Electrocorticographic Encoding of Human Gait in the Leg Primary Motor Cortex

Abstract

While prior noninvasive (e.g., electroencephalographic) studies suggest that the human primary motor cortex (M1) is active during gait processes, the limitations of noninvasive recordings make it impossible to determine whether M1 is involved in high-level motor control (e.g., obstacle avoidance, walking speed), low-level motor control (e.g., coordinated muscle activation), or only nonmotor processes (e.g., integrating/relaying sensory information). This study represents the first invasive electroneurophysiological characterization of the human leg M1 during walking. Two subjects with an electrocorticographic grid over the interhemispheric M1 area were recruited. Both exhibited generalized γ-band (40-200 Hz) synchronization across M1 during treadmill walking, as well as periodic γ-band changes within each stride (across multiple walking speeds). Additionally, these changes appeared to be of motor, rather than sensory, origin. However, M1 activity during walking shared few features with M1 activity during individual leg muscle movements, and was not highly correlated with lower limb trajectories on a single channel basis. These findings suggest that M1 primarily encodes high-level gait motor control (i.e., walking duration and speed) instead of the low-level patterns of leg muscle activation or movement trajectories. Therefore, M1 likely interacts with subcortical/spinal networks, which are responsible for low-level motor control, to produce normal human walking.

Configuration of electrical spinal cord stimulation through real-time processing of gait kinematics

“…Gait events can also be detected from brain signals that encode movement. A range of different electrophysiological techniques can be used to decode gait parameters, including non-invasive EEG recordings [50][51][52][53] , electrocorticographic (ECoG) signals recorded using electrodes positioned on the cortical surface 25,54,55 , and local field potentials and action potentials of neuronal ensembles recorded using electrodes implanted into the cortex 8,56,57 . Generally, the decoding accuracy and robustness increase with the increasing spatial resolution .…”

Cyclic movement execution and its influence on motor programmess

“…Examples of ALM are walking, front crawl and back bar pull-ups. One paper that studied walking drew a number of conclusions that coincide with those presented [9] in that walking is an extremely individual form of locomotion, both in kinematics, dynamics, kinetics and EMG of muscle activity, in which either flexor or extensor muscles can dominate. Additionally, the paper noted that inter-individual differences in walking motor control cannot be distinguished by studying standard walking modes, such as step speed and number.…”

“…Based on the walking study and the presented results, it can be assumed that whole-body cyclic movements are regulated by a cascade of central rhythm generators, each of which controls the movements of only a certain segment or extremity. General coordination is carried out on central motor command from the higher structures of central nervous system, in particular from the motor cortex [9]. In ontogenesis, walking is no doubt formed very early, while rowing is trained much later.…”

Cortical Oscillations during Gait: Wouldn’t Walking Be So Automatic?

“…Beta-band power increases in scalp EEG data are related to movement suppression or more probably to sensorimotor integration of the movement since this synchronization disappears when sensory information is disrupted [69]. Recently, electrocortigraphic recordings in two subjects pointed out the precise role of the primary motor cortex (M1) in gait pattern generation [70]. Mu, beta, and gamma oscillations were recorded during steady gait and gait across multiple walking speeds.…”