NSC 4354 Exam 4: Complex Brain Functions Review PDF

NSC 4354 Exam 4: Complex Brain Functions Review Review video: https://youtu.be/V3DDjB7x954 Review slides: Cognitive Functions ● Association cortex ○ The association cortex integrates information from multiple modalities - sensory, motor, emotional ○ Parietal association cortex analyzes space, genera...

NSC 4354 Exam 4: Complex Brain Functions Review Review video: https://youtu.be/V3DDjB7x954 Review slides: Cognitive Functions ● Association cortex ○ The association cortex integrates information from multiple modalities - sensory, motor, emotional ○ Parietal association cortex analyzes space, generates attention, and transmits sensory information to the motor system ○ Temporal cortex (hippocampus) organizes declarative memory, also involved in higher-order visual and auditory processing, language ○ Frontal association cortex governs “executive functions” - plans behavior, facilitates working memory, inhibits responses ● (pre-) Frontal cortex ○ Prefrontal cortex = Dorsolateral and orbital frontal cortex ● Phineas Gage ○ In 1848, Mr. phineas Gage’s left frontal lobe was destroyed when a metal rod passed through his head after a freak explosion. ○ First documented personality change due to frontal lobe damage. ○ Before the accident he was described as hard-working, responsible and popular with his coworkers; after the accident he lost all social skills, was impatient, obstinate and unfocused. ● Overview - Functions of PFC ○ Effects of PFC lesions in primates by sub-region ○ Orbital ■ Inability to suppress distracting stimuli ■ Impaired decision making ■ Flattened affect ■ Impairec social behavior ○ Medial ■ Inability to focus attention ■ Apathy, loss of attention to surroundings ○ Dorsolateral ■ Inability to sustain attention ■ Lack of motivation and awareness ■ Deficits in working memory ■ Deficits in (motor) planning (temporal organization of behavior) ● Dorsolateral PFC Executive Functions: ○ Attention ○ Working memory ○ Planning ○ Response inhibition ● “Planning neurons” ○ Delayed response task ■ Monkey watches experimenter place food in 1 or 2 wells ■ Followed by a delay period (screen lowered) ■ Monkey gets one chance to choose well containing food ○ Bilaterally lesion prefrontal cortex ■ Diminished/abolished ability to locate food ○ Neurons in the prefrontal cortex specifically fire to delay response task ○ Maximally active during short delay period ■ As if their firing represented information about the location of the food morself maintained from the presentation part of the trail ○ Same neurons have reduced activity during the motor response ■ Indicates neurons are active in short-term memory and planning, rather than the actual movement itself ● Orbital cells encode reward valence ○ Activity of an OFC neuron in response to different types of reward ■ The monkey first accepts Raisins as a reward and firing during the delay is enhanced ■ When other, “better” rewards (Potato and Cabbage) become available the monkey refuses the Raisin and the cell stops firing during these trials ■ The cell continues firing during “Potato” and “Cabbage” rewarded trials ■ Later, whe the animals accepts Raisins agai, firing returns. ■ The behavioral performance (reaction time) also changes. ● The Pepsi Coke Challenge ○ Subjective preference for Coke vs. Pepsi (expressed as “Coke” selections) activates the orbitofrontal PFC Cortial States Memory ● Memory - types and temporal categories ● ● ● ● ● ● ● ○ Increasing the digital span by practice and the development of associatinal strategies ○ The normal human capacity for remembering relatively meaningless information is surprisingly limited ■ String of 7 to 9 numbers ○ A person’s digit memory span can be increased dramatically with practice Associations: the role of previous knowledge and/or motivation ○ Motivated memory: ■ Hungry subjects scored better on a test of recognition memory (“have you seen this picture before?”) when they had to identify food-related items The case of patient H.M. ○ Henry Molaison (H.M.) underwent bilateral temporal surgery for the treatment of epilepsy in 1953, at age 27 ○ H.M. died in 2008 (age 82) - never again formed another conscious memory ■ Anterograde amnesia ○ Ablations involved hippocampus, parahippocampal