Topic 11 Clinical neuropsychology implications Flashcards
Patient L.M. has been labelled as motion blind, is it likely that a person could be totally blind to motion information while substantially retaining all other visual abilities?
No. Because if a person is totally blind to motion, the V1 must be damaged. But V1 damage is not selective, so other visual ability will also be impaired.
What is the pattern of deficits that patient LM has and what abilities are retained? How does this pattern make sense given what we know about how the brain processes visual information?
Selective motion deficit:
Feel uncomfortable with motion; see moving objects as images; worse visually guided movement with eyes open.
General cognitive functioning is normal (e.g., intellectual abilities); non-motion visual abilities is normal (e.g., stereopsis, colour vision, visual identification & recognition and visual localisation).
Normal ability on non-motion visual processing indicates that V1 is functioning, therefore motion deficit is likely to be due to damage to cortical area V5 &/or higher areas. V1 local-motion units are functional, but global-motion units are not, making unable to compare LM outputs to extract the motion signal.
What is cerebral achromatopsia?
A loss of colour vision / A type of colour blindness caused by damage to the cortex.
What are the different forms of visual agnosia?
1) Apperceptive agnosia
2) Associative agnosia
If a person is suffering from apperceptive visual agnosia, what could you do with an object in order to make it easier for the person to determine what it is? Why does this work?
Have it move.
Use the motion input to the form pathway.
Does it make sense to think that a particular visual attribute, like colour or motion, is processed in a single cortical area? Why? (Hint: think about it with respect to parallel pathways, hierarchical processing stages and the many uses of a particular visual attribute).
No.
One attribute (i.e., motion, colour) is processed by parallel pathway and hierarchal (multiple) processing stages.
Interaction between pathways: ventral pathway does not only receive direct projection from V1 motion units, but also projection from V5.
A stimulus attribute can be used for different purposes.
