicit memory § The medial temporal lobe is critical for forming declarative memories. o Semantic Memory: - Memory for facts and general knowledge - Is context-independent, meaning we don't necessarily remember the circumstances under which we learned the information. o Episodic Memory: - Memory for personal experiences and events including details about what happened, where, when, and with whom - always involve the self as the actor or recipient of an action - hippocampus plays a key role in encoding and retrieving episodic memories. 2. Non-Declarative Memory § Non-declarative memory refers to memory for skills, habits, and behaviors that we cannot consciously access or verbalize § also called implicit memory § independent of the medial temporal lobe o Procedural Memory: - Memory for motor and cognitive skills, such as riding a bike or reading - requires extensive and repeated experiences. o Priming: -refers to a change in response to a stimulus or the ability to identify a stimulus after prior exposure - Types of priming include perceptual, conceptual, and semantic priming. o Classical Conditioning: - A form of associative learning in which a neutral stimulus is paired with an unconditioned stimulus that elicits an unconditioned response - After repeated pairings, the neutral stimulus elicits a conditioned response. o Spatial Memory: - Enables person to remember locations as well as where an object is located in correlation to other objects o Non-Associative Learning: - refers to changes in response to a stimulus after repeated exposure, without associating it with another stimulus - Examples include habituation and sensitization LG2) What does the case of patient HM tell us about the role of the medial temporal lobe (hippocampus) in long-term memory? Insights from the Case of Patient H.M. bilateral removal of most of his temporal lobes to treat his epilepsy è H.M. su]ered from severe anterograde amnesia, meaning he was unable to form new declarative memories related to facts and events that could be consciously recalled and verbalized retained memories of events from his life before the surgery but struggled to recall any events that occurred afterward able to follow conversations and remember a series of numbers for a short time, but he could not repeat them an hour later His short-term memory function was normal; for instance, he could repeat word lists, indicating that the medial temporal lobe is not necessary for encoding sensory information in short-term memory. Was able to learn new skills, such as mirror drawing, even though he had no memory of practicing or learning the new skill è demonstrates that his non-declarative memory (or procedural memory) for perceptual and motor behaviors was intact insights into the role of the medial temporal lobe in long-term memory: 1. The medial temporal lobe, including the hippocampus, is crucial for forming new declarative memories o H.M.'s inability to learn new facts and events highlights the role of this brain region in consolidating information from short-term memory into long-term memory 2. The medial temporal lobe is not the area where long-term memories get stored o H.M. retained memories of events from his life before the surgery, suggesting that long-term memories are stored elsewhere in the cortex 3. Di]erent types of long-term memory are processed by di]erent brain regions o H.M.'s ability to learn new skills while being unable to recall new facts or events underscores the distinction between declarative and non- declarative memory and their reliance on separate neural systems LG3) What are the di]erent types of forgetting (anterograde vs. retrograde amnesia)? Which brain areas are involved in long-term memory formation / amnesia? Types of Forgetting Amnesia refers to a severe memory impairment typically caused by injury or illness di]erent types of forgetting: o Retrograde Amnesia: Di]iculty recalling memories formed before the onset of amnesia. This often a]ects events that occurred hours, days, or even a year prior to the event that triggered amnesia. o Anterograde Amnesia: The inability to form new memories starting from the onset of a disturbance. Brain Areas Involved in Long-Term Memory Formation and Amnesia Medial Temporal Lobe This brain region, which includes the hippocampus, entorhinal cortex, perirhinal cortex, and parahippocampal cortex, is crucial for forming new declarative memories. o hippocampus acts as the brain's ﬁnal hub, combining information from nearby cortical regions, and is especially important for connecting an object with its speciﬁc context, like where or when it was encountered o perirhinal cortex is thought to mediate the sense of familiarity with an object in memory o parahippocampal cortex appears to process contextual aspects of memory, including spatial cognition Medial Diencephalon This region, which includes the dorsomedial thalamus and mammillary bodies, also plays a role in long-term memory formation o Damage to this region, as observed in Patient N.A., can also lead to anterograde amnesia, suggesting it works in conjunction with the medial temporal lobe to support memory Other Brain Regions: Various other regions are involved in di]erent forms of non- declarative memory, including: o Basal Ganglia: Involved in skill learning o Cerebellum: Plays a role in classical conditioning o Amygdala: Engaged in emotional processing and conditioning, such as fear o Neocortex: Involved in storing declarative memories and in priming o Prefrontal Cortex: Engaged in working memory processes and encoding information LG4) How are long-term memories formed? What is memory consolidation? How Are Long-Term Memories Formed? 1. Encoding: processing incoming information from sensory channels transferring it into short-term memory Various brain areas contribute to the initial processing of stimuli è but only a few are associated with successful encoding o For example, encoding visual elements in photos involves stronger activation of the right prefrontal cortex and the parahippocampal cortex in both hemispheres o For words, the critical areas are the left prefrontal cortex and the left parahippocampal cortex 2. Consolidation: memories transition from a temporary and fragile state to a more stable and lasting form è ﬂeeting short-term memory contents are transformed into more durable long- term memories can take days, months, or even years, gradually leading to stronger representation of the memory o The medial temporal lobe, particularly the hippocampus, is critical for consolidating information from short-term to long-term memory o Long-term storage of information tends to occur in cortical regions where the information was initially processed and held in short-term memory 3. Retrieval: The process of searching for a memory and finding it Retrieval from long-term memory is guided by various cognitive processes, including attention o Evidence suggests that retrieval temporarily makes memories plastic again, allowing them to be updated and strengthened before being reconsolidated into a stable state What Is Memory Consolidation? The process of stabilizing a memory over time after initial acquisition It is a critical step in forming long-term memories and involves both cellular and systemic processes Synaptic Consolidation: § refers to structural and functional changes at synapses in response to learning and experience § These changes can include the formation of new synapses, strengthening of existing synapses, and alterations in neurotransmitter release Systems Consolidation: § involves