PSY 241 Lecture 12

• 28 day menstrual cycle in females
• Mood changes across the seasons (Winter vs. Spring)

Biological rhythms that fluctuate about ever 24 hours

• Sleep/Awake pattern
• Body Temperature
• Growth Hormones
• Stress Hormones

• Yes
• These rhythms are endogenous (generated from within)

No

a slightly longer cycle as a result an individual wakes up later and later

A rhythm that occurs when no stimuli reset or alter the rhythm

Sun light

Stimulus that resets the circadian rhythm

• Light (in land organisms)
• Tidal waves (in sea organisms)
• Exercise
• Noise
• Meals
• Temperature of environment

Region of brain serves as biological clock that maintains circadian rhythms to a 24 hour period

Neurons in the SCN are very active during the day and show low activity during the night.

• Disrupt hormone release and sleep-wake cycles
• Without SNC, you get a free-running rhythm

• Small portion of the optic nerve extends directly from retina to SCN
• Retina input does not come from rods and cones
• Input comes from retinal ganglion cells with melanopsin
• Ganglion cells respond to light

• 175,000 hours in lifteime
• 7,291 days
• 243 months
• 20 years

• Measures electrical activity recorded from electrodes attached to person's scalp
• Measures gross electrical activity of the neocortex or "brain waves"

Records eye movements

Records physiological activity of muscles

• Irregular frequency and smaller amplitude
• Vertex spikes, or sharp waves
• Heart rate slows, muscle tension reduces, eyes move about
• Lasts several minutes
• 

• Defined by waves of 12 to 14 Hz that occur in bursts, called sleep spindles
• K-complexes appear - sharp negative EEG potentials
• 

• Early:
• Continued sleep spindles as in stage 2
• Defined by appearance of large-amplitude, very slwo eaves called delta waves
• Delta waves occurs about once per second

Late: Delta waves present half the time

• Follows SWS
• Active EEG with small-amplitude, high-frequency waves, like an awake person
• Muscle relaxed - paradoxical sleep
• Increased activity of sympathetic nervous system

• Sleep time ranges: 7-8 hours
• 45-50% stage 2, 20% REM sleep
• Cycles last 90-110 minutes
• Cylces early in night have more stage 3 SWS 
• Later cycles have more REM sleep

REM is at higher levels during infancy and decreases through adulthood.

Total daily sleep decreases with age.

Ascending axons to brain, descending axons to spinal cord

• Ascending axons send excitatory projections to hypothalamus, thalamus, basal forebrain, cortex
• Release glutamate
• Damage = coma or hypersomnolence (excessive sleeping)

Descending axons associated with motor control (maintaining muscle tone)

Stimulate and you awaken individuals or increases alertness in awake individuals

• Basal forebrain and brainstem have large groups of cholinergic neurons
• Promote wakefulness and REM sleep
• Participate in learning, memory, cognition
• Ascending projections to cortex and hippocampus
• Basal forebrain contains GABA neurons that inhibit GABA neurons inthe cortex, providing more activity

• Cell bodies in locus coeruleus (LC)
• Ascending projections to cortex
• Stimulate arousal
• Increase NE, increase retention of recent memories and wakefulness
• Neurons silent during sleep

• 15 different receptors
• Cell bodies in Raphe Nuclei (several - dorsal, median, caudal, rostral)
• Ascending projections to cortex
• Promote wakefulness, suppress REM sleep
• Neurons silent during sleep
• Antideppresants increase wakefulness and suppress REM sleep

• Wake-promoting effects
• Give drugs that block dopamine and people get sleepy
• Parkinson's get sleepy
• Ventral tegmental area and substantia nigria cell firing does not respond with sleep and wakefulness

• Produces excitatory effects throughout brain
• Originate from mammillary body (posterior to hypothalamus)
• High during arousal and alertness, silent during sleep
• Antihistamines produce drowsiness if they cross blood-brain barrier

• Peptide synthesize in lateral and posterior hypothalamus
• Projections to mammillary body and locus coeruleus
• Promotes wakefulness and suppress NREM and REM
• Keeps you awake rather than wake you up
• Lack of peptide = narcolepsy (trouble severe sleepiness and cataplexy

• Rhytmic biological event whose period is shorter than circadian
• severeal minutes-several hours
• Ex: Feeding

• Rhythmic biological event whose period is longer than circadian
• Ex: 28-day menstrual cycle

• Energy conservation
• Niche adaption
• Body restoration
• Memory consolidation

• Forebrain system - generates slow-wave sleep
• Brainstem system - activates sleeping forebrain into wakefulness
• Pontine system - triggers REM sleep
• Hypothalamic system - coordinates other 3 brain regions to determine which state we're in

• Intense attacks of sleep that last 5-30 minutes
• Exhibit normal sleep pattern at night but suffer abrupt, overwhelming sleepiness during the day

Hypocretin