NUMERICAL SIMULATIONS TO STUDY THE ROLE OF BIOMECHANICS IN TACTILE SENSATION

这个子项目是许多利用资源的研究子项目之一 由NIH/NCRR资助的中心拨款提供。子项目的主要支持 而子项目的主要调查员可能是由其他来源提供的， 包括其它NIH来源。 列出的子项目总成本可能 代表子项目使用的中心基础设施的估计数量， 而不是由NCRR赠款提供给子项目或子项目工作人员的直接资金。 研究生物力学在触觉中作用的数值模拟PI：Dr. Mandayam A. Srinivasan，主任，麻省理工学院触摸实验室摘要皮肤组织的生物力学在人类触觉机制中起着重要作用。当我们的手指与物体接触时，施加在指垫上的表面负荷被传递到皮肤组织中嵌入的神经末梢（机械感受器）。这些机械感受器产生机械信号的神经代码，使我们能够感觉到物体。与视觉和听觉机制不同，触觉编码机制的建模一直是一个挑战，至今仍是一个未解决的问题。为了更好地理解皮肤和物体之间的接触机制，必须很好地理解底层组织的机械特性。为了评估皮肤生物力学在触觉响应中的作用，二维（Srinivasan和Dandekar，1996年; Maeno等人，1998年）和三维有限元（FE）模型（Dandekar，Raju和Srinivasan，（2003年）的人和猴子指尖与现实的外部几何形状和内部分层结构的皮肤和皮下组织已开发使用线弹性模型的基础组织.这些模型使研究人员能够估计机械感受器位置的应激状态，并将其与机械感受器神经反应联系起来。Dandekar等人（2003）假设机械感受器位置处的应变能密度是SA-1机械感受器的相关刺激的良好候选者。本研究的3D有限元模拟使用NSF匹兹堡超级计算中心的资源进行。本研究是Dandekar等人（2003）基于纯弹性材料模型所做工作的后续研究。本研究的目的是开发粘弹性有限元模型（使用ADINA）的灵长类动物的手指能够预测率依赖性机械感受器响应动态负载。除此之外，我们将利用类似的方法来研究一种新的模式生物，线虫，秀丽隐杆线虫的生物力学。我们最近完成了实验，以表征灵长类指尖的粘弹性和C。elegans组织通过微和纳米机械刺激。此外，我们有灵长类动物指尖对线载荷的表面偏转数据（Srinivasan，1989）。目前的工作将集中在开发现实的灵长类动物的手指和蠕虫的有限元模型，校准这些模型通过模拟压痕实验在ADINA和匹配的模型响应与现有的实验数据（线负载表面偏转数据（Srinivasan，1989年），以及从我们的压痕实验的力响应）。然后，这些校准模型将用于预测机械感受器的生物力学和神经生理学反应，并与文献中已有的数据相匹配（Srinivasan和Lamotte，1991和OHagan等人，2004）。Dandekar，K.，B.I. Raju和MA斯里尼瓦桑，（2003）。“人类和猴子指尖的3-D弹性元件模型，以研究触觉的力学。《生物力学工程杂志》，第125卷，第125页。682-691，ASME Press. Maeno，T.，小林，K.，和Yamazaki，N.，（1998），人类手指组织结构与触觉感受器位置之间的关系，JSME Int. J.，41，pp. 94100. Srinivasan，M.A.，（1989年）。灵长类动物指尖在线载荷作用下的表面变形。生物力学杂志22，343349。斯里尼瓦桑湾A.和K. Dandekar（1996年）。“一项使用灵长类指尖二维模型的触觉力学研究。生物力学工程杂志118：48-55。斯里尼瓦桑湾A.和R. H. LaMotte（1991）.皮肤机械感受器反应中的形状编码。体感系统中的信息处理。Wenner-Gren Intl.系列研讨会。O. Franzen和J. Westman，Macmillan出版社。O'Hagan R，Chalfie M，Goodman MB，（2005）.“秀丽隐杆线虫触觉受体神经元的MEC-4 DEG/ENaC通道转导机械信号”。自然神经科学; 8（1）：43-50

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Numerical Simulations to Study the Role of Biomechanics in Tactile sensation PI: Dr. Mandayam A. Srinivasan, Director, MIT Touch Lab Abstract The biomechanics of skin tissues play a major role in the human tactile mechanisms. When our fingers come in contact with an object, surface loads imposed on the finger pad are transmitted to embedded nerve terminals (mechanoreceptors) in the skin tissues. These mechanoreceptors generate neural codes of the mechanical signals, enabling us to feel the object. Unlike visual and auditory mechanisms, modeling tactile encoding mechanisms has been a challenge and is as yet an unsolved problem. To better understand the mechanics of contact between the skin and an object, it is imperative to have a good understanding of the mechanical properties of the underlying tissues. To gauge the role of skin biomechanics in tactile response, two dimensional (Srinivasan and Dandekar, 1996; Maeno et al, 1998) and three dimensional finite element (FE) models (Dandekar, Raju and Srinivasan, 2003) of the human and monkey fingertips with realistic external geometry and internal layered structure of the skin and subcutaneous tissues have been developed using linear elastic models of the