interaction between di]erent brain regions, particularly the hippocampus and neocortex § two main theories about systems consolidation: o Standard Consolidation Theory: suggests that the neocortex is essential for storing fully consolidated long-term memories, while the hippocampus plays only a temporary role o Multiple Trace Theory: suggest that the hippocampus remains involved in retrieving episodic memories, regardless of whether they are consolidated, while semantic information is stored exclusively in the neocortex Factors Inﬂuencing Memory Consolidation: Sleep: studies in rats have shown that neurons in the hippocampus repeat activity patterns during sleep that occurred during learning, suggesting that the brain "replays" learned tasks during sleep Stress: Both physical and psychological stress can inﬂuence memory consolidation o Acute stress, combined with adrenaline, can enhance the initial encoding and consolidation of information perceived around the time of the stressor o Chronic stress, however, can negatively a>ect memory, possibly by impairing long-term potentiation (LTP) in the hippocampus. LG5) What is long-term potentiation (LTP)? Explain how LTP works. What is the role of calcium in LTP? How is LTP related to neural activity during perception / working memory? What Is Long-Term Potentiation (LTP)? synaptic strength between two neurons increases after repeated, strong stimulation identiﬁed through classical experiments (1970s) on the hippocampus of rats, researchers observed that stimulating presynaptic axons with high-frequency bursts (tetanus) led to enhanced responses on postsynaptic neurons è this heightened responsiveness (LTP) can last for weeks or even longer considered one of the key mechanisms behind learning and memory formation How Does LTP Work? Occurs at synapses that use the excitatory neurotransmitter glutamate and is critically dependent on a speciﬁc subtype of glutamate receptor (NMDA receptor) 1. Normal Synaptic Transmission: During regular, low-level activity, the release of glutamate at a synapse primarily activates AMPA receptors. NMDA receptors remain unresponsive because their calcium channels (Ca2+) are blocked by magnesium ions (Mg2+) 2. Induction of LTP: When presynaptic neurons are stimulated with a burst of action potentials (tetanus), a large amount of glutamate is released. This strongly activates AMPA receptors, depolarizing the postsynaptic membrane. 3. Removal of Mg2+ Block: If depolarization reaches a threshold, Mg2+ ions are expelled from NMDA receptors, allowing them to respond to glutamate and permit the entry of Ca2+ ions into the postsynaptic neuron. 4. Activation of Protein Kinases: The inﬂux of Ca2+ activates intracellular enzymes called protein kinases, such as CaMKII, which modify or activate other proteins. These changes a]ect AMPA receptors in signiﬁcant ways. 5. Strengthening of the Synapse: Activated CaMKII promotes the production of more AMPA receptors and their insertion into the postsynaptic membrane. Existing AMPA receptors are also redistributed to the active synapse, and their ion conductivity increases. These adjustments make the synapse more sensitive to released glutamate. 6. Retrograde Signaling: In addition to postsynaptic changes, the activation of NMDA receptors triggers the release of a retrograde messenger from the postsynaptic cell, which travels back to the presynaptic cell and prompts it to release more glutamate, further strengthening the synapse. The Role of Calcium in LTP Calcium (Ca2+) plays a critical role in the induction of LTP The inﬂux of Ca2+ through NMDA receptors serves as the key signal triggering the downstream cascade that strengthens the synapse: Ca2+ as an Intracellular Messenger: Ca2+ acts as a signal indicating high synaptic activity Activation of Protein Kinases: Increased Ca2+ levels activate protein kinases like CaMKII, which phosphorylate AMPA receptors and enhance their functionality Long-Term Changes: Calcium-mediated processes lead to the insertion of additional AMPA receptors and increased glutamate release, making the synapse stronger and more e]icient LTP and Neural Activity During Perception and Working Memory Perception: - LTP may underlie the neural circuits involved in processing and storing sensory information ð Strengthening synapses in sensory cortices (=areas in the brain that process sensory information) in response to repeated stimuli could improve perception and recognition of these stimuli Working Memory: - involves the temporary storage and manipulation of information over seconds to minutes - LTP may help sustain (erhalten) neural activity in prefrontal cortical circuits involved in working memory tasks ð Strengthening synapses in these circuits may aid in keeping information accessible for processing Methods in Neuroscience LG1) How does MRI work? Why are some parts shown as gray and others appear white? Magnetic Resonance Imaging Magnet strength is measured in Tesla (T) ð Most hospital use 0,5-3T ð The stronger the magnetic ﬁeld the more detailed the image HO2 molecules particularly the Hydogen-molecules are signiﬁcant for an MRI ð hypogene have 1 proton that acts as a tiny magnet that randomly spins around ( => Precession) ð Body consist of 60% water Placing the body into a strong magnetic ﬁeld causes the protons orientation to align with the ﬁeld Radio frequency pulse ( weaker electromagnetic ﬁeld) points in a diOerent direction than the magnetic ﬁeld disrupting the protons causing them to become misaligned with the magnetic ﬁeld Once Radiofrequency turned oO, protons turn back to their old position (with the magnetic ﬁeld) giving oO energy in the process To measure this energy another tool called coil is placed around the body part that is being imaged Protons from diOerent kinds of tissue give of diOerent energy -> various types of tissues can be told apart (gray and white) MRS: Magnetic Resonance Spectroscopy - MRI scanner is conﬁgured to scan speciﬁc metabolites - Providing a tool to measure the concentration of neuroransmitters LG2) Explain the study of Angelo Mosso 'human circulation balance' - the first functional neuroimaging device This technique measured blood flow in response to cognitive tasks Balance of the table was so sensitive that it could detect changes in body weight distribution due to blood flow. è When the participant was engaged with a cognitive task, the table would shift indicating blood ﬂow towards the head -> increase in cerebral blood ﬂow associated with mental eBort LG2.1) Are there modern neuroimaging methods that are somehow still related to this early approach? fMRI – functional Magnetic Resonance Imaging works like a MRI with the addition of BOLD BOLD – Blood-Oxigen-Level-Dependent Areas of the brain that are more active tend to receive higher levels of oxygenated blood – blood ﬂow changes = hemodynamic response è Measures BOLD and can therefore show which areas of the brain are more active PET – Positron Emission Tomography Measure metabolic changes correlated with neural activity LG3) What are the diFerent neuroimaging methods and their functions? Strengths? Weaknesses? MRI - Magnetic Resonance Imaging Function: Creates detailed images of internal structure Used to provide information or diagnose structural abnormalities Strengths: + Non-invasive + High spatial resolution + distinguish between tissue´s Weaknesses: - cost - accessibility - time-consuming -> take around 30-60min -> difficult for patients to remain still this long - motion sensitivity -> movement can negatively effect images - use