The Electrocorticogram Signal Can Be Modulated With Deep Brain Stimulation of the Subthalamic Nucleus in the Hemiparkinsonian Rat

Lehmkuhle MJ, Bhangoo SS, Kipke DR. The electrocorticogram signal can be modulated with deep brain stimulation of the subthalamic nucleus in the hemiparkinsonian rat. J Neurophysiol 102: 1811-1820, 2009. First published July 22, 2009; doi: 10.1152/jn.90844.2008. Electrocorticogram (ECoG) recordings of the 6-hydroxydopamine (6-OHDA)- lesioned parkinsonian rat have shown an increase in the power of cortical beta-band (15-30 Hz) oscillations ipsilateral to the lesion. The power of these oscillations is decreased with dopamine agonist administration. Here, we demonstrate that stimulation of an electrode implanted in the subthalamic nucleus alters the power of cortical beta and gamma oscillations in 6-OHDA-lesioned animals. These alterations are dependent on stimulation frequency, charge, and amplitude/pulse width. Oscillations were significantly reduced during 200- and 350-Hz stimulation. A minimum charge of 4 nC was required to elicit a reduction in oscillation power. A number of amplitude and pulse width combinations that reached 4 nC were tested; it was found that only the combinations of 33 mu A/120 mu s and 65 mu A/60 mu s significantly reduced cortical oscillations. The reduction in beta/gamma oscillation power due to deep brain stimulation (DBS) was consistent with a significant reduction in the animals' rotational behavior, a typical symptom of parkinsonism in the rat. A significant shift from high beta to low gamma was observed in the peak frequencies of ECoG recordings while animals were at rest versus walking on a treadmill. However, DBS exhibited no differential effect on oscillations between these two states. EEG recordings from rodent models of DBS may provide surrogate information about the neural signatures of Parkinson's disease relative to the efficacy of DBS.