Effect of vagus nerve stimulation on neural adaptation in thalamo-cortical system in rats.

Vagus nerve stimulation (VNS) is a therapy on medically refractory epilepsy, and recently reported to improve cognitive function including learning and memory. The thalamo-cortical system may underlie such VNS-induced cognitive improvements. Thus, the present study targeted the auditory cortex and thalamus in rats, and investigated whether and how VNS modulates stimulus-specific adaptation (SSA) of the neural activity in these nuclei. A depth electrode array recorded auditory evoked potentials from the auditory thalamus and cortex under an oddball paradigm either with or without VNS. Consequently, VNS weakened SSA in the cortex, but did not affect that in the thalamus, indicating that VNS has neuromodulatory effects on the cortical inhibitory system and the thalamo-cortical projections, but not on the feedforward projections from the auditory periphery up to thalamus.