We studied performance on tests of visual neglect and left lateral gaze after caloric stimulation in 18 patients with left-sided visual neglect after strokes. Except for one patient with absent vestibulo-ocular responses, all improved during caloric stimulation on the left by cold (LC) or on the right by warm water (RW). Improvement seemed to depend on the facilitation of left lateral gaze and on past-pointing to the left. During LC and RW caloric stimulation, patients worked from left to right instead of their usual right to left. Caloric stimulation may be of use in training patients with hemispatial neglect to orient toward the affected hemispatial field.

Amnesic patients perform poorly on explicit memory tests that require conscious recollection of recent experiences, but frequently show preserved facilitations of performance or priming effects on implicit memory tasks that do not require conscious recollection. We examined implicit memory for novel visual objects on an object decision test in which subjects decide whether structurally possible and impossible objects could exist in three-dimensional form. Patients with organic memory disorders showed robust priming effects on this task---object decision accuracy was higher for previously studied objects than for nonstudied objects---and the magnitude of priming did not differ from matched control subjects or college students. However, patients showed impaired explicit memory for novel visual objects on a recognition test. We argue that priming is mediated by the structural description system, a subsystem of the perceptual representation system, that operates at a presemantic level and is preserved in amnesic patients.

We compared the courses of right and left lateral (sylvian) fissures by superimposing left lateral and reversed right lateral photographic slide projections and tracing the sulci and fissures of each hemisphere in different colors. A characteristic pattern of divergence of posterior regions of the lateral fissures was noted in 25 of 36 adult brains. After pursuing similar courses, the right lateral fissure angulates sharply upward into the inferior parietal area while the left one continues posteriorly. As a consequence, on the right, there is a smaller parietal operculum, a shorter planum temporale, a higher sylvian point, and compensatory expansion of the inferior parietal region posterior to the lateral fissure.

We studied apraxia in 28 patients with senile dementia of the Alzheimer type (SDAT). Although SDAT patients were impaired compared with age-matched controls on tests of ideomotor and ideational apraxia, not all types of movements were affected to the same degree. Limb transitive movements were especially vulnerable, while limb intransitive, buccofacial, and axial movements were relatively spared. When pantomiming limb transitive movements, SDAT patients made frequent body part as object and spatial errors. There was no significant difference between performance on verbal command and imitation, but there was considerable improvement with the use of actual objects. Disorders of skilled movement in SDAT were qualitatively similar to the apraxic syndromes following left parietal damage. Apraxia in SDAT suggests posterior left hemisphere cortical involvement and may be apparent even in patients with good language functions.

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