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Extended practice of a motor skill is associated with reduced metabolic activity in M1.

Picard N, Matsuzaka Y, Strick PL - Nat. Neurosci. (2013)

Bottom Line: After extended practice, we observed a profound reduction of metabolic activity in M1 for the performance of internally generated compared to visually guided tasks.These findings suggest that the development of skill through extended practice results in a reduction in the synaptic activity required to produce internally generated, but not visually guided, sequences of movements.Thus, practice leading to skilled performance results in more efficient generation of neuronal activity in M1.

View Article: PubMed Central - PubMed

Affiliation: Center for the Neural Basis of Cognition and Systems Neuroscience Institute, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.

ABSTRACT
How does long-term training and the development of motor skills modify the activity of the primary motor cortex (M1)? To address this issue, we trained monkeys for ~1-6 years to perform visually guided and internally generated sequences of reaching movements. Then, we used [(14)C]2-deoxyglucose (2DG) uptake and single-neuron recording to measure metabolic and neuron activity in M1. After extended practice, we observed a profound reduction of metabolic activity in M1 for the performance of internally generated compared to visually guided tasks. In contrast, measures of neuron firing displayed little difference during the two tasks. These findings suggest that the development of skill through extended practice results in a reduction in the synaptic activity required to produce internally generated, but not visually guided, sequences of movements. Thus, practice leading to skilled performance results in more efficient generation of neuronal activity in M1.

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Single neuron activity in a penetration through an area of low 2DG uptake (N14). The rasters and histograms illustrate the activity of four neurons recorded in penetration “b” (see Fig. 3d). 2DG uptake at this site was relatively low (−3%). See Fig. 5 for conventions.
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Figure 6: Single neuron activity in a penetration through an area of low 2DG uptake (N14). The rasters and histograms illustrate the activity of four neurons recorded in penetration “b” (see Fig. 3d). 2DG uptake at this site was relatively low (−3%). See Fig. 5 for conventions.

Mentions: Our observation of a relative decrease in 2DG uptake in arm M1 for highly practiced sequences of movements raises a fundamental question — Is there a similar decrease in neuron activity in M1 for highly practiced sequences of movements? To answer this question, we recorded the activity of M1 neurons in two monkeys as they performed the Random and Repeating tasks. Then, we performed a 2DG experiment in the same monkeys to compare directly neuron activity and 2DG uptake. We have previously reported the results from recording single neuron activity in these animals during the Random and Repeating tasks20. Briefly, we recorded 234 task-related neurons in the proximal arm representation of M1. Many task-related neurons displayed changes in activity that were comparable during the two tasks. However, 40% of the task-related neurons were differentially active during the two tasks: 27% displayed enhanced activity during the Repeating task (e.g., Fig., 5, neuron #4; Fig. 6, neuron #4), and 12% displayed enhanced activity during the Random task. The discovery of such a substantial number of differential responses was part of the motivation for exploring the patterns of metabolic activity in the same animals during the Random and Repeating tasks.


Extended practice of a motor skill is associated with reduced metabolic activity in M1.

Picard N, Matsuzaka Y, Strick PL - Nat. Neurosci. (2013)

Single neuron activity in a penetration through an area of low 2DG uptake (N14). The rasters and histograms illustrate the activity of four neurons recorded in penetration “b” (see Fig. 3d). 2DG uptake at this site was relatively low (−3%). See Fig. 5 for conventions.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3757119&req=5

Figure 6: Single neuron activity in a penetration through an area of low 2DG uptake (N14). The rasters and histograms illustrate the activity of four neurons recorded in penetration “b” (see Fig. 3d). 2DG uptake at this site was relatively low (−3%). See Fig. 5 for conventions.
Mentions: Our observation of a relative decrease in 2DG uptake in arm M1 for highly practiced sequences of movements raises a fundamental question — Is there a similar decrease in neuron activity in M1 for highly practiced sequences of movements? To answer this question, we recorded the activity of M1 neurons in two monkeys as they performed the Random and Repeating tasks. Then, we performed a 2DG experiment in the same monkeys to compare directly neuron activity and 2DG uptake. We have previously reported the results from recording single neuron activity in these animals during the Random and Repeating tasks20. Briefly, we recorded 234 task-related neurons in the proximal arm representation of M1. Many task-related neurons displayed changes in activity that were comparable during the two tasks. However, 40% of the task-related neurons were differentially active during the two tasks: 27% displayed enhanced activity during the Repeating task (e.g., Fig., 5, neuron #4; Fig. 6, neuron #4), and 12% displayed enhanced activity during the Random task. The discovery of such a substantial number of differential responses was part of the motivation for exploring the patterns of metabolic activity in the same animals during the Random and Repeating tasks.

Bottom Line: After extended practice, we observed a profound reduction of metabolic activity in M1 for the performance of internally generated compared to visually guided tasks.These findings suggest that the development of skill through extended practice results in a reduction in the synaptic activity required to produce internally generated, but not visually guided, sequences of movements.Thus, practice leading to skilled performance results in more efficient generation of neuronal activity in M1.

View Article: PubMed Central - PubMed

Affiliation: Center for the Neural Basis of Cognition and Systems Neuroscience Institute, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.

ABSTRACT
How does long-term training and the development of motor skills modify the activity of the primary motor cortex (M1)? To address this issue, we trained monkeys for ~1-6 years to perform visually guided and internally generated sequences of reaching movements. Then, we used [(14)C]2-deoxyglucose (2DG) uptake and single-neuron recording to measure metabolic and neuron activity in M1. After extended practice, we observed a profound reduction of metabolic activity in M1 for the performance of internally generated compared to visually guided tasks. In contrast, measures of neuron firing displayed little difference during the two tasks. These findings suggest that the development of skill through extended practice results in a reduction in the synaptic activity required to produce internally generated, but not visually guided, sequences of movements. Thus, practice leading to skilled performance results in more efficient generation of neuronal activity in M1.

Show MeSH