Functional neuroimaging studies of human somatosensory cortex

Area of Science:

• Neuroscience
• Neuroimaging
• Somatosensory System

Background:

• Understanding the human somatosensory system is crucial for neuroscience.
• Echoplanar fMRI (functional Magnetic Resonance Imaging) at 3.0 Tesla offers potential for high-resolution brain activity analysis.

Purpose of the Study:

• To evaluate the applicability of echoplanar fMRI at 3.0 T for analyzing human somatosensory mechanisms.
• To investigate the detailed representation of tactile stimuli within the somatosensory cortex.

Main Methods:

• Two studies were conducted: one using vibrotactile stimulation of digits, the other combining microneurography with fMRI.
• Microneurography involved isolating, characterizing, and microstimulating individual median-nerve mechanoreceptive afferents during fMRI.
• Analysis focused on identifying activation clusters and their precise locations within somatosensory areas.

Main Results:

• Vibrotactile stimulation reliably activated primary (SI) and secondary (SII) somatosensory cortex, area 43, pre-central gyrus, insula, and parietal cortex.
• Digit-specific responses were separable in SI, reflecting the known somatotopic organization.
• fMRI combined with microneurography demonstrated robust, focal, and physiologically orderly hemodynamic responses.

Conclusions:

• Echoplanar fMRI at 3.0 T is a viable technique for detailed somatosensory system analysis in humans.
• This approach facilitates studies on body surface representation, tactile plasticity, and attentional effects.
• It also offers opportunities to investigate the BOLD (Blood-Oxygen-Level-Dependent) effect and optimize fMRI and EEG modalities.