Big Study Guide - Cognitive Neuroscience PDF

- **[Chapter 1: Introduction to Cognitive Neuroscience]** - Cognitive neuroscience is concerned with how the brain processes information - Brain is powerful because of **emergent properties** -- the complex functions are due to interacting simple parts - Considers human behavior,...

- **[Chapter 1: Introduction to Cognitive Neuroscience]** - Cognitive neuroscience is concerned with how the brain processes information - Brain is powerful because of **emergent properties** -- the complex functions are due to interacting simple parts - Considers human behavior, perception, and decision making, as well as the biological bases of these behaviors - Neuroscience is only possible because of innovative research methods - **Connectional Methods** examine functional connections from neurons to specific brain regions - Some involve the injecting of a **tracer** **substances**, which are taken into tracts of neurons, producing a map of inputs and outputs - Brain regions must be removed to be observed - - **Diffusion Tensor Imaging (DTI)** tracks diffusion of water molecules in living tissue - Connection fibers (axons) tend to bundle together in tracts, which water molecules travel along -  - **Correlational Research Methods** observe brain activity in real time with individual behaviors - **Invasive measures** involve direct implantation of **microelectrodes, microdialysis probes**, or **voltammetry probes** into brain tissue - **Positron Emission Tomography (PET)** uses radioactively labeled compounds to map distribution of a chemical of interest in the brain - **Magnetic Resonance Imaging (MRI)** uses magnetic pulses instead of radiation - **Functional Magnetic Resonance Imaging (fMRI)** maps blood flow and oxygenation in the brain - Note: Correlation ≠ Causation - **Lesion Methods** examine impaired brain function due to damage (traumatic injuries, strokes, tumors) - **Paul Broca**'s patient -- Ability to speak was impaired but not language comprehension - Lesion of **Broca's area** -- brain region involved in language production - Lesions rarely only neatly impact one specific brain structure - Can be difficult to pinpoint which specific brain structure produces the observed deficiency - **Stimulation Methods** examine the effects of stimulating certain brain regions on cognition and behavior - **Transcranial Magnetic Stimulation (TMS)** generates focused magnetic field pulses to activate neurons in a specific brain region - **Transcranial Direct Current Stimulation (tDCS)** utilizes two electrodes that go through the scalp - **Cathode** -- Positively charged, inhibitory - **Anode** -- Negatively charged, excitatory - IJERPH \| Free Full-Text \| Could tDCS Be a Potential Performance-Enhancing Tool for Acute Neurocognitive Modulation in eSports? A Perspective Review - It important to be aware of our brain's **biases** when performing research - **Anchoring Bias** -- We are most easily influenced by our first observations/encounters - **Confirmation Bias** -- We seek out information that is consistent with our preexisting beliefs - **Availability Heuristic** -- Equating frequency of an event based on how easily or recently it came to mind - **Affect Heuristic** -- Making decisions based on emotion rather than logic - **[Chapter 2: The Brain and Nervous System]** - The nervous system of some lower-level organisms (jellyfish, sea anemones) consists of a **nerve net** which coordinates movement and feeding - Characteristic of organisms with a top and bottom but no front, back, left, or right (**radial symmetry**) - Humans have **bilateral symmetry** as a dual-segmented animal - Segmented organisms have more control requirements, necessitating a more complex nervous system - Local centralized network in each body segment (responds to sensory input from outside world) - Longitudinal transmission of information up and down body segments - The Nervous System at a Glance -  - Some Definitions to keep in mind moving forward: - **Afferent Neurons** bring sensory information from sensory organs to the brain - **Efferent Neurons** carry signals from the brain to the peripheral nervous system to initiate an action - The **Peripheral Nervous System** consists of the nerves that branch out from the brain and spinal cord to **effector** organs of the body - Further divided into **Somatic Nervous System** and **Autonomic Nervous System** - Somatic Nervous System processes information from external stimuli - Autonomic nervous system coordinates activity of internal organs and is further divided into: - **Sympathetic Nervous System**: "Fight or Flight" responses -- feeding, fighting. Fleeing, sexual activity - **Parasympathetic Nervous System**: "Rest or regenerate" responses -- relaxation of muscles, directs blood flow to digestive system - The somatic nervous system has somatic afferent **sensory** neurons for input (from skin, muscles, joints) and efferent **motor neurons** for output - The autonomic nervous system has visceral afferent sensory neurons for input (from internal organs) and visceral efferent neurons for output - A diagram of a human brain Description automatically generated - The **Central Nervous System** consists of the brain and spinal cord - The segments of the spinal cord consist of **gray matter** and **white matter** - Gray matter handles sensory and motor information of local neuron connections - White matter indicates presence of **myelin**, necessary for communication with distant neurons (more on this in Chapter 