gyrus, and amygdala ○ H.M. had severe (complete) deficits in acquiring new declarative memory ■ Episodic (Personal/autobiographical knowledge) ■ Semantic (Facts/knowledge) ○ Old declarative memory (events before the surgery) remained intact ○ However, non-declarative (implicit) memory remained largely intact → Improved/learned performance on a motor task even though he never remembered that he had performed the task before Areas involved in declarative memory - the hippocampus Testing hippocampal function in animals ○ Spatial learning in the Morris water maze - Hippocampus and parahippocampal gyrus are needed to encode and consolidat memories The hippocampus in London taxi drivers ○ Posterior hippocampus appears to be particularly useful in remembering spatial information ○ Larger in London taxi drivers than in age-matched control subjects Conditioned Learning ○ Learning - classical conditioning (Pavlov) (686) ■ Occurs when an innate reflex is modified by associating its normal trigger with an unrelated stimulus; by repeated association, the unrelated stimulus eventually triggers the original response. ○ Learning - operant conditioning (Skinner) (686) ■ Form of learning in which an individual’s behavior is modified by its consequences; the behavior may change in form, frequency, or strength ■ Reinforcement is a consequence that causes behavior to occur more often ■ Punishment is a consequence that causes a behavior to occur less frequently ■ Extinction is caused by the lack of any consequence following a behavior (687) Emotion ● Emotions as a subjective feeling ○ Emotions are expressed via the ‘emotional motor system’: ■ Visceral motor changes ● Involve activation of sympathetic ANS (fight or flight) ■ Somatic motor responses (facial expression) ● Recruited lower motor neurons ■ Subjective “feeling” ● Limbic system, amygdala, cortical regions ● Hypthothalamus: Critical Center for Integration ○ Philip Bard (1928) removed cerebral hemispheres (front half of brain) in cats, which elicited spontaneous rage he termed ‘sham rage’ → No obvious target (705) ■ Cerebral cortex was cut out ○ Altered visceral motor component = increased blood pressure and heart rate, pupil dilation, piloerection of hairs ○ Altered somatic motor component = arched back, extended claws, tail lashing, snarling ○ ‘Sham rage’ only occurred if the hypothalamus was intact ○ No ‘sham rage’ if the hypothalamus was completely removed ○ “Uninhibited hypothalamic discharge” has 3 known causes in humans: ■ Hypothalamic lesions ■ Carbon monoxide poisoning ■ Hypoglycemia (low blood sugar level) ○ The experience of emotion may depend on the cerebral cortex, but the expression of emotion depends on the connection between the hypothalamus and brainstem ○ Duchenne de Boulogne, 1862 ○ Contrive, voluntary smile ■ “Pyramidal smile” → Motor cortex via pyramidal tract ○ Spontaneous, emotional smile ■ “Duchenne smile” → Anterior cingulate via reticular formation ○ The lesion in descending projection from the motor cortex: Difficulty in producing voluntary movement/ smile ● ● ● ● ○ The lesion in the extrapyramidal motor pathway: inability to produce an “emotional” smile The Limbic Lobe ○ 1850s: Paul Broca used the term limbic lobe to refer to the part of the cerebral cortex that forms a rim around the corpus callosum ○ Two prominent components: ■ Cingulate gyrus ■ Parahippocampal gyrus Modern conception of the limbic system (708) ○ The concept of a forebrain circuit has been revised over time to include: ■ Amygdala ■ Parts of the orbital and medial prefrontal cortex ■ Ventral parts of the basal ganglia ■ The mediodorsal nucleus of the thalamus The amygdala (710) ○ The amygdala links cortical sensory regions with the hypothalamus and brainstem ○ There are 3 major functional and anatomical subdivisions: ■ Central (CeA) = connections with hypothalamus and brainstem (expression of emotion) ■ Medial (MeA) = extensive connections with olfacy bulb and cortex ■ Basolateral (BLA) = major connections with orbital/medial prefrontal cortex, associational cortex of anterior temporal lobe (sensory convergence, emotional significance) Fear and the Human Amygdala (713-714) ○ Patient S.M. suffers from a rare condition called Urbach-Wiethe disease ■ Bilateral calcification