Wang Chenyu, Imai Hirohiko, Fukunaga Masaki, Yamamoto Hiroki, Yu Yinghua, Seki Kazuhiko, Hanakawa Takashi, Umeda Tatsuya, Yang Jiajia
Graduate School of Interdisciplinary Science and Engineering in Health Systems, Okayama University, Okayama, Japan.
Innovation Research Center for Quantum Medicine, Gifu University School of Medicine, Gifu, Japan.
NMR Biomed. 2025 Sep;38(9):e70105. doi: 10.1002/nbm.70105.
Common marmosets (Callithrix jacchus), small-bodied New World primates that share similar sensory processing pathways with human beings, have gained great interests. Their small body size allows imaging of brain activity with high spatial resolution and on a whole-brain scale using ultrahigh-field (UHF) magnetic resonance imaging (MRI) scanners. However, the strong magnetic field and the small size of the hand and forearm pose challenges in delivering tactile stimulation during fMRI experiments. In the present study, we developed an MR-compatible tactile dual-point stimulator to provide high-precision mechanical stimulation for exploring somatosensory processing in small-bodied animals. The study population consisted of a water phantom and three male common marmosets. Cerebral blood volume (CBV) weighted fMRI data were obtained with a gradient echo (GE), echo-planar imaging (EPI) sequence at 7T scanner. The output performance of the device was tested by a pressure sensor. The MR compatibility of the device was verified by measuring the temporal signal-to-noise ratio (tSNR) of a water phantom. To test the effectiveness of tactile stimulation, we conducted block designed tactile stimulation experiments on marmosets. A one-way repeated measures ANOVA was conducted for comparing the tSNR results. We performed one-sample t-tests to investigate the negative response of the forearm and hand stimulation with a threshold of t > 1.96 (p < 0.05). Performance tests revealed that mechanical stimulation (averaged force: 31.69 g) was applied with a delay of 12 ms. Phantom experiments confirmed that there was no significant difference in the tSNR among three (10 Hz, 1 Hz, and no-stimulus) conditions (F (2, 798) = 0.71, p = 0.49). The CBV activity results showed that the stimulator successfully elicited hand and forearm somatosensory activations in primary somatosensory areas. These results indicated that the device is well suited for small-bodied animal somatosensory studies.
普通狨猴（绢毛猴）是一种小型新大陆灵长类动物，其感觉处理途径与人类相似，因此备受关注。它们体型小，能够使用超高场（UHF）磁共振成像（MRI）扫描仪在全脑尺度上以高空间分辨率对大脑活动进行成像。然而，强磁场以及手部和前臂的小尺寸给功能磁共振成像（fMRI）实验中的触觉刺激传递带来了挑战。在本研究中，我们开发了一种与磁共振兼容的触觉双点刺激器，以提供高精度的机械刺激，用于探索小型动物的体感处理。研究对象包括一个水模体和三只雄性普通狨猴。在7T扫描仪上使用梯度回波（GE）、回波平面成像（EPI）序列获取脑血容量（CBV）加权的fMRI数据。通过压力传感器测试该设备的输出性能。通过测量水模体的时间信噪比（tSNR）来验证该设备的磁共振兼容性。为了测试触觉刺激的有效性，我们对狨猴进行了分组设计的触觉刺激实验。进行单因素重复测量方差分析以比较tSNR结果。我们进行单样本t检验，以研究前臂和手部刺激的负反应，阈值为t > 1.96（p < 0.05）。性能测试表明，施加的机械刺激（平均力：31.69克）延迟为12毫秒。模体实验证实，在三种条件（10Hz、1Hz和无刺激）下tSNR没有显著差异（F(2, 798) = 0.71，p = 0.49）。CBV活动结果表明，该刺激器成功地在初级体感区域引发了手部和前臂的体感激活。这些结果表明，该设备非常适合小型动物的体感研究。
