biology and behavior ch 12, 15

what is consolidation?

brain forms permanent representation of memory

• memories need to be reconsolidaed after retrieval

  • most vulnerable to changes and suggestions during this time

where does consolidation occur?

hippocampus, prefrontal cortex

• often during sleep when hippocampus is less active

  • over 100 genes increase in activity during sleep

  • napping just 90 mins a day improves consolidation of memories

what neurotransmitters are involved in memory consolidation?

glutamate

• impairs hippocampus

• impaired learning in water maze (rodents)

• consolidation problems in humans

dopamine

• reward neurotransmitter

• increases of dopamine are effective both before and after a learning experience

  • great for acquiring and reinforcing knowledge

what is retrograde amnesia?

loss of information that was learned before the onset of amnesia

what is anterograde amnesia?

inability to learn new information after the onset off amnesia

• damage to hippocampus common

when can both forms of amnesia occur?

both can occur in the same patient

• damage to hippocampys CA1 results in moderate aterograde and minimal retrograde amnesia

• patient henry morison (HM) had his hippocampus removed by a doctor and struggled with past memorie while losing the ability to form new memories

what is the function of the frontal lobe and the prefrontal cortex for memory?

frontal lobe and language

• language knowledge stored near brain speech area, Broca’s area

hippocampus and prefrontal cortex (consolidation and retrieval)

• when hippocampus is less active memories transfer to cortex

  • longest-lasting memories stored in prefrontal cortex

  • prefrontal cortex often used in efforts to retrieve memories

motor cortex

• procedural memory

  • memory of step-by-step actions

what is stored in the temporal lobe?

temporal lobe stores memory of

• objects

• faces

• colors

home of hippocampus and amygdala

• hippocampus: memory consolidation

• amygdala: emotional events in your life

which protein “cleans house” in the brain?

protein phosphatase 1 (PP1)

study on rats

• 2 groups of rats: control vs experimental (inhibit PP1)

• results: mice in which PP1 was inhibited did better on learning and memory tests (finding objects and location)

• distributed practived vs massed practice

what is long-term potentiation (LTP)?

Hebb rule'

• if the axon of a presynaptic neuron is active while the postsynaptic neuron is firing the connection between them will be strengthened

• results in LTP

  • persistent strengthening of the synapse

• opposite can occur from lack of use

  • long-term depression (LTD) occurs when stimulation is insufficient to activate a postsynaptic neuron

can single-celled organisms form memories?

even single-celled organisms can form memories

• most temporary

• typically used to avoid danger

relationship between memory and classical conditioning

• even with the loss of important brain regions (hippocampus) for memory creation and consolidation associative learning via classical conditioning can still occur

what is working memory?

part of the short-term memory

• active processing system that allows manipulation of different types of information to keep it available for current use

what memory does the cerebellum contain?

memory for skills

• as its the hindbrain, which is required for basic functions of the body, damage to this area often results in death

  • patients with neurodegenerative diseases, brain damage, or stroke will still retain memory for skills

know the location of specific memory storage

what is the function of sleep?

unclear

• research has identifiied physiological aspects of sleep but not the reason we need it

what is the restorative hypothesis of sleep?

species with higher metabolic rates typically spend more time in sleep

• ex.: hummingbirds sleep 12 hrs a dayhow does

how does lack of sleep impact performace?

performance deficits show the importance of sleep

• deprivation studies

  • performance declines in shift workers

  • in long-termn deprivation studies, performance declines at night and recovers somewhat during the day

• night-time accidents most prevalent between 12-4am

  • driving accidents peak at 2 am

  • the chernobyl meltdown, the bhopal chemical plant leakage, and the exxon valdez oil spill occur in the early morning hours

traveling eastward across timezones decreases performance

• ex: west coast teams playing in the east won fewer games than east coast times playing in the west

• jet-lag is the most severe traveling from west to east

what is the most adaptive hypothesis of sleep?

the amount of sleep depends on the availability of food and safety considerations

• body size and danger account for 80% variability in sleep time

• ex: predators (lions, bears) and animals that can hide (bats) sleep a lot

• vulnerable animals without shelter (cattle) and those that need to spend hours feeding (elephants) sleep very little

what hormone regulates sleep?

