Injury-induced plasticity of the flexor reflex in chronic decerebrate rats

摘要: The hindlimb-flexor-withdrawal reflex elicited by stimulation of the skin hindpaw has been examined in chronic decerebrate rats. This flexor manifests as a typical phasic avoidance response when measured either behaviourally rat or electrophysiologically decerebrate-spinal preparation. Once threshold cutaneous flexor-reflex afferents have exceeded brief burst activity with only short afterdischarge occurs motoneurones. to sustained stimuli adapts rapidly. In absence any treatment hindlimb threshold, duration and responsiveness remains stable tested repeatedly. Thermal chemical sufficient intensity produce tissue injury prolonged local inflammation result marked long-lasting (several weeks) alterations ipsilateral withdrawal reflex. mechanical necessary elicit falls so that light touch brush can now instead firm pressure pinch required pre-injury. Suprathreshold inflamed generate oscillating pattern flexion contrast flicking movement found control animals. Electromyographic recordings from hamstring muscles show decreased mechanothresholds, increased spontaneous activity, afterdischarges slowly adapting tonic stimulation. Populations single mechanoreceptive C-primary recorded both untreated rats an are indistinguishable terms their properties. There is no difference between two populations. possible mechanisms responsible for conversion high into low discussed implications sensory disorders accompany man.