3) - Sensory information from the PNS is relayed to the CNS via sensory afferent neurons in the spinal cord - Information from afferent and efferent neurons are connected by **circuits** - **Reflex Arc** is a circuit activated by an excitatory signal from sensory neurons, which in turn activates a motor neuron - **"Knee-jerk" reflex** operates by this mechanism - Patellar reflex - Wikipedia - Terminology for anatomical directions when examining the brain -  - **Rostral** -- towards the head - **Caudal** -- towards the tail - **Dorsal** -- Posterior - **Ventral** -- Anterior - The **Brainstem** is the most posterior region of the brain, which links the spinal cord and **cerebellum** - Further divided into: - **Medulla --** breathing, heart rate, blood pressure - **Pons --** bridge of tracts of white matter connecting to cerebellum, responsible for arousal, sleep, breathing, swallowing, bladder control, eye movement, facial expressions, hearing, equilibrium, and posture - **Midbrain** -- appetitive behaviors, agnostic behaviors, reproductive behaviors - The medulla and pons form the **hindbrain** - The midbrain also coordinates activities in the **forebrain** - **Reticular Formation** regulates states of consciousness - **Locus Coeruleus** sends alerting signals with the neurotransmitter **norepinephrine** - **Substantia nigra** is the main source of **dopamine** which plays key roles in movement, cognition, motivation, and reward. - **The midbrain raphe nuclei a**re the main source of the neurotransmitter serotonin. Serotonin has diverse functions in mood, sleep, and social behavior. - The cerebellum contains more neurons than both hemispheres of the cerebrum and is mainly involved with smooth, efficient movement and balance - Inputs from the brainstem are connected to interneurons of the **cerebellar cortex** - Operates via **forward model** of upcoming movements -- outgoing motor commands are based on predictions - The neurons of the **hypothalamus** are responsible for maintaining **homeostasis** - Basic drives -- Hunger, thirst, sexual arousal, temperature regulation, sleep - Functions are regulated via **homeostatic set points** - Deviations from set point triggers autonomic responses, endocrine responses, or behavioral responses - Master control gland of the **neuroendocrine system**, sending control signals for hormone signaling via the **pituitary gland** - The **thalamus** acts as the brain's relay station to the **cerebral cortex** - Synchronization of neuron activity between regions from other motor control structures and between areas of the cerebral cortex itself - Regulates attention, awareness, and consciousness via stimulation of the **reticular nucleus** - Neurons here are all inhibitory - The **Cerebral Cortex** is important for "higher mental functions" - The **central sulcus** divides the "front" and "back" of the cerebral cortex - Front is responsible for motor planning and action - **Precentral gyrus** contains **primary motor cortex** - **Prefrontal cortex** is involved in cognition and goal planning - **Orbitofrontal cortex** enables us to set priorities - Back of central sulcus is involved in sensory processing - **Postcentral gyrus** houses the **primary somatosensory cortex** which handles sensory input from skin, muscles, and joints - **Posterior parietal lobe** is involved in attention - **Occipital lobe** processes visual stimuli - **Temporal lobe** processes auditory information - The **corpus callosum** bridges the two hemispheres of the brain - The **Basal ganglia** consist of gray matter structures - Limb movement, eye movement, planning/goal setting - A diagram of the brain Description automatically generated - The **Limbic System** is central to motivation and emotion - Made up of hypothalamus, midbrain, brain stem, **amygdala,** and **hippocampus** - Amygdala is responsible for fear response (and emotions) through autonomic and hormonal mechanisms - Hippocampus is involved in memory and learning - **[Chapter 3: Neurons & Synapses]** - [NOTE: The material in this outline is covered in a different order than the PowerPoint and textbook, but contains all the same topics ] - The neuron is the fundamental unit (cell) of the nervous system - Neurons receive information from other neurons via chemical signals (neurotransmitters) and they send out information via electrical signals (**action potentials**) - **Dendrites** extend from the cell body and contain receptive regions for chemical signals from other neurons - Upon **excitation** (more on this later), an electrical signal travels down the **axon** of the neuron towards the **axon terminals**, where neurotransmitters reside - The gaps between two communicating neurons are called **synapses** -  - **Glial cells** play a supportive role in the nervous system - **Oligodendrocytes** are responsible for **myelination** (more on this later) - **Schwann cells** perform this function in the PNS - **Astrocytes** repairs injuries and maintains chemical balance outside the neuron - **Microglia** form the nervous system's immune defense system - Neuronal communication is triggered via an action potential, which occurs on an all-or-nothing basis - Involves movement of **ions** (charged particles) across the neuronal cell membrane - Affects overall charge of the cell - Voltage changes caused by signals from other neurons influences the overall charge of the cell membrane - **Inhibitory post synaptic potentials** (IPSPs) make the resting potential more negative, making it harder to reach action potential