PSYCH261 Chapter Notes - Chapter 9: Genetic Disorder, Amay, Oxidative Stress

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!"#$%&'()(*(+,&&$(#-.(/01,1203#,(4"5%"67(
8(9"5701,1203#,(#-.(/&"#:01;'#,(<&73'0$%01-(1=(+,&&$(
! Sleep&is&behaviour;&it&is&not&distinguished&by&movement&
+%#2&7(1=(+,&&$(
!&best&research&on&human&sleep&is&conducted&in&a&sleep&laboratory&&
+,&&$&,#>1'#%1'5!&experimenter&prepares&the&sleeper&for&electrophysiological&measurements&by&
attaching&electrodes&to&the&scalp&to&monitor&the&electroencephalogram&(EEG)&and&to&the&chin&to&monitor&
muscle&activity,&recorded&as&the&Electromyogram&(EMG)&
?,&3%'16512'#6(@?ABC(!&An&electrical&potential&recorded&from&an&electrode&placed&on&or&in&a&muscle.&
?,&3%'1D13;,12'#6(@?EB(D&An&electrical&potential&from&the&eyes,&recorded&by&means&of&electrodes&placed&
on&the&skin&around&them;&detects&eye&movement.&
! During&the&wakefulness&the&EEG&of&a&normal&person&shows&two&basic&patterns&of&activity:&alpha&
activity&and&beta&activity.&&
8,$"#(#3%0:0%5&!&Smooth&electrical&activity&of&8!12&Hz&recorded&from&the&brain;&generally&associated&with&
a&state&of&relaxation.&When&person&is&not&excited&or&aroused.&Although&alpha&waves&sometimes&occur&
when&a&person’s&eyes&are&open,&they&are&much&more&prevalent&when&they&are&closed.&
/&%#(#3%0:0%5(D&Irregular&electrical&activity&of&13!30&Hz&recorded&from&the&brain;&generally&associated&with&
a&state&of&arousal.&Beta&activity&shows&desynchrony;&it&reflects&the&fact&that&many&different&neural&circuits&
in&the&brain&are&actively&processing&info.&Desynchronized&activity&occurs&when&a&person&is&alert&and&
attentive&to&events&in&the&environment&or&is&thinking&actively.&&
&
+%#2&7(1=(+,&&$(
+%#2&(FC&G"&%#(#3%0:0%5!&EEG&activity&of&3.5!7.5&Hz&that&occurs&intermittently&during&early&stages&of&slow&
wave&sleep&and&REM&sleep!&indicates&firing&of&neurons&in&the&neocortex&is&becoming&more&synchronized.&
(this&stage&is&a&transition&between&sleep&and&wakefulness).&&
+%#2&(HC&About&10&minutes&later&enter&this&sleep&stage.&The&EEG&is&generally&irregular&but&contains&
periods&of&theta&activity,&sleep&spindles&and&Kcomplexes.&&
+,&&$(7$0-.,&7:&are&short&bursts&of&waves&of&12!14&Hz&that&occur&between&2&and&5&times&a&minute&
during&stages&1!4&of&sleep.&&They&play&role&in&memory&and&increased&sleep&spindles&are&correlated&
with&increased&scores&on&test&of&intelligence.&&
I(316$,&J&7:&sudden&sharp&waveforms,&which,&unlike&sleep&spindles,&are&usually&found&only&
during&stage&2&sleep.&At&the&rate&of&approx&one&per&minute&but&often&can&be&triggered&by&
noisesespecially&unexpected&noises.&
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! K&complexes&appear&to&be&the&forerunner&of&delta&waves,&which&appear&in&the&deepest&levels&of&
sleep.&
+%#2&(KC(<&,%#(#3%0:0%5!&Regular,&synchronous&electrical&activity&of&less&than&4&Hz&recorded&from&the&
brain;&occurs&during&the&deepest&stages&of&slow!wave&sleep.&About&15&minutes&later&the&subject&enters&
stage&of&sleep,&signaled&by&the&occurrence&of&high!amplitude.&&&
! The&distinction&between&stage&3&and&4&is&not&clear!cut,!stage&3&contains&20!50%&delta&activity,&
and&stage!4&contains&more&than&50%&
+,1LDL#:&(7,&&$!&+%#2&(K(#-.(M&of&Non!REM&sleep,&characterized&by&synchronized&EEG&activity&during&
its&deeper&stages.&
! The&most&important&feature&of&slow!wave&activity&during&sleep&is&slow&oscillations&of&less&than&
1Hz.&Each&oscillation&consists&of&a&single&high!amplitude&biphasic&wave&of&slightly&less&than&1Hz.&&
First!Part!of!the!Wave:&.1L-(7%#%&!a&period&of&inhibition&during&a&slow&oscillation&during&slow&wave&
sleep;&neurons&in&the&neocortex&are&silent&and&resting.&
Second!Part!of!the!Wave:(;$(7%#%&!&a&period&of&excitation&during&a&slow&oscillation&during&slow!wave&
sleep;&neurons&in&the&neocortex&briefly&fire&at&a&high&rate.&
