neurophysiological psychology chapter eight

endogenous circannual rhythm

an internal calendar that prepares a species for annual seasonal changes

endogenous circadian rhythm

internal rhythms that last about a day (ex: wakefulness + sleepiness)

circadian rhythms are also present in?

eating, drinking, urination, secretion of hormones, sensitivity to drugs, + other variables

body temperature fluctuates between?

98.6 degrees F at night and 98.96 degrees F in late afternoon

zeitgeber

stimulus that’s necessary for resetting circadian rhythm

*light is dominant stim for land animals

_____ _______ are hearty and robust and very resistant to environmental stressors/influences.

biological clocks

jet lag

disruption of biological rhythms due to crossing time zones

*helps to keep room light when you need to stay awake

phase delay

happens w circadian rhythm when travel west; stay awake late + awaken next day partly adjusted to new schedule

phase-advance

happens w/ circadian rhythm when travel east; sleep + awaken earlier than usual

Recent studies have shown that repeated adjustments of circadian rhythm can?

increase levels of cortisol which can damage hippocampus + cause memory loss

One’s natural circadian rhythm predisposes them to be either ___ (early risers) or _____ (evening people). This rhythm may change w/ ___.

larks; owls; age

suprachiasmatic nucleus

nucleus located above optic chiasm in hypothalamus; controls rhythms for sleep + temperature

*its neurons generate impulses that follow a circadian rhythm (generate 24-hr rhythms by themselves)

how light resets the SCN

SCN is reset by retinohypothalamic path that extends directly from retina to SCN

retinohypothalamic path

small branch of optic nerve

how does the SCN regulate sleeping and waking?

by controlling the pineal gland which releases melatonin

pineal gland

endocrine gland that resembles a pine cone; controlled by SCN + releases hormone melatonin

melatonin

SE-derived hormone released by pineal gland that increases sleepiness (modulates sleep patterns); stimulates receptors in SCN to reset biological clock

*release usually starts 2-3 hrs before bedtime

sleep

state that the brain actively produces, characterized by decreased response to stimuli

coma

extended period of unconsciousness caused by head trauma, stroke, or disease; characterized by low brain activity throughout the day + little or no response to stimuli — including pain

vegetative state

person alternates between periods of sleep + moderate arousal, although they show no awareness of their surroundings

minimally conscious state

person shows occasional, brief periods of purposeful actions + limited speech comprehension

brain death

no sign brain activity + no response to stimulation

*physicians usually wait 24 hrs before pronouncing death

electroencephalograph EEG

records gross electrical potentials in an area of the brain through electrodes attached to scalp

polysomnograph

combination of EEG + eye-movement records

alpha waves

have a frequency of abt 8-12 brain waves / sec and these waves are typical of relaxed state of consciousness

stages of sleep

stage 1

• light sleep noted by presence of irregular, jagged, low-voltage waves

stage 2

• characterized by sleep spindles + k-complexes

stages 3 and 4

• known as slow-wave sleep SWS

• comprised of slow, large amplitude waves

k-complexes

sharp, high-amplitude waves followed by a smaller, positive wave

sleep spindles

burst of 12-14 Hz waves that last approx 0.5 sec

paradoxical sleep is synonymous w?

REM sleep

paradoxical sleep

sleep stage discovered in cats where brain is active but muscles are completely relaxed

*deep sleep in some ways while light sleep in others (thus the paradox)

REM sleep

repeated eye movements associated w/ paradoxical sleep + characterized by fast low-voltage brain waves, plus breathing + HR similar to stage 1 sleep

*rapid eye movement sleep

**many animal species lack eye movements

NREM sleep

stages of sleep other than REM

order of stages of sleep? what changes throughout the night?

order: stage 1 »» stage 2 »» stage 3 »» stage 4 »» stage 3 »» stage 2 »» REM

*cycle repeats w/ each complete cycle lasting 90 min

early in night: stages 3 and 4 predominate

toward morning: stage 4 grows shorter + REM grows longer

what type of sleep is associated w/ dreaming?

• REM is often associated w/ dreaming

• but dreams can happen in NREM sleep

reticular formation

structure that extends from medulla into forebrain; only one of several systems involved in arousal

*lesions here decrease arousal

pontomesencephalon

part of reticular formation that contributes to cortical arousal; stimulation here awakens sleeping individual or increases alertness in someone already awake

locus coeruleus

structure in pons thats inactive most times but emits impulses + releases NE in response to meaningful events

*imp for storing information + is usually silent during sleep

hypothalamus

• certain areas

  • stimulate arousal by releasing NT histamine

• axons of lateral nucleus of hypothalamus

  • release peptide NT orexin

histamine

NT that produces excitatory effects throughout brain

antihistamine

drugs that produce drowsiness if they cross BBB

orexin

peptide NT thats necessary for staying awake; also called hypocretin

basal forebrain

area anterior + dorsal to hypothalamus; some of its axons release GABA + are essential for sleep (these neurons receive input from anterior + preoptic areas of hypothalamus) while another set of axons release ACh

During sleep, ____ ____ and _____ ___ decrease slightly.

body temperature; metabolic rate

sleep depends on?

GABA mediated inhibition; while spontaneously active neurons continue to fire at normal rate, we are unconscious bc GABA inhibits synaptic activity

how is sleepwalking possible?

• sleep can be localized

• possible bc sleepwalker is awake in one part of brain + asleep in another part

brain function in REM sleep

• activity increases in pons, limbic system, parietal + temporal cortex of brain

• activity decreases in primary visual cortex, motor cortex, DLPFC

• REM sleep depends on SE + ACh activity for its onset + continuation

NE, SE, ACh and REM sleep

SE - interrupts or shortens REM

ACh - stimulation of ACh synapses quickly moves sleeper into REM

NE - from locus coeruleus also blocks REM sleep

insomnia

can be caused by: noise, uncomfortable temps, stress, pain, diet, meds, psychiatric + neurological d/os, shifts in circadian rhythm

phase delayed vs phase advanced insomnia

• phase delayed - shift in rhythm where someone has trouble falling asleep at usual time

• phase advanced - shift in rhythm where someone falls asleep easily but awakens early

sleep apnea

inability to breath during sleep, sx include sleepiness during day, impaired attention, depression, some heart problems, headaches

causes: genetics, hormones, obesity

*ppl w/ SA have many brain areas that appear to have lost neurons

**increased risk in overweight males

narcolepsy

sx include gradual or sudden attacks of sleepiness, occasional cataplexy, sleep paralysis, hypnagogic hallucination; ppl w narc lack the hypothalamic cells that produce + release orexin

*each sx of narc is interpreted as REM sleep intruding into wakefulness

**tx w/ stimulant drugs (eg methylphenidate - Ritalin)

periodic limb movement disorder

repeated involuntary movements of the legs + arms that can cause insomnia

*limb movements occur mostly during NREM sleep

*often tx w/ tranquilizers

REM behavior disorder

disorder where ppl move around vigorously during their REM periods apparently acting out their dreams

*likely due to the inability of the pons to inhibit spinal motor neurons

night terrors

an abrupt, anxious awakening from NREM sleep (1st few hrs of sleep)

*more common children than adults

sleepwalking

usually occurs during stages 3 or 4 early in the night; usually runs in families + is more common when ppl are sleep deprived or under unusual stress

*more common in children than adults

**also NREM sleep

Everyone dreams ____ times a night — during REM sleep dreams are?

several; vivid, emotional, bizarre