engleski

Reversal of passive avoidance behavior six months after disruption of cortical cholinergic innervation

The ventromedial globus pallidus and adjacent magnocellular neurones of basal forebrain (NB) provide the major cholinergic innervation to the neocortex in the rat. The purpose of this study was to examine the passive avoidance behavior twenty days and six months after the NB lesion. Male Wistar rats weighing 200-250 g were used. Unilateral or bilalateral electrolytic NB lesions were made stereotaxically. The site of the lesions was histologically verified. Twenty days later the passive avoidance task according to the procedure of Ashford and Jones (1976) was performed. A chamber with a grid floor continuously electrified was used. The central area of the platform contained a wooden platform. Each rat was placed on the platform and left in the apparatus for three minutes. The total time spent on the platform was recorded. A total of four consecutive daily sessions were given. Six months later the passive avoidance task was repeated in bilateral lesioned rats. Results of our experiments show that both unilateral and bilateral lesions of the NB impaired the passive avoidance responses in the rat. The effect of bilateral lesions was statistically significant. Six months later significant improvement of passive avoidance behavior was noted in bilateral lesioned rats. It is concluded that destruction of the NB neurons can be compensated by the plasticity of the residual NB neurons and other central cholinergic and noncholinergic structures which are involved in learning and memory processes.

NB lesion; passive avoidance; stereotaxy; plasticity; rat

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