Cross-modal transfer effects on visual discrimination depends on lesion location in the rat visual system

The effects of postoperative visual and auditory training on a brightness d iscrimination task were examined after lesions of various structures in the visual system. In Experiment 1, rats were trained to avoid shock with visu al intensity cues. Twenty-four hours later, each rat received bilateral les ions in one of the following areas of the visual system: (1) sham, (2) visu al cortex (VC), (3) pretectal (PT) area, (4) combined PT/VC, (5) superior c olliculus (SQ, or (6) combined SC/VC. Six days later, each rat received eit her training with visual or auditory intensity cues, or no training. The ne xt day all rats were retrained on the preoperative visual avoidance task, A ll lesions except those in the SC condition produced relearning deficits. A uditory training reduced these deficits significantly more than visual trai ning, except in rats with combined SC/VC lesions. In Experiment 2, sham and combined PT/VC lesion rats were given either direct or reversal intensity training using visual or auditory cues before relearning the visual discrim ination. Rats given auditory direct training relearned the task faster than rats given reversal training or visual direct training. Postinjury trainin g with an intact sensory system can enhance functional recovery more effect ively than training with the damaged system. The differential effects of di rect and reversal training suggest that cross-modal training involves both specific and nonspecific transfer that may be mediated through the VC or th e SC. (C) 2001 Elsevier Science Inc. All rights reserved.