of magnetic field limits number of patients who can use an MRI i.e. patient with metal implants - claustrophobia and loud noise can cause the patient to stop the scan fMRI – functional Magnetic Resonance Imaging Functions: Mapping brain activity (during cognitive tasks) Diagnosis and treatment monitoring i.e. with epilepsy Strengths: + Non-Invasive + High spatial resolution + monitors whole brain Weaknesses: - cost - accessibility - indirect measure of neurol activity since it only measures the blood flow - time limitations – BOLD signals appear 4-6 seconds after neural activity - motion sensitivity - claustrophobia and loud noise can cause the patient to stop the scan PET - Positron Emission Tomography Function: scans show where a specific function in the body takes place Can detect cancer, test heart function, track Alzheimer, tumors Strengths: + ability to trace specific biochemical pathways + early disease detection - can identify abnormal activity in the brain before structural changes appear + high sensitivity for cancer imaging Weaknesses: - cost - accessibility - radiation exposure - lower spatial resolution - tracers don´t last long which means the procedure need to happen immediately after injection SPECT - Single-Photon Emission Computed Tomography Like PET but with longer lasting tracers Weakness: - lower resolution than PET CT – Computed Tomography Function: Uses X-rays and computer processing to create detailed cross-sectional (queerschnitt) image Identifying tumors and cancers Diagnosing acute conditions (trauma, internal bleeding, brain injuries) Strengths: + Quick (essential for emergency scans) + detailed imaging of bone + whole body imaging Weaknesses: - radiation exposure - no big contrast between tissues - only provides structural information DTI – Diffusion Tensor Imaging Function: specialized form of MRI that maps the diffusion of water molecules in white matter in the brain visualizing the orientation and integrity (information processing speed) of these pathways provides valuable insights into brain connectivity and structure studying brain disorders i.e. Alzheimer, schizophrenia, autism, traumatic brain injury Strengths: + detect subtle changes in white matter that may not be visible on standard MR Weaknesses: - Lower Spatial Resolution Compared to MRI - sensitive to movement - complex to interpret - struggles to accurately represent areas with complex fiber configurations EEG – Electroencephalography Functions: used to measure electrical activity in the brain during a specific event (event-related potential ERP)or to measure spontaneous activity Used to diagnose epilepsy and characterize seizure activity in the brain, to monitor sleep for the diagnose of sleep disorders or to provide information about a variety of other brain dysfunctions Strengths: + relatively low cost + can measure brain activity in the order of milliseconds Weaknesses: - poor spatial precision ( doesn´t show where exactly in brain activity happens - limited ability to accurately record deeper structures than cortex ECoG – Electrocorticography Function: Works like EEG but sits right on the brain Strengths: + resolution of signals is much greater than EEG Weaknesses: - invasive MEG – Magnetoencephalon Functions: Measures magnetic signals generated by the brain Sensitive magnetic detectors placed along the scalp measure small magnetic fields produced by electrical activity of neurons Can be used similar to ERP´s Strengths: + spatial resolution + non-invasive Weaknesses: - cost - availability CAT- computerized axial tomography Function: lots of X-rays Strengths: overall image of brain Weaknesses: low resolution LG4) What are the diFerences between structural and functional methods? Structural: focus on brain anatomy and structure measures physical properties neuroimaging methods: CT and MRI Functional: focuses on visualizing brain activity measures neural activity neuroimaging methods: EEG, ECoG, PET, fMRI LG5) How does an EEG work? Electroencephalography - Measures electrical activity in the brain primarily postsynaptic potentials è Measures activity of large groups of neurons that are active at the same time - Can be used to measure brain activity during a speciﬁc event (event-related potential)or to measure spontaneous activity - Used to diagnose epilepsy and characterize seizure activity in the brain, to monitor sleep for the diagnose of sleep disorders or to provide information about a variety of other brain dysfunctions direct measures: causation indirect measures: correlation -> preference on what measure is more useful depends on what one wants to measure LG6)What are the dimensions to describe and compare the diFerent methods? characteristics which can be measured in quality 1. Spatial Resolution 2. Temporal Resolution 3. Invasiveness 4. Penetration Depth 5. Degree of immobility choosing which dimension to use depends on what one wants to measure and which neuroimaging methods are available LG7) What are diFerent ways to manipulate brain activity? TMS - Transcranial magnetic stimulation: procedure that uses magnetic fields to stimulate nerve cells in the brain Pharmacology - Drugs Optogenetics: precisely controlling and monitoring the biological functions of a cell, group of cells, tissues, or organs with high temporal and spatial resolution by using optical system and genetic engineering technologies. Motor LG1) How does the chicken live without a head? Due to unique anatomy of chickens - Brainstem is located lower in the head and neck (responsible for basic bodily functions) - Highly developed reﬂex system, -> even without the brain the spinal cord can still generate reﬂexive movements (chicken may continue running) - In the case of mike the headless chicken, the farmer missed the jugular vein and brainstem, which is why the chicken could continue to move around and have a beating heard LG2) What’s the role of the jugular vein? Plays a crucial role in the circulatory system (transport network, delivers oxygen, nutrients hormones, and removes waste products) ð Speciﬁcally in the transport of deoxygenated blood from the head to the heart (where it gets pumped into the lungs for oxygenation) Two main types of jugular veins: 1. External Jugular Vein Drains blood from the superﬁcial areas of the head and neck (e.g. face and shape) 2. Internal Jugular Vein Drains blood form deeper structures, including the brain and parts of the face and neck Jugular veins merge with other large veins (e.g. subclavian vein) to deliver blood into the superior vena cava, which empties into the heart Important for maintaining normal intracranial pressure (pressure inside the skull) by ensuring eKicient blood ﬂow out of the skull LG3) How do di?erent levels of spinal cord relate to motor control? è Spinal cord is the communication gateway between the brain and spinal nerves 31 pairs of spinal nerves Spinal cord extends from the brainstem to the level of upper lumbar vertebrae (L1 or L2) ð In the grey matter neurons transmit information to each other ð White matter is made of bundles of axons who conduct information of and down the cord – these bundles are organized into speciﬁc groups with speciﬁc functions, forming the spinal tracts Spinal tracts carry speciﬁc information in a one-way traKic, between the spinal cord and a certain area in the brain Ascending tracts conduct sensory information up to the brain Descending tracts carry motor instructions down the cord Information is transmitted contralaterally: Some tracts cross over to the over side of the cord, before reaching the