Neuroscience Chapter 10

nightmare

A long, frightening dream that awakes the sleeper from REM sleep

circadian rhythm

A pattern of behavioral, biochemical, or physiological fluctuation that has a 24 hour period

biological rhythm

A regular fluctuation in any living process E.g., hormone levels, body temperature, drug sensitivity

most people sleep appreciable less as they age

Sleep in the elderly is characterized by decrease in stage 3 sleep and increase in awakenings sleep less in general as you age

alpha rhythm

a brain potential of 8-12 hertz that occurs during relaxed wakefulness

sleep spindle

a characteristic 14 to 18 hertz wave in the EEG of a person said to be in stage 2 sleep

narcolepsy

a disorder that involves frequent, intense episodes of sleep which last from 5 to 30 minutes and can occur anytime during the usual waking hours

general anesthetics

a drug that renders an individual unconscious (e.g., barbiturates and anesthetic gases) stimulate GABA (A) receptors, same ones involved in generating SWS

melanospin

a photopigment found in those retinal ganglion cells that project to the suprachiasmatic nucleus; in this way, retinal ganglion do not have to rely on traditional photoreceptors (e.g., rods and cones) to learn about light.

hypothalamic system in sleep

a region in the hypothalamus including neurons that use orexin as a neurotransmitter, sends axons to the other three sleep centers and seems to coordinate them, enforcing the patterns of sleep. Loss of orexin can lead to disorganized sleep, such as REM-like muscle atonia while still awake (in narcolepsy)

tuberomammillary nucleus

a region of the basal hypothalamus near the pituitary stalk that plays a role in generating SWS

K complex

a sharp, negative EEG potential that is seen in stage 2 sleep

vertex spike

a sharp-wave EEG pattern that is seen during stage 1 sleep

phase shift

a shift in the activity of a biological rhythm, typically provided by a synchronizing environmental stimulus (e.g., light)

REM behavior disorder

a sleep disorder in which a person physically acts out a dream

sleep apnea

a sleep disorder in which respiration slows or stops periodically, waking the patient. Excessive daytime sleepiness results from frequent nocturnal awakening

locus coeruleus

a small nucleus in the brainstem whose neurons produce norepinephrine and modulate large areas of the forbrain REM production

suprachiasmatic nucleus (SCN)

a small region of the hypothalamus above the optic chiasm that is the location of a circadian clock

stage 2 sleep

a stage of sleep that is defined by bursts of regular 14 to 18 hertz EEG waves called sleep spindles

sleep paralysis

a state, during the transition to or from sleep, in which the ablility to move or talk is temporarily lost

night terror

a sudden arousal from stage 3 sleep that is marked by intense fear and autonomic activation; the sleeper does not recall a vivid dream but may remember a crushing feeling on the chest common in children

basal forebrain

a ventral region in the forebrain that has been implicated in sleep, specifically generation of SWS Neurons in this region become active at sleep onset and release GABA that binds to GABA (A) receptors near the tuberomammillary nucleus in the posterior hypothalamus

rapid eye movement

aka paradoxical sleep (because brain waves look awake, but flaccid muscle state; brainstem regions are profoundly inhibiting motoneurons) A stage of sleep characterized by small-amplitude, fast EEG waves, no postural tension, and rapid eye movement

how does sleep enforce niche adaptaion

almost all animals are diurnal or nocturnal, and this specialization is part of the organism's ecological niche -> unique assortmen of environmental opportunities and challenges to which each organism is adapted * when do I gather food? when do I sleep? do I have good hearing vs good sight? Sleep debt and unpleasant feelings of sleepiness enforce the circadian rhythm characteristic to your species, forcing it to conform to the ecological niche for which it is well adapted

desynchronized EEG

also called beta activity A pattern of EEG activity comprising a mix of many different high frequencies with low amplitude

orexin

also called hypocretin. a neuropeptide produced in the hypothalamus that is involved in switching between sleep states, in narcolepsy, and in the control of appetite

reticular formation

also called reticular activating system extensive region o the brainstem (extending from the medulla through the thalamus) that is involved in arousal projects axons to the forebrain, activating it to promote wakefulness

stage 3 sleep

also called slow wave sleep (SWS) A stage of nonREM sleep that is defined by the presence of large amplitude, slow delta waves

