The effect of tactile stimulation on spatial memory and hippocampal neuronal density in male rats with sensory deprivation during a critical period

It is well known that sensory information driven from whiskers serves as an example of tactile perception in rodents, and plays an important role in social behavior, environmental exploration, and decision-making processes, the influence of manipulations performed during the development of whiskers, on learning has been received little attention in the literature. This study aimed to evaluate the effect of tactile stimulation (TS) on spatial memory performance and neuronal density in the hippocampus during adulthood in early sensory-deprived rats. Wistar albino male rats were divided into four groups: control (CTL), bilateral whisker trimming (BWT), tactile stimulation (TS), and bilateral whisker trimming+tactile stimulation (BWT + TS). All whiskers were trimmed between P0-10, a critical period for whisker development. TS was applied from P3 to P21 using a soft brush. In this study, the 8-arm radial maze test was conducted from postnatal days 77 to 81 to assess spatial memory Animals sacrificed by intracardial perfusion and neuronal density in CA1, CA3, vDG, and dDG regions of the hippocampus were evaluated by Nissl staining. TS exposure negatively affected spatial memory performance and hippocampal neuronal density compared to BWT. We conclude that TS in healthy offspring can cause stress by interrupting maternal care, given the vulnerability of early development. On the contrary, the sensory deprivation protocol in this study was terminated at a time of high homeostatic plasticity and did not produce complete whisker deprivation, have triggered learning by inducing moderate stress early in development.