Sleep and Circadian Rhythms Flashcards
what does an electroencephalogram measure?
the synchronous, electrical activity from large populations in the brain.
how is the electrical filed created?
by cellular, ionic movement.
where are the electrodes usually placed?
on the scalp.
what are the pros of the electroencephalogram?
non-invasive,
easy to administer,
date easily gathered,
and high temporal resolution.
what are some cons of the electroencephalogram?
there is low spatial resolution - only cortical activity is detected.
what are the basic factors of non-REM sleep?
low neuronal activity,
low metabolic rate,
low brain temp,
heart rate and blood pressure decline.
what is stage 1?
drowsiness.
what are the basic factors of stage 1?
awakened easily,
eyes move slowly,
eyes slowly roll,
and muscle activity slows.
what is the EEG like in stage 1?
characterised by low voltage activity and mixed frequencies.
what is stage 2?
light sleep.
what are the basic factors of stage 2?
eye movement stops,
body temp. drops,
heart rate slows,
what is the EEG like in stage 2?
characterised by a mixture of waves called sleep spindles (at 12 - 14 Hz) and K complexes.
what is stage 3?
deep sleep.
what are some basic factors associated with stage 3?
sleep walking, night terrors, sleep talking, bed wetting.
what is the EEG like in stage 3?
slow delta waves interspersed with small rapid waves.
what is stage 4?
very deep sleep.
what is a factor of stage 4?
disorientation for several minutes following arousal.
what is the EEG like in stage 4?
almost exclusively delta waves,
slow wave activity dominates.
what is stage 5 sleep?
REM sleep.
what are some factors of REM sleep?
rapid eye movements,
muscles are paralysed,
brain temp and metabolic rate increases.
what is the EEG like for stage 5?
low voltage activity,
mimics wakefulness,
increased neural activity.
how long is each cycle?
approx. 90 - 110 minutes.
what is the diffuse modulatory neurotransmission system?
norepinephrine and serotonin neurons in the brain.
what does the diffuse modulatory system control?
rhythmic behaviour in the Thalamus - inhibition of motor neurons.
how do we know the brain stem is involved in wakefulness?
lesions to the brain stem can cause sleep and comas, and stimulation of the brain stem causes awakening.
sleeping and wakefulness follow what rhythm?
the circadian rhythm - 24 hours.
what are some factors of circadian rhythms?
they are endogenous and persist without environmental cues,
they are modulated by external timing cues (zeitgebers) which adapt to the rhythm of the environment.
what part of the brain regulates the circadian rhythms?
the suprachiasmatic nucleus and this receives input from retinohypothalamic tract.
how do we know the suprachiasmatic tract is involved?
lesioning of this tract dampens down the circadian rhythm of sleep.
what does the suprachiasmatic nucleus regulate specifically?
regulates the timing of sleep,
it is not responsible for sleep itself.