melatonin

an amine hormone that is secreted by the pineal gland at night, thereby signaling day length to the brain

isolated brain

an experimental preparation in which an animal's brainstem has been separated from the spinal cord by a cut below the medulla

isolated forebrain

an experimental preparation in which an animal's nervous system has been cut in the upper midbrain, dividing the forebrain from the brainstem

fatal familial insomnia

an inherited disorder in which humans sleep normally at the beginning of their life but in midlife stop sleeping and 7-24 months later, die. no obvious damage to any single organ system, but suffer from diffuse bacterial infections

sleep enuresis

bed-wetting

sleep state misperception

commonly, a person's perception that he has not been asleep when in fact he has. Typically occurs at the start of a sleep episode

prolonged, total sleep deprivation in mammals

compromises the immune system and leads to death (see fatal familial insomnia)

sudden infant death syndrome (SIDS)

crib death sudden, unexpected death of an apparently healthy human infant who simply stops breathing, usually during sleep

sleep-onset insomnia

difficulty falling asleep

sleep-maintanence insomnia

difficulty staying asleep

unilateral sleep

one hemisphere is asleep at a time Allows -dolphins to come up to the surface to breathe -birds to watch out for predators -birds to fly long distances

activation-synthesis theory

our experiences in REM sleep are the more or less random results of which neurons happen to get activated. the brain strings together these disparate activated elements into a more or less coherent story

how does sleep restore the body and brain

people who lack sleep are at risk for other pathologies and death also, sleep may clean out the brain by allowing glia cells to move the cerebronspinal fluid faster and more efficiently cleaning out the brain

what triggers REM sleep

pontine system near the locus coeruleus is a region that sends widespread projections to promote REM. Axons projecting to the spinal cord profoundly inhibit motorneurons so that they cannot fire, causing deep muscle relaxation (atonia)

free-running

referring to a rhythm of behavior shown by an animal deprived of external cues about time of day

non-REM sleep

sleep, divided into stages 1-3, that is defined by the presence of distinctive EEG activity that differs from that seen in REM sleep

somnambulism

sleep-walking

in which stage is GH secreted primarily

stage 3 sleep (SWS)

stage 1 sleep

the initial stage of non-REM sleep which is characterized by small-amplitude EEG waves of irregular frequency, slow heart rate, and reduced muscle tension

period

the interval of time between two similar points of successive cycles, such as sunset to sunset

sleep deprivation

the partial oar total prevention of sleep

sleep recovery

the process of sleeping more than normally after a period of sleep deprivation, as though in compensation In the first night of sleep recovery, there is a marked increase in stage 3 sleep (at the expense of stage 2)

entrainment

the process of synchronizing a biological rhythm to an environmental stimulus

electroencephalography (EEG)

the recording of gross electrical activity of the brain via large electrodes placed on the scalp

retinohypothalamic pathway

the route by which retinal ganglion cells send their axons to the suprachiasmatic nuclei

delta waves

the slowest type of EEG wave characteristic of stage 3 sleep

zeitgeber

the stimulus (usually the light-dark cycle) that entrains circadian rhythms (e.g., light)

ecological nihe

the uniquw assortment of environmental opportunities to which each organism is adopted

how does sleep conserve energy

we use less energy when we sleep than when we are awake (e.g., SWS has reduced muscle tension, heart rate, blood pressure, temperature, respirations) -> diminished metabolic activity small animals have high metabolic rates and consequently sleep more

mammals sleep more during infancy than during adulthood

* clear cycle of sleeping an waking takes several weeks to establish in human infants, but a 24 hour rhythm is generally established by 16 weeks * Infant sleep characterized by shorter sleep cycles than adults (duh, immaturity of the brain) * infant mammals show large % of REM sleep (e.g., 1/2 of sleep is REM in first 2 weeks) So, they sleep more and sleep more often in REM

different species provide clues about the evolution of sleep

- Nearly all mammals display both REM and SWS sleep - of other vertebrates, only birds display REM and SWS -> either REM was present in common ancestors to humans and birds, or evolved independly in each -absense of REM in dolphins as later adaptations for when mammals took to the sea; because dolphins have to be able to move when they sleep so they can come up to the surface to breathe -adaptation in dolphins: only one side of their brain engages in SWS at a time = UNILATERAL SLEEP

