Pneumatical-Mechanical Tactile Stimulation Device for Somatotopic Mapping of Body Surface During fMRI

Background: There is a need for devices that allow reproducible stimulation of skin areas of humans for investigating somatosensory mapping of the whole-body surface. However, their design is not simple, due to the magnetic field of MRI scanners. Purpose: To accurately characterize the mapping of somatosensory presentation of the whole-body surface of subjects during functional (f)MRI scans. Study Type: Prospective. Population: A water phantom and six healthy participants (age 23–27 years; two males) were recruited for the fMRI experiment. Field Strength/Sequence: T₁-weighted magnetization-prepared rapid acquisition gradient-echo, T₂*-weighted gradient echo sequence at 3T. Assessment: The stimulation device for somatotopic mapping was composed of three units: an air-generating unit, a control unit, and an execution unit. The fMRI in response to tactile stimulation was measured to characterize somatotopic mapping of the right-side body consisting of hand, arm, and leg in six healthy subjects. Statistical Tests: Pared-samples t-test for the conditions in SII. Results: The pneumatical-mechanical tactile stimulation offered a wide range of stimulation intensities (0–400 g) in each channel. The predetermined physical pressure was successfully reached within ~5 msec and returned to baseline within 5 msec after the end of stimulation. With this tactile device, the digressive rate of the signal-to-noise ratio (SNR) (271.44 without the device, 269.68 with the device) was 0.65% in the magnetic field environment. For the fMRI experiment, the primary somatosensory activation contralateral to the stimulation site was detected in response to spatial task and attentive task. Data Conclusion: This stimulation device characterized the mapping of somatosensory representation of the whole-body surface in individual participants during fMRI scans. Level of Evidence: 2. Technical Efficacy Stage: 1. J. Magn. Reson. Imaging 2020;52:1093–1101.