Studying the Effects of Deep Brain Stimulation and Medication on the Dynamics of STN-LFP Signals for Human Behavior Analysis

TL;DR

This study investigates how deep brain stimulation and medication influence the dynamics of STN-LFP signals for behavior recognition in Parkinson's disease patients, highlighting the potential for adaptive closed-loop DBS systems.

Contribution

It is the first to analyze behavior recognition accuracy from STN-LFP signals under different stimulation and medication conditions, revealing robustness of classification during stimulation.

Findings

Beta power is significantly suppressed by medication and stimulation.

Behavior classification accuracy remains around 85% during stimulation.

Support vector machines effectively predict actions from LFP spectrograms.

Abstract

This paper presents the results of our recent work on studying the effects of deep brain stimulation (DBS) and medication on the dynamics of brain local field potential (LFP) signals used for behavior analysis of patients with Parkinson s disease (PD). DBS is a technique used to alleviate the severe symptoms of PD when pharmacotherapy is not very effective. Behavior recognition from the LFP signals recorded from the subthalamic nucleus (STN) has application in developing closed-loop DBS systems, where the stimulation pulse is adaptively generated according to subjects performing behavior. Most of the existing studies on behavior recognition that use STN-LFPs are based on the DBS being off. This paper discovers how the performance and accuracy of automated behavior recognition from the LFP signals are affected under different paradigms of stimulation on/off. We first study the notion of beta power suppression in LFP signals under different scenarios (stimulation on/off and medication on/off). Afterward, we explore the accuracy of support vector machines in predicting human actions (button press and reach) using the spectrogram of STN-LFP signals. Our experiments on the recorded LFP signals of three subjects confirm that the beta power is suppressed significantly when the patients take medication (p-value<0.002) or stimulation (p-value<0.0003). The results also show that we can classify different behaviors with a reasonable accuracy of 85% even when the high-amplitude stimulation is applied.