Task 7 Flashcards
Doctrine of concordance
cognitive processes, behavior and phenomenal experience are highly correlated
- in some cases, there can be dissociation btw them
Korsakoff syndrome
Amnesia and confabulation caused by the effects of alcohol and thiamine deficiency caused by malnutrition in heavy drinkers
- destruction of mammillary bodies and dorsomedial nucleus of the thalamus
Amnesia (types)
- anterograde amnesia: inability to form new LTM while STM remains intact
- retrograde amnesia: loss of LTM that stretches back into the past while classical conditioning and procedural learning remain intact –> evidence of priming
Are amnesic patients conscious
a) yes they are awake, responsive, able to talk, laugh and show emotions
b) no, no capacity to lay down ne memories, so the self is trapped in the past
Wanda test
Drug is injected that turns off one hemisphere at a time: done to localize memory and language functions
Neglect
ANOSOGNOSIA: stroke paralyzes one side of the body: if it is the left side, the person doesn’t recognize any deficit (part of mind seems to know the fact, the other doesn’t)
- connection btw autobiographical memory and body representation based on that lobe are destroyed, which affects the core self
ANTONS SYNDROME: patients are blind but insist that they can see
- parts of the visual system are gone, so there are no neurons calling for info coming from the eyes (no neurons to notice that there is info lacking)
HEMIFIELD/UNILATERAL NEGLECT: patients don’t see left side of the world.
Right brain damage:
- it is not that they have lost half their vision: responsiveness can be detected in their neglected area (cathedral in Milan)
- emotional stimuli can influence attention (burning house)
- stimuli that are not consciously seen prime later responses
Why? Explained as attention deficit to left side of the world
Lower level processes still function, while higher level processes don’t.
Blindsight
Ability of people to respond to stimuli that they don’t consciously see because they are blind.
Damage: lesions in V1: most have extensive damage to only one side –> cause degeneration of cells in LGN and retina.
- other non-cortical pathways are intact
- similar phenomena ‘blindsmell’
Experiment: presented with a circle full of black and white stripes in blind field and asked in which way the stripes would go: guess was 90-95% right
Interpretation of Blindsight regarding to consciousness
a) BLINDSEER HAS VISION WITHOUT CONSCIOUSNESS: would prove that consciousness is separate from vision (Partial zombies)
- quail would exist
- functionalism would be wrong
This would imply that quail happens in V1 while rest of vision goes elsewhere
Problem: the hard-problem would still ben there (conscious vs. unconscious brain area, how does quail arise from objective brain processes…)
- there are numerous patients with V1 damage who seem to be aware of some events in blind field
b) BLINDSIGHT DOESN’T EXIST:
a) light might have strayed from blind field into seeing field (not true)
b) blindisght is nothing more than degraded vision (not true, because confidence ratings are not correlated to accuracy, and this is the case in degraded vision)
c) signal deduction theory: people are just overly cautious about saying they can see something the response criterion was altered by varying the proportion of stimuli to blank trials. This did not affect blindsight)
c) BLINDSIGHT MIGHT DEPEND ON RESIDUAL ISLANDS OF CORTICAL TISSUE: many patients don’t have such residual islands
there are many different pathways from eye to brain areas:
- 85% LGN –> V1
- 15% Superior colliculus –> cortical and subcortical area
If V1 is destroyed, other subcortical pathways remain intact
Superblindsight
there is still consciousness: after training of confidence in intuition people shawl be able to act on, talk about and use the blind field (doest exist)
a) functionalism: the person would then be conscious
b) Epiphenomenalists: the person wouldn’t be conscious, because function and quail are different things (blindseers would have one but not the other)
Sensory substitution
People are given info in one sense to replace another
- this would conclude that consciousness comes with increasing function rather than being separate from it
Neurobiology in blindsight
OTHER PATHWAYS THAT DON’T GO TO V1 DON’T DEGENERATE:
- ventral LGN is responsible for the detection of light levels
- Optic tract: detection of self motion & subsequent postural adjustment
These areas from LGN to subcortical structures may be responsible for residual function in blindsight
RETINAL CELLS:
- alpha (M) cells: center surround - contrast
- beta (P) cells: wavelength and color
both project to dLGN but may also project to striate cortex. Degenerated dLGN projects to extra striate cortex which could mediate residual functions
- Gamma cells: project to midbrain (wavelength bias)
When V1 is destroyed, many cells degenerate within a week, but some cells survive
- Alpha & gamma mediate residual functions: motion & stimulus location
- dLGN to superior colliculus: saccadic eye movements
- Beta cells: reason why blindseers still detect colors
- Extrastriate cortical areas: sensitive to motion
Millner & Goodale’s opinion on blindsight
Blindsight is only paradoxical If vision is seen as an unitary construct.
- there is no single visual presentation
a) ventral stream - perception
b) dorsal stream - visuomotor control
Marzi: opinion on blindsight
reisdual functions in blindsight are banned from consciousness because neural activity doesn’t reach consciousness
Holt: opinion on blindsight
blindsight is evidence for quail
Block: opinion on blindsight
Arguments often confuse access consciousness and phenomenal consciousness:
- blindseers don’t have access to access consciousness nor to phenomenal consciousness (This is so because the patient denies having any phenomenal experience and because the only access he has comes from hearing his own voice when he has been forced to make a guess.)
