Brain Damage and Recovery of Function in the Adult System

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DESCRIPTION (provided by applicant): Our long-term goal is to determine how to help adult victims of brain injury recover the function of brain areas damaged by stroke or other afflictions. To that end, the goal of this study is to determine the mechanisms that underlie the recovery of function after damage to the adult brain. The present proposal builds upon two conceptually complementary observations. We have observed that the recovery of complex courtship behavior (the nest coo) after bilateral hypothalamic lesion in the adult male ring dove is facilitated when a male ring dove is housed with a female. Secondly, after electrolytic lesions of the adult hypothalamus, newborn neurons were detected at the lesion site concurrent with recovery at the lesion site of units exhibiting normal firing responses to female nest coo stimulation and behavioral recovery 2-3 months after lesion. These observations suggest an alternative explanation to the widely accepted principle of recovery of function. Recovery might be mediated not only by existing, undamaged neurons, but also by lesion-induced new neurons recruited into the network of reorganization. We test the hypothesis that lesion-induced new neurons are involved in the recovery of physiological activity and nest coo behavior by blocking neurogenesis and observing the effects on recovery (Aim I) and the determining whether the new neurons are biologically functional, namely, whether they are integrated into the network of nest coo behavior. This will be tested by measuring endocrine output associated with the nest coo behavior, and by determining axonal connections of new neurons using combined immunohistochemistry of tract tracing and neuronal markers (Aim II). In sum, the present proposal seeks to determine the role of lesion-induced neurogenesis in the context of the recovery of function in the mature dove brain.