Sleep and Circadian Rhythms

Question 1

what does an electroencephalogram measure?

Answer 1

the synchronous, electrical activity from large populations in the brain.

Question 2

how is the electrical filed created?

Answer 2

by cellular, ionic movement.

Question 3

where are the electrodes usually placed?

Answer 3

on the scalp.

Question 4

what are the pros of the electroencephalogram?

Answer 4

non-invasive,
easy to administer,
date easily gathered,
and high temporal resolution.

Question 5

what are some cons of the electroencephalogram?

Answer 5

there is low spatial resolution - only cortical activity is detected.

Question 6

what are the basic factors of non-REM sleep?

Answer 6

low neuronal activity,
low metabolic rate,
low brain temp,
heart rate and blood pressure decline.

Question 7

what is stage 1?

Answer 7

drowsiness.

Question 8

what are the basic factors of stage 1?

Answer 8

awakened easily,
eyes move slowly,
eyes slowly roll,
and muscle activity slows.

Question 9

what is the EEG like in stage 1?

Answer 9

characterised by low voltage activity and mixed frequencies.

Question 10

what is stage 2?

Answer 10

light sleep.

Question 11

what are the basic factors of stage 2?

Answer 11

eye movement stops,
body temp. drops,
heart rate slows,

Question 12

what is the EEG like in stage 2?

Answer 12

characterised by a mixture of waves called sleep spindles (at 12 - 14 Hz) and K complexes.

Question 13

what is stage 3?

Answer 13

deep sleep.

Question 14

what are some basic factors associated with stage 3?

Answer 14

sleep walking, night terrors, sleep talking, bed wetting.

Question 15

what is the EEG like in stage 3?

Answer 15

slow delta waves interspersed with small rapid waves.

Question 16

what is stage 4?

Answer 16

very deep sleep.

Question 17

what is a factor of stage 4?

Answer 17

disorientation for several minutes following arousal.

Question 18

what is the EEG like in stage 4?

Answer 18

almost exclusively delta waves,

slow wave activity dominates.

Question 19

what is stage 5 sleep?

Answer 19

REM sleep.

Question 20

what are some factors of REM sleep?

Answer 20

rapid eye movements,
muscles are paralysed,
brain temp and metabolic rate increases.

Question 21

what is the EEG like for stage 5?

Answer 21

low voltage activity,
mimics wakefulness,
increased neural activity.

Question 22

how long is each cycle?

Answer 22

approx. 90 - 110 minutes.

Question 23

what is the diffuse modulatory neurotransmission system?

Answer 23

norepinephrine and serotonin neurons in the brain.

Question 24

what does the diffuse modulatory system control?

Answer 24

rhythmic behaviour in the Thalamus - inhibition of motor neurons.

Question 25

how do we know the brain stem is involved in wakefulness?

Answer 25

lesions to the brain stem can cause sleep and comas, and stimulation of the brain stem causes awakening.

Question 26

sleeping and wakefulness follow what rhythm?

Answer 26

the circadian rhythm - 24 hours.

Question 27

what are some factors of circadian rhythms?

Answer 27

they are endogenous and persist without environmental cues,

they are modulated by external timing cues (zeitgebers) which adapt to the rhythm of the environment.

Question 28

what part of the brain regulates the circadian rhythms?

Answer 28

the suprachiasmatic nucleus and this receives input from retinohypothalamic tract.

Question 29

how do we know the suprachiasmatic tract is involved?

Answer 29

lesioning of this tract dampens down the circadian rhythm of sleep.

Question 30

what does the suprachiasmatic nucleus regulate specifically?

Answer 30

regulates the timing of sleep,

it is not responsible for sleep itself.