17Su11Lec7

17Su11Lec7 - CS17 Neurobiology of Cognition Summer 2011...

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CS17 Neurobiology of Cognition Summer 2011 Lecture 7: Sleep STAGES OF WAKEFULLNESS / SLEEP Electro-Encephalogram ( EEG ) used to characterize brain activity during different states of wakefulness/sleep - Gross average of the electrical potentials of the neurons in a general area of the brain (mostly Neocortex) - Electrodes attached to scalp record Frequency (average amplitude) - Simultaneous changes in potential (negative graphed above zero axis, positive below) summate such that. .. - Neural de-synchrony => High Frequency (w/variable Voltage) waves = Multiple sources of stimulation: “many pebbles” - Neural synchrony => Low Frequency , High Voltage waves = Coherent source of stimulation: “one big rock” Awake, active => Beta Activity = 18-24 Hz, Very high frequency - very desynchronized Awake, relaxed => Alpha Activity = 8-12 Hz, Like above, but somewhat lower frequency, somewhat desynchronized Sleep 1 => Theta Activity = 4-7 Hz, Lower freq , still quite irregular, significantly more synchronized Sleep 2 => Mostly Theta Activity, but with many interspersed Spindles and K Complexes - Spindle and K Complex = intermittent bursts of high freq or voltage, as brain settles into deeper sleep Sleep 3 => Delta Activity = < 4 Hz observed in less than 50% of this stage, Very low freq , higher voltage , very synchronized Sleep 4 => Delta Activity, in more than 50% of this stage, hardest to wake Stages 3 and 4 = Slow Wave Sleep (SWS) - SO, as move into deeper sleep, freq decreases as brain activity becomes synchronized - Heart rate and breathing rate also decrease, and brain is less responsive to external stimuli REM ( Rapid Eye Movement ) or Paradoxical Sleep because of contradictory set of conditions that occur: - EEG is desynchronized , High freq (like Sleep 1 or even Awake), Low voltage (only Sleep 1 is lower): Imaginary pebbles?! - Heart rate, breathing rate, blood pressure more variable than in other sleep stages - Eyes move , genitalia active, but postural muscles paralyzed, loss of muscle tonus thru most of body (=
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This note was uploaded on 09/07/2011 for the course COGS 17 taught by Professor Pineda during the Spring '06 term at UCSD.

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17Su11Lec7 - CS17 Neurobiology of Cognition Summer 2011...

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