A Translatable System For Bi-directional Stimulation And Evoked Response Measurement To Enable Neuronal Network Exploration

Abstract

Neural stimulation therapies and neural sensing continues to evolve as new technologies are introduced into clinical practice. A major confound in these types of neural recordings is the contamination of the signal of interest with electrical stimulus artifact, which can obscure short latency evoked activity and corrupt spectral analysis of longer duration signals. Approach. Here we describe the design and early pre-clinical evaluation of a neurostimulator with improved capabilities for both sensing and stimulation, with particular emphasis on managing stimulus artifact. The system was tested in three ovine deep brain stimulation (DBS) subjects, one with a DBS lead targeting the hippocampus, and two with DBS leads targeting the subthalamic nucleus (STN). All leads were externalized with percutaneous lead extensions. Results demonstrate that it was possible to record evoked potentials with a latency of 1–2 ms following stimulation in all subjects with the new system. Recordings from the hippocampal target showed clear short-latency responses exhibiting behavior consistent with evoked compound action potentials (ECAPs). In contrast, recordings from the STN target demonstrated highly resonant activity, dependent upon stimulus frequency, which could persist for 20–30 ms following individual stimuli. Both directional stimulation and directional recordings were evaluated to determine their influence on this evoked resonant neural activity (ERNA). The system was also characterized for sensing in one spinal cord stimulation (SCS) ovine subject and one sacral nerve modulation (SNM) ovine subject.