Cells in the mammalian (1)___________ make two proteins: (2)____________ and (3)______________ that bind together to form a (4)___________________. The (5)_______________________ then binds to the cell's DNA to promote the transcription of other genes, including (6)_______________. The proteins made from these other genes go back to (7)______________ the action of (8)_______________ and (9)________________ which started the whole process. Because those (10)_____________ proteins (11)____________ with time, eventually the (12)____________ is lifted, starting the whole cycle over again. The entire cycle takes about (13)___________ hours to complete, and it is this (14)________________________ cycle that drives (15)___________________________..

1. SCN 2. Clock 3. cycle 4. dimer 5. Clock-Cycle dimer 6. Per and Cry 7. inhibit 8. Clock 9. Cycle 10. inhibitory 11. degrade 12. inhibition 13. 24 14. 24 hour molecular 15. 24 hour activity cycle of SCN cells

the four biological functions of sleep

1. energy conservation 2. niche adaptation 3. body and brain restoration 4. memory consolidation

what are the four interactive neural systems underlying sleep

1. forebrain system that generates SWS 2. brainstem system that activates sleeping forebrain into wakefulness 3. pontine system that triggers REM sleep 4. hypothalamic system that coordinates other three brain regions to determine which state were in

Chapter 10 opening: Barry

Big surges of emotion seemed to trigger sudden paralysis lasting anywhere from seconds to minutes -> made social life a lot more difficult (jokes, playing, sex) -> connection to problems with the brain and sleep

describe the research that led to the discovery of the forebrain's role in SWS

Bremer transected the brain at one of two levels: between the spinal cord and medulla (isolated brain) or between the midbrain and the forebrain (isolated forebrain) Transection of the lower brainstem exhibits signs of alternating between wakefulness, SWS, and REM -> systems controlling sleep are found in the brain Transection og the brainstem at the midbrain produces isolated forebrain which exhibits constant SWS -> forebrain system promotes SWS and brainstem systems promote wakefulness and REM sleep

Properties of REM sleep and Non REM sleep: SKELETAL MUSCULAR SYSTEM -postural tension -knee-jerk reflex -twitches -eye movement

REM -eliminated -suppressed -increased -rapid, coordinated non REM -progressively reduced -normal -reduced -infrequent, slow, uncoordinated

Properties of REM sleep and Non REM sleep: AUTONOMIC ACTIVITIES -heart rate -respiration -brain temperature -cerebral blood flow

REM -variable, w high bursts -variable, w high bursts -increased -high non REM -slow decline -slow decline -decreased -reduced

dreams during REM vs nonREM

REM - characerized by visual imagery; more apt to include a story that involves odd perceptions and the sense that the person is there experiencing it nonREM - thinking type; thinking about problems

Properties of REM sleep and Non REM sleep: NEURAL FIRING RATES -cerebral cortex activity

REM - increased firing rates nonREM - many cells reduced

Properties of REM sleep and Non REM sleep: COGNITIVE STATE -Dream state

REM - vivid dreams, well organized non REM - vague thoughts

how does sleep aid in memory consolidation

REM sleep improves performance on tests that involve learning perceptual skills

describe research that led to our understanding of the SCN's role as a biological clock

Ralph and Menaker The SCN of male hamsters with the genetic mutation tau (which leads to a shorter than 24 hr free-running period) was transplanted into another male hamster whose own SCN had been lesioned. Hamsters receiving the transplant ended up with a free-running period similar to the donor...not their own. The only case of transplanting brain tissue from one individual to another in which the recipient displays donor's behavior! Conclusion: Within the SCN itself there must be a mechanism that can drive a circadian rhythm in activity, and this biological clock is affected by mutation of the gene tau.

infraradian

Referring to a rhythmic biological event with a period longer than a day e.g., menstrual cycle, breeding, depression

ultradian

Referring to a rhythmic biological event with a period shorter than a day. Usually from several minutes to several hours long e.g., bouts of activity, feeding, and hormone release

cataplexy

sudden loss of muscle tone, leading to collapse of the body without loss of consciousness; sometimes is a component of narcoleptic attacks