DEVELOPMENT OF PLASTICITY OF BRAIN-FUNCTION WITH REPEATED TRAININGS AND PASSAGE OF TIME AFTER BASAL FOREBRAIN LESIONS IN RATS

Basal forebrain (BF) lesion-induced amnesia in rats is widely used as an animal model of Alzheimer's disease (AD). To study the plasticity o f brain function in BF-lesioned rats, we examined the effects of repea ted trainings and the passage of time after the lesion on learning abi lity 3 weeks and 3 months after BF-lesions with ibotenic acid, using a n eight-arm radial maze and passive avoidance tasks, and measured chol ine acetyltransferase (ChAT) activity. Both time and re-training playe d important roles in the recovery of the ability to learn, as measured with the eight-arm radial maze task, but not the passive avoidance ta sk. In contrast, ChAT activity in the frontal cortex, which was low 3 weeks after the lesion, still low 3 months after lesion, even though t he ability to learn had recovered. Recovery of the ability to learn ca n be attributed to undamaged cholinergic neurons, or to other neuronal systems, or to both. This animal model can be used to demonstrate the plasticity of brain function.