brain, they convey sensory information from one side of the body to the other side of the brain Information is transmitted ipsilaterally: tracts that stay on the same side horns called dorsal (gets sensory input) + ventral horn (contains motor neurons) interneuron Spinal nerves: mixed nerves which contain both sensory and motor ﬁbers ð Sensory ﬁbers enter the cord via the dorsal root/sensory root ð Motor ﬁbers exit the cord via the ventral root/motor root Motor Pathways: Upper motor neurons Lower motor neurons Spinal Levels: Divided into 31 segments (strarting from the neck) Cervical nerves: C1-8: controls neck, shoulders, arms and diaphragm, hands (majos muscle of respiration). Thoracic nerves: T1-12: controls the trunk and intercostal muscles for breathing, the ribs Lumbar nerves: L1-5: controls the hips, thighs, lower legs Sacral nerves: S1-5: controls the pelvis, buttocks and feet Coccygeal nerve: Coc 1: minimal motor function, related to the tailbone LG4) Look into topographic maps/cortical homunculus (focus on motor control) Motor homunculus: Visual representation of the areas in the primary motor cortex Primary motor cortex (M1): § Located in the precentral gyrus of the frontal lobe § Contains neurons responsible for initiating voluntary movements § Organized somatotopically, meaning body parts are represented in speciﬁc regions of cortex -> based on the amount of motor control required, not the size of the body part -> body parts with ﬁne motor control (e.g. ﬁngers, face) occupy larger areas of the motor cortex Medial Cortex: represents the lower body Middle Cortex: represents the upper body Lateral Cortex: represents the face and tongue, which require highly precise motor control LG5) Why is Parkinson’s happening? What happens in the brain? How does Parkinson’s occur? How is the basal ganglia involved in Parkinson‘s? Motor Symptoms: 1) Bradykinesia (slowness of movements) 2) Rigidity (stiK muscles) 3) Resting tremor 4) Postural instability (balance issues) How is the Basal Ganglia Involved in Parkinson? Consist of: substantia nigra, striatum, globus pallidus, subthalamic nucleus, and thalamus Why is Parkinson´s happening? Caused by the progressive loss of dopaminergic neurons in the substantia nigra pars compacta, a part of the basal ganglia ð Dopamine is crucial for regulating movement, mood and motivation Presence of Lewy bodies (abnormal protein) which disrupts normal cellular functions What happens in the brain? 1. Dopamine Deﬁciency: Substantia nigra produces dopamine and sends it to the striatum (part of basal ganglia) Dopamine levels decrease when neurons in the substantia nigra die, which disrupts communication between the basal ganglia and other motor related brain regions 2. Altered Basal Ganglia Circuitry: Basal ganglia regulates voluntary movements by balancing activity in two pathways: a) Direct pathway: excites motor cortex to initiate movement b) Indirect pathway: inhibits motor cortex to suppress unwanted movement Dopamine loss weakens the direct pathway and over activates the indirect pathway How does Parkinson occur? 1. Starts with a gradual loss of substantia nigra neurons 2. Dopamine levels fall below a critical threshold, leading to noticeable symptoms 3. Over time, other brain regions, such as cortex, can also be aKected LG6) What is the role of the SMA and the cerebellum in terms of motor control and alcohol? Supplementary Motor Area (SMA): Location: part of the medial frontal lobe Functions: 1. Planning and initiating movement 2. Coordination between hemispheres (e.g. tying shoelaces) 3. Motor learning – active during learning of new motor tasks 4. Works with basal ganglia to select and prepare motor programs Alcohol: reduces ability to plan and initiate complex movements Delays in voluntary movement Disrupted bimanual coordination (function 2) Cerebellum: Location: positioned at the back of the brain, beneath the occipital lobe Functions: 1. Coordination of movements – ensures smooth, precise and coordinated movements by integrating sensory input and motor commands 2. Balance and Posture – adjusts muscle tone and posture in response to body position 3. Error correction – compares intendent movement (from motor cortex) with actual performance and makes adjustments in real time 4. Timing – optimizes the timing of muscle contractions for ﬂuid motion Alcohol: Ataxia: diKiculty standing or walking straight Dysmetria: movements become inaccurate, individuals may overshoot or undershoot targets (e.g. ﬁnger to nose test) Slurred speech: cerebellums role in coordinating ﬁne motor movements extends to the muscles involved in speech Structure Motor Control Role Impact of Alcohol SMA Plans and initiates DiKiculty planning and voluntary, complex, and executing precise sequential movements. movements Coordinates bimanual tasks Cerebellum Ensures smooth Ataxia, loss of balance, coordination, maintains impaired coordination balance, corrects errors, and timing and optimizes timing in motor tasks LG7) What‘s the readiness potential? Which area is the ‘unmoved mover’ of our brain? Readiness potential/Bereitschaftspotential: = moderate buildup of neural activity, detectable via EEG, that begins about 1-2 seconds before a voluntary movement Signiﬁcance: Reﬂects brain´s preparation for movement and its thought to originate from motor planning regions It challenges the perception of “free will” because the readiness potential appears before a person consciously decides to move Early Phase: Begins in the SMA Late Phase: Activity spreads to the primary motor cortex and other regions to execute the movement “Unmoved Mover” = Supplementary Motor Area It generates the readiness potential in the early phase Acts as the origin point of voluntary action, organizing the intention to move before conscious awareness arises LG8) Is there a circuit diagram of the human motor system? LG9) Lesions related to motor control (-> look at brain damages related to motor control) SMA Lesions: DiKiculty starting movements Bimanual Coordination Problems: DiKiculty with tasks requiring both hands to work together Alien Hand syndrome: rare condition where one hand acts involuntarily Basal Ganglia Lesions: Parkinson disease (Substantia Nigra Dopaminergic neuron loss9 Huntington´s disease(Striatal Neuron loss): Chorea (involuntary, dance-like movements) and loss of voluntary movement control Hemiballismus (subthalamic nucleus damage): violent, ﬂinging movements of one side of the body Disorders from DiKuse Brain: Stroke: Traumatic Brain Injury LG10) What are the deﬁnitions of the words in the diagram? What does damage to these areas do? Dopamine: neurotransmitter that plays a key role in regulating mood, motivation, reward and motor control Muscle: tissue in the body that contracts and relaxes to produce movement, maintain posture, and generate heat Cerebellum: responsible for coordinating voluntary movements, maintaining balance, and reﬁning motor control by comparing intended and actual movement Complex Movements: movements that require the coordination of multiple muscles and joints, often involving ﬁne motor control Motor Neuron: A nerve cell that transmits electrical impulses from the central nervous system to muscles or glands, enabling movement or secretion Pyramidal Tracts: Neural pathways that carry motor signals from the brain´s motor cortex to the spinal cord, involved in voluntary control of body movements. Most known are the corticospinal tracts and corticobulbar tracts Sensory cortex: region of the brain located in the parietal lobe, responsible fro processing