Somatosensory function and cortical unit activity in cats with only dorsal column fibers

Abstract

Cats received lesions that transected the entire thoracic cord except for partial sparing of the dorsal columns. The cats were required to discriminate the side on which they were touched, the size of simultaneously presented discs, or the direction their fur was stroked to obtain food reward. All cats found by anatomical and/or electrophysiological criteria to have any functional continuity in the dorsal columns were able to master the first of these tasks; some responded above chance on the second. Performance was at chance on blank trials, and cats with complete cord transection failed to discriminate. Lesioned cats did not orient or otherwise react to any nonrewarded stimulus below the level of the lesion. A total of 532 units were recorded under light barbiturate anesthesia from the hind paw projection near the tip of the ansate sulcus in these and other similarly prepared cats. Three-fourths of the units found before and acutely after the cord lesions were made were driven by hind limb stimulation. Only 27% of the units recorded 10 or more days afterwards could be driven. Of these driven units, 15 (38%) responded to foreleg stimulation, 13 exclusively so. No such units were found in intact or acutely lesioned cats.

Effects of spinal tractotomy on spatial sequence recognition in macaques

“…2B), because the spinoreticular tracts were interrupted to a large extent contralaterally, in conjunction with total ipsilateral section. The excellent performance of this monkey contrasts with the relatively debilitating effects of interrupting all non-DC spinal pathways at one level (Frommer et al, 1977;Myers et al, 1974) or lesioning the reticular formation directly (Sprague et al, 1963). Complete interruption of the lateral and ventral columns at one level and at one time produces especially profound deafferentation of the brain stem by eliminating conduction via the propriospinal system (Basbaum, 1973;Breazile and Kitchell, 1968), and this could contribute to differences in performance of animals with simultaneous vs. sequential lesions of the lateral and ventral columns.…”

“…Several previous attempts to isolate the dorsal columns have used a difficult preparation, involving section of all spinal white matter except the dorsal columns (Frommer et al, 1977;Myers et al, 1974). These animals detected the presence of electrical stimulation or touch involving segments below the section.…”