Recovery of associative function following early amygdala lesions in rats

Adult rats with amygdala lesions made at either Postnatal Day (PND) 10 or P ND40 were tested on a series of reversal tasks that tap the ability to form stimulus-reward associations. PND40 rats were significantly impaired relat ive to both controls and PND10 rats on learning rate of the original discri mination and subsequent reversals. Analyses of discrete learning phases rev ealed that the impairment was specific to the postchance phase. The PND10 g roup was not impaired relative to controls on any measure. These results co nfirm prior findings that amygdala lesions sustained in adulthood impair th e formation of stimulus-reward associations. They also demonstrate that sub stantial sparing or recovery of function is possible when the lesion is mad e during early development. Furthermore, the findings support the view that behavioral recovery may be more likely if the lesion is sustained near the time of peak synaptogenesis.