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Chapter 5

Chapter 5 Exam Notes - PSYA01

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University of Toronto Scarborough
Steve Joordens

Chapter 5 ConcisousnessBY DAVE S 2014Saturday July 5 2014742 PM51 Biological Rhythms of ConsciousnessConciousnessIs a persons subjective awareness including thoughts perceptions experiences of the world and selfawarenessBiological RhythmsCircannual Organisms have evolved biolgoical rhythms that are neatly adapted to the cycles in the environmentRhythmFor example bears are well known for hibernating during the cold winter monthsBecause this behaviour happens on a yearly basis it is part of a circannual rhythm literally meaning a yearly cycleCircadian RhythmsAre internally driven daily cycles of approximately 24 hours affecting physiological and behavioural processesThey inovlved the tendency to be asleep or awake at specific times to feel hungrier during some parts of the day and even the ability to concentrate better at certain timesWhen are you most alrtAt most times of day do you fee th most tiredNight shift workers and night owls aside we tend to get most our sleep when it is dark outside because our circadian rhythms are circulated by daylight interacting with our nervous and endocrine systemsOne key brain structure in this process is the suprachisasmatic nucleus SCN of the hypothalamusCells in the retina of the eye relay messages about light levels in the environment ot the SCNPolysomnographyRefers to a set of objective measurements used to examine physiological variables during sleepSome of the devices used in this type of study are familiar such as one to measure respiration and a thermometer to measure body temperatureHowever sleep cycles themselves are most often defined by the electroencephalogram EEG a device that measures brain wavesEEGThe output of an EEG is a waveformThese waves can be described by their Frequency theof updown cycles every second andTheir Amplitude the height and depth of the updown cycleBetawavesHighfrequency lowamplitude waves are characteristic of wakefulnessTheir irregular nature reflects the bursts of activity in different reigons of the cortex and they are often interpreted as a sign that a person is laertAlpha WavesAs the individual begins to shift into sleep the wavesstart to become slower larger and more predictableThese Alpha Waves signal that a person may be daydreaming meditating or starting to fall asleepEEG SignalsThe EEG signals during sleep move through 4 different stagesStage 1 Brain waves slwo down and become higher in amplitudes known as Theta WavesBreathing blood pressure and heart rate all decrease slightly as an individual begins to sleepStage 2 After 10 to 15 minutes the sleeper enters stage 2 during which the brain waves continue to slowIncludes Sleep Spindlesand K Complexeswhich are periodic bursts of EEG activity evidence suggest they may play a role in helping maintain a state of sleep and in the process of memory storageStage 3 approximately 20 minutes later in which brain waves continue to slow down and assume a new form called delta waves Stage 4 The process continues with the deepest stage of sleep stage 4 during which time the sleeper will be difficult to awakenAbout an hour after falling asleep we reach the end of our 1st stage 4 deep phaseAt this point the sleep cycle goes in reverse and we move back toward stage 1 patterns not all the way back but to a unique stage of REM SleepStage 5REM Sleep Stage of sleep characterized by quickening of brain wavesinhibited body movement and rapid eye movements REMStage is sometimes known as Paradoxical sleepREM ReboundWhen we are deprived of sleep we typical experience a phenomenon called REM reboundOur brains spend an increased time in REMphase sleep when given the chanceRestore and Repair HypothesisThe idea that the body needs to restore energy levels and repair any wear and tear on the body from the days activitiesPreserve and Protect HypothesisSuggests that two more adaptive functions of sleep are pres
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