CHAPTER 6 Flashcards
Consciousness
conscious awareness of oneself and one’s environment
Gerhard Roth (2004)
- consciousness comprises many states; these lie on a continuum from coma to sleep to alertness.
- Roth defines two forms:
- background stream
- actual stream
William James (1892)
-first proposed the concept of a “stream” of consciousness
background stream
DEFINITION: long-lasting sensory experiences
- sense of personal identity
- awareness of one’s body; control of body and intellect
- location in space/time
- level of reality of experience; fantasy vs. reality
actual stream
DEFINITION:concrete, often rapidly alternating states of awareness.
- awareness of processes in one’s body and environment
- cognitive activities, emotions, feelings, and needs (e.g., hunger)
- wishes, intentions, and acts of will
- sharpened by processes of attention
which kinds of studies were used to implicate mutable areas of the _____
PET/FMRI studies were used to implicate mutable areas of the association cortex for these two aspects of consciousness
David J. Chalmers (1995):
- defines two kinds of problems in understanding consciousness
- the “easy problems”
- the “ hard problem”
- Chalmers is skeptical that neuroscience can provide answers to these “hard” questions
- the “easy problems”
are ones that psychology and neuroscience are trying to answer (and are actually quite challenging):
- How can we discriminate sensory stimuli and react to them appropriately?
- How does the brain integrate information and use this to control behaviour?
- How is it that we can verbalize our internal states?
- the “hard problem”
Is the question of how physical processes in the brain give rise to subjective experience:
- Why is it that when our brains process light of a certain wavelength, we have a particular experience (of red, for example)?
- Why do we have any experience at all?
- Could not an unconscious automaton have performed the same tasks just as well?
visual form agnosia
person cannot visually perceive global structure (e.g., object identity, shape, orientation), despite intact low-level sensory processing (e.g., acuity, colour, and brightness discrimination); likely due to a failure of binding at an early stage of visual processing
patient D.F. had diffuse damage to occipitotemporal cortex
had visual form agnosia
- could not recognize, discriminate, or copy complex visual forms, like shapes
- but (to her own surprise) she could accurately reach for and grasp objects
implication of visual form agnosia
holistic visual perception (“what”) is different from visually guided action (“how”)
visual object agnosia
person cannot visually identify objects, even though they can “see” and describe them
Oliver Sacks’ patient Dr. P. had damage in….
(visual object agnosia)
- Oliver Sacks’ patient Dr. P. had damage in visual association cortex
- could copy pictures, but not identify them
implication of visual object agnosia
visual perception and identification are different processes
blindsight
person has no visual experience (i.e., they are blind), but can perform visually guided tasks better than chance level
patient G.Y
(blindsight)
had left primary visual cortex removed
- could correctly guess which way a line was moving and could grasp objects in his blind field
implications of blindsight
there must be another visual pathway that bypasses the primary visual cortex; some aspects of vision are not conscious
circadian rhythm
body’s biological sleep/wake cycle
Kleitman & Richardson (1938)
- stayed in Mammoth Cave in Kentucky for 33 days
- went to sleep and woke up 1 hour later each day
- confound: amount of artificial light exposure
Czeisler et al. (1999)
- carefully controlled amount of light exposure in a lab
- free-running circadian rhythm found to be 24 hours, 11 minutes long
- optic nerve connects tosuprachiasmatic nuclei(SCN) of the hypothalamus, reset by light each day
- SCN inhibits pineal gland from producingmelatonin, the “sleep hormone”
Brain/muscle activity measured with electroencephalogram (EEG)
electrodes pasted to scalp/face measure activity.
- measure beta and alpha waves.
beta waves
- occur in awake, active state; irregular, low amplitude, high frequency.
Alpha waves
occur in awake, relaxed state; medium amplitude, medium frequency
how many stages of sleep are there
4
stage 1
Light sleep, lasts 2-10 min.; transition period
- breathing, brain waves slow down
- alpha waves;theta waves
- may experience hallucinations/images, sensation of falling, hypnic jerks
stage 2
deeper sleep; 15-20 min.
- irregular activity;sleep spindle: bursts of activity correlated with memory consolidation
- k-complex
k-complex
brief spike of very high-amplitude activity; can occur in response to sounds (knocking?) on the first presentation, or hearing one’s name
stage 3
~15 min.
• somedelta waves
delta waves
high amplitude, low frequency
theta waves
irregular, medium amplitude, slower frequency (4-8 Hz)
stage 4
deepest sleep, ~15 min.
