This paper reports and illustrates in figurine style results obtained by electrical stimulation of the cortex in 20 patients and by recording of cortical evoked potentials (EPs) in 13 of these patients, whose surgery required wide exposure of the Rolandic or paracentral regions of the cortex. This study is unique in that cutaneous receptive fields related to specific cortical sites were defined by mechanical stimulation, as is done in animals, in contrast to electrical stimulation of peripheral nerves at fixed sites, as in scalp EP recordings. Observations were made on pre- and postcentral gyri, on the second somatic sensory-motor area, on the supplementary motor area, and on the supplementary sensory area. In two patients with phantom limb pain, the pain was elicited in one on stimulation of the postcentral arm area, and in the other on stimulation of the supplementary sensory leg area. Surgical removal of these areas had the immediate effect of abolishing the phantoms and the pain. Long-term follow-up review was not possible. In one patient with severe Parkinson's disease, stimulating currents subthreshold for the elicitation of movement resulted in disappearance of tremor and rigidity for short periods after stimulation of the precentral gyrus. The possible patterns of organization of the human pre- and postcentral areas are considered and compared with those of the chimpanzee and other primates. In patients in whom data from pre- and postcentral gyri were adequate, it appeared that the precentral face-arm boundary is situated 1 to 2 cm higher than the corresponding postcentral boundary.
THIRTY-ONE FIGURESThe purpose of this report is to present experimental evidence concerning thalamo-cortical connections of the auditory region of the cerebral cortex in the cat and to examine the findings in relation to the cellular structure of the region and to available functional data. The divisions of the auditory region as used here are those described in the previous paper (J. E. Rose, '49).
MATERIAL AND METHODSThalamo-cortical connections were studied in 21 hemispheres by the method of retrograde degeneration. The animals were sacrificed usually 4 weeks after the operation. The brains, embedded in paraffin, were cut horizontally at 20p. The sections were stained with thionin. The cortex surrounding each operative lesion was studied in respect t o its cytoarchitecture and the extent of the operative lesion was plotted on the photographs of the respective brains, thus graphically reconstructing the series. Brains of two animals (cats 16 and 18) were plotted on a standard diagram. The
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