Role of the Posterior Parietal Cortex in the Processing of Sensory Information

Study Overview
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Brief Summary
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Although the primary motor cortex is considered has the common final pathway of motor commands, it is influenced by several structures as, for example, the premotor cortex and the posterior parietal cortex which are involved in motor planning and programming and which integrates movement-induced sensory impute (parieto-frontal circuits). Several studies have shown that there are some direct functional connections between the premotor cortex and the posterior parietal cortex and from these two regions to the primary motor cortex. The posterior parietal cortex can then be considered as a sensorimotor interface whose function in planification and motor control of upper limb is well demonstrated. The hypothesis is that the posterior parietal cortex could participate to the modulation of motor cortex excitability by proprioceptive sensory inputs namely long latency afferent inhibition and afferent induced facilitation.

Official Title
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Role of the Posterior Parietal Cortex in the Processing of Sensory Information Modulating the Excitability of the Primary Motor Cortex in Humans

Conditions
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Healthy Subject

Intervention / Treatment
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* Device: Transcranial Magnetic Stimulation (TMS)
* Device: Electrical Muscle Activity (EMG)


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Right handed No neurological troubles Informed consent signed Affiliated to a social security Exclusion Criteria: Psychiatric antecedent Neurological disease Contra-indication to TMS Under psychiatric treatment Pregnancy Contra-indication to MRI

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 40 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Healthy arm<br>posterior parietal cortex (PPC) transitory inactivation | Device: Transcranial Magnetic Stimulation (TMS)<br>* Transitory inactivation of the posterior parietal cortex and measure of sensorimotor integration.<br>Device: Electrical Muscle Activity (EMG)<br>* Electrodes for the collection of EMG activity will be glued on the skin next to the first interosseus dorsalis muscle, the Abductor digiti minimi, the Extensor carpi radialis and the Abductor pollicis brevis. EMG signals will be stored on computer for off-line analysis using Signal © software (Cambridge Electronic Design, Cambridge, UK)<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Afferent induced facilitation | Motor cortex facilitation following median nerve stimulation at interstimulus intervals of 70ms | Baseline | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Interaction between long latency afferent inhibition and long latency intracortical inhibition (LICI) | Effect of median nerve stimulation on LICI at 100ms interval | Baseline |