Cortical Representation of Ipsilateral Arm Movements in Monkey and Man

Abstract

A fundamental organizational principle of the primate motor system is cortical control of contralateral limb movements. Motor areas also appear to play a role in the control of ipsilateral limb movements. Several studies in monkeys have shown that individual neurons in primary motor cortex (M1) may represent, on average, the direction of movements of the ipsilateral arm. Given the increasing body of evidence demonstrating that neural ensembles can reliably represent information with a high temporal resolution, here we characterize the distributed neural representation of ipsilateral upper limb kinematics in both monkey and man. In two macaque monkeys trained to perform center-out reaching movements, we found that the ensemble spiking activity in M1 could continuously represent ipsilateral limb position. Interestingly, this representation was more correlated with joint angles than hand position. Using bilateral electromyography recordings, we excluded the possibility that postural or mirror movements could exclusively account for these findings. In addition, linear methods could decode limb position from cortical field potentials in both monkeys. We also found that M1 spiking activity could control a biomimetic brain-machine interface reflecting ipsilateral kinematics. Finally, we recorded cortical field potentials from three human subjects and also consistently found evidence of a neural representation for ipsilateral movement parameters. Together, our results demonstrate the presence of a high-fidelity neural representation for ipsilateral movement and illustrates that it can be successfully incorporated into a brain-machine interface.

Gain Field Encoding of the Kinematics of Both Arms in the Internal Model Enables Flexible Bimanual Action

“…Interestingly, movement of the ipsilateral arm also modifies the activity of neurons in these motor areas (Donchin et al, 1998;Cisek et al, 2003;Ganguly et al, 2009). Therefore, when the left arm is adapted to a force field while the right arm is being moved in a particular direction, the representation of the force field is constructed specifically for the right-arm movement direction.…”

Development of an invasive brain-machine interface with a monkey model

“…In the 1980s, Georgopoulos et al [34,35] constructed a standard center-out task, in which monkeys were trained to move a lightweight, frictionless joystick to capture one in eight randomly lighted targets to obtain a liquid reward. This paradigm has been improved and employed in many BMI studies to research forelimb movement in later 30 years [36,37]. Some other paradigms are also developed for decoding the movement trajectory of monkey arm, hand or finger [38].…”

Muscle synergies after stroke are correlated with perilesional high gamma

“…We also tested and did not find any evidence for significant correlation with other frequency bands (i.e. δ = 1–4 Hz, θ = 4–8 Hz, α = 8–12 Hz, β = 18–26 Hz, low γ = 30–50 Hz11, 12, 13). …”