Tactile Sensory Responses in Motor Cortex and Their Relevance to Brain-Machine Interfaces.

[摘要] The loss of hand function is a distressing and debilitating experience. Brain-machine interfaces (BMIs) hold the potential to restore natural movement to those with limb loss and paralysis by obtaining prosthetic control signals directly from the brain. Cortical BMI performance lags behind advances in prosthetic hardware, which may be due to lack of sensory feedback to the user and incomplete understanding of how motor cortex processes and uses sensory information. In this thesis, we explore tactile sensory representation in primary motor cortex (M1) and its relevance to the refinement of upper limb BMI with three independent but related studies.The first study quantifies the frequency and robustness of tactile somatosensory responses within the same M1 cortical populations that are used for motor decoding. We show that M1 neurons are tuned to specific tactile fingertip inputs in both nonhuman primates and humans, and that units can be tuned differently to different sensory modalities. The modulation in firing rates is strong enough to interfere with motor decodes trained only on active motor tuning.The second study investigates the source of this information stream, and its importance to sensory perception, using ketamine anesthesia. We show that corticocortical communication of tactile information between sensory cortex (S1) and M1 is interrupted during anesthetic-induced unconsciousness. When viewed along with the literature, the data suggest that M1/S1 communication is necessary for accurate conscious perception of sensory inputs, further reinforcing the need for sensory feedback in BMI experiments to enable naturalistic motor planning and execution.The final study presents the design and testing of intracortical optogenetic stimulation devices for the further exploration of sensory processing, as well as the delivery of sensory feedback, by manipulation of specific neuronal subpopulations. We demonstrate that our implantable LED devices can safely drive neural activity in transgenic mice, and describe how they can be used to further refine closed-loop BMI.Overall, we have advanced our understanding of M1 tactile sensory processing and developed stimulation devices for continued progress toward high performance neuroprosthetic systems.

[发布机构] University of Michigan

[效力级别] Biomedical Engineering

[关键词] Tactile Sensory Responses in Motor Cortex and Their Relevance to Brain-Machine Interfaces;Biomedical Engineering;Engineering;Biomedical Engineering