PubMed · 8332869
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Z Shen, S Z Lin. 1993. [Cognitive function of the temporal cortex].. https://pubmed.ncbi.nlm.nih.gov/8332869/
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A 52-year-old, right-handed female presented with visuospatial dysfunction including left hemineglect, incomplete Balint's syndrome, and environmental agnosia, together with left-sided motor symptoms such as unskillful movement, dystonic postures, and myoclonus in the left hand, without significant dementia. Symptoms progressed to akinetic mutism prior to her death 10 years after onset of illness. Imaging studies such as MRI, SPECT, and PET studies showed severe, predominantly right-sided involvement of parietal and parieto-occipital areas. The motor signs might originate from the right parietal lesions such as area five or somatosensory area. Neuropathologic studies including immunocytochemistry showed tau-positive neurofibrillary tangles and abundant neuritic plaques with amyloid deposits, confirming the diagnosis of Alzheimer's disease. An analysis of serum apolipoprotein E revealed epsilon3/epsilon3 homozygosity. This case represents a variant of Alzheimer's disease conspicuous for progressive motor signs and visuospatial dysfunction with a striking laterality, reflecting asymmetric parietal involvement. Alzheimer's disease with asymmetric parietal atrophy is difficult to be clinically distinguished from corticobasal degeneration characterized by progressive unilateral motor signs and focal cortical signs.
Studies of patients with focal brain damage suggest that topographical representation is subserved by dissociable neural subcomponents. This article offers a condensed review of the literature of "topographical disorientation" and describes several functional MRI studies designed to test hypotheses generated by that review. Three hypotheses are considered: (i) The parahippocampal cortex is critically involved in the acquisition of exocentric spatial information in humans; (ii) separable, posterior, dorsal, and ventral cortical regions subserve the perception and long term representation of position and identity, respectively, of landmarks; and (iii) there is a distinct area of the ventral occipitotemporal cortex that responds maximally to building stimuli and may play a role in the perception of salient landmarks. We conclude with a discussion of the inferential limitations of neuroimaging and lesion studies. It is proposed that combining these two approaches allows for inferences regarding the computational involvement of a neuroanatomical substrate in a given cognitive process although neither method can strictly support this conclusion alone.
A case of apperceptive visual agnosia, revealing difficulties only in the performance on a standard overlapping-figures test, has been studied. Unusually, the patient demonstrated difficulties only with two semantic categories of the overlapped figures (clothes and school accessories); preserving, however, the knowledge of the same figures when presented isolated. We propose that the underlying deficit is only of a pseudo-semantic nature and is actually due to certain similarities of the two overlapping combinations, creating difficulties still on the apperception level only.