What is the Regular Activating System (RAS)? (DBSEC)
- determines level of alertness
- brain stem, thalamic relay station
- sensory nerve pathways meet, talk to relay neurons which talk to cortex
- excites relay neurons
- coordinates sleep/wake cycle
What are the pons? (CRC)
- connect 2 sides of cerebellum, controls autonomic function
- REM motor paralysis/atonia
- continue functioning smooth muscle: diaphragm, intestines/stomach
What is the Superchiasmatic Nucleus (SCN)? (LSIP)
- location of “biological clock”
- synchronise w/ light-dark cycles of environment
- influences endocrine system
- promotes wakefulness
What are biochemical “players”? (AAGGHML)
Acetylcholine: NT during low-voltage & high frequency EEG (waking & REM)
Adenosine: builds up when awake, abated w/ caffeine
Glutamate: excitatory NT, helps produce slow waves & spindles
Glyine: inhibitory NT, spinal cord
- assists in paralysis during REM
Histamine: hypothalamus, produce wake state
Melatonin:
- mildly sleep producing, speed sleep onset - stays high until wakening - light blocks production
Leptin: hormone
- elevates during sleep - reduces appetite, hunger - converse w/ ghrelin
What is electroencephalogram (EEG)? (EUMEMV)
measurement of surface brainwaves: manifestation of bioelectric activity
What is electrooculargram (EOG)? (ETERP)
electrical activity measured when eyes move under closed eyelids
What is electromyogram (EMG)? (ERGM)
measures electrical activity from continuous contraction of muscle fibers
What is relaxed wakefulness in terms of recordings?
- EEG:
- beta waves: irregular, sharp peaks & valleys
- close eyes = start of alpha waves
- EOG: quick movement; eyes closed - slow-rolling begins
- EMG: highest amplitude
What are N1 characteristics?
- EEG: theta waves, some alpha
- EOG: slow-rolling/pendular, possibly binocularly asynchronous, large movements
- EMG: reducing, some body movements
- sleep onset: retrograde amnesia, sleep starts/hypnic jerks
What are N2 characteristics?
- EEG: “mid-amplitude”, sleep spindles, K complexes
- EOG: none
- EMG: reduced, w/ some phasic activity
What are N3 characteristics?
- EEG: delta waves, K complexes
- EOG: none
- EMG: very few movements, phasic
What are REM characteristics?
- EEG: similar to wake, saw tooth waves
- EOG: rapid, sporadic movement, mirror-image recording with quiet periods
- EMG: low, paralysis of voluntary muscles, “twitching” phasic bursts
What is sleep latency?
time it takes from bedtime to sleep onset (MSLT)
- increase/strong sleep tendency = short/decreased sleep latency
What is the biological clock?
consists of controls & timing mechanisms that maintain daily 24hr oscillations
- interaction based on transcription-translation feedback loops of “clock genes” & their protein products
What is the opponent process model?
interaction of sleep homeostasis & clock-dependent alerting to produce sleep/wakefulness cycle
