Intra-cortical connectivity in multiple sclerosis: a neurophysiological approach.

Area of Science:

• Neuroscience
• Neurology
• Biophysics

Background:

• Multiple sclerosis (MS) is a central nervous system (CNS) autoimmune disease impacting white matter and causing cortical disconnection.
• Functional connectivity, reflected by neuronal firing synchronization, is crucial for cerebral region communication.

Purpose of the Study:

• To quantify intra-cortical connectivity (ICC) using magnetoencephalography (MEG) in primary somatosensory cortex (S1) of mild relapsing-remitting MS patients.
• To investigate the relationship between ICC, lesion load, and clinical/subclinical disease markers in early MS.

Main Methods:

• Magnetoencephalography (MEG) was used to calculate an ICC index in S1 of 21 mild RR-MS patients.
• 3D MRI quantified lesion load (black hole and non-black hole) normalized by brain volume.
• Patients were assessed for disability (EDSS), disease duration, sensory conduction time, and therapy.

Main Results:

• MS patients exhibited reduced ICC and loss of finger-specific functional specialization in S1 compared to controls.
• ICC impairment did not correlate with disease duration, spinal cord lesions, or current therapy.
• A slight correlation was observed between ICC and MRI-quantified lesion load.

Conclusions:

• Mildly disabled RR-MS patients show altered intrinsic cortical connectivity in S1, independent of clinical sensory deficits.
• Diffuse CNS damage in MS affects not only large-scale networks but also intrinsic cortical connectivity.
• The S1 ICC index is a sensitive functional measure for evaluating intra-cortical synchronization in early MS.