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Abstract
The study of the cortical control of movement experienced a conceptual shift over recent decades, as the basic currency of understanding shifted from single-neuron tuning towards population-level factors and their dynamics. This transition was informed by a maturing understanding of recurrent networks, where mechanism is often characterized in terms of population-level factors. By estimating factors from data, experimenters could test network-inspired hypotheses. Central to such hypotheses are ‘output-null’ factors that do not directly drive motor outputs yet are essential to the overall computation. In this Review, we highlight how the hypothesis of output-null factors was motivated by the venerable observation that motor-cortex neurons are active during movement preparation, well before movement begins. We discuss how output-null factors then became similarly central to understanding neural activity during movement. We discuss how this conceptual framework provided key analysis tools, making it possible for experimenters to address long-standing questions regarding motor control. We highlight an intriguing trend: as experimental and theoretical discoveries accumulate, the range of computational roles hypothesized to be subserved by output-null factors continues to expand.
How does motor-cortex activity well before movement not drive motor outputs? In this Review, Churchland and Shenoy detail how searching for answers transitioned the understanding of neural activity during movement from single-neuron tuning towards population-level factors and revealed an essential computational role of output-null factors.
Details
; Shenoy, Krishna V. 2 1 Columbia University, Department of Neuroscience, New York, USA (GRID:grid.21729.3f) (ISNI:0000 0004 1936 8729); Columbia University, Grossman Center for the Statistics of Mind, New York, USA (GRID:grid.21729.3f) (ISNI:0000 0004 1936 8729); Columbia University, Kavli Institute for Brain Science, New York, USA (GRID:grid.21729.3f) (ISNI:0000 0004 1936 8729)
2 Stanford University, Department of Electrical Engineering, Stanford, USA (GRID:grid.168010.e) (ISNI:0000 0004 1936 8956); Stanford University, Department of Bioengineering, Stanford, USA (GRID:grid.168010.e) (ISNI:0000 0004 1936 8956); Stanford University, Department of Neurobiology, Stanford, USA (GRID:grid.168010.e) (ISNI:0000 0004 1936 8956); Stanford University, Department of Neurosurgery, Stanford, USA (GRID:grid.168010.e) (ISNI:0000 0004 1936 8956); Stanford University, Wu Tsai Neurosciences Institute, Stanford, USA (GRID:grid.168010.e) (ISNI:0000 0004 1936 8956); Stanford University, Bio-X Institute, Stanford, USA (GRID:grid.168010.e) (ISNI:0000 0004 1936 8956); Howard Hughes Medical Institute at Stanford University, Stanford, USA (GRID:grid.413575.1) (ISNI:0000 0001 2167 1581)