Pure agraphia and Gerstmann's syndrome as a visuospatial-language dissociation: an experimental case study.

A right-handed man suffered a left parieto-occipital cerebral infarction, causing agraphia with Gerstmann's syndrome but without major aphasia, alexia, or apraxia. Oral spelling was superior to written spelling. Experiments were performed involving (1) analysis of errors in writing, (2) tasks of visual imagery, and (3) identifying letters drawn without leaving a visual trace. The results suggest that the agraphia and Gerstmann's syndrome are due to a dissociation of language skills and visuospatial skills caused by a dominant parieto-occipital lesion.

Crossed buccofacial apraxia.

The cerebral hemisphere contralateral to the preferred hand is generally dominant for learned representational motor acts, including those involving buccofacial muscles. It is generally also language-dominant. This buccofacial apraxia has, with rare exceptions, been associated with left hemispheric lesions in right-handers. We describe two patients with severe buccofacial apraxia caused by large middle cerebral artery territory infarcts in the hemisphere ipsilateral to the preferred hand and nondominant for language. Neither patient had aphasia or major limb apraxia. Computed tomographic scans in the first patient and neuropathologic examination in the second failed to reveal an abnormality of the hemisphere contralateral to the preferred hand. Hence, in some individuals, the hemisphere controlling skilled representational buccofacial movements may not be the one that is dominant either for handedness or for language.

Hippocampal pyramidal cells and aging in the human: a quantitative study of neuronal loss in sectors CA1 to CA4.

A number of investigators have proposed that hippocampal pathology contributes to the memory impairment seen in normal aging. The published morphometric studies of aging-associated quantitative changes in pyramidal cells in human hippocampus have yielded somewhat inconsistent results. We measured the volume, pyramidal cell density, and neuronal and nuclear cross-sectional areas in sectors CA1 through CA4 in right and left hippocampi from the brains of 23 normal subjects (age range 4 to 98 years) in the Yakovlev Collection. All four hippocampal sectors tended to show a decline in volume and pyramidal cell density with age, but the degree of neuronal loss was statistically significant only in CA4. The aging-related cell loss did not appear to be linear, but was most obvious after age 65. Elderly subjects had 19% (CA1), 16% (CA2), 17% (CA3), and 25% (CA4) lower mean pyramidal cell density compared with subjects under age 65. The relatively greater neuronal loss in CA4 could possibly be related to its high catecholaminergic innervation.