lecture 23: sleep

Question 1

mearuing sleep

Answer 1

EEG: record brain wave activity
EMG:record muscle activity
EOG: record eye movements

Question 2

electrooculogram

Answer 2

records eye movements

measures dipole activity- front (+) vs back (-) of eyeball

Question 3

waking state (beta)

Answer 3

EEG: beta waves, small amplitude waves with fast frequency
EMG: muscle tone, contract to some degree
EOG: eyes move

Question 4

waking state (alpha)

Answer 4

larger amplitude and slower waves
awake but relaxed, with eyes closed
generated around occipital cortex

Question 5

N1 sleep (drowsy state: sleep onset)

Answer 5

EEG: mixed waveforms, some slower (theta)
EMG: muscles have tone
EOG: eye rolling

Question 6

N2 sleep (asleep)

Answer 6

EEG: stable theta waves with sleep spindles and K-complexes
EMG: muscles have tone
EOG: not moving

Question 7

N3 sleep (deep sleep)

Answer 7

difficult to arouse, groggy, quick return to sleep
EEG: delta waves: large amplitude slow waves
EMG: muscles have tone
EOG: not moving

Question 8

R sleep (REM)

Answer 8

EEG: same as waking, beta waves
EMG: muscles have no tone (atonia)
EOG: rapidly moving

Question 9

how long do these cycles last

Answer 9

several sleep state changes in roughly 90 min periods
NREM dominates early, REM domintates later
- adults who sleep 8 hours spend 2 hours with REM
- infants spend half time in REM

Question 10

dreaming

Answer 10

vivid dreams occur during REM, NREM are less vivid

• get longer throughout a sleep session
• a number of times each night, most people forget

Question 11

psychoanalytic theories on what we dream about

Answer 11

sigmund freud: dreams are symbolic fulfillment of unconscious wishes
manifest content: loosely connected, latent: true meaning
Carl jung: dreams are expressions of collective unconscious

Question 12

what do we dream about

Answer 12

most dreams related to recent events and ongonig problems
- 64% associate with negative emotion
18% associate with positive emotion

Question 13

bottom up

Answer 13

dreams as meaningless brain activity:
activation synthesis –> cortex bombarded with signals from brainstem producing pattern of waking EEG so generates images, actions and emotions
fragmented without external verification, frontal activation is suppressed which suppresses memory/attention

Question 14

top down: dreams as coping strategy

Answer 14

coping hypothesis: dreams highly organized and biased toward threatening images, important because lead to enhanced performance in dealing with life events

Question 15

what does sleep accomplish

Answer 15

3 possibilities: biological adaptation, restorative process, memory mechanism
- sleep is not passive process

Question 16

sleep as a biological adaptation

Answer 16

energy conserving strategy: gather food at optimal times and sleep to conserve energy

• animals with nutrient rich diet spend less time foraging for food and more time sleeping
• predatory animals sleep more than prey

Question 17

exceptions to sleep as a biological adaptation

Answer 17

opossums: herbivores but sleep excessively

may have specialized energy conservation

Question 18

sleep as a restorative process

Answer 18

we are tired at the end of day but feel refreshed with suffecient sleep
- chemical events that provide energy to cells may be reduced during waking and replenished during sleep

Question 19

sleep deprivation studies

Answer 19

no lasting physiological effects (up to 18 days)
- decreases cognitive performance that require attention
microsleep is a confounding factor

Question 20

REM sleep deprivation

Answer 20

wake up subjects when they enter REM sleep

• increased tendency to enter REM sleep
• REM rebound: spend more time in REM in first available session

Question 21

3 phases of memory storage

Answer 21

1. encoding (labile): new memory encoded, fragile and easily lost
   consolidation: relatibely permanent representation of memory solidifed
   recall: neural networks that represent memory area ctivated for use
   - sleep solidifies and organizes memory

Question 22

3 theories of sleep and memory storage

Answer 22

multiple process: different memories stored in different sleep states ex. facts in N sleep, motor in R sleep
Sequential process: memory manipulated in different ways during different sleep states, refined in N sleep stored in R
storage process: brain regions handle different kinds of memory during waking continue to do so during sleep

Question 23

NREM and explicit memory consoldiation

Answer 23

recordings from 100 place cells in 3 conditions: NREM, food search, NREM after food search
- NREM sleep after food search correlated activity of place cells

Question 24

REM and implicit memory consolidation

Answer 24

PET imaging to record brain activity while performing serial reaction time task
- sleep imaging revealed brain regions active during task are active during REM
therefore subjects may be dreaming about what they learned, REM sleep strenghtens memory