Coronal somatosensory unit responses in cats with dorsal column lesions

Abstract

1. (1) Extensive chronic dorsal column (DC) lesions (greater than 90% of cross-sectional DC area) decrease the proportion of coronal somatosensory cells which respond to somatic stimuli, reduce the proportion of cells which borders, and increase the average receptive field size. Such lesions were estimated to involve approximately 90% of the DC fibers from the forepaw contralateral to the recording electrode.2. (2) Cats with extensive chronic DC lesions have proportionately fewer units with short latencies (10 msed or less) than intact cats.3. (3) Cats with chronic DC lesions showed a higher proportion of units with prolonged depression of post-response excitability; this property was related, not to the extent of the lesion, but to the length of time since surgery.4. (4) A higher proportion of units with latencies of 20 msec or less and small receptive fields (0-5 sq. cm) are found in cats with acute DC, acute dorsolateral, or chronic dorsolateral lesions.5. (5) The results show that, as in behavioral studies, functional deficits can be detected following nearly complete DC lesions.