The effects of cerebral sensory cortical ablation on instrumental conditioned reflex in cats with cerebellar lesions.

Cats were trained to reach with their fore limbs for food placed in horizontally mounted cylinders of various diameters. The chain instrumental reflex (entering cylinder, reaching for, grasping and bringing food toward the mouth) survived cerebellar paravermal cortical ablation or interposite-dentate nuclear lesion, with some exaggerated flexor or extensor responses respectively. Movements improved with time. Cats were then subjected to ablation of cerebral sensory cortex, SI and SII. SI or compined SI and SII lesion resulted in an initial period of decompensation of cerebellar symptoms. Sensory loss was also noted for 30-40 days after SI lesion and throughout the observation period up to 53 days after combined SI and SII lesion. The conditioned responses were soon accomplished at preoperative level. Furthermore, visual occlusion did not change the performance in conditioning situation. The result indicates that the compensation of cerebellar symptoms does not depend on an intact cerebral sensory cortex. It also suggests that functional accomplishment can be obtained through training despite neurological deficits following certain brain damage.