Neuro Exam 4: Disorders Of Spatial Cognition/agnosias

Front 1

What are the "two visual systems"?

Back 1

1. Occipital temporal visual system: For recognition (the "what" system); dysfunction (generally bilateral) causes visual agnosia
2. Occipital parietal visual system: for spatial location (the "where" system); dysfunction (generally bilateral) causes spatial cognitive deficits (e.g., Balint's syndrome)
-- disorders of where system are very rare (more rare than visual agnosia)

Front 2

Describe Balint's syndrome

Back 2

-Inability to saccade to or point to a visualized point in space
-Inability to see how all small parts of a picture fit together

Front 3

What does agnosia refer to?

Back 3

-An inability to recognize (or "know") despite an adequate primary sensory modality
-Normal visual acuity/adequate visual fields. Can trace/copy drawing confirming adequate perception. But cannot identify or recognize the object (when presented in auditory or tactile modality it is recognized and named).
-Caused by bilateral occipital temporal lesions that spare some of the primary visual area

Front 4

How can you tell if someone has an agnosia versus anomia?

Back 4

In visual agnosia, patient can name the object in different modalities (touch, hear); in anomia the patient still cannot name the objects when use other modalities

Front 5

What is prosopagnosia?

Back 5

Special case of visual agnosia in which a person is unable to identify a familiar face

Front 6

What is Balint’s syndrome?

Back 6

An object or part of an object is seen and recognized, but cannot be placed into the mental representation of external space (bilateral lesions in the “where” system)

Front 7

What produces hemi-inattention or hemi-neglect?

Back 7

-A disorder of spatial cognition (e.g., the “where system)
The language nondominant hemisphere is dominant for extrapersonal spatial functions
- Hemi-neglect/hemi-inattention indicates a lesion of the contralateral forebrain (e.g., A right hemisphere or diencephalic lesion may produce hemi-neglect for contralateral left space)

Front 8

How can you tell the difference between hemi-neglect and homonymous hemianopia?

Back 8

HH: Aware of the deficit, patient moves to compensate and see the full field
HN: Unaware of the deficit, patient thinks they see everything and as soon as they move, the neglected space changes or follows

Front 9

What is constructional apraxia?

Back 9

-A disorder of spatial cognition (e.g., the “where” system)
-Inability to put parts together into a whole (e.g., making a drawing, copying a drawing, putting blocks together)
-Indicates a lesion of the forebrain (left/right, anterior/posterior, cortical/subcortical); no localization value
-May be harder to detect in left hemisphere patient due to aphasia
-Very common defect

Front 10

What are the three steps in being able to name an object?

Back 10

Perception (visual defects), Recognize (Agnosia), Name (Anomia)