sensory information from the body Reﬂex: an involuntary and rapid motor response to a stimulus, mediated by the spinal cord or brainstem Brain Stem: lower part of the brain that connects spinal cord and rest of the brain, responsible for basic life functions such as heart rate, breathing and motor control Homunculus: distorted representation of the human body in the brain, illustrating the relative areas of the brain responsible for motor and sensory control of diKerent body parts. Motor Homunculus maps out areas of the body controlled by motor neurons Sensory Homunculus shows sensory areas Motor Adaption: process by which the brain and body adjust motor output in response to changing conditions or environments, such as learning a new motor skill or adjusting to a diKerent posture Golgi Tendon Organ: a sensory receptor located in tendons that detects changes in muscle tension, providing feedback to the brain to help regulate force production and prevent muscle damage from excessive tension Contraction: process by which muscle ﬁber shorten or tighten, leading to the generation of force and movement SMA: part of frontal lobe involved in planning and initiating voluntary movements, primarily those requiring complex sequences or bimanual coordination Sensory nerve: Nerve that carries sensory information form sensory receptors to the central nervous system, allowing the brain to interpret sensations such as touch, pain, and temperature Neurons LG1) What is a neuron? How is it built and what are the functions? Neuron (nerve cell): basic unit of nervous system (information-processing unit) 1. Receiving input from other cells 2. Integrating those inputs 3. Distributing processed information to other neurons è Arranged in networks neurons define and control all of our abilities and behaviors Dendrites: receive information cellular extensions, form a multitude of smaller or larger branches on which synapses are located Synapses: contact points where information from other neurons arrive Cell body (soma; pl. somata): Processes and integrates information Axon: Carries information along long distances from one part of a neuron to another Boundle of axons traveling together is called a nerve Anterograde transport: movement of materials from cell body towards axon terminals Retrograde transport: movement of used materials back to the cell body for recycling Axon terminal: Transmits information to the next cell in the chain Saltatory Conduction: - Myelin speeds up transmition è Action potential signal jumps along the part of the axon covered by sheaths (jumps from node to node) - In peripheral nervous system ( outside brain and spinal cord) sheaths are formed schwann cells Gaps between schwann cells are called nodes of ranvier - In central nervouse system (brain and spinal cord) sheaths are formed by oligodendrocytes Types of neurons: Multipolar: most common Bipolar: most commonly found in sensory system, such as vision Unipolar/Monopolar: involved in transmitting touch information Types of Neurons based on their function: 1. Interneurons: receive, process, and transmit information between other neurons, froming complex neural circuits 2. Motor Neurons (motonneurons): control muscle contractions and gland secretion (sweat, tears, salvia, milk, digestive juices) Long axons that extend from the brain and spinal cord to target muscles and organs 3. Sensory Neurons: detect and convey sensory information from the environment to the brain and spinal cord Synaptic Transmission: communication between neurons LG2) What is action potential and how does it work? rapid electrical impulse that travels along the membrane of a neuron – neuron fires - Stimulus above the threshold creates action potential - All-or-None Principle: An action potential either happens fully or doesn’t happen at all. If the threshold is reached, a full action potential fires. Electrical gradian: difference in charge across the membrane Chemical gradient: difference in concentration of molecules across the cell membrane è Electro chemical gradient è Electrochemical equilibrium (resting-membrane potential) is reached concentration and charge for each ion is equal and opposite on inside and outside Membrane potential = difference in total charge inside and outside the membrane è Example: potential of -70 millivolts means inside of cell is 70 millivolts less positive than outside Ion-Chanels (protein in membrane): specified for Ion ( Sodium or Potassium) only allow a small fraction of ions to pass thorugh voltage-gated only allows one Acc - DLPFC Convergence Absolute Refractory Period: The short period after an action potential during which the neuron cannot fire again, ensuring that action potentials only travel in one direction. Relative Refractory Period: LG3) Define diffusion, electrostatic force, and selective permeability Diffusion: the movement of particles from an area of higher concentration to an area of lower concentration until a uniform distribution is achieved example: to accomplish the resting potential of a neuron, potassium ions (K⁺) tend to diffuse out of the cell where they are in higher concentration, moving toward the outside where their concentration is lower. This process helps establish the cell’s resting potential. Electrostatic Force: the force of attraction or repulsion between particles due to their electric charge. Opposite charges attract, while like charges repel. Selective Permeability: the ability of a membrane to allow certain molecules or ions to pass through it more easily than others. Example: During an action potential, voltage-gated channels selectively allow Na⁺ ions to rush into the cell, followed by K⁺ ions leaving LG4) What is sodium/potassium pump and how does it work? actively transports sodium (Na⁺) and potassium (K⁺) ions across the cell membrane to help maintain the resting membrane potential Functions: Maintains resting membrane potential Allows neurons to quickly polarize and depolarize The sodium-potassium pump is an active transport mechanism è Requiring energy in the form of ATP (adenosine triphosphate) to function è Uses this energy to open the pump in needed direction and pull and release the molecules LG5) What kind of energy does the brain use? 1. Chemical energy from Glucose (a type of sugar) è ATP is the primary chemical energy that fuels most of the brains cellular functions 2. Electrical Energy è Action potentials, synaptic transmission (electrical signals) 3. Electrochemical Energy Neurotransmitters LG1) What are neurotransmitters and how do they work? ð Chemical messengers that facilitate communication between neurons and others cells ( such as muscle cells or gland cells) at synapses ð Synaptic transmission: The role of Neurotransmission Synapses: Specialized junctions where neurons communicate with each other or with other cell types Synaptic vesicles: small, spherical(kugelförmig) structures located within the presynaptic axon terminal, which contain neurotransmitter molecules Presynaptic Membrane: specialized membrane of the axon terminal of the transmitting neuron > Voltage-Gated Calcium Channels > Specialized proteins for vesicle fusion (i.e. SNARE) – they mediate the docking and fusion Synaptic Cleft: A narrow gap that separates the presynaptic and postsynaptic neurons Postsynaptic Membrane: specialized membrane on the receiving neuron´s dendrite or cell body > Populated with receptors Receptors: specialized protein molecules embedded in the postsynaptic membrane, which bind to speciﬁc neurotransmitter molecules a) What is the di8erence