• delta waves predominate; people difficult to awaken
s
Stages 3 & 4 are called…
slow-wave sleep because of the delta wave
You then return through stages 3 & 2, which is followed by
REM(rapid eye movement) sleep
REM(rapid eye movement) sleep
- sawtooth waves occur; similar to beta waves (REM is called (“paradoxical sleep”)
- heart rate increases, irregular breathing, genitals become aroused, brainstem paralyzes muscles
- dreams experienced
- REM rebound
dreams experienced
have narrative form; often emotional
REM rebound
if REM is interrupted, one returns to it much more quickly and stays in it longer on subsequent nights
sleep architecture
Cycling through sleep stages continues; sleep cycle ~90 minutes
Restoration theory
- Adaptive significance: helps one recuperate physically/mentally
- Energy conserved; growth hormone released during sleep
- Amount of sleep is correlated with strength of immune system
Preservation and protection Theory
adaptive significance: helps one avoid dangers and predators that are hard to see in the dark
Learning & Memory
- Adaptive significance: sleep consolidates recent memories
- People are more than twice as likely to discover insight into a numerical cognitive task after 8 hours of sleep (Wagner et al., 2004)
Sleep Deprivation
- physical fatigue is different from sleepiness
- how much sleep do you need? (Maas and colleagues, 1998)
- don’t need alarm clock to wake up
- don’t struggle to get out of bed
- not tired/irritable during the day
- don’t fall asleep watching TV
- sleep depends on culture and age
effects of deprivation
- intense sleepiness (worse at night; maximal at 62 hours)
- reduced immune system function (3× more likely to get a cold)
- psychotic symptoms
- decreased cognitive functioning, including impaired decision making and memory impairment (“recovery” sleep does not help)
Stanley Coren (1996)
- Teens need 10 hours of sleep; get 7-7½
- Deprivation affects IQ scores: for each hour under 8, 1-2 IQ points lost; effects may be cumulative
- Traffic accidents in Canada increased by 7% after spring time change; 7% lower after fall time change
dyssomnias
disturbances in the amount, quality, or timing of sleep
insomnia
difficulty initiating or maintaining sleep for at least 1 month, not caused by any other disorder
- affects 10-15% of population
- sleeping pills reduce REM and slow-wave sleep; sleep less satisfying; leads to
vicious circle:
can’t sleep==> sleeping pill==> dependence
better plan for sleep hygiene
» sleep on a regular schedule (even on weekends)
» only consume caffeine in morning/early afternoon, and don’t eat before bedtime
» don’t exercise in evening; just relax before bedtime
» limit light exposure in the evening (especially blue light/screens)
» don’t do anything in bed but sleep
narcolepsy
symptoms include excessive daytime sleepiness, vivid nightmares, cataplexy (loss of muscle control, often triggered by intense emotions)
- in narcolepsy, REM occurs at sleep onset; periods of REM and non-REM (NREM) sleep are disturbed
- normally treated with stimulants, nap scheduling
affects 0.1% of population
sleep apnea
cessation of breathing during sleep, which causes sleeper to awaken to breathe
central
breathing control centres in the brain interrupted; can be caused by depressants/sedatives
obstructive
physical blockage of airflow; can be caused by upper respiratory infection; linked to obesity
what the most common method of measuring consciousness
self report, BUT behavioural measures are also used.
parasomnia
sleep disorders involving abnormal or unnatural movements, behaviors, emotions, perceptions, or dreams
somniloquy(“sleep talking”)
- words/gibberish spoken during sleep
- occurs during brief arousals from NREM sleep, or during REM
- affects 50% of children, 5% of adults
somnambulism(“sleepwalking”)
- walking, eating, bathing, driving while asleep (eyes are open); no memory for the episode; no response if spoken to
- occurs in slow-wave sleep (not acting out a dream)
- affects 18% of population; more common in children
- not indicative of psychological problem
night terrors
- person appears terrified and cannot regain consciousness (difficult to awaken); is not a nightmare
- occurs in slow-wave sleep; may last 10-20 minutes
- mostly affects children (about 3%); may be linked to emotional stress
Dreams
- more activity in cortical areas associated with visual imagery, movement perception, and emotion; also in pons
- less activity in dorsolateral prefrontal cortex, associated with volitional action and evaluation of what is logical and socially appropriate
Psychoanalytic view(Freud, 1900)
wish fulfillment
- dreams are “the royal road to the unconscious”
manifest content
surface content of dream, based on preoccupations of life; safe version of…
latent content
underlying, unconscious wishes and desires that are too dangerous to admit
Physiological view(Hobson & McCarley, 1977)
activation-synthesis model
- dreams provide otherwise dormant brain with stimulation
- dreams are cognitive interpretations of random signals
evidence for Physiological view(Hobson & McCarley, 1977)
greater activity in visual and emotional brain regions; less activity in lateral prefrontal cortex (logical reasoning, decision making, and working memory)
Cognitive view(Cartwright, 1991; Winson, 1990)
Learning/memory/problem solving
- dreams work to consolidate memories & learned experiences; help solve problems
evidence for Cognitive view(Cartwright, 1991; Winson, 1990)
REM sleep enhanced learning of logic games, foreign language acquisition, problem solving, studying
Psychoactive Drugs
- affect perceptions and/or moods
- may enter brain by crossingblood-brain barrier
blood-brain barrier
blood vessels in brain less porous; closely surrounded by supporting cells
Stimulants
increase neural activity, alertness, body functions; may elevate mood
amphetamines
- produce alertness & euphoria.