melatonin

• hormone that induces sleep

• released in higher quantities when light is low

• can be inhibited or suppressed by objects that give off light

  • computers, cell phones, TV

how long is the circadian rhythm?

within each 24 hr period

2 circadian rhythms important to sleep

• sleep/wakefulness cycle

• body temperature

interact with ultradian rhythm

• shorter than circadian rhythm and can lead to periods of drowsiness

how does the ultradian rhythm result in the afternoon slump?

afternoon slump

• sleep urge and need begins to increase after lunch time

  • some sleepiness is normal but excessive tiredness could be related to sleeping problems

caused by ultradian rhythm

• variety of other rhythms in body work with circadian rhythm (hormones, alertness)

  • these rhythms are shorter than the circadian rhythm resulting in a dip in the early morning and afternoon hours

    • cant be avoided by skipping lunch

• also appears in primates

• some cultures schedule breaks for this time period

what pathway regulates the circadian rhythm?

increased levels of light suppress melatonin

light pollution impacts circadian rhythm through retinohypothalamic pathway

• begins in the retina

• then projects to the SCN

• SCN then signals pineal gland to secrete melatonin

external light, such as artificial lighting cell phones, computers, TVs, etc, all result in reduced melatonin secretion

what is a zeitgeber?

environmental stimuli that regulate sleep/wake cycle thorugh light cycles

if kept in isolation from a light cycle (undergrounder bunker, cave)

• circadian rhythm changes to 25 hrs a day

• sleep onset starts progressively later

typically include stimuli that keep us on a regular cycle (natural light, work schedules, alarms, etc)

what are the stages of sleep?

brain waves synchronize to following waves

• beta waves (15-30 Hz)

  • awake, alert, REM

• alpha waves (9-14 Hz)

  • relaxed, calm

• theta waves (4-8 Hz)

  • deep relaxation

• delta waves (1-3 Hz)

  • deep sleep (slow-wave sleep)

how does body temperature affect sleep?

stage 3 & 4 - slow-wave sleep (1-3 Hz), deep sleep

• large slow delta waves

• can be encouraged by increased brain temperature

  • use of hair dryer before bed can induce slow wave sleep

• difficult to wake a person in this stage

  • nightmares, sleepwalkig, and bedwetting all common in children during this stage

  • sleep disorders such as night terrors and excessive movement often occur at this stage

what is a good indicator of stage 2 sleep?

stage 2 - deeper sleep

• begins 10 mins after stage 1 sleep begins

• k-complex - sharp large waves that occur once per minute

• sleep spindles - brief bursts (12-14 Hz) that prevent external stimuli from waking sleeper

what is REM sleep?

REM - Rapid Eye Movement

• typically 4-5 cycles a night

• more time spent in REM sleep as night goes on

• lack of sleep will cut off REM sleep and decrease restful feeling

  • studies have shown that we “catch up” or have more REM sleep on days when we sleep more

what is the most self-diagnosed sleep disorder?

insomnia

know the different sleep disorders and the characteristics of each

insomnia (too little sleep)

• inability to sleep or obtain quality sleep

• can shorten the lifespan and may contribute to obesity

• affected by stress, most commmon in people with psychological problems

• persists 1 month or more

sleep apnea (breathing disorder that results in waking)

• a person stops breathing because the throat closes

• results in frequent awakenings during the night

• obesity can be one factor in development of disorder

narcolepsy (sleeping at the wrong time)

• fall asleep almost instantly

• sleep is brief but refreshing

• may also have sleep paralysis

sleep terrors (intense nightmares)

• episodes of screaming, intense fear and moving while still asleep

• not remembered after waking

• occurs durring slow-wave sleep

sleepwalking (getting up and walking while still asleep)

• occurs during slow-wave sleep

• most frequent in childhood

• can be triggered by stress, alcohol and sleep deprivation

• individual may engage in complex behavior while sleepwalking

• vulnerability to sleepwalking is in part geneticm evidenced by family studies

• gene in sleepwalking is associated with the immune system, possible cells important in sleep regulation attacked by own immune cells

REM sleep behavior disorder (intense movement and acting out scenario while sleeping

• physically active during REM sleep

• often injure themselves or bed partners

• often associated with the prescence of neurological disorders

  • parkinson’s diseases or brain stem tumor

sleep-related eating (eating while asleep)

• while asleep will walk and get food to eat

• no awareness

• may have other sleep disorders