between various types of neurotransmitters? Amino Acid Neurotransmitters: fundamental building blocks of protein o Glutamate: most widespread neurotransmitter, primary excitatory neurotransmitter in the central nervouse system -> playing crucial roles in learning, memory and synaptic plasticity too much can be toxic and cause cell death ( stroke, epilepsy,Alzheimer, parkinsons) - NMDA receptor and AMPA receptors o Gamma-aminobutyric acid (GABA) : second most widespread neurotransmitter main inhibitory (hemmend) neurotransmitter counterbalancing glutamate´s excitatory actions and contributing to the regulation of neural activity and the prevention of overexcitation too little can lead to seizure too much increase in heart rate, emotional recation, blood pressure Neurotransmitters LG1) What are neurotransmitters and how do they work? ð Chemical messengers that facilitate communication between neurons and others cells ( such as muscle cells or gland cells) at synapses ð Synaptic transmission: The role of Neurotransmission · Synapses: Specialized junctions where neurons communicate with each other or with other cell types Synaptic vesicles: small, spherical(kugelförmig) structures located within the presynaptic axon terminal, which contain neurotransmitter molecules Presynaptic Membrane: specialized membrane of the axon terminal of the transmitting neuron > Voltage-Gated Calcium Channels > Specialized proteins for vesicle fusion (i.e. SNARE) – they mediate the docking and fusion Synaptic Cleft: A narrow gap that separates the presynaptic and postsynaptic neurons Postsynaptic Membrane: specialized membrane on the receiving neuron´s dendrite or cell body > Populated with receptors Receptors: specialized protein molecules embedded in the postsynaptic membrane, which bind to speciﬁc neurotransmitter molecules a) What is the di8erence between various types of neurotransmitters? Amino Acid Neurotransmitters: fundamental building blocks of protein o Glutamate: most widespread neurotransmitter, primary excitatory neurotransmitter in the central nervouse system -> playing crucial roles in learning, memory and synaptic plasticity too much can be toxic and cause cell death ( stroke, epilepsy,Alzheimer, parkinsons) - NMDA receptor and AMPA receptors o Gamma-aminobutyric acid (GABA) : second most widespread neurotransmitter main inhibitory (hemmend) neurotransmitter counterbalancing glutamate´s excitatory actions and contributing to the regulation of neural activity and the prevention of overexcitation too little can lead to seizure too much increase in heart rate, emotional recation, blood pressure o Aspartate: excitatory neurotransmitter, often working alongside glutamate o Glycine: inhibitory neurotransmitter, particularly in the spinal cord and brainstem Biogenic Amines/Monoamines: 1) Catecholamines: neurotransmitters share catechol ring structure and are synthesised from the amino acid tyrosine § Dopamine: ﬁve diSerent types labelled from D1 to D5 plays role in reward, motivation, motor control, arousal, cognition § Norepinephrine: involved in arousal, attention, mood regulation and “ﬁght-or-ﬂight” response § Epinephrine (adrenaline): produced in the adrenal glands (located in kidney) and acts as a hormone, but also functions as a neurotransmitter, contributing to stress responses 2) Indoleamines: synthesized from the amino acid tryptophan § Serotonin: diverse roles in regulating mood, sleep, cognition, appetite, behavior, temperature § Melatonin: regulates sleep-wake cycle Neuropeptides: can be categorized in 5 subgroups a) Tachykins (brain-gut peptides) b) Neurohypophyseal hormones c) Hypothalamic releasing horones d) Opioid peptides: includes endorphins and enkephalins e) Other neuropeptides: insuline, secretins (e.g. glucagon) Acetylcholine (ACh): in its own bio-chemical group Excitatory as well as inhibitory eSect depending on receptor Nicotine binds to Nicotinic acetylcholine receptors to increase arousal, enhancing learning/memory 1. What is the process of neurotransmission? 1. Arrival of the action potential – this depolarizes the presynaptic membrane 2. Calcium Inﬂux: The depolarization opens voltage-gated calcium ( Ca2+) channels. This allows an inﬂux of Ca2+ ions into the axon terminal 3. Vesicle fusion with presynaptic membrane: The inﬂux of Ca2+ ions triggers synaptic vesicles to fuse with the presynaptic membrane – Fusion is mediated(vermittelt) by specialized proteins like SNAREs 4. Neurotransmitter release: The neurotransmitters are released through exocytosis (process of a cell moving large material from intracellular to extracellular (inside and outside of cell) using vesicles) 5. Receptor binding: The neurotransmitter molecules bind to speciﬁc receptor proteins embedded in the postsynaptic membrane 6. Postsynaptic Potential: The binding of neurotransmitters to receptors triggers changes in the postsynaptic neuron § Opening of ion channels, resulting in either an excitatory postsynaptic potential (EPSP) => depolarizing the postsynaptic membrane OR inhibitory postsynaptic potential (IPSP) => hyperpolarizing postsynaptic membrane § Activate G protein-coupled receptors (GPCRs) initiating slower, indirect eSects on the postsynaptic membrane through second messenger systems. Second messenger can modulate various cellar processes, including the opening of other ion channels or alterations in gene expression (process by which the information encoded in a gene turned into a function) After exerting their e;ects on the postsynaptic neuron, neurotransmitters must be removed from the synaptic cleft to prevent continuous stimulation. This event can occur through several mechanisms Neurotransmitter clearance: 1. Reupatke: The presynaptic neuron reabsorbs the neurotransmitter molecules back into the axon terminal (recycling - Retrograde transport ) 2. Enzymatic Degradation: Enzymes in the synaptic cleft break down the neurotransmitter molecules (destroying) 3. DiMusion: Neurotransmitter molecules diSuse away from the synaptic cleft. Clinical signiﬁcance of Neurotransmitters Drug thing LG2) What is post-synaptic potential and how does it work? ð Electrical changes in the membrane potential of the postsynaptic neuron, triggered by the binding of neurotransmitters to receptors on the postsynaptic membrane Two types 1. Excitatory Postsynaptic Potentials (EPSPs): neurotransmitter-receptor interaction opens channels that allow positively charged ions, like sodium, to ﬂow into the postsynaptic neuron -> membrane becomes depolarized -> making the neuron more likely to ﬁre action potential 2. Inhibitory Postsynaptic Potential (IPSPs): neurotransmitter-receptor interaction opens channels for negatively charged ions, like chloride (Cl-) to enter postsynaptic neuron OR for positevly charged ions, like Potassium, to leave -> membrane becomes hyperpolarized -> making neuron less likely to ﬁre action potential Signal Integration: neuron receives inputs from thousands of synapses -> postsynaptic membrane integrates these numerous EPSPs and IPSPs -> combined eSect of both potentials (like a calculater) determines whether overall change in membrane potential at axon hillock reaches the threshold for triggering an action potential LG3) How does serotonin inﬂuence the neurotransmission? (focus also in terms of depression) Widespread projections: serotonin projects to various brain regions (like, limbic system, cortex, cerebellum, spinal cord) ð This enables serotonin to have inﬂuence on diverse range of functions, like sleep, mood, sexual behavior, anxiety and cognition Interacts with