Frequency-specific optogenetic deep brain stimulation of subthalamic nucleus improves Parkinsonian motor behaviors

Document Type

Article

Publication Date

4-14-2020

Department

Department of Biological Sciences

Abstract

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is an effective therapy for the motor symptoms of Parkinson's disease (PD). However, the neural elements mediating symptom relief are unclear. A previous study concluded that direct optogenetic activation of STN neurons was neither necessary nor sufficient for relief of parkinsonian symptoms. However, the kinetics of the ChR2 used for cell-specific activation are too slow to follow the high rates required for effective DBS, and thus the contribution of activation of STN neurons to the therapeutic effects of DBS remains unclear. We quantified the behavioral and neuronal effects of optogenetic STN DBS in female rats following unilateral 6-hydroxydopamine lesion using an ultrafast opsin (Chronos). Optogenetic STN DBS at 130 pulses per second reduced pathological circling and ameliorated deficits in forelimb stepping similarly to electrical DBS, while optogenetic STN DBS with ChR2 did not produce behavioral effects. As with electrical DBS, optogenetic STN DBS exhibited a strong dependence on stimulation rate; high rates produced symptom relief while low rates were ineffective. High rate optogenetic DBS generated both increases and decreases in firing rates of single neurons in STN, globus pallidus externa and substantia nigra pars reticular (SNr), and disrupted beta band oscillatory activity in STN and SNr. High rate optogenetic STN DBS can indeed ameliorate parkinsonian motor symptoms through reduction of abnormal oscillatory activity in the STN-associated neural circuit, and these results highlight that the kinetic properties of opsins have a strong influence on the effects of optogenetic stimulation.

Publication Title

The Journal of neuroscience : the official journal of the Society for Neuroscience

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