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Corticospinal Excitability Modulation During Action Observation
Published on: December 31, 2013
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A somato-cognitive action network alternates with effector regions in motor cortex
Evan M Gordon1, Roselyne J Chauvin2, Andrew N Van2,3
1Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, MO, USA. egordon@wustl.edu.
Nature
|April 19, 2023
Summary
The motor cortex (M1) is not a continuous homunculus but features distinct regions for action planning, called the somato-cognitive action network (SCAN), alongside effector-specific areas for fine motor control.
Area of Science:
- Neuroscience
- Cognitive Neuroscience
- Neuroimaging
Background:
- The motor cortex (M1) was traditionally viewed as a continuous somatotopic map (homunculus) for motor control.
- Emerging evidence suggested functional zones and maps for complex actions, challenging the simple homunculus model.
- The role of M1 in integrating action planning with physiological control and arousal remained incompletely understood.
Purpose of the Study:
- To investigate the detailed functional organization of the human motor cortex (M1) using high-resolution fMRI.
- To identify and characterize distinct functional regions within M1 beyond the classic somatotopic representation.
- To explore the connectivity, structure, and function of these regions and their relation to action planning and control.
Main Methods:
- Utilized precision functional magnetic resonance imaging (fMRI) on human participants across multiple large datasets.
- Conducted cross-species (macaque) and developmental (pediatric) fMRI studies to examine evolutionary and developmental aspects.
- Employed a battery of motor and action fMRI tasks, alongside analysis of cortical thickness and functional connectivity.
Main Results:
- Discovered that M1 is interrupted by distinct inter-effector regions, alternating with effector-specific (foot, hand, mouth) areas.
- These inter-effector regions show decreased cortical thickness, strong functional connectivity with each other, and link to the cingulo-opercular network (CON).
- Identified these inter-effector regions as part of a proposed somato-cognitive action network (SCAN), involved in action planning and whole-body movement, lacking specific movement representation.
Conclusions:
- The motor cortex (M1) comprises two intertwined systems: effector-specific regions for fine motor control and the SCAN for integrated action planning.
- The SCAN integrates goals, physiology, and body movement, challenging the traditional view of M1 as solely a somatotopic map.
- Evidence suggests cross-species and developmental precursors of this SCAN system, highlighting its fundamental role in motor control.
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