and atrophy of the anterior-medial temporal lobes, including the amygdala ○ Asked to rate intensity of emotion in photographs ■ Cannot recognize the emotion of fear ○ Patient S.M. encounters with snakes, spiders, haunted house, scary movies = no fear ○ No self reports of fear in daily life over 3 months, all other emotions reported ● Speech and Language ● The major brain areas involved in the comprehension and production of language ○ Linguistic abilities depend on the integrity of several specialized areas located primarily in the association cortices of the left temporal, parietal and frontal lobes ○ The loss of language has such devastating consequences that neurosurgeons make every effort to identify and preserve those cortical areas involved in its comprehension and production ● Language: Wernicke and Broca ● ● ● ● ○ Broca’s area (frontal cortex): Language/speech production ■ Broca’s aphasia: ■ Expressive aphasia; slow, laborious, non-fluent speech ● Patients “know what they want to say, they just cannot get it out” ● Problems with fluency, articulation, word-finding, word repetition, and producing and comprehending complex grammatical sentences, both orally and in writing ● Typically able to comprehend words, and sentences with a simple syntatic structure, but are more or less unable to generate fluent speech ■ Motor planning deficits - Lesions in the left posterior frontal lobe ○ Wernicke’s area: understanding of written and spoken language ■ Wernicke's aphasia: ■ Sensory or receptive aphasia - impairment of language comprehension (written and spoken) ● Speech is phonetically and grammatically normal, but meaningless ● Inability to convert thoughts into words ● Often accompanied by denial of deficit Lateralization of language - Roger Sperry ○ Split brain patients: transection of the corpus callosum and anterior commissure as a treatment for epilepsy ■ Right hand or right visual field (left hemisphere) → Able to name object ■ Left hand or left visual field (right hemisphere) → Problem naming object ○ Stereognosis: the ability to perceive and recognize the form of an object in the absence of visual information ○ Stereognosis (exploration by hand) or brief exposure in one of the visual fields Variability of language representation (left hemisphere) ○ Stimulation of these areas interfered with speech (original studies by Wilder Penfield) ○ Stimulation of these areas interfered with speech production and perception (Numbers are out of 117 patients) ○ Highly variable between subjects! ○ In bilingual subjects areas for the same function may differ across languages Language-related regions of the left hemisphere ○ Language tasks such as listening to words and generating word associations elicit activity in Broca’s and Wernicke’s areas ■ Also activity in primary and association sensory and motor areas ○ Language processing involves many cortical regions in addition to the classic language areas The critical period for language learning ○ Becoming fluent requires linguistic experience relatively early in life ○ Decline in fluency of non-native speakers as a function of age ○ Children can usually learn to speak a 2nd language without accent and with fluent grammar until about age 7-8 ○ After this age, performance gradually declines no matter what the extent of practice or exposure Sleep ● Sleep ○ Sleep is a naturally recurring state characterized by reduced or absent consciousness, relatively suspended activity, and inactivity of all voluntary muscles ○ Occurs in all mammals =, birds, and most reptiles, amphibians, fish ○ Governed by brainstem nuclei with diffuse projections to the brain and spinal cord ■ Brain similarly active during sleep and wake ○ Humans spend roughly ⅓ of their lives, or 7.5 hours per day sleeping ● Measuring sleep ○ Electroencephalography (EEG) = scalp recording of electrical activity. ○ Low spatial resolution = frontal, temporal, central, parietal, and occipital leads ○ Measure the signal of thousands of cells ○ Sleep is a cortical brain state. We see electrical activities slow during sleep. ● Sleep is important, but why? ● Possible functions of sleep ○ Ecological adaptation ■ Hunting/avoiding predators is difficult when relying on vision at night ○ Energy conservation and restoration ■ Sleep