NEUR200 Exam 4

circadian rhythm

- 24 hour biological cycle

- influences regulation of sleep

- hypothalamus = circadian clock

suprachiasmatic nucleus (SCN)

- groups of neurons in hypothalamus that regulate sleep-wake cycle

- influenced by light

- controls melatonin release (pituitary gland)

- watched video on hamster getting a different hamster's SCN --> completely changes sleep-wake cycle

reticular formation

arousal

locus coeruleus (LC)

main synthesizer of norepinephrine (arousal)

histamine

- hypothalamus

- must be low to sleep well

- antihistamines make you sleepy

orexin

- hypothalamus

- necessary to stay awake

- people with narcolepsy lack

NREM stage numbers

1, 2, 3, 4

stage 1 sleep

- lasts 5-10 minutes

- theta waves

stage 2 sleep

- brief bursts of higher frequency brain waves

- k-complex: sharp waves, helps to keep you asleep through noise

- sleep spindles: generated in thalamus, more = better sleep

stage 3 and 4 sleep

- slow-wave sleep, high amplitude

- synchronized low frequency delta waves

- memory consolidation

- some dreams

REM sleep (stage 5)

- rapid eye movement

- high frequency beta waves

- dreams

- amount of REM increases as night goes on

insomnia

- chronic problems in getting adequate sleep

- causes: anxiety (adrenaline), tension, depression

narcolepsy

- irresistible onsets of sleep during normal waking periods

- causes: lack of orexin, Huntington's

sleep apnea

- frequent, reflexive gasping for air that awakens a person

- causes: obesity, genetics, hormones, old-age

night terrors

- abrupt awakenings from NREM (stage 2) sleep

- accompanied by intense autonomic arousal and feeling of panic

- common in children

nightmares

anxiety-arousing dreams that lead to awakening

REM behavior disorder

- people who move vigorously during REM, acting out dreams

- causes: GABA deficiency

sleepwalking

motor cortex is awake

lucid dreaming

monitoring areas (frontal lobe) are awake

sleep paralysis

waking up while you still can't move

fatal familial insomnia

- inherited rare disease

- initially looks like insomnia

- causes: large amounts of PrPres --> degeneration of thalamus

- consequences: absence of sleep spindles and k-complexes, deep sleep is reduced, weight loss, hallucinations, seizures, coma, death

differences in sleep among species

- fishes that don't sleep live in caves with no difference between day and night

- humans have changed sleep habits (used to wake up for period of time in night)

- hibernation is analogous to how we sleep to conserve energy

EEG during sleep

- resembles those that occur during learning

- sleep spindles increase after new learning

dorsal pathway

- parietal --> prefrontal = ACTION

ventral pathway

temporal --> prefrontal = PERCEPTION

encoding

- from sensory system --> STM

- using memory to learn something

- visual objects: right prefrontal and right parahippocampal cortex

- concepts/words: left prefrontal and left parahippocampal cortex

consolidation

- STM --> LTM

- be able to talk about things in the future

- medial temporal lobe

- key area = hippocampus and "what" pathway (ventral)

retrieval

- bringing memories to consciousness using working memory

- requires attention (frontal areas)

- retrieval from LTM make memories plastic again and can be updated

explicit memory

- conscious

- episodic and semantic

episodic memory

memory of personal experiences

semantic memory

memory of facts and general knowledge

implicit memory

- unconscious

- priming, procedural, perceptual learning, and classical conditioning

priming

past experiences influences thoughts of responses

procedural memory

memory for how to do skills and tasks thru repetition (hard to consciously change once learned)

perceptual learning

improved perception thru experience

classical conditioning

learning connections between stimuli

neural substrates for memory

- temporal-frontal lobes

- ventral stream

- temporal lobe (hippocampus and rhinal cortex)

neurotransmitters for memory

- acetylcholine

- serotonin

- noradrenaline

spatial memory

- place cells: hippocampus, directions and navigation (rainbow video), neuron fires when in same spot

- grid cells: entorhinal cortex, learning unknown space or room (black dots in grid), mapping the environment

contextual memory

- memory for context surrounding an event

- hippocampus: links everything together

- parahippocampal cortex: processes scenes and places

fear conditioning

- depends on amygdala (fear/anxiety)

- damage to amygdala abolishes emotional memory

- gut feeling like something is wrong but you don't know what (haunted house)

procedural learning

- depends on basal ganglia (habits/skills)

- people with Parkinson's have this impaired

basal ganglia

- includes striatum, globus pallidus, and substantia nigra

- gradual learning of habits (procedural learning)

- reinforcement- based teaching

- early in learning we rely on prefrontal cortex, but with practice the control shifts to basal ganglia (driving a car)

prefrontal cortex

- used when learning new things for the first time before habits are developed

- can be changed more easily than procedural

long-term potentiation

- glutamate receptors: AMPA and NMDA

- AMPA regularly allows sodium ions thru (causes depolarization)