underlying tissue. These models enabled researchers to estimate the stress state at mechanoreceptor locations and relate it to the mechanoreceptor neural response. Dandekar et al. (2003) hypothesized that the strain energy density at a mechanoreceptor location is a good candidate to be the relevant stimulus for SA-I mechanoreceptors. The 3D finite element simulations for this study were conducted using the resources at the NSF Pittsburgh supercomputing Center. The present study is a follow up to the work done by Dandekar et al. (2003) which was based on purely elastic material models. The goal of present study is to develop viscoelastic finite element models (using ADINA) of the primate finger capable of predicting rate dependent mechanoreceptor responses to dynamic loading. In addition to this we will utilize similar methods to study the biomechanics of a new model organism, the nematode, C.elegans. We have recently completed experiments to characterize the viscoelastic properties of primate fingertip and elastic properties of C. elegans tissue through micro and nano mechanical stimulation. In addition, we have data on the surface deflection of primate fingertips to line loads (Srinivasan, 1989). The present work will be focused at developing realistic finite element models for the primate finger and the worm, calibrating these models by simulating the indentation experiments in ADINA and matching the model response with available experimental data (line load surface deflection data (Srinivasan, 1989) as well as force response from our indentation experiments). These calibrated models will then be used to predict biomechanical and neurophysiological response of mechanoreceptors and match with data already present in literature (Srinivasan and Lamotte, 1991 and OHagan et al, 2004). References Dandekar, K., B.I. Raju and M.A. Srinivasan, (2003). "3-D Finite-Element Models of Human and Monkey Fingertips to Investigate the Mechanics of Tactile Sense." Journal of Biomechanical Engineering, Vol. 125, pp. 682-691, ASME Press. Maeno, T., Kobayashi, K., and Yamazaki, N., (1998), Relationship Between the Structure of Human Finger Tissue and the Location of Tactile Receptors, JSME Int. J., 41, pp. 94100. Srinivasan, M.A., (1989). Surface deflection of primate fingertip under line load. Journal of Biomechanics 22, 343349. Srinivasan, M. A. and K. Dandekar (1996). "An investigation of the mechanics of tactile sense using two dimensional models of the primate fingertip." Journal of Biomechanical Engineering 118: 48-55. Srinivasan, M. A. and R. H. LaMotte (1991). Encoding of shape in the responses of cutaneous mechanoreceptors. Information Processing in the Somatosensory System. Wenner-Gren Intl. Symposium Series. O. Franzen and J. Westman, Macmillan Press. O'Hagan R, Chalfie M, Goodman MB, (2005). "The MEC-4 DEG/ENaC channel of Caenorhabditis elegans touch receptor neurons transduces mechanical signals". Nature Neuroscience; 8 (1): 43-50