Define object agnosia, prosopagnosia, color agnosia, and movement agnosia. What causes these syndromes?

Question

What will be an ideal response?

Answer 1

Object agnosia is the impaired ability to recognize objects despite maintaining the ability to see and object, describe it in detail, and identify it using other senses such as touch or smell. This deficit is caused by damage to the inferior temporal cortex, an area responsible for reassembling different characteristics of an object for recognition.
Prosopagnosia is the impaired ability to visually recognize familiar faces despite maintaining the ability to identify others by characteristics such as speech and mannerisms and maintaining the ability to determine facial expressions, age, and gender. This deficit is also cause by damage to an area in the inferior temporal cortex called the fusiform face area (FFA).
Color agnosia is the loss of the ability to perceive colors due to damage to the brain. Although studies show malfunctioning between V1 and the FFA, it is speculative whether this effect is due to damage in area V4, which has been attributed to processing color.
Movement agnosia involves an impaired ability to detect movement. Symptoms are caused by damage to area V5/MT and, based on observations of one patient, can include the ability to distinguish between moving and stationary objects only in peripheral vision; difficulty making visually guided eye and finger movements; trouble detecting movement of people when there are more than two people in a room; and an inability to detect radial movement, which implicates an area that receives input from the MT called MST (medial superior temporal area).