deprivation compromises the immune system ■ Glycogen levels fall during the day = replenishing brain glycogen ■ Metabolism decreases during sleep = reduces heat loss in colder night ○ Memory consolidation ■ Increase strength of synaptic connections induced by experiences during waking hours ■ Studies of remembered spatial location in rodents = ensembles of hippocampal neurons activated during a spatial memory task are reactivated during sleep ■ Humans show sleep-dependent improvement in learning ● Whatever the reason - sleep is essential! ○ Experimental rate kept awake = EEG triggers movement of the cage floor ○ The control animal can sleep intermittently (sleeps while the experimental rat is awake and the floor is still) ○ Loss of body weight despite increased food intake ○ Total sleep deprivation in rats leads to death in 3-4 weeks ● Effects of Sleep deprivation ○ Irritability ○ Cognitive Impairment ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ Memory lapses or loss Impaired moral judgment Severe yawning Hallucinations Symptoms similar to ADHD Impaired immune system Risk of diabetes type 2 Increased heart rate variability Risk of heart disease Increased reaction time Decreased accuracy Tremors Aches Other: ■ Growth suppression ■ Risk of obesity ■ Decreased temperature ● Sleep is a Highly Conserved Behavior ○ Sleep = period of physiological inactivity, BUT the brain remains active ○ Predatory animals (humans) typically have a single long period of nocturnal or diurnal sleep ○ Prey maintain vigilance = sleep in short intervals (minutes) ○ Dolphins and seals: ■ Sleep alternates between 2 hemispheres ■ One hemisphere exhibits (EEGs) signs of wakefulness ■ The other hemisphere “sleeps” ● First hour of sleep = non - REM sleep ○ Occurs in 4 stages within the first hour of going to sleep: ■ Stage I: drowsy period; decrease in frequency, slight increase in amplitude of EEG waves ■ Stage II: light sleep; decrease frequency, increase amplitude, intermittent spike clusters ■ Stage III: moderate to deep sleep; decrease frequency, increase amplitude ■ Stage IV: deep sleep; low frequency, high amplitude delta waves ● Rapid eye movement (REM) sleep periods ○ Follows non-REM sleep ● ● ● ● ○ First period of REM sleep lasts about 10 minutes then cycles back through the four non-REM stages ○ Usually about 5 periods of REM sleep/night, each period gets longer as sleep continues ○ EEG recordings of REM sleep are remarkably similar to the awake state Synchronous Activity of Delta Waves = Deep Sleep ○ Alpha and beta waves = wake ○ Theta and delta waves = sleep ○ Brain controls switch between waves ○ Deep sleep is characterized by synchronous activity in pyramidal cortical neurons ○ Synchronization = increased amplitude of EEG waves as in deep sleep delta waves Physiological changes during sleep states ○ A: EEG shows REM sleep increases from 10 min to 50 min in the final cycle; stage 4 non-REM sleep is only present in the first 2 cycles ○ B: Electrooculogram (EOG) shows eye movement in REM; electromyogram (EMG) shows muscle movement at the onset of sleep and just before waking ○ C: Heart rate and respiration slow in non-REM and increase in REM When does dreaming occur? ○ REM sleep is characterized by dreaming = experience not related to corresponding sensory stimuli arising from the present environment of memory and hallucinations ○ Sleepwalking and sleep-talking occur during non-REM sleep; they are not usually accompanied or motivated by dreams ○ About 2 hours each night (both REM and non-REM sleep) ○ Study: wake subjects during REM or non-REM sleep and ask about dreams ○ During REM sleep: elaborate, vivid, emotional (sometimes bizarre and emotional) ○ During non-REM sleep: fewer dreams, more conceptual, less vivid, less emotional, related to everyday activities, and more thought-like (Sigmund Freud’s “day residue”: events and conflicts of the day) Why does dreaming occur? ○ Consolidation of memories ■ Dreams may help consolidate learned tasks, perhaps by further strengthening synaptic changes associated with recent experiences ○ To dispose of unwanted memories ■ Dreams might reflect a mechanism for expunging ‘parasitic’ modes of thought that would otherwise become overly intrusive (as in compulsive thought disorders) ○ Activation