PSYC101 Lecture 3: psyc101 - states of consciousness
PSYC101: Introduction to Behavioural sciences !
States of Consciousness
What is consciousness
-Is the awareness of internal and external stimuli
-Fluctuates continuously (stream of consciousness, William James)
-Sigmund Freud (c1900) suggested consciousness has depth
•Based his theory of ‘psychoanalysis’ on this conceptualisation
-Consciousness and unconcious process reflect different levels of awareness
Measuring consciousness
-Self-report; most direct
-Behavioural observation; sleep, infants, chimps, mirrors
-Cognitive experiments – subliminal priming
-Measuring the extent of alteration of consciousness induced by relaxation, hypnosis
-Pharmacological measures; drug effects
-Physiological measures; brain electrical activity
-Electroencephalogram (EEG)
•measures electrical brain activity over time
•Amplitude and frequency (cycles per second, Hz)
•Different EEG patterns associated with different states of consciousness
-e.g. alert and problem-solving > beta
-relaxing and resting > alpha
-deep sleep > delta
Biological rhythms
-Biological rhythms partly drive variations in consciousness
-They are periodic fluctuations in physiological functioning
•Internal ‘biological clock’ that controls these rhythms
-Classified according to frequency of occurrence
•Circadian: daily (sleep/wake cycle)
•Ultradian: > once per day (digestion)
•Infradian: < once per day (menstrual cycle)
•Circannual: once per year (bird migration)
-Circadian rhythm
•The suprachiasmatic nuclei (SCN) become active during the day and reduce the pineal
gland’s release of melatonin
-Low melatonin —> increased body temperature and heightened alertness
•At night, SCN stop inhibiting melatonin release
-High melatonin —> decreased body temperature, relaxation, sleepiness
•Daily cycles also affect rhythmic variations in BP, urine production, hormonal secretion and
other physiological functions (e.g. melatonin, body temp)
•Light is the most important ‘zeitgeber’
-Disruptions of circadian rhythms
•Jet Lag
-Crossing of time zones
-Symptoms include:
•Sleepiness during the day
•Sleeplessness at night
•Impaired concentration
-Caused by the mismatch of internal circadian clock and external time
•Shift work
-People that sleep irregularly (i.e. not during the biological night)
•Duration of sleep depends on when go to bed
•Circadian rhythm doesn’t completely change, artificial light at night is only moderately
effective in resetting rhythms
•To readjust biological clocks:
-Melatonin
•Effectiveness for jetlag inconsistent
•Timing of dose crucial
-Bright light
•Shift workers
•Accelerate workers adaption to new sleep-wake cycle
•Effects modest – also not realistic for all work settings
Sleep
-Spend over 1/3 of our life asleep
-Important part of daily life + biology
-Mystery as to why we sleep
-Dreaming
•Sleep represent the most common ‘altered state of consciousness’ where our awareness is
somehow changed from that of our normal waking state
•In these ‘altered states’ our perceptions are different, thinking is uncritical, bizarre ideas may
seem real and acceptable (eg. flying dreams)
•When we sleep we relinquish conscious control of our thoughts and actions, and upon
awakening we remember very little of what occurred during sleep, so cannot self-report, but
we can study sleep using a number of measures
What is sleep
-Period of reduced activity
-Results in a decreased responsiveness to external stimuli
-A state that is relatively easy to reverse (distinguishing it from other states of reduced
consciousness; hibernation, coma)
-A state that the brain actively produces
Stages of sleep
-Not a single, uniform state of physical and mental inactivity - various rhythms are evident
throughout the sleeping state.
-These occur in regular 90 minute cycles
-Sleep is divided into 2 broad types:
•Non-rapid eye movement (NREM)
•Rapid eye movement (REM)
-NREM is further subdivided into 4 stages (1,2,3,4)
-All stages are characterised by differences in:
•EEG (electrical activity in the brain)
•EOG (eye movements)
•• EMG (muscle tone)
-Age trends
•Newborns = 6-8 times/day
-16 hours, 50% REM sleep, 1st year 30% REM and continues to decrease
•Adults
-20% REM sleep.
-SWS v, % in stage 1 sleep
-Lighter sleep + ^ night-time wakening
Neurobiology of sleep
-Reticular formation
•Important for sleep and wakefulness
•Physiological arousal
-Pons and midbrain
•REM sleep
-Hypothalamus
•Wakefulness / sleep
-Medulla, thalamus, basal forebrain also implicated in sleep
Theories of sleep
-Restoration model
•Sleep is a time for replenishing the body
•Revitalising and restoring the physiological processes burnt up during the day
•Genes associated with restoration and metabolic pathways have been shown to be turned on
only during sleep
-Energy conservation model
•That sleep in some ways is analogous to hibernation, that is, to save energy
•However, the energy saving of sleeping vs resting/inactivity while awake is minimal
-Brain Plasticity and Memory Consolidation Models
•Sleep facilitates the consolidation of information acquired during the day
•Studies have shown that people who slept after learning a task performed better
-Synaptic Homeostasis
Sleep deprivation and importance of sleep
-Sleep deprivation tells us that sleep is vital
-Symptoms
•Brain/mind
-Irritability
-Cognitive impairment
-Severe yawning
-Hallucinations
-Symptoms similar to ADHD
•Body
-^ heart rate variability
-^ risk of heart disease
-v reaction time and accuracy
-Tremors, aches
-And more..
-There is a lack of awareness about the importance of sleep
-Just as important as marinating a healthy diet and exercising
-It’s more about maintaining a regular routine than duration of sleep
Document Summary
Is the awareness of internal and external stimuli. Fluctuates continuously (stream of consciousness, william james) Sigmund freud (c1900) suggested consciousness has depth: based his theory of psychoanalysis" on this conceptualisation. Consciousness and unconcious process re ect different levels of awareness. Measuring the extent of alteration of consciousness induced by relaxation, hypnosis. Electroencephalogram (eeg: measures electrical brain activity over time, amplitude and frequency (cycles per second, hz, different eeg patterns associated with different states of consciousness. Biological rhythms partly drive variations in consciousness. They are periodic uctuations in physiological functioning: internal biological clock" that controls these rhythms. Classi ed according to frequency of occurrence: circadian: daily (sleep/wake cycle, ultradian: > once per day (digestion, infradian: < once per day (menstrual cycle, circannual: once per year (bird migration) Circadian rhythm: the suprachiasmatic nuclei (scn) become active during the day and reduce the pineal gland"s release of melatonin.
