Luria on nondominant parietal lobe

The Working Brain p, 160

Luria notes the absence of acalculia but the presence of unawareness of the left visual field in patients with a field defect (unlike left hemisphere lesions). Its also true in spontaneous construction and drawing . Cites Korchazinskaya, 1971 (Unilateral spatial agnosia in brain lesions, dissertation, Moscow). Luria also notes anosognosia, inability to notice and correct mistakes, in patients with right hemisphere (parietal) lesions.

He also discusses the lack of familiarity with known objects or faces, despite intact perception, such as in prosopagnosia. He calls it a paragnosia --replacement of a direct correct perception of an object by uncontrollable guesses about its nature. Constructional apraxia and representations of external space are much more common than in left sided lesions.

Luria cites Sperry's split brain model as evidence that the right hemisphere can neither participate in any extent in speech function or in complex motor acts. Logical reasoning and logical grammatical structures are not affected. However, Luria cites Teuber as evidence that the right hemisphere is less differentiated than the left. For example, sensory agnosia localizes much more sharply in the left hemisphere than the right. In the right hemisphere, disorders are more likely polymodal and polysensory. Problems of the "body schema" are more common in the right hemisphere, including a sense of disproportionality of particular body parts. The right hemisphere does participate in direct visual perceptions and direct visual relationships with the world (Hughlings Jackson, 1874). Dressing apraxia refers to right hemisphere about 80 percent of the time.

Anosognosia,or lack of awareness of deficit (such as hemiplegia) is explained by lack of awareness of deficits not related to speech mechanisms (p. 168).

Disorders of personality and consciousness may include confusion, and disorientation, and subterfuge through humor or speech to hide or disguise the deficit. Lack of logical operation allowed such patients to believe they were in two different places at the same time, without a contradiction in the statement.

Luria hints at a role for the right hemisphere in consciousness, which he will address in a series of papers being prepared for publication.