variety of receptor subtypes Excitatory neurotransmitter LG4) What is the role of the receptors in neurotransmission? Acting as gatekeepers that determine how neurons respond to the chemical signals they receive Specialized protein molecules embedded in the postsynaptic membrane Recognize and bind to speciﬁc neurotransmitters released from the presynaptic neuron Two main types of recptors: 1. Ionotropic Receptors (Ligand-Gated Ion Channels): - Directly coupled ion channels è When neurotransmitter binds to ionotropic receptor, the channel opens -> allowing ions to ﬂow across the membrane+this ﬂow rapidly alters the membrane potential -> either EPSP or IPSP depending on the type of ion channel involved 2. Metabotropic Receptors (G Protein-Coupled Receptors): - Not directly linked to ion channels è Neurotransmitter binds to metabotropic receptor, it activates a G protein -> protein interacts with other eSector proteins, like enzymes or ion channels - Activate G protein-coupled receptors (GPCRs) initiating slower, indirect eSects on the postsynaptic membrane through second messenger systems. - Second messenger can modulate various cellar processes, including the opening of other ion channels or alterations in gene expression (process by which the information encoded in a gene turned into a function) A single neurotransmitter can often activate multiple receptor subtypes è Example: acetylcholine activates both nicotinic and muscarinic receptors Receptor plasticity: number and sensitivity of receptors can be regulated, inﬂuencing the strength of synaptic connections Key mechanism underlying learning and memory è Example: repeated activation of a synapse can lead to an increase in the number of receptors -> making the synapse more responsive to the neurotransmitter Video explains https://www.youtube.com/watch?v=_sM8KBZ9k4Q Antagonist Agonist partial-agonist inverse agonist Neurotransmission and Drugs: SSRI Drug – Selective Serotonin Reuptake Inhibitors Typically used as antidepressants Vision I 1. What are the di,erent parts of the eye and their functions? 1) Cornea 2 clear covering over pupil and iris Function: provides 66% of optic power refracting (bending) the light – helps focus acts as a protective shield 2) Pupil 2 Dark, circular opening in the center of the iris Function: Controls amount of light entering the eye by expanding (dilated)and contracting (undilated) ð Adjustment to diEerent light levels allows the right amount of light to enter the eye 3) Iris Colored part of the eye surrounding the pupil Function: Contains muscles that adjust the size of the pupil to regulate Similar to cameras 4) Lens Located just behind the iris and pupil Flexible and transparent Function: by changing shape it helps focus light onto retina ð allowing us to see objects at various distances 5) Ciliary Muscle Smooth muscle ﬁbers in the ciliary body, which surrounds the Lense Function: Changes the shape of the lens ð Near vision: muscle contracts (anspannen), causing lens to become more rounded, increasing its refractive power to focus ð Distant vision: muscle relaxes, allowing lens ð to become ﬂatter, reducing its refractive power, making git easier to focus on distant objects 6) Retina Thin layer of tissue at the back of the eye Function: Acts as the eye´s “ﬁlm”, capturing images and sending signals to the brain via the optic nerve 7) Photoreceptors Specialized cells in the retina Function: Convert light into neural signals, which are then processed by the brain into images Cones Rods Photopigments Three types (opsins) Rhodopsin Each sensitive to speciﬁc Highly sensitive to light wavelengths of light Can detect small amounts of corresponding to red, green, or light blue Don´t diEerentiate between Less sensitive to light colors, because they absorb è Provide high-resolution light across a broad spectrum & color vision without è monochromatic vision being overwhelmed by Best in nightlight (scotopic bright light condition) Best in daylight (photopic condition) Function and signal processing Optimized for color Optimized for sensitivity rather discrimination and sharp detail than sharpness or color in bright light Crucial for detecting detecting One-on-one or near on-on-one light in dim environments connections to bipolar cells Multiple rods converge onto a è Maintaining detail and single bipolar cell, reducing color speciﬁcity spatial detail è Increasing sensitivity Distribution in retina Most dominant in fovea most dominant in peripheral retina Adaption to light levels Adapt quickly to changes in More eEective in the dark but brightness and continue to saturate (stop responding) in function in bright conditions, bright light because their making them the dominant rhodopsin cannot regenerate photoreceptor during the day fast enough under high illumination 3 types of cones: Long for red Middle for green Short for blue 8) Macula Small, central part of the retina Function: Responsible for sharp, detailed vision ð Enables activities that require high visual activity, like reading and recognizing faces 9) Fovea Located within the macula Function: Point of highest visual activity with a high concentration of cones ð Providing sharp central vision and color sensitivity 10) Optic disc Point on retina where optic nerve ﬁbers leave the eye Function: entry and exit for blood vessels blind spot, since it contains no rods or cones it cannot detect light crucial for transmitting for transmitting visual information 11) Optic nerve Function: Carries visual information from the retina to the brain ð Serving as a pathway 12) Vitreous Humor Clear, gel-like substance that ﬁlls the space between the lens and the retina Function: Helps maintain the eye´s shape Allows light to pass through to the retina 13) Aqueous Humor Clear ﬂuid located between cornea and the lens Function: Nourishes these structures Removes waste Helps bend light into the retina Helps maintain eye pressure 14) Sclera Tough, white outer layer of the eye Function: Protecting inner components 15) Suspensory Ligament fine fibres connecting the lens to the ciliary muscles 16) Choroid Vascular (something with vessels) layer between retina and sclera Function: Providing oxygen and nutrients to retina (blood) ð keeping it healthy 2. What are the di,erent steps from light hitting our eye to our brain understanding it? (1) Light enters eye I. Passes through cornea which refracts (bends) light toward pupil II. Iris adjusts the size of pupil, controlling amount of light entering the eye (2) Focusing light I. Once through pupil light reaches lens II. Lens adjusts based on the distance of the object, with the help of the ciliary muscle helping change the shape of lens. -> focusing light onto retina (accommodation) (3) Light hits retina and photoreceptors respond I. Light reaches retina II. Photoreceptors convert light into electrical signal (4) Conversion of light to electrical signals (Phototransduction) I. Phototransduction occurs: light sensitive pigments in rods and cones undergo a chemical change when struck by light, producing electrical signals II. Signals travel to other cells in retina, like bipolar cell and ganglion cells III. Direct or indirect pathway (5) Signal transmission via the optic nerve Electrical signals (which is still somewhat unprocessed, mostly a collection of light intensity, color and basic shape infroamtion)+ pass through optic nerve (6) Crossing at the optic chiasm I. Optic nerves from each eye meet at a point called optic chiasm, where nerve ﬁbers cross over to the opposite side of the brain II. Crossover allows