synthesis theory: dreams are caused by the random firing of neurons in the cerebral cortex during the REM period. The forebrain then “creates a story” in an attempt to make sense of the nonsensical sensory information → that explains the irrationality of the mind during REM sleep. ○ REM sleep deprivation for as much as 2 weeks has little or no obvious effect on behavior ■ Individuals taking SSRIs have markedly less REM sleep Questions: ● True or False: “Planning neurons” fire at their maximal rate (are most active) during the delay period between a cue presentation and the subsequent behavioral response. ○ True ● True or false: A clinician or behaviorist will only use one behavioral test to determine whether a given function is impaired, as secondary tests would be redundant. ○ False ● Reward activity in the orbitofrontal cortex and the VTA _____. ○ Fire most strongly when the reward is given at first, then shift their activity to fire in anticipation of a reward after learning has occurred. ● Which of the following is not a deficit produced when Phineas Gage lost his prefrontal cortex? ○ Disruption of speech comprehension ○ Damage to the ventromedial prefrontal cortex produced erratic behavior demonstrating that activity in the (ventral) orbitofrontal cortex provides inhibitory control over behavior (impulse control) ● The Wisconsin Card sorting task is designed to test which frontal cortex-dependent cognitive definition ○ Working Memory ● The histological hallmarks of Alzheimer’s disease ○ Amyloid plaques ○ Tau Tangles ● True or False: “Phylogenetic memory” refers to innate behaviors hard-wired into a species behaviors from birth ○ True ● Working memory, short term memory and long-term memory can be subjected to the process of forgetting. ● The phenomenon of improving memory acquisition by applying a set of rules to simplify a complex problem is referred to as _____. ○ Chunking ● Stored declarative memories are spread out throughout the cortex ● The amygdala is most associated with fear ● An individual feeling happiness, but genuinely smiles, their face droops and the emotional context of their facial expression is unclear. Which system is lesioned? ○ The extrapyramidal motor pathways ● Which of the following is not a symptom of Kluver-Bucy Syndrome? ○ Reduce emotional reactions ○ Increased emotional reactions ○ Hyperphagia ○ Hypersexuality ● The specific area of the temporal lobe that is responsible for speech is called Wernicke’s area, and it is usually located in the left hemisphere. ● A patient presents with impaired speech production and sentence repetition. Their comprehension is normal and they can identify and name objects with ease. What temporal lobe structure is likely damaged? ○ Broca’s area ● True or False: Cortical responses to speech sounds in individuals with Autism Spectrum Disorder are both weaker and slower compared to neurotypical patients. ○ True ● True or False: Sign language production and recognition follows the same pattern as verbal language production and recognition ○ True ● Recognition of the emotional content of someone’s verbal communication is performed by language centers in ○ The right hemisphere ● Declarative memory is stored in the cortex ○ The hippocampus is responsible for the generation of declarative memories, but the actual long-term storage is occurring in the cortex.Hippocampus can be destroyed, but stored memories can remain intact because that process is independent of the hippocampus. ● The pairing of a neutral stimulus with an unconditioned stimulus, which leads to the neutral stimulus eliciting the same response as the unconditioned stimulus (becoming a conditioned response) is called ○ Classical conditioning ● The form of memory that includes motor skills and puzzle solving abilities is called ____ ○ Non-declarative memory ● The surgical practice of leukotomoy was used to destroy which part of the brain, resulting in “alleviation” of psychotic symptoms by removing their physical substrate? ○ Frontal cortex ● The area od the cortex, found in the temporal lobe, that is responsible for understanding of language is ○ Wernicke’s area ● The area of the cortex that houses the neurons which are responsive to facial features, or “recognition neurons” is ○ The temporal cortex