Showing papers by "Kenneth M. Heilman published in 1979"

Mechanisms underlying hemispatial neglect

Abstract: If patients with left-sided hemispatial neglect bisect lines incorrectly because hemianopia or sensory hemiinattention prevents them from seeing how far the line extends to the left, a strategy that ensures their seeing the left side of the line in their normal field should improve performance. If patients have hemispatial hypokinesia, moving the line toward the normal half of body space should improve performance. Six patients with left-sided neglect from right hemisphere infarctions were required to identify a letter at either the right or the left end of a line before bisecting that line. The task was given with the lines placed at either the right, the center, or the left of the body midline. Performance in trials when subjects were required to look to the left before bisecting a line did not differ from when they were required to look right. Performance was significantly better when the line was placed to the right side of the body than to the left. These observations support the hypothesis that patients with hemispatial neglect have hemispatial hypokinesia. An alternative hypothesis is that these subjects had a hemispatial memory defect. Although they saw the left side of the line in their normal field, they were incapable of forming a stable trace and performed as if they did not see the left side of the line.

Apraxic agraphia with neglect-induced paragraphia.

Abstract: • Agraphia may result from the loss or unavailability of the memory of movements necessary to form written letters. For this mechanism to be invoked, it must first be demonstrated that there is no language deficit and that there is no disconnection between language and motor areas. A left-handed patient demonstrated bilateral agraphia and apraxia, but not aphasia, following a right parietal infarction. Preservation of the ability to type with the left hand demonstrated that the right hemisphere was not disconnected from language input. In addition, paragraphic errors while typing were shown to be secondary to left hemispatial neglect.

Wernicke's and Global Aphasia Without Alexia

Abstract: • It has been proposed that the comprehension of written language requires transcoding from the visual (grapheme) to the auditory (phoneme). It has also been proposed that visual word images can be comprehended without grapheme-phoneme transcoding. We describe three aphasic patients with left hemisphere impairment who had poor speech comprehension but could comprehend written language. One of these patients had a subsequent right hemisphere lesion and lost his ability to read. We propose that the right hemisphere in some individuals may be capable of extracting semantic information from iconic images (ideogram) without phonological processing.

The Neuropsychological Basis of Skilled Movement in Man

Abstract: There are many ways of investigating the neuropsychological basis of skilled movements—ablation, stimulation, electrophysiological recording (EEG and single cell), and neurochemistry. Although some stimulation and EEG (evoked potential and contingent negative variations) studies have been performed in man, much of what we know about the neuropsychology of skilled movement comes from the studies of patients with such disorders.