NEURONAL PLASTICITY INDUCED BY SELF-STIMULATION REWARDING EXPERIENCE IN RATS - A STUDY ON ALTERATION IN DENDRITIC BRANCHING IN PYRAMIDAL NEURONS OF HIPPOCAMPUS AND MOTOR CORTEX

Self-stimulation rewarding experience promoted structural changes in p yramidal neurons of the CA3 region of the hippocampus and the Vth laye r of the motor cortex in adult male Wistar rats. Self-stimulation expe rience was allowed for 1 h daily for a duration of 10 days through bip olar electrodes placed bilaterally in lateral hypothalamus and substan tia nigra - ventral tegmental area. At the end of 10 days, rats were s acrificed, and rapid Golgi examination of the CA3 hippocampal and laye r V pyramidal neurons of the motor cortex was made for a grand total o f 1600 neurons from 80 rats divided into 4 groups. The neurons of the self-stimulation experienced (SS) group revealed a significant (ANOVA, F-test) increase in dendritic branching in the perisomatic domains. S uch changes were not observed in neurons of sham control (SH), experim enter administered stimulation (EA) and normal control (NC) groups. SS animals also showed a significant increase in the thickness of lacuno sum and radiatum laminae of CA3 neurons of the hippocampus. Our result s reveal that both limbic and neocortical neurons undergo changes in d endritic branching patterns due to self-stimulation rewarding experien ce. It is tempting to hypothesize that neuronal plasticity is the resu lt of motivation and learning experienced by rats which underwent self -stimulation.