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Neuron. 2017 Jul 5;95(1):195-208.e9. doi: 10.1016/j.neuron.2017.05.023. Epub 2017 Jun 15.

Motor Cortical Visuomotor Feedback Activity Is Initially Isolated from Downstream Targets in Output-Null Neural State Space Dimensions.

Author information

1
Neurosciences Graduate Program, Stanford University, Stanford, CA 94305, USA. Electronic address: sstavisk@stanford.edu.
2
Electrical Engineering Department, Stanford University, Stanford, CA 94305, USA.
3
Electrical Engineering Department, Stanford University, Stanford, CA 94305, USA; Department of Neurosurgery, Palo Alto Medical Foundation, Palo Alto, CA 94301, USA.
4
Neurosciences Graduate Program, Stanford University, Stanford, CA 94305, USA; Electrical Engineering Department, Stanford University, Stanford, CA 94305, USA; Neurobiology and Bioengineering Departments, Stanford University, Stanford, CA 94305, USA; Bio-X Program, Stanford University, Stanford, CA 94305, USA; Stanford Neurosciences Institute, Stanford University, Stanford, CA 94305, USA; Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA.

Abstract

Neural circuits must transform new inputs into outputs without prematurely affecting downstream circuits while still maintaining other ongoing communication with these targets. We investigated how this isolation is achieved in the motor cortex when macaques received visual feedback signaling a movement perturbation. To overcome limitations in estimating the mapping from cortex to arm movements, we also conducted brain-machine interface (BMI) experiments where we could definitively identify neural firing patterns as output-null or output-potent. This revealed that perturbation-evoked responses were initially restricted to output-null patterns that cancelled out at the neural population code readout and only later entered output-potent neural dimensions. This mechanism was facilitated by the circuit's large null space and its ability to strongly modulate output-potent dimensions when generating corrective movements. These results show that the nervous system can temporarily isolate portions of a circuit's activity from its downstream targets by restricting this activity to the circuit's output-null neural dimensions.

KEYWORDS:

brain-machine interface; motor control; motor cortex; sensorimotor system; visuomotor feedback

PMID:
28625485
PMCID:
PMC5547570
DOI:
10.1016/j.neuron.2017.05.023
[Indexed for MEDLINE]
Free PMC Article

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