Response characteristics of barrel cortical neurons in layers IV/V of juvenile rats with autism-like traits after tactile stimulation

Abstract

The barrel cortex is a specialized region of the primary somatosensory cortex that processes tactile information from whiskers. This study investigates how tactile stimulation (TS) affects excitatory receptive fields and surrounds suppression in barrel cortex neurons of male and female autistic-like rats, using various whisker displacement protocols. The animals were categorized into control, Valproic acid pre-treated (Val), and Val-TS treatment groups. In male Val-TS rats, TS reduced layer IV ON/OFF amplitudes for principal and adjacent whisker displacements, while only OFF response latency to principal whisker displacement decreased. In females, Val group showed increased ON/OFF amplitudes, which decreased in Val-TS, returning to control levels. ON/OFF response latency to principal whisker displacement increased in Val-TS, returning to control. Tactile stimulation more effectively remodeled receptive fields and temporal timing in female barrel cortex. In layer V, male Val-TS rats showed no significant amplitude differences but decreased ON/OFF latencies to principal whisker displacement. Adjacent whisker responses were largely unchanged. In females, Val-TS rats had increased ON/OFF amplitudes to principal whisker displacement, but no latency changes. Adjacent whisker responses showed amplitude and latency differences, suggesting receptive-field expansion and remodeling. In terms of inhibitory responses, conditioning test (CT) ratio analysis indicated significant group effects for both ON and OFF responses in layer IV, with the Val-TS group showing higher CT-ratios than the Val and control groups for both sexes. Layer V responses indicated similar trends, with elevated CT-ratios in male rats under Val-TS conditions, whereas females did not show significant differences. Overall, these findings reveal distinct variations in responses of the barrel cortex neurons based on sex and treatment conditions, emphasizing the nuanced impact of interventions on neuronal responsiveness. This research enhances our understanding of sex-dependent neural adaptations and their implications for sensory processing and neuroplasticity in response to external stimuli.