visual information from the right eye go to left hemisphere and vice versa III. Crossing helps brain create a cohesive, three-dimensional image from the information gathered (7) Visual processing in the thalamus I. Signals reach lateral geniculate nucleus (LGN) in the thalamus II. Thalamus organizes and transmits the visual information to the visual cortex (8) Interpretation in the visual cortex Visual cortex processes and interprets signals, recognizing shapes, color, depth, and motion, combining them to from an image (9) Understanding and perception Once brain has processed visual infroamtion, it combines it with memory and context from other brain areas, helping us recognize objects, faces, text and the context of what we are seeing 3. What are receptive ﬁelds and how do they work? (deﬁne “on” and “o,” ﬁelds) Groups of photoreceptors that send input to a particular bipolar cell or retinal ganglion cell+ Speciﬁc area on retina or vision ﬁelds On-Center Receptive Fields: When light shines on the center of an on-center cell´s receptive ﬁeld, it increases the cell´s ﬁring rate, signaling the presence of light. If light instead shines on the surrounding area (periphery), it suppresses the cell´s activity. Optimal for detecting light spots against darker backgrounds O,-Center Receptive Fields: When light strikes the periphery of an oE-center cell´s receptive ﬁeld, it increases the cell´s ﬁring rate, while light in the center reduces it. Optimal for dark spots against lighter background. ð On and oE center ﬁelds work together to help the visual system detect contrast and edges in a visual scene ð By having cell tuned to both increases and decreases inn light, the eye is highly sensitive to diEerences in brightens, which aids to recognizing shapes, patterns and texture ð Helps ﬁlter out unimportant information 4. Deﬁne the functions of the di,erent parts (Ganglion cells, bipolar cells, receptors, etc) Bipolar Cells: Organize visual information by diEerentiating between light and dark contrast (on and oE response) Receive signals from rods and cones, process these signals before transmitting them to the ganglion cells Ganglion Cells: Final output neurons of retina Receive processed information from bipolar cells and reﬁne it by detecting patterns like edges, motion, and contrast Generate action potentials and transmit these signals through their axons(which form the optic nerve) 5. Explain the di,erence between direct and indirect pathway Refers to routes through which visual information ﬂows from photoreceptors to ganglion cells Direct Pathway: Straight route from photoreceptors to bipolar cells and then to ganglion cells Minimal detours and fewer synaptic connections Advantages: Clear, high-resolution vision Particularly eEective for tasks that require focus (i.e. reading or recognizing faces) Indirect Pathway: Involves additional retinal cells called horizontal cells and amacrine cells (1) Photoreceptors send signal to bipolar cells, but horizontal cells modify these signally by integrating input from surrounding photoreceptors. Then input goes to bipolar cell ð Creates a center-surround structure that enhances contrast and helps detect edges (2) Amacrine cells further process and reﬁne the signals, adding aspects like motion detection and contrast adjustments, before relaying them to ganglion cells More common in periphery of retina, where rods dominate Advantages: Help in identifying contrast, movement, and edges Allows for a broader, more generalized view of the environment Crucial for detecting objects and motion 6. What properties in our eyes can lead to optical illusions? Afterimage and Photoreceptor adaption Afterimages occur when photoreceptors become fatigued after staring at a stimulus for a prolonged period, causing an image in complementary colors to appear when looking away For example: staring at a bright color like red and then looking at a neutral backround can lead to seeing the color green Vision II LG1) What is LGN and what happens there? located in thalamus Receives informaion form the optic tract Sends information via the optic radiations to the primary visual cortex (V1) Function: § Regulation of information ﬂow : signal is smaller after passing the LGN § Feedback processing: LGN receives more signal from the cortex than it does from the retina. This suggests that feedback from the brain plays a role in shaping the information that the LGN sends to the cortex. § Maintaining receptive ﬁelds: neurons in the LGN have concentric receptive ﬁelds. (ON-Cell) -> suggests that the LGN is important for detecting contrast and edges in the visual scene. § Color processing: The LGN is organized into six layers. The four outer layers are called parvocellular layers, and contain P Ganglion Cells. The two inner layers are called magnocellular layers and contain M Ganglion Cells. Magnocellular layers receive input from large ganglion cells which do not discriminate between wavelengths of light and are not involved in color vision. Parvocellular layers receive input from cones, which are sensitive to diOerent wavelengths of light. P Ganglion Cells can discriminate between wavelengths, and some exhibit spectral opponency, meaning they are excited by some wavelengths and inhibited by others. -> Basis for color perception feature M Ganglion Cell P Ganglion Cell Cell size Large Small Input Source Rods (and broader Cones (specific cone types) photoreceptor input) Temporal Resolution High (motion detection) Low Spatial Resolution Low (less detail) High (fine detail) Color Sensitivity No (achromatic) Yes (color vision) Pathway Magnocellular layer of LGN Parvocellular layer of LGN Role Motion, flicker, large pattern Detail, color, fine spatial analysis § Relaying information between eyes and brain: essential for vision, as it ensures that information from the eyes is processed correctly and eOiciently LG2) What happens in the ﬁrst picture Monocular zone = zone that is only visible by one eye, more limited input Binocular Zone = zone that is visible for both eyes (were the monocular zones overlap -> 3D vision) 1) The light form the zones hit the eye and retina and from there on go through the optic nerve/tract, which consits of the axons oft he ganglion cells located in the retina 2) At the optic chiasm the optic nerves meet : - Retina is divided into nasal hemiretina (closer to nose) and the temporal hemiretina (closer to temple) - At optic chiasm, axons from nasal hemiretinas cross over to the opposite side oft he brain (contralateral = opposite side) – the temporal hemiretinas remain on the same side (Ipsilateral = same side) 3) Lateral Geniculate Nucleus: The optic tracts carry visual information to the LGN in the thalamus. The LGN has six distinct layers: - Layers 1 and 2 (Magnocellular pathway) process motion and broad outlines, primarily detecting movement and contrast. - Layers 3 to 6 (Parvocellular pathway) process ﬁner details, including color and texture 4) Visual Cortex: The signals are transferred from the LGN tot he primary visual cortex (V1) in the occipital lobe, where the information gets further porcessed - Magnocellular pathway (blue lines) contributes to processing motion and spatial relationships. - Parvocellular pathway (red lines) contributes to fine detail and color perception. LG3)How is the primary visual cortex organized? Retinotopic map = point-to-point correspondence between locations on the retina and locations in V1 I.e. if a light shines on a particular point on the retina, neuro

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