! Each&oscillation&consists&of&an&inhibitory&hyperpolarizing&silent&phase&(.1L-(7%#%&)&followed&by&
an&excitatory&depolarizing&phase&during&which&the&neuron&fires&at&a&high&rate&(;$(7%#%&).&
! 45&minutes&after&the&onset&of&Stage&4&sleep&we&notice&an&abrupt&change&in&number&of&
physiological&measures&recorded&from&our&subject.&&
! The&EEG&suddenly&becomes&mostly&desynchronized,&with&a&sprinkling&of&theta&waves,&similar&to&
Stage&1.&
! Eyes&rapidly&dart&back&and&forth&beneath&closed&eyelids.&&
! Person&actually&becomes&paralyzed&during&REM&sleep.&
4?A(+,&&$!&A&period&of&desynchronized&EEG&activity&during&sleep,&at&which&time&dreaming,&rapid&eye&
movements,&and&muscular&paralysis&occur;&also&called&paradoxical&sleep.&
! Stage&4&is&the&deepest&stage&of&sleep;&when&awakened&person&acts&confused.&&
! During&REM&sleep&a&person&might&not&react&to&noises,&but&he&or&she&is&easily&aroused&by&
meaningful&stimuli,&such&as&sound&of&his&or&her&name.&&When&awaked&from&REM&sleep&person&
appears&alert&or&attentive.&&
! During&the&rest&of&the&night&our&subjects&sleep&alternates&between&periods&of&REM&and&nonREM&
Sleep&
N1-4?A(7,&&$!&All&stages&of&sleep&except&REM&sleep.&&
! Each&cycle&is&about&90&minutes&long;&contain&about&20!30&minute&of&REM&sleep.&&
! 8!hour&sleep&will&contain&4!5&periods&of&REM&sleep.&&
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! Most&slow&wave&sleep&(stage&3&and&4)&occurs&during&the&first&half&of&night.&
! During&REM&sleep&cerebral&blood&flow&and&oxygen&consumption&are&accelerated.&
A&-%#,(83%0:0%5(<;'0-2(+,&&$(
! When&experimenters&wake&sleeping&subjects,&the&reports&that&the&subjects&give&make&it&clear&
that&they&were&conscious&while&sleeping.&
! Researchers&have&found&that&the&rate&of&cerebral&blood&flow&in&the&human&brain&during&REM&
sleep&is&high&in&the&visual&association&cortex&but&low&in&the&primary&visual&cortex&and&the&
prefrontal&cortex.&&
! The&lack&of&activity&in&the&primary&visual&cortex&reflects&the&fact&that&the&eyes&are&not&receiving&
visual&input;&the&high&level&of&activity&in&the&visual&association&cortex&undoubtedly&reflects&the&
visual&hallucinations&that&occur&during&dreams.&&
! Dreams&are&characterized&by&good&visual&images&but&are&poorly&organized&with&respect&to&time;&
for&e.g.&past,&present&and&future&are&often&interchanged.&
! Evidence&indicates&that&the&particular&brain&mechanisms&that&become&active&during&a&dream&are&
those&that&would&become&active&if&the&events&in&the&dream&were&actually&occurring.&E.g.&cortical&
and&subcortical&motor&mechanisms&become&active&during&a&dream&that&contains&movement&as&if&
the&person&were&actually&moving.&
! Mental&activity&can&also&accompany&slow&wave&sleep.&Some&of&the&most&terrifying&nightmares&
occur&during&slow!wave&sleep,&especially&stage&4&Sleep.&
&
<071'.&'7(1=(+,&&$(
! Spend&1/3&of&our&lives&sleeping,&sleep&disorders&can&have&a&significant&impact&on&our&quality&of&
life&
O-716-0#(
! Affects&about&25%&of&the&population&occasionally&and&9&%&regularly.&
! Characterized&as&difficulty&falling&asleep&after&going&to&bed&or&getting&up&in&the&middle&of&the&
night.&
! Insomnia&is&one&of&the&few&medical&problems&that&physicians&treat&without&having&direct&clinical&
evidence&(lab)&for&its&existence.&&
! Researchers&now&recognize&that&the&true&evaluation&of&a&sleeping&medication&must&be&made&
during&wakefulness&the&following&day,&and&“hangover&free”&drugs&are&finally&being&developed.&
! A&particular&form&of&insomnia&is&caused&by&an&inability&to&sleep&and&breathe&at&the&same&time.&
+,&&$(#$-&#!&caused&by&an&inability&to&sleep&and&breathe&at&the&same&time&
! During&a&period&of&sleep&apnea&the&level&of&carbon&dioxide&in&the&blood&stimulates&
chemoreceptors&(neurons&that&detect&the&presence&of&certain&chemicals),&and&the&person&wakes&
up,&gasping&for&air.&
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