Decoding unconstrained arm movements in primates using high-density electrocorticography signals for brain-machine interface use

Kejia Hu,Mohsen Jamali,Ziev B Moses,Carlos A Ortega,Wendong Xu,Ziv M Williams,Gabriel N Friedman

doi:10.1038/s41598-018-28940-7

Abstract

Motor deficit is among the most debilitating aspects of injury to the central nervous system. Despite ongoing progress in brain-machine interface (BMI) development and in the functional electrical stimulation of muscles and nerves, little is understood about how neural signals in the brain may be used to potentially control movement in one’s own unconstrained paralyzed limb. We recorded from high-density electrocorticography (ECoG) electrode arrays in the ventral premotor cortex (PMv) of a rhesus macaque and used real-time motion tracking techniques to correlate spatial-temporal changes in neural activity with arm movements made towards objects in three-dimensional space at millisecond precision. We found that neural activity from a small number of electrodes within the PMv can be used to accurately predict reach-return movement onset and directionality. Also, whereas higher gamma frequency field activity was more predictive about movement direction during performance, mid-band (beta and low gamma) activity was more predictive of movement prior to onset. We speculate these dual spatiotemporal signals may be used to optimize both planning and execution of movement during natural reaching, with prospective relevance to the future development of neural prosthetics aimed at restoring motor control over one’s own paralyzed limb.

Highlights

Motor paralysis can be secondary to a disruption in the neural pathways between the brain and muscle without disrupting normal cognitive ability
Most previous brain-machine interface (BMI) approaches have focused on the primary motor cortex (M1) as an area of brain signals for recording neural activity during movement, at it has been found to be directly relevant to movement execution and motor imagery[5,6,7,8]
Two rhesus macaques were trained to perform the functionally unconstrained reach-return arm movements, while high-density ECoG or local field potential (LFP) signals were recorded from the PMv area (Fig. 1, see Methods)

Summary

Introduction

Motor paralysis can be secondary to a disruption in the neural pathways between the brain and muscle without disrupting normal cognitive ability. Most previous BMI approaches have focused on the primary motor cortex (M1) as an area of brain signals for recording neural activity during movement, at it has been found to be directly relevant to movement execution and motor imagery[5,6,7,8]. Unconstrained functional movements are involved in higher level cognitive aspects of motor control such as decision making, movement selection, and planning, and require complex interactions between multiple sensory, cognitive, and motor areas. ECoG signals provide long-term stability and less invasive surgical procedures than surgeries to implant microelectrodes, which require penetrating the cortex to obtain single-unit neuron activity and local field potentials[22]. Movements may be characterized with significant confusion and may be deemed inadequate for multi-degrees-of-freedoms (DOF) decoding, which is crucial to restoring functionally unconstrained movement

Objectives

Methods

Results

Discussion

Conclusion