click below
click below
Normal Size Small Size show me how
Regulation Behavior
Biological Rhythms
Question | Answer | . |
---|---|---|
Biorythms Terms | •Period •Entrainment •Endogenous •Exogenous •Zeitgeber •Phase shift •Suprachiasmatic Nucleus | . |
Multiple rhythms | •Circadian •Ultradian(freq more than 1X a day) •Infradian (freq less than 1X a day) •Seasonal | . |
Components of Circadian Rhythms | Light > entrainment PWs > Circadian Pacemaker > output PW > Overt Rhythm (feedback to circadian pacemaker) | . |
Circadian Rhythms- Research | Mutant mouse lacking gap junctions in SCN: Impaired circadian rhythms •WT and KO show rhythmic behavior in light-dark conditions, but KO becomes fragmented in dark-dark conditions. | . |
Evidence of Multiple Clocks | Human Subject: Bed-rest episodes (black) and body temp (yellow) were entrained to 24-hr day. In temporal isolation, the two rhythms were synchronized for 35 days and then spontaneously desynchronized. | . |
Biological Clock: Location and Operation | . | . |
Circadian Rhythm in the metabolic activity of the SCN | Greater metabolic activity in SCN during light phase vs dark phase | . |
Hypothalamus: SCN as circadian clock | •lesion the SCN (bilaterally), abolish circadian rhythms •isolate the SCN and activity retains a circadian rhythm •transplant an SCN into an animal without, and circadian rhythms are restored | •transplant a mutated SCN into an animal without any SCN, and abnormal circadian rhythms are induced |
Disorders of Rhythms | •Desynchronization due to mismatch between environmental and endogenous cues: –Zeitgeber treatment –Exogenous melatonin | |
Sleep: defined | •Reduced motor activity •Decreased response to sensory stimulation, and reduced interaction with the environment •Stereotypic postures •Easy reversibility (to distinguish from coma, anesthesia, hibernation) | |
Why sleep | •To keep ourselves out of trouble •To conserve energy •To restore something critical in the brain (i.e. to rest) •To help remember, and to consolidate memories •To help us forget | . |
Sleep EEG | Awake: alpha rhythms - beta rhythms REM: beta rhythms - PGO spikes Stage 1: theta rhythms Stage 2: spindles, k complex Stage 3: delta rhythms Stage 4: delta rhythms | |
Properties of Slow Wave and REM Sleep | NON-REM: Reduced muscle tone; few, slow eye movements, low body temp but regulated, parasympathetic activity, low heart rate/blood pressure | REM:Paralyzed, profound atonia, except REM, middle ear, diagram muscles move,no thermoregulation (body temp drops), Sympathetic activity, highest brain metabolic rate, Penile erections, clitoral engorgement (not dream related) |
Neuroanatomy of Sleep | –ACh and NE appear to modulate the rhythms of the thalamus •Three interacting systems of sleep: –Forebrain system can display SWS –Reticular formation (RAS) in brain stem: activates forebrain system from sleep into wakefulness. | Projects to thalamus, bforebrain, bganglia –Brain Stem (Pons and medulla) •Pontine system: Triggers REM sleep (ACh). Lesions abolish REM-related paralysis or abolish REM entirely |
Transection Studies | 1. Isolated brain shows EEG signs of alterations among SWS,REM and wakefulness 2. Isolated forebrain shows constant SWS and sometimes REM-like atonia 3. Transection behind pons causes alternation btw waking, SWS and REM | |
Serotonergic System | •Serotonin system (and tryptophan, 5-HT precursor) promotes sleep (though some serotonergicneurons are involved in waking states) •However, rapheneurons become inactive during REM stage. | . |
Neurotransmitter Alterations that Affect Sleep and Arousal | *5HT: Raphe nuclei: Increase (Promotes sleep), Decrease (Reduces sleep) *NE: Locus coeruleus :Increase (Promotes waking, inhibits REM sleep), Decrease (Abolishes loss of muscle tone in REM ) | *DA: Basal ganglia : Increase (Arousal), Decrease (Biphasic effects on sleep) *Ach :Basal forebrain: Increase (Induces REM), Decrease (Suppresses REM) |
Classification of Sleep Disorders | •Disorders initiating and maintaining sleep –Ordinary insomnia –Drug related insomnia –Sleep apnea –Psychiatric (depression and early awakening) •Daytime sleepiness –Narcolepsy –Daytime sleepiness secondary to insomnia | •Disorders of sleep -waking schedule –Persistent irregular rhythm –Situational: Jet lag or shift work •Sleep and partial arousal dysfunction –Sleepwalking, enuresis (bedwetting) –Nightmares, night terrors |
. | . | . |
. | . | . |