Development of a Piezoelectric Actuated Tactile Stimulation Device for Population Receptive Field Mapping in Human Somatosensory Cortex With fMRI

Abstract

Background: Multichannel tactile stimulation devices is need to investigate human finger population receptive field (pRF) characteristics in the primary somatosensory cortex during functional magnetic resonance imaging (fMRI).

Purpose: To accurately characterize right-hand somatosensory representation based on the Bayesian pRF model.

Study type: Prospective.

Population: A water phantom and six healthy participants (four males, mean 23.8 years old).

Field strength/sequence: T1-weighted magnetization-prepared rapid gradient-echo, T2*-weighted echo planar imaging at 3 T.

Assessment: The piezoelectric actuated tactile stimulation device consisted of execution unit and control unit. The output performance of the device was measured by a laser displacement sensor. The effect of the device on images' signal-to-noise ratio (SNR) was measured by phantom experiments. The activation representation arrangement order, relative volumes, and receptive field size of the right hand were assessed during the along-digits and cross-digits paradigms.

Statistical tests: The normality of the data was tested by the Shapiro-Wilk method. A paired-sample t test was performed to test pRF characteristics for all digit pairings. The significance level was set to P = 0.05 (false discovery rate [FDR] correct).

Results: Percussive stimulation provided by the piezoelectric actuated tactile stimulator had a stable displacement (2.64 mm) over a wide range of vibration frequencies (0-30 Hz). The output delay of the device was 1 millisecond. The device did not affect the image's SNR (without the device: SNR = 138.24 ± 7.87, temporal SNR [TSNR] = 440.03 ± 52.08. With the device: SNR = 138.06 ± 8.44, TSNR = 438.52 ± 56.38. P_SNR = 0.88, P_TSNR = 0.46). Representations of right-hand fingers showed the same arrangement order in both experiments (D1-D5 arranged along the central sulcus). However, the relative volumes of D3 showed significant differences in S1 (P = 0.003). Among four subareas, the relative volumes of D3 were significantly different in area 1 (P = 0.047).

Data conclusion: This developed stimulator, through experimental verification, could play a role in pRF mapping exploration.

Level of evidence: 2 TECHNICAL EFFICACY STAGE: 1.

Keywords: fMRI; piezoelectric actuated; population receptive field; primary somatosensory cortex; tactile stimulation device.