SENSORY HIND-LIMB REPRESENTATION IN SML CORTEX OF CAT AFTER SPINAL TRACTOTOMIES

The functional properties of single neurons in the hind-limb area of the primary somatosensory cortex were studied in cats with surgical interruption of the various sectors of the midthoracic spinal cord. Lesions which spared or isolated the dorsal spinal column in no way altered mechanoreception. Lesions severing the dorsal column reduced the cortical representation of hair follicle receptors. Lesions which isolated the contralateral lateral funiculus increased the cortical representation of receptors whose adequate stimulus was light tap. Cortical organization in depth and in topography was unchanged by the above lesions. Tactile and proprioceptive reflexes were not impaired by chronic lesions limited to the dorsal column. Lesions severing both the contralateral dorsal column and the dorsal part of the lateral funiculus completely eliminated the cortical representation of lowthreshold mechanoreceptors and released the cortical representation of high threshold mechanoreceptors. Somatic nonspecific influences were detected in the superficial and the deep cortical layers. There was no evidence for a tactile component of the spinothalamic tract. In the chronic state, tactile and proprioceptive reflexes were gravely impaired, as was also the ability to localize pinch. © 1968.