The nature of the alleged mental representations that underlie the act of pointing to target body parts have been a controversial issue. Originally, it was diagnosed as the effects of general mental deterioration or of aphasia on the task of pointing to body parts on verbal command. However, contemporary neuropsychological therapy seeks to establish the independence of<unk>  from other disorders. With such a general definition, a patient that presents with a dysfunction of or failure in accessing one of four mental representation systems suffers from<unk> . Through observational testing, the type of mental misrepresentation of the body can be deduced: whether semantic, visuospatial, somatosensory, or motor misrepresentations. Neuropsychological tests can provide a proper diagnosis in regards to the specificity of patient's agnosic condition. 1) Test 1: Body Part Localization: Free vision and no vision conditions This exploratory approach assesses the patient's ability to localize one's body parts and those of the examiner in several different conditions. The examiner and subjects are seated facing one another at a one-meter distance. At the start of each trial, the examiner ensures that the subject's hands are at rest on the arms of the chair and legs uncrossed. In addition, errors are categorized as (1) left-right reversal: response to correct part on incorrect side; (2) spatial: response to area contiguous with target; (3) functional/semantic: response to area non-contiguous with target, but sharing function or a part of a larger unit; (4) unrelated to examiner's request. Test 1 Specifications Description A Verbal Command: Point to Self Examiner names a body part, and the subjects are instructed to point to that part on themselves. B Verbal Command: Point to Examiner Examiner names a body part, and subjects are instructed to point to that named part on the examiner. C Visual Cue: Point to Self Examiner points to body parts on himself, and subjects are required to point to the homologous part on themselves. D Visual Cue: Point to Examiner Examiner points to a body part on the subjects, and they are required to point to the homologous part on the examiner. E Blindfold Post-Visual Cue: Point to Self Same as Study 1c., except subjects are blindfolded after examiner points to himself, prior to response execution. 2) Test 2: On-line positioning of body vis-à-vis objects If deficits in body part localization are due to impairments in body schema, then patients should be deficient in reaching and grasping objects. This test evaluates the specificity of the patient's insufficiency, in regards to the specific positioning of body parts with respect to objects. 3) Test 3: Localization of objects on the body surface Patients were asked to point to small objects mounted on the body, acting as a body reference system (body schema). The investigation is to determine whether localization of the same points on the body surfaces assessed in Test 1 might be improved when these points correspond to external objects. 4) Test 4: Body part semantic knowledge Patient is shown photographs of 10 items of clothing and 7 grooming tools, 1 per trial, and asked to point to the part of his own body associated with each item. 5) Test 5: Matching body parts: Effect of viewing angle Assessment of whether the patient's deficit in body part representation extends to individual body parts, and whether visual attributes of the body and its parts, such as viewing angle, affect their recognition.
Autotopagnosia
Integrative agnosia
Visuospatial dysgnosia
Apperceptive agnosia
Finger agnosia
Hemispatial neglect
Phonagnosia
Associative visual agnosia