threshold - **Excitatory post synaptic potentials** (EPSPs) make the resting potential more positive, making it easier to reach action potential threshold - At rest (**resting potential**) the inside of the cell is more negative than the outside (-70 mV) - Na^+^ ions are more abundant outside the cell and K^+^ ions are more prominent inside the cell - When a threshold is crossed (-60 mV), sodium **voltage-gated ion channels** open, causing Na^+^ ions to rush into the cell, making the cell more positive - This is called **depolarization** - Rapid increase of overall charge causes opening of potassium voltage-gated ion channels, and K^+^ ions leave the cell, resulting in **repolarization** - As cell rapidly becomes negative, **hyperpolarization** occurs, as channels remain open for potential to reach a charge more negative than resting level - A **refractory period** follows an action potential, making voltage-gated Na^+^ channels less likely to open - Ensures neurons are not constantly activated - A screenshot of a game Description automatically generated - The action potential travels down the whole length of the axon due to **myelin sheath**, which function similarly to insulation on a wire - Made up of lipids, hence why white matter indicates presence of myelin - Gaps between myelin sheath are called **nodes of ranvier** - Necessary to keep signal flow unidirectional - Contain sodium voltage-gated ion channels which propagate depolarization as the signal travels down the axon - Myelination \| BioNinja - When an action potential reaches the axon hillock, calcium voltage-gated ion channels open, causing a calcium influx into the cell - **Vesicles** containing neurotransmitters fuse to the **presynaptic membrane** upon calcium activation - Neurotransmitters are released into the **synaptic cleft** (the space between the presynaptic cell \[sending the signal\] and the postsynaptic cell \[receiving the signal\]) - Neurotransmitters then bind to receptor on the postsynaptic cell, causing either EPSPs or IPSPs -  - IPSPs and EPSPs are summed to influence the overall effect on the charge of the neuronal cell body - **Temporal summation** -- signals that arrive at the soma at the same time are combined - **Spatial summation** -- signals from different dendrite branches converge at the soma and are combined - Neurotransmitters only bind for a short period of time and are removed via three mechanisms: - **Degradation** via enzymes - **Diffusion** out of the synapse via a concentration gradient - **Reuptake** into the original cell - **[Chapter 8: Attention and Consciousness]** - Awareness requires attention - Consider illusions and magic tricks -- **change blindness** - Large changes in visual scenes go unnoticed when there is a brief visual interruption - **Inattentional blindness** -- Subjects fail to notice an obvious stimulus because attention is focused elsewhere - Implications for multitasking (think texting and driving) - 37% decrease in parietal lobe activity (visual attention) during distracted driving - Shift in activity to different areas of brain - Attention cannot be directly measured, so different research paradigms test a *correlate* to attention - **Example: Orienting paradigm** -- A subject is oriented to a central object while a target stimulus appears on either side of the center object, subject is then tasked with pressing a button as quickly as possible once stimulus is perceived - Test of reaction time - **Cueing** has shown benefits for reaction time - Allows us to study **top-down mechanisms** (attention is deliberately focused) and **bottom-up mechanisms** (attention jumps to salient unexpected features of the environment) - figure\_08\_07.jpg - **Hemineglect** is caused by damage to the parietal and temporal lobes of the right hemisphere or medial motor regions and results in deficits in attention to one side of space (typically the right side) - Primary sensory cortices are activated but activation is not spread -  - **Attention deficit hyperactivity disorder (ADHD)** is an impairment of selective attention - Abnormal function of the pre-frontal cortex, which is involved in selective attention - **Stroop effect** tests are a measure of selective attention - Neurons of the **midbrain reticular activating system** fire up arousal levels via ascending circuitry - Firing slows down during sleep and is frequent when awake - Interacts with **intralaminar nuclei** of the thalamus - Deep brain stimulation of the intralaminar nuclei is a potential treatment to restore consciousness - Theories of Consciousness - Descartes: **Mind-Body dualism** - **Functional theories of consciousness** -- Mental states depend on function rather than "hardware" - **Higher-order theory of consciousness** -- conscious perception requires a lower-order representation, a higher-order representation, and a functional link to connect the two - **Integrated information theory of consciousness** -- consciousness is informative and highly integrated - **[Chapter 9: Memory]** - **Donald Hebb's** hypothesis of experience-dependent plasticity (memory as synaptic change) - Connection between two neurons is strengthened with repeated stimulation - Leads to **long-term potentiation (LTP)** - Dependent on order of activity as well, changes in presynaptic cell must happen first - A diagram of synapse and synapse connection Description automatically generated - **Glutamate** (an excitatory neurotransmitter) acts on **NMDA receptors** during LTP - In normal stimulation, only non-NMDA