amphetamine psychosis
hallucinations and paranoid delusions
downsides to amphetamines
- amphetamine psychosis
- controversial treatment for attention-deficit hyperactivity disorder: methylphenidate (Ritalin®)
- interfere with NE & DA reuptake
MDMA(3,4-methylenedioxymethamphetamine, “ecstacy”)
- acts as stimulant and hallucinogen; causes general sense of openness, empathy, energy, euphoria, and well-being
downsides toMDMA(3,4-methylenedioxymethamphetamine
- impairs attention, concentration, learning, and memory
- stimulates secretion and inhibits reuptake of large amounts of 5-HT, as well as DA and NE
- chronic high doses lead to destruction of terminal buttons of 5-HT neurons
cocaine
- initial “rush” lasts minutes-hours
downsides to cocaine
“crash,” paranoia, convulsions, heart failure, psychosis
- blocks reuptake of NE, DA, & 5-HT
nicotine
- increases heart rate, BP; decreases emotional reactivity
downsides to nicotine
- more addictive than heroin; tobacco contains several dozen known carcinogens
- activates nicotinic ACh receptors
caffeine
- increases heart rate, BP
- antagonist for the inhibitory neuromodulator adenosine; increases dopamine levels; also stimulates pituitary gland to secrete hormones which cause the adrenal glands to produce more adrenaline
Depressants/Tranquilizers
decrease neural activity, body functions, anxiety
benzodiazepines
- antianxiety drugs; GABA agonists
barbiturates
- “hypnotic”/sedative; GABA agonists
alcohol
- reduces judgment, decreases inhibitions; disrupts processing of experiences into long-term memory
- GABA receptor agonist, and glutamate receptor antagonist
- does not kill brain cells, but damages dendrites, which may be repaired with abstinence.
Opioids/Narcotics:
produce feelings of euphoria, analgesia
•oxycodone(OxyContin®),fentanyl,morphine,heroin:
like endorphins; inhibit production of endogenous opioids
downsides to opcodes/ narcotics
- dependence, respiratory depression
- attach to opioid receptors, which reduce GABA, which normally inhibits DA release
Hallucinogens
distort perceptions, moods
- LSD
LSD
- (lysergic acid diethylamide)
- only a few micrograms needed for a “trip”; lasts 6-12 hours
- CIA’s Project MKUltra used LSD on people to find if it could turn them into “robots agents”
THC
- (tetrahydrocannabinol)
- found in leaves of hemp plant (cannabis/marijuana/hashish)
- effects range from mild euphoria; to perceptual and time distortions; to hallucinations, delusions, and distortions of body image (depending on dose)
downsides to THC
» disrupts short-term memory, impairs reaction time, judgment, and peripheral vision
» long-term use of marijuana can trigger onset of psychosis and accelerate development of schizophrenia
» cannabis contains 50% more carcinogens than tobacco smoke
- acts like anandamide, an endogenous cannabinoid
antipsychotics
remove symptoms of psychosis
tricyclics (TCAs)
- may inhibit reuptake of NE and 5-HT
monoamine oxidase inhibitors(MAOIs)
- inhibit enzyme that breaks down 5-HT, NE, or DA (==>agonist)
selective serotonin reuptake inhibitors(SSRIs)
- bind to serotonin transport (SERT) proteins.
- there is little evidence that depression is caused by low levels of serotonin (are headaches caused by low levels of aspirin?)
