6.6

• Most visual cortex neurons in this stream respond most robustly to spatial stimuli, such as those indicating the location of objects or their direction of movement. It is involved in the perception of “where” objects.

  Dorsal stream
• Flows from the primary visual cortex to the dorsal prestriate cortex to the posterior parietal cortex.

  Dorsal Stream
• Most neurons in the ________ respond to the characteristics of objects, such as color and shape.

  Ventral Stream
• stream responsible to identify “what” objects are

  Ventral Stream
• A major implication of the “where” versus “what” theory of vision is that damage to some areas of cortex may abolish certain aspects of vision while leaving others unaffected.
• Goodale and Milner’s revised the where-what theory to “control of behavior” versus “conscious perception”
• visual agnosia for face

  Prosopagnosia
• Prosopagnosia acquired either during development

  developmental prosopagnosia
• prosopagnosia a result of brain injury

  acquired prosopagnosia
• Agnosia is a failure of recognition that is not attributable to a sensory deficit or to verbal or intellectual impairment.
• Visual agnosia is a specific agnosia for visual stimuli.
• True or False, prosopagnosics sometimes can’t recognize themselves too.

  True
• Is prosopagnosia specific to faces?

  No.
• What brain pathology is associated with prosopagnosia?

  The diagnosis of acquired prosopagnosia is usually associated with damage to either or both of the fusiform face area and the occipital face area.
• It is located on the ventral surface of the boundary between the occipital and temporal lobes. It is selectively activated by human faces.

  fusiform face area (FFA)
• A part of the brain that is associated with prosopagnosia. It is located in the ventral surface of the occipital lobe.

  occipital face area (OFA)
• Besides the OFA and the FFA, the lateral prefrontal cortex also plays a role in face identification.
• Can prosopagnosics perceive faces in the absence of conscious awareness?

  Yes.
• It is the deficiency in the ability to see movement progress in a normal smooth fashion—individuals affected by it only see periodic snapshots of the world.

  Akinetopsia
• When akinetopsia is the result of an acquired brain injury, it is often associated with damage to area MT.