Recognition and imitation of pantomimed motor acts after unilateral parietal and premotor lesions: a perspective on apraxia.

Publisher Summary This chapter examines motor and perceptual functions of the left hemisphere and their interaction. The cerebral hemispheres are organized asymmetrically for functional behavior. The left hemisphere in almost all right-handed individuals is specialized for language, the right for nonverbal functions. Most of the literature regarding the nature and function of the dominant left hemisphere stresses the representational or sign-referent characteristics of language. A number of research studies have suggested a variety of nonlinguistic behaviors that are better performed by the left hemisphere. Though in themselves nonlinguistic, these specialized motor and perceptual abilities may underlie and subserve the left hemisphere's capacity for linguistic behavior. This chapter reviews some of the evidence for specialized motor functions of the left hemisphere and summarizes the auditory perceptual abilities in which it excels. It also presents evidence which supports a specialized, tightly knit interdependence of input–output capabilities in the dominant hemisphere which may serve as the fundamental basis on which language develops and depends.

Motor and Perceptual Functions of the Left Hemisphere and Their Interaction

Visual, acoustic, and semantic processing of word pairs.

Publisher Summary This chapter reviews pictorial perception in neuropsychology, and focuses on hemispheric specialization and developmental regression in the neurologically impaired. Neuropsychological investigation of visual perceptual behaviors and the associated brain systems is less advanced than that which has taken place for language. One obvious reason for this lack of empirical work is that visual processing within the brain appears to be more diffuse and less restricted to circumscribed areas than is the case for language. Nevertheless, various differences in visual perception abilities do appear to be associated differentially with the two hemispheres of the brain. In the neuropsychological literature, there are three general areas of research in which pictures have been used: (1) face perception, (2) visual agnosia, and (3) drawing ability. The results of facial recognition and identification work seem to indicate the superiority of the right hemisphere for these tasks in the absence of readily distinguishable features. The contribution of the left hemisphere to facial tasks appears to involve the application of appropriate names and, possibly, the discrimination of individual details of the face. Empirical work on drawing and copying of two-dimensional forms by neurologically impaired patients reveals that the left and right hemispheres both contribute to performance.

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Papers

The concepts of agnosia, apraxia and aphasia after a history of a hundred years.