Multiple frequency functional connectivity in the hand somatosensory network: an EEG study.

Area of Science:

• Neuroscience
• Systems Neuroscience
• Computational Neuroscience

Background:

• The primary somatosensory cortex processes tactile information, but its communication dynamics are not fully understood.
• Non-invasive methods are crucial for studying human brain networks in vivo.

Purpose of the Study:

• To investigate the communication dynamics within the primary somatosensory neuronal network.
• To differentiate transmission properties in low (LF) and high (HF) frequency ranges of somatosensory evoked responses.

Main Methods:

• Multichannel EEG recorded median nerve stimulation in six healthy participants.
• Functional Source Separation (FSS) identified five neuronal nodes (brainstem, thalamus, sensorimotor cortex).
• Partial Directed Coherence (PDC) assessed directional connectivity in LF (1-200 Hz) and HF (450-750 Hz) ranges.

Main Results:

• LF forward connectivity showed peaks at 16, 20, 30, and 50 ms post-stimulus, modulated by feedback.
• HF forward connectivity peaked at 20, 30, and 50 ms with no apparent feedback modulation.
• Directional connectivity was documented across subcortical and cortical somatosensory pathways.

Conclusions:

• This study provides the first non-invasive human documentation of directional somatosensory pathway connectivity.
• The combined use of FSS and PDC clarifies the functional interplay of LF and HF components in somatosensory perception.
• These frequency components may serve as potential biomarkers for pathological conditions.