Fixation of spinal reflexes in rats by central and peripheral sensory input


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Abstract

Used 2 methods in 5 experiments (55 male hooded Long-Evans rats) to demonstrate retention of postural asymmetries after spinal cord section. In the 1st preparation, postural asymmetries of the hindlimbs were induced by placing electrolytic lesions in the anterior cerebellum. Asymmetry was found to consistently outlast a spinal cord section if 45 min were allowed between brain lesion and cord section. A certain percentage of Ss allowed 35 or 40 min also demonstrated the retention. In the 2nd preparation, postural asymmetries induced by 45 min of direct hindlimb stimulation were also retained after spinal section. Rhizotomy prior to stimulation resulted in a lack of appreciable asymmetry on termination of the stimulation. Retention of a hindlimb-stimulation-induced asymmetry was observed in Ss that underwent a spinal section before stimulation. Results demonstrate that the “spinal fixation” phenomenon can be obtained by induction of postural alterations from central (cerebellar lesion) and peripheral (hindlimb stimulation) sources. Results obtained from spinal Ss indicate that retention of peripherally induced asymmetry is not crucially dependent on higher brain center activity but rather seems to be more dependent on long-term alterations that occur directly in the spinal reflex system. (15 ref) (PsycINFO Database Record (c) 2006 APA, all rights reserved)

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