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This Article Full Text Full Text (PDF) All Versions of this Article: 102/5/2667    most recent 00572.2009v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Frigon, A. Articles by Rossignol, S. PubMed PubMed Citation Articles by Frigon, A. Articles by Rossignol, S.

RESEARCH-ARTICLE

Asymmetric Changes in Cutaneous Reflexes After a Partial Spinal Lesion and Retention Following Spinalization During Locomotion in the Cat

¹Groupe de Recherche du Système Nerveux Central, Department of Physiology, Université de Montréal, Montreal, Quebec, Canada; ²Multidisciplinary Team on Locomotor Rehabilitation after Spinal Cord Injury (Strategic Initiative), Canadian Institutes for Health Research, Ottawa, Ontario, Canada; and ³Centre National de la Recherche Scientifique, Université Bordeaux 1, Bordeaux, France

Submitted 2 July 2009; accepted in final form 26 August 2009

ABSTRACT

Locomotion involves dynamic interactions between the spinal cord, supraspinal signals, and peripheral sensory inputs. After incomplete spinal cord injury (SCI), interactions are disrupted, and remnant structures must optimize function to maximize locomotion. We investigated if cutaneous reflexes are altered following a unilateral partial spinal lesion and whether changes are retained within spinal circuits after complete spinal transection (i.e., spinalization). Four cats were chronically implanted with recording and stimulating electrodes. Cutaneous reflexes were evoked with cuff electrodes placed around left and right superficial peroneal nerves. Control data, consisting of hindlimb kinematics and electromyography (bursts of muscular activity and cutaneous reflexes), were recorded during treadmill locomotion. After stable control data were achieved (53–67 days), a partial spinal lesion was made at the 10th or 11th thoracic segment (T₁₀–T₁₁) on the left side. Cats were trained to walk after the partial lesion, and following a recovery period (64–80 days), a spinalization was made at T₁₃. After the partial lesion, changes in short-latency excitatory (P1) homologous responses between hindlimbs, evoked during swing, were largely asymmetric in direction relative to control values, whereas changes in longer-latency excitatory (P2) and crossed responses were largely symmetric in direction. After spinalization, cats could display hindlimb locomotion within 1 day. Early after spinalization, reflex changes persisted a few days, but over time homologous P1 responses increased symmetrically toward or above control levels. Therefore changes in cutaneous reflexes after the partial lesion and retention following spinalization indicate an important spinal plasticity after incomplete SCI.