Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America.
Department of Mechanical Engineering, Colorado State University, Fort Collins, Colorado, United States of America.
PLoS One. 2020 Aug 7;15(8):e0237142. doi: 10.1371/journal.pone.0237142. eCollection 2020.
Electrical stimulation of nerve endings in the tongue can be used to communicate information to users and has been shown to be highly effective in sensory substitution applications. The anterior tip of the tongue has very small somatosensory receptive fields, comparable to those of the finger tips, allowing for precise two-point discrimination and high tactile sensitivity. However, perception of electrotactile stimuli varies significantly between users, and across the tongue surface. Despite this, previous studies all used uniform electrode grids to stimulate a region of the dorsal-medial tongue surface. In an effort to customize electrode layouts for individual users, and thus improve efficacy for sensory substitution applications, we investigated whether specific neuroanatomical and physiological features of the tongue are associated with enhanced ability to perceive active electrodes. Specifically, the study described here was designed to test whether fungiform papillae density and/or propylthiouracil sensitivity are positively or negatively associated with perceived intensity and/or discrimination ability for lingual electrotactile stimuli. Fungiform papillae number and distribution were determined for 15 participants and they were exposed to patterns of electrotactile stimulation (ETS) and asked to report perceived intensity and perceived number of stimuli. Fungiform papillae number and distribution were then compared to ETS characteristics using comprehensive and rigorous statistical analyses. Our results indicate that fungiform papillae density is correlated with enhanced discrimination ability for electrical stimuli. In contrast, papillae density, on average, is not correlated with perceived intensity of active electrodes. However, results for at least one participant suggest that further research is warranted. Our data indicate that propylthiouracil taster status is not related to ETS perceived intensity or discrimination ability. These data indicate that individuals with higher fungiform papillae number and density in the anterior medial tongue region may be better able to use lingual ETS for sensory substitution.
舌部神经末梢的电刺激可用于向使用者传递信息，并且在感觉替代应用中已被证明非常有效。舌尖具有非常小的躯体感觉感受野，与指尖相当，可实现精确的两点辨别和高触觉灵敏度。然而，电触觉刺激的感知在不同使用者之间以及舌表面的不同位置存在显著差异。尽管如此，之前的研究都使用统一的电极网格来刺激舌背-中侧表面的区域。为了针对个体用户定制电极布局，从而提高感觉替代应用的效果，我们研究了舌部的特定神经解剖学和生理学特征是否与增强感知主动电极的能力有关。具体来说，这里描述的研究旨在测试舌部的乳突密度和/或丙硫氧嘧啶敏感性是否与舌部电触觉刺激的感知强度和/或辨别能力呈正相关或负相关。研究确定了 15 名参与者的乳突数量和分布，并使他们接触电触觉刺激（ETS）模式，并要求他们报告感知强度和感知刺激数量。然后，使用全面和严格的统计分析将乳突数量和分布与 ETS 特征进行比较。我们的研究结果表明，乳突密度与电刺激的辨别能力增强相关。相比之下，乳突密度平均而言与主动电极的感知强度无关。但是，至少有一个参与者的结果表明，需要进一步研究。我们的数据表明，丙硫氧嘧啶味觉者的状态与 ETS 的感知强度或辨别能力无关。这些数据表明，在前侧舌中部区域乳突数量和密度较高的个体可能更能够使用舌部 ETS 进行感觉替代。
