NEUR200 Exam 4

Circadian rhythms

Exposure of light readjusts people’s biological clocks by affecting the activity of the hypothalamus

Hypothalamus: Suprachiasmatic Nucleus

Maintains circadian rhythms, makes adjustments to the circadian clock through the retinohypothalamic pathway, controls release of melatonin in pineal gland

Brain structures for arousal

Locus coeruleus (pons) and hypothalamus

Histamine

Promotes wakefulness and alertness (hypothalamus)

Orexin

Necessary to stay awake, inhibition causes rats to fall asleep quickly (hypothalamus)

Sleep stage 1

Lasts 5-10 minutes, EEG theta waves, low amplitude/high frequency

Sleep stage 2

Brief bursts of high frequency waves, includes K-complex and sleep spindles

K-complex

Sharp waves, temporal inhibition of neuronal firing

Sleep spindles

High frequency waves, more sleep spindles better learning, generated in the thalamus

Sleep stages 3 and 4

Deep/slow wave sleep, delta waves (high amplitude/low frequency), synchronization of low-waves, reduction of sensory input

Sleep stage 5 (REM)

High frequency beta waves, vivid dreams

Insomnia

Chronic problems in getting sleep

Narcolepsy

Sleep during normal waking periods, lacks hypothalamic cells that produce orexin (Huntington’s)

Sleep apnea

Frequent, reflexive gasping for air that awakens a person (obesity, genetics)

Night terrors

Abrupt awakenings from NREM sleep accompanied by intense autonomic arousal and feelings of panic

Nightmares

Anxiety around dreams that lead to awakening

Sleep as a local phenomenon

One part of the brain has good inhibition (GABA)

Sleep walking

Motor cortex isn’t fully sleeping, not properly inhibited

REM Behavior disorder

People acting out their dreams during REM (GABA deficiency)

Lucid dreaming

Frontal lobe/monitoring areas are awake

Sleep paralysis

Waking up while you cannot move

Fatal familial insomnia

Degeneration of thalamus (PrP converts to PrPres), absence of sleep spindles and k-complexes, constant stage 2

Sleep and memory

Memories that are more important will be consolidated better during sleep

Working memory (short term memory)

Dorsal enables vision for action, ventral enables vision for perception, from the parietal cortex and temporal lobe to different prefrontal cortical regions

Processes in STM and LTM: Encoding

From sensory system to STM, visual objects - right prefrontal cortex and right parahippocampal cortex, words - left prefrontal cortex and parahippocampal cortex

Processes in STM and LTM: Consolidation

Into LTM, bringing what you learn for the first time and consolidating it, medial temporal lobe (hippocampus), what pathway

Processes in STM and LTM: Retrieval

Bringing things from the past to the present, working memory, frontal lobe (attention)

Explicit memory

Conscious

Episodic memory (Explicit)

Memory for specific events (birthday party)

Semantic memory (Explicit)

General knowledge, not tied to any time or place (knowing basic math)

Neural substrate for Explicit memory

Temporal frontal lobe, what stream, temporal lobe (hippocampus and rhinal cortex), acetylcholine, serotonin, noradrenaline

Hippocampus and explicit (episodic) memory

Cares about where you are when you learn things, spatial memory (morris water maze)

Hippocampus and place cells

In relation to navigation (spatial map), fires only when an animal is in a particular area of its environment (taxi drivers have more developed hippocampus)

Grid cells

Found in nearby entorhinal cortex, navigation, fires at regular intervals to form a hexagonal grid, parahippocampal gyrus

Implicit memory

Revealed by indirect tests

Procedural/muscle memory (implicit)

Knowing how (skills)

Priming memory (implicit)

Changes in perception and beliefs caused by previous experience (yellow with banana)

Perceptual learning (implicit)

Calibration of perceptual systems as a result of experience (recognizing specific perfume)

Classical conditioning (implicit)

Learning about associations among stimuli (Pavlov)

Fear conditioning (amygdala)

Damage abolishes emotional memory (fear) but has little effect on other types of implicit or explicit memory

Procedural learning (basal ganglia)

Striatum, Globus Pallidus, Substantia Nigra, gradual learning through trial and error, less flexible

Prefrontal cortex

More flexible in learning

Attention

Narrowing awareness selectively to a part of the sensory environment or to a class of stimuli

Consciousness

Is synonymous at a primary level with awareness and at a secondary level with awareness of awareness

Alerting network

Reticular activating system (RAS) → Locus coeruleus (noradrenaline) → acts to prepare regions (alertness), especially in prefrontal and posterior and parietal cortex, for detecting stimuli rapidly

Orienting network

Acetylcholine, prioritizes sensory input

Dorsal attention system

Top-down visuospatial, right-lateralized (neglect syndrome)

Default mode network

Thinking about one’s past, thinking about the future, or mind wandering

Salience network

Most active when a behavioral change is needed, if the salience network is not functioning properly, the default network shows excessive activity