The full potential of HF DBS may not yet be realized as the neurophysiological basis of motor improvement during HF DBS is not well understood and there is no consensus as to the optimal site for the active electrode of the DBS lead in the STN region.Įvidence points to excessive synchronization of neuronal activity in the beta (8–35 Hz) frequency band as a possible pathophysiological marker of the Parkinsonian state: it is observed in the widespread sensorimotor network in Parkinsonian animals ( Nini et al., 1995 Bergman et al., 1998 Raz et al., 2000, 2001 Courtemanche et al., 2003) and in human patients with PD ( Brown et al., 2001 Marsden et al., 2001 Williams et al., 2002 Kuhn et al., 2005 Fogelson et al., 2006 Lalo et al., 2008 de Solages et al., 2010 Litvak et al., 2011). High frequency deep brain stimulation (HF DBS) in sensorimotor regions of the subthalamic nucleus (STN) provides patients with moderate to advanced PD a better quality of life than with medication alone ( Deuschl et al., 2006 Williams et al., 2010). Parkinson's disease (PD) is a progressive, debilitating neurological disease that is estimated to affect 6.3 million adults worldwide. The spatially-specific suppression of beta synchrony in the motor cortex support the hypothesis that DBS may treat Parkinsonism by reducing excessive synchrony in the functionally connected sensorimotor network. Cortical signals over the estimated origin of the HDP also demonstrated attenuation of beta hypersynchrony during DBS dorsal to or within STN, whereas signals from non-specific regions of motor cortex were not attenuated.
The degree of attenuation was monotonic with increased DBS voltages in both locations, but this voltage-dependent effect was greater in the central STN than dorsal to the STN ( p < 0.05). The results demonstrated that local beta power was attenuated during HF DBS both dorsal to and within the STN. We used diffusion tensor imaging (DTI) to guide the placement of subdural cortical surface electrodes over the DTI-identified origin of the hyperdirect pathway (HDP) between motor cortex and the STN. We measured local field potentials dorsal to and within the STN of PD patients, and additionally in the motor cortex in a subset of these patients. The present study examined the effect of STN HF DBS on neural synchrony within the cortico-basal ganglia network in patients with PD. Scalp EEG studies demonstrated that stimulation of the STN can activate motor cortex antidromically, but the spatial specificity of this effect has not been examined.
Additionally, the effect of STN HF DBS on neural synchrony in functionally connected regions of motor cortex is unknown and is of great interest. The optimal location of high frequency deep brain stimulation (HF DBS) within the subthalamic nucleus (STN) region and the location of maximal beta hypersynchrony are currently matters of debate. Parkinson's disease (PD) is marked by excessive synchronous activity in the beta (8–35 Hz) band throughout the cortico-basal ganglia network. 2Department of Neurosurgery, Stanford University, Stanford, CA, USA.1Department of Neurology and Neurological Sciences, Stanford University, Stanford, CA, USA.Henderson 2,1 and Helen Bronte-Stewart 1,2* Diane Whitmer 1, Camille de Solages 1, Bruce Hill 1, Hong Yu 2,1, Jaimie M.