- NMDA can allow sodium and calcium but is blocked by magnesium

- glutamate released --> sodium enters thru AMPA --> large depolarization --> magnesium unblocks NMDA --> sodium and calcium enter thru NMDA --> strengthens synapse

anterograde amnesia

inability to form new memories

retrograde amnesia

loss of memories formed before onset of amnesia

time-dependent amnesia

- type of retrograde amnesia

- lose most recent memories first, childhood memories last

HM patient

- had severe epilepsy --> surgeons removed hippocampus and part of amygdala

- suffered anterograde and retrograde amnesia

- severe impairment of episodic memory (personal events) and LTM

- difficult imagining the future and making plans

- intact STM/working memory, but when distracted info is lost

- intact procedural memory (video games)

attention

narrowing or focusing awareness on specific part of environment

alertness

state of arousal and readiness to respond to stimuli (part of attention)

consciousness

primary level of awareness (yourself and surroundings)

top-down processing

start with expectations/memory --> interpret what you're seeing

bottom-up processing

start with what you see/hear --> brain figures out what it is

alerting network

- function: maintains alertness / readiness to respond

- region: reticular activating system (RAS)

- neurotransmitter: noradrenaline (from locus coeruleus)

- prepares prefrontal and posterior parietal to detect stimuli quickly

orienting network

- function: helps with prioritizing stimuli

- region: parietal and frontal cortex

- neurotransmitter: acetylcholine

- more stimulus-driven (bottom-up)

dorsal attention system

- function: helps you stay focused on a task (goal-directed attention)

- region: frontal eye fields and intraparietal sulcus

- more top-down visuospatial

- right-lateralized (damage = neglect syndrome)

neural synchrony

- neurons fire at same time --> timing makes signals more impactful and easier to transmit

- attentional system increases synchrony which boosts important signals and filters out noise

resting potential

- sodium outside, potassium inside (-70mV)

- inside of neuron is more negative

- sodium-potassium pump moves 3 Na out, 2 K in

- creates electrical gradient that stores energy for AP

action potential

- depolarization: Na enters neuron

- threshold = -55 mV

- at peak: Na channels close, K channels open

- K exits cell --> repolarization restores negativity

refractory period

- neuron cannot immediately fire again

- Na channels closed, K channels open

- AP moves forward, triggers adjacent channels

- no backfiring due to hyperpolarization

all-or-none law

if threshold is reached, full AP fires

myelin sheath

- fatty insulation around axons

- oligodendrocytes (CNS) and Schwann cells (PNS)

EEG

- measures electrical activity in brain

- high temporal (time) resolution

- poor spatial (place) resolution

neuroimaging

- measures brain activity indirectly

- high spatial (place) resolution

- poor temporal (time) resolution

primary motor cortex (M1)

- located in frontal lobe

- responsible for executing voluntary movements

premotor cortex

- located in front of M1

- responsible for planning and organizing movements

somatic nervous system

- part of PNS

- controls voluntary/conscious movement

- acetylcholine

- ex. walking, writing, waving

autonomic nervous system

- part of PNS

- works automatically/unconsciously

- acetylcholine and norepinephrine

- ex. heart rate, digestion, pupil dilation

visual field disorders

- hemianopsia: loss of half of visual field (opposite sides)

- blindsight/cortical blindness: no conscious visual perception but can respond to stimuli unconsciously

- cortical color blindness: cannot perceive color (V4)

object agnosias

- apperceptive: cannot form perception

- associative: can perceive but not identify

other agnosias

- prosopagnosia: face blindness (right FFA)

- alexia: word blindness (left FFA)

simultanagnosia

- cannot perceive more than one object at a time

- damage to dorsal stream or Balint's syndrome

amusia

- impairment in pitch discrimination

- Heschl's gyrus (musicians have larger)

auditory hallucinations

- perception of sound without external stimuli

- caused by spontaneous activity in A1

Wernicke's aphasia

- word deafness

- affects language comprehension

Geschwind syndrome

- temporal-lobe personality

- egocentric, aggressive, pedantic speech

central executive network

- present moment attention

- when central executive more active --> default mode is less active

default mode network

- thinking about past, future, or mind-wandering

- when default mode more active --> central executive is less active

salience network

- most active when behavioral change is needed

- snaps you out of mind-wandering

nonfluent aphasias

• Brocas

• Transcortical motor (TMA) - good repetition

fluent aphasias

• Wernicke

• Transcortical sensory (TSA) - good repitition

• Conduction

  • disconnection between Broca and Wernicke areas

  • can understand and produce language but can’t relay info between

pure aphasias

• agraphia: writing

• alexia: reading

• anarthria: speech production problem

meditation

reduces activity in default mode and increases salience and central executive

dual executive networks

• frontoparietal: active when you first get instructions, adjust strategies

• congulo-opercular: active throughout entire rask, sustained attention