Targeted neuroplasticity in rat primary auditory cortex with vagus nerve stimulation and near-threshold tones

摘要

Vagus nerve stimulation (VNS) is a method for driving therapeutic, targeted neuroplasticity in clinical populations suffering from tinnitus and stroke. VNS facilitates specific cortical changes through the phasic release of plasticity promoting neuromodulators simultaneously paired with delivery of a sensory stimulus, such as tones or speech. Recent clinical evidence and ongoing pre-clinical experiments in rats show that VNS paired with near-threshold somatosensation of the hand/paw can significantly reduce elevated sensory thresholds resulting from neural injuries after only one week of therapy. A possible explanation for this quick and robust recovery is that VNS is more effective at driving neuroplasticity in cortical circuits when paired with stimuli just above the response threshold of neural receptive fields. To date, all auditory VNS therapies have used stimuli considerably above auditory thresholds, potentially diminishing the therapeutic effect of VNS-paired treatments. To test the effectiveness of VNS-paired, near-threshold stimuli in driving auditory neuroplasticity, unimpaired adult rats will receive VNS repeatedly paired with the brief presentation of a 10 dB SPL 9 kHz tone for one week. A cortical map of receptive field properties in primary auditory cortex will be made one day later and compared to the maps of naive rats.