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