EFFECTS OF PARTIAL VERSUS COMPLETE LESIONS OF THE AMYGDALA ON CROSS-MODAL ASSOCIATIONS IN CYNOMOLGUS MONKEYS

Aspiration lesions of the amygdala plus subjacent cortex were found ea rlier to produce a severe impairment in cross-modal (tactual-to-visual ) recognition (Murray & Mishkin, 1985). To determine whether more sele ctive lesions would also produce this effect, we trained 8 naive cynom olgus monkeys on a tactual-visual version of delayed nonmatching-to-sa mple and then injected ibotenic acid bilaterally into either the basol ateral (n = 4) or centromedial (n = 4) subdivisions of the amygdala. N either of the excitotoxic lesions affected performance. In a second ex periment, we aspirated the amygdala plus subjacent cortex in similarly trained monkeys. The performance of these animals fell significantly and remained substantially below preoperative levels despite extensive postoperative retraining. The findings suggest that the severe defici t in cross-modal recognition following the aspiration lesion is attrib utable to complete amygdala damage, damage to the subjacent cortex, or the two in combination.