Graduate School of Interdisciplinary Science and Engineering in Health Systems, Okayama University, 3-1-1 Tsushima-Naka, Kita-ku, Okayama 700-8530, Japan; Section on Functional Imaging Methods, National Institute of Mental Health, Bethesda, MD, USA.
Section on Functional Imaging Methods, National Institute of Mental Health, Bethesda, MD, USA.
Neuroimage. 2021 May 1;231:117754. doi: 10.1016/j.neuroimage.2021.117754. Epub 2021 Jan 14.
Haptic object perception begins with continuous exploratory contact, and the human brain needs to accumulate sensory information continuously over time. However, it is still unclear how the primary sensorimotor cortex (PSC) interacts with these higher-level regions during haptic exploration over time. This functional magnetic resonance imaging (fMRI) study investigates time-dependent haptic object processing by examining brain activity during haptic 3D curve and roughness estimations. For this experiment, we designed sixteen haptic stimuli (4 kinds of curves × 4 varieties of roughness) for the haptic curve and roughness estimation tasks. Twenty participants were asked to move their right index and middle fingers along the surface twice and to estimate one of the two features-roughness or curvature-depending on the task instruction. We found that the brain activity in several higher-level regions (e.g., the bilateral posterior parietal cortex) linearly increased as the number of curves increased during the haptic exploration phase. Surprisingly, we found that the contralateral PSC was parametrically modulated by the number of curves only during the late exploration phase but not during the early exploration phase. In contrast, we found no similar parametric modulation activity patterns during the haptic roughness estimation task in either the contralateral PSC or in higher-level regions. Thus, our findings suggest that haptic 3D object perception is processed across the cortical hierarchy, whereas the contralateral PSC interacts with other higher-level regions across time in a manner that is dependent upon the features of the object.
触觉物体感知始于连续的探索性接触，人类大脑需要随着时间的推移不断积累感官信息。然而，目前尚不清楚在进行触觉探索时，初级运动感觉皮层（PSC）如何与这些更高层次的区域相互作用。这项功能磁共振成像（fMRI）研究通过检查触觉 3D 曲线和粗糙度估计过程中的大脑活动，来研究随时间推移的触觉物体处理。在这项实验中，我们设计了十六种触觉刺激（4 种曲线×4 种粗糙度）用于触觉曲线和粗糙度估计任务。二十名参与者被要求用他们的右食指和中指两次沿着表面移动，并根据任务指令估计两个特征之一-粗糙度或曲率。我们发现，在触觉探索阶段，当曲线数量增加时，几个更高层次区域（例如双侧顶后皮质）的大脑活动呈线性增加。令人惊讶的是，我们发现，只有在晚期探索阶段，而不是在早期探索阶段，对侧 PSC 才会被曲线数量参数调节。相比之下，在触觉粗糙度估计任务中，无论是在对侧 PSC 还是在更高层次的区域中，我们都没有发现类似的参数调制活动模式。因此，我们的研究结果表明，触觉 3D 物体感知是在皮质层次结构中处理的，而对侧 PSC 则以依赖于物体特征的方式随时间与其他更高层次的区域相互作用。
