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Measuring and Manipulating Functionally Specific Neural Pathways in the Human Motor System with Transcranial Magnetic Stimulation
Published on: February 23, 2020
Functional connectivity in human cortical motor system: a cortico-cortical evoked potential study
Riki Matsumoto1, Dileep R Nair, Eric LaPresto
1Department of Neurology, The Cleveland Clinic Foundation, Cleveland, OH 44195, USA.
Brain : a Journal of Neurology
|October 19, 2006
Summary
This study mapped human motor cortex connections using cortico-cortical evoked potentials (CCEPs). CCEPs revealed a reciprocal motor network linking medial and lateral motor cortices, crucial for understanding motor control and epilepsy spread.
Area of Science:
- Neuroscience
- Motor System Connectivity
- Human Brain Mapping
Background:
- Understanding the motor system's functional organization requires knowledge of cortico-cortical connections.
- In vivo human neuronal connectivity data is limited, hindering clinical and research insights.
- Cortico-cortical evoked potential (CCEP) offers a method to electrically track these connections.
Purpose of the Study:
- To investigate in vivo cortico-cortical connections between the lateral motor cortex (LMCx) and medial motor cortex (MMCx) in humans.
- To characterize the anatomical and functional connectivity within the human motor network.
- To assess the reciprocal nature of connections between LMCx and MMCx.
Main Methods:
- Applied CCEP methodology in seven epilepsy patients with subdural electrodes covering frontal motor areas.
- Performed electrical stimulation of MMCx and LMCx, recording evoked potentials.
- Utilized MRI co-registration for precise electrode localization and regression analysis for connectivity patterns.
Main Results:
- Short-latency CCEPs were observed between LMCx and MMCx in both stimulation directions (mean latencies 21.6 ms and 29.4 ms).
- A consistent correlation was found between stimulation sites and CCEP responses along the rostrocaudal axis.
- Stimulation of motor areas elicited CCEPs in somatotopically homologous regions (71% LMCx to MMCx, 82% MMCx to LMCx), with high reciprocality (78-94%).
Conclusions:
- Demonstrated a human motor cortico-cortical network connecting LMCx and MMCx.
- Established connectivity along the rostrocaudal cognitive-motor gradient and between somatotopically homologous regions.
- Confirmed the reciprocal nature of these connections, vital for motor control and understanding epileptic network dynamics.
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