Problem 7 Flashcards
Korsakoffs syndrome
Refers to the most common form of amnesic syndrome, which entails 2 different kings of amnesia
- Anterograde amnesia
- -> inability to form new LTMs w/ STM intact - Retrograde amnesia
- -> loss of LTM that dates back
BUT: EM remains intact, but can’t create new ones
What causes Korsakoffs syndrome ?
The toxic effects of alcohol + thiamine deficiency caused by malnutrition in heavy drinkers
–> ultimately resulting in the destruction of
- mammillary bodies
- dorso-medial nucleus of the thalamus
- frontal lobes
Korsakoffs syndrome basically sounds like a complete loss of memory.
How can one then go about a daily life ?
Classical conditioning + procedural learning remains intact
e.g.: learning to drive or use a computer could be learned
Patient H.M.
His medial temporal lobes including both hippocampi were bilaterally removed to counteract his severe seizures.
–> left him with permanent memory loss
Are amnesic patients conscious ?
This is debatable
–> sure they are awake + responsive, but w/o the ability to make new memories the person is stuck in the past and unrelated to the events + people around him or her of the present
Antons syndrome
Anosognosia
Refers to a condition where the patient is blind but insist that they can see
Hemifield neglect/
Unilateral neglect
Refers to a condition where the patient does not seem to realize that the left-hand side of the world even exists
–> only occurs with right brain damage
How can Hemifield neglect be explained ?
It might arise due to lack of attention
–> as no visual problems seen
Hemianopia/
Blindsight
Refers to condition where lesion to V1 on one side will result in blindness on the eye of the opposite side
BUT: when asking patients what they saw with just that eye they guessed correctly 95% of the time, even though they were sure they didn’t see anything
Are people suffering from blindsight conscious ?
This is highly debatable,
as they have vision without the visual qualia that goes with seeing
–> so consciousness must be something separate
Access consciousness
Refers to the availability of info for use in
a) reasoning
b) speech
c) action
Access consciousness
Refers to the availability of info for use in
a) reasoning
b) speech
c) action
Blocks take on cosciousness
According to him Blindsight is Access consciousness without phenomenal consciousness
Doctrine of concordance
Refers to the agreement that
a) cognitive processes
b) behavior
c) phenomenal experience
are highly correlated
BUT: there can be dissociations btw the 3 as seen in certain diseases
Anosognosia
Refers to a condition where the person is unaware of having it
–> part of the mind knows the fact whereas the other part doesn’t, resulting in denial
BUT: only occurs w/ damage to particular parts of the right parietal lobe
There has been a lot of debating about whether the phenomenon of “Blindsight” really exists.
Name the 4 strongest reasons why it does not exist.
Blindsight is
- just light that strayed from blind into seeing field
- degraded normal vision
- results from the patient being overly cautious about saying they see sth
- depends on residual islands of cortical tissue
BUT: all of these have been disproven, thus it must be real
Evidence for phenomenal awareness of the blind field comes from 3 separate phenomena.
Name them
- Riddoch phenomenon
- Hemianopic completion
- After-images
Hemianopic completion
Occurs when a visual stimulus is presented across both HPs and the patients are bale t complete the whole figure
–> most effective when symmetric or some regularity
After images
Refers to a repression of a vivid image after the image has ceased
There have been demonstrations of V1 playing a crucial factor in awareness.
But is it really the gatekeeper of awareness ?
Probably not,
but nonetheless it might play an important role since it has recurrent loops with a lot of regions
–> so neural responsiveness is affected by lesions in V1
Super blindsight
After training the patients confidence in his intuition he or she should be able to talk, act upon + use info from the blind field
Sensory substitution
Patients are given info to one sense to replace another
e.g.: sound replaces vision