receptors (called AMPA receptors) open - High frequency repeated stimulation depolarizes the postsynaptic membrane potential, causing magnesium plugs to be removed from NMDA receptors - Calcium ions then flow through the open channel and induces a second-messenger system that leads to long-term structural changes (synaptic changes) - Long-term depression occurs when the post-synaptic cell does not respond to repeated weak input - For an overview of this process watch the video on p. 292 of the online textbook - Alternatively, - **Working memory** draws on short-term or long-term storage to address immediate situations - **The phonological loop**: repeating something in your head to remember it - **Visuospatial sketchpad** -- retaining a visual image - Limited information-holding capacity - **Long-term memory** are capable of encoding, storing, and retrieving information over longer periods of time - **Implicit memory** -- encodes information that is not consciously recalled - Unconscious motor memories (think riding a bike or emotional memories) - **Classical conditioning** -- conditioned stimulus is paired with unconditioned stimulus to bring about a (conditioned) response -  - **Operant conditioning** -- rewards encourage a behavior and punishment dicourages a behavior - Operant Conditioning: What It Is, How It Works, and Examples - **Nonassociative learning** refers to long-term changes in reflex pathways - **Habituation** -- adapting to repeated exposure of the same stimulus - **Sensitization** -- response to a stimulus increases following exposure - **Explicit memory** is consciously recalled - **Episodic memory --** memories of specific autobiographical events - **Semantic memory** -- factual information -  - The anterior parts of the **hippocampus** are responsible for object recognition memory, while the posterior parts are for spatial memory - Lesions of the hippocampus impair recollection and **prospection, imagination** - **Confabulation** -- creation of alternate versions of the past and acting in congruence with this confabulated past - Can be **provoked** (when prompted for more details than can be remembered) or **spontaneous** (without external cues) - Occur following damage to medial orbitofrontal and prefrontal cortex, as well as damage to dorsomedial thalamus or hypothalamus - Errors/confabulations in memory are common in healthy individuals as well - **Misattribution** -- When we attribute a memory to the wrong source - **Suggestibility** -- False memories implanted by information we hear after an event (do you remember your first words, or do you only know them because your parents told you) - **Bias** -- Current knowledge distorts past knowledge - **[Chapter 13: Emotions]** - **Emotions** have survival value as a means of communication, their role in cognitive functions, and overall mental health and wellness - Basic emotions do not depend on learning or memory (emotional expression in infants) - The **James-Lange theory of emotion** states that physiological reactions in the body produce emotions - Think **fight-or-flight responses** - Bottom-up theory -- stimuli are detected by the peripheral nervous system and interpreted by the higher areas of the central nervous system - The **Cannon-Bard theory** suggests that sensory information relayed through the thalamus splits into two pathways - Information to the cortex triggers emotion - Information to the hypothalamus produces emotional responses within the body - figure\_13\_04.jpg - **Two-factor theories** view emotions as combination of top-down and bottom-up processes - Physiologic stimuli and cognitive context interact to produce emotional states - Demonstrated by the **Schachter-Singer theory of emotion** - Saline or epinephrine injection controls for physiology - The mannerism of the actor manipulated situational context -  - The hypothalamus can influence the internal state via: - Autonomic output simulating the sympathetic and parasympathetic nervous systems - Neuroendocrine pathways and hormone levels - Motivational pathways to the forebrain - The amygdala is sensitive to the facial expressions in others - Output pathway leads to somatic and autonomic nuclei in the brainstem - Influences hypothalamic nuclei for hormone secretion - Influences cortex and evaluation, motivation, and behavioral control - Damage to bilateral amygdala causes difficulties in learning and expressing fear, as well as difficulties determining sense of personal space - The spatial and episodic memory functions of the hippocampus are interrelated - Emotional valence of a location coupled with map of physical space - figure\_13\_19.jpg - The **ventral striatum** is involved in pleasure and reward - Rat studies -- electrodes implanted into septal area of rat produced a rewarding effect when stimulated - Limbic regions of the cortex generate and modulate emotional states - **Interoceptive insula** produces bodily sensations associated with emotion states - The **ventromedial prefrontal cortex** is responsible for our "gut feeling" - **Iowa gambling task** implications -- patients with damage to VMPC continue to draw from riskier deck - **Serotonin** plays an important role in regulating mood - When deficient in tryptophan (serotonin precursor), people have a negative mood bias - **Selective serotonin reuptake inhibitors (SSRIs)** are commonly used to treat depression - Effects of increasing **norepinephrine** are similar to increasing serotonin - **GABA**, an inhibitory neurotransmitter decreases excitability and anxiety