Randomized cortical stimulation could ameliorate locomotive inability in Parkinsonian rats: a pilot study

OBJECTIVE Parkinson's disease (PD) is a neurodegenerative disease for which there is no known cure. Deep brain stimulation (DBS) is a surgical treatment effective in reducing motor symptoms for PD patients. Previous work implicates DBS may directly influence motor cortex through stochastic antidromic spikes originating from the site of stimulation. Here we tested the hypothesis that direct randomized cortical stimulation is therapeutically effective in PD animal models. APPROACH As a proof-of-principle study, we utilized a multi-channel stimulating system to mimic the effects of stochastic antidromic activation on the motor cortex of rat, by delivering microcurrents randomized temporally and spatially, and assessed the efficacy in ameliorating motor symptoms in a rat PD model. MAIN RESULTS We found that different combinations of frequency, amplitude and pulse width of randomized electrical currents delivered to the motor cortex exerted different effects on Parkinsonian rats. Among these, some stimulus patterns, defined by specific ranges of pulse width and stimulation frequencies, were able to produce transient beneficial effect on locomotive ability assessed by open-field locomotor activities. These results indicate that, in principle, cortical stimulation could achieve therapeutic outcome in PD. SIGNIFICANCE Direct cortical simulation based on a randomized protocol could be a less invasive approach than standard DBS in treating Parkinsonism. More refined mode of stimulation to achieve long-lasting and more robust effect should be explored.