This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. In mammals the motor cortex plays a crucial role in controlling limb movements. After losing connections between motor cortex and muscles (as in spinal cord injury or lesions of the corticospinal tract) primates lose their ability to voluntarily activate limb muscles, although cortex and muscles may still be functional. Toward testing whether this gap can be bridged with an artificial connection, we have developed an implantable 'brain-computer interface' [BCI]. A miniature computer chip amplifies and detects the activity of a cortical neuron recorded through an implanted movable electrode, and a second chip records EMG activity of 2 arm muscles. The neural and muscle activity patterns during free behavior are stored for subsequent download via an infrared interface. We found that the correlations between motor cortex cells and arm muscles are significantly different while the monkey moves freely about the home cage than during controlled movement tasks in the recording booth. The BCI can also operate in a recurrent mode, converting the recorded action potentials to stimulus pulses delivered to an adjacent site in the motor cortex. Continuous operation of this artificial recurrent connection has produced consistent changes in the output effects evoked by microstimulation of the connected sites. Future applications of the recurrent BCI will deliver stimuli to forearm muscles or spinal cord sites. By leaving this artificial feedback loop in place chronically we will study the monkeys' ability to incorporate this additional new circuit into normal behavior. If successful, the recurrent BCI would have clinical applications to aid patients paralyzed by ALS or spinal injury to regain some motor control directly from cortical cells.
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