Comparison of neural responses to whisker and ultrasound stimulation using a novel dual-stimulation protocol

The sensory system allows organisms to perceive and respond to environmental stimuli. This study investigates neural response differences between whisker and ultrasound stimulation in rats to evaluate cortical specificity to sensory inputs.

A novel dual-stimulation protocol combining a step motor and ultrasound system was developed to alternately stimulate the C2 whisker and corresponding barrel column region. Experiments were conducted under varying stimulation sequences (whisker-ultrasound and ultrasound-whisker) and time intervals (10 ms, 25 ms, and 100 ms). Neural response signals were recorded, and statistical analyses (ANOVA and T-test) were performed to compare response amplitudes and peak latencies.

Whisker stimulation consistently elicited significantly stronger neural responses than ultrasound stimulation (*p < 0.05), regardless of sequence or interval. The efficiency of neural responses to ultrasound was closely tied to frequency, with higher frequencies producing greater amplitudes and faster latencies. Notably, at a 25 ms interval in the ultrasound-whisker sequence, whisker responses were significantly enhanced compared to whisker stimulation alone, suggesting a pre-activation effect of ultrasound.

Unlike single-modal whisker or ultrasound stimulation, the dual-stimulation protocol can enhance sensory responses, highlighting its neuromodulatory potential.

This study reveals distinct cortical activation patterns induced by whisker and ultrasound stimulation. While whisker stimulation is more sensitive, ultrasound stimulation-when optimized for frequency and timing-can effectively modulate neural responses under dual-stimulation protocol. These findings provide insights into ultrasound-based neuromodulation and sensory processing.