Brain and Behavior - Wakefulness and Sleep

Flashcards about wakefulness, sleep, and brain activity.

What is the approximate cycle length of circadian rhythms?

Approximately 24 hours

What is a free-running rhythm?

A rhythm that occurs without external stimuli

What is a zeitgeber?

Any stimulus that resets the circadian rhythms, such as light, meals, or temperature

What is the retinohypothalamic pathway?

A small branch of the optic nerve that feeds into the suprachiasmatic nucleus (SCN)

What is the main function of the Suprachiasmatic Nucleus (SCN)?

Master pacemaker of circadian rhythms

Where is the SCN (Suprachiasmatic Nucleus) located?

Hypothalamus

What photopigment do photosensitive ganglion cells contain?

Melanopsin

What hormone does the pineal gland produce in response to darkness?

Melatonin

How does the SCN control the sleep cycle?

Regulates the pineal gland, which secretes melatonin

What is the precursor to melatonin?

5-HT (derived from tryptophan)

What is a polysomnograph?

A combination of EEG and eye-movement records

What type of brain activity is associated with irregular, jagged, and low voltage waves?

Distributed activity or slow-wave sleep

What type of brain activity is associated with Synchronized activity?

slow & large amplitude waves

What brain waves are present at the start of relaxation?

Alpha waves (steady ≈ 8-12/sec)

Slow Wave Sleep

EEG = slow, large amplitude waves; Highly synchronized neuronal activity; ↓in heart & breathing rate.

Describe REM sleep

Rapid eye movement; paradoxical sleep. EEG = irregular, low-voltage, and fast waves. Pons-geniculate-occipital (PGO) waves. Pons activates brain areas and inhibits large muscles; dreaming