L12

• What damage causes what kind of

  blindness?

  follow the pathways back to the retina and shade in

  the corresponding visual fields to find out.
• Patient DB had surgical removal of a

  tumour in his right occipital lobe

  He suffers from left homonymous hemianopia hatched marks represent islands of marginal

  vision
• Patient DB displays two interesting

  visual problems

  Can’t identify a static visual object but can

  localize it in space. Says he can’t even see an

  object.

  Can’t identify a moving visual object but can

  localize it in space. The difference is that with moving objects he says he has the sensation that something is out there. He does not feel that way with static visual objects.
• How can we accommodate these two aspects of DB’s vision?

  localizing an object that he can’t see is a result of information is reaching the dorsal stream

  • sensing a moving object is a result of information reaching V5
  • not being able to identify a static or moving object is because information is bypassing V1