Pathophysiology
1. Agnosia: inability to perceive objects even though sensory channels are functioning normally
2. Loss of stereognosis, the ability to identify objects by touch
3. Inability to integrate somatic sensory input and other sensory modalities to give rise to perceptions and to focus attention on extrapersonal space; gives rise to “neglect”
4. Neglect syndrome: deficit in body image in the perception of spatial relations and in selective attention
–a. neglect of the external world
–b. loss of awareness of personal space; may deny the existence of parts of the body