Mitev Deyan Ivaylov, Koldewyn Kami, Downing Paul E
Department of PsychologyBangor University, Bangor, United Kingdom.
J Neurophysiol. 2025 Jan 1;133(1):177-192. doi: 10.1152/jn.00160.2024. Epub 2024 Dec 3.
Human body movements are supported by a somatotopic map, primary motor cortex (M1), that is found along the precentral gyrus. Recent evidence has suggested two further motor maps that span the lateral occipitotemporal cortex (LOTC) and the precuneus. Confirmation of these maps is important, as they influence our understanding of the organization of motor behavior, for example by revealing how visual- and motor-related activity interact. However, evidence for these recently proposed maps is limited. We analyzed an open functional MRI (fMRI) dataset of 62 participants who performed 12 different body part movements. We analyzed the magnitude of responses evoked by movements with novel quantitative indices that test for maplike organization. We found strong evidence for bilateral somatotopic maps in precentral and postcentral gyri. In LOTC, we found much weaker responses to movement and little evidence of somatotopy. In the precuneus, we found only limited evidence for somatotopy. We also adopted a background connectivity approach to examine correlations between M1, LOTC, and the precuneus in the residual time series data. This revealed a ventral-posterior/dorsal-anterior distinction in the connectivity between precuneus and M1, favoring the head and arms, respectively. Posterior right hemisphere LOTC showed some evidence of preferential connectivity to arm-selective regions of M1. Overall, our results do not support the existence of a somatotopic motor map in LOTC but provide some support for a coarse map in the precuneus, especially as revealed in connectivity patterns. These findings help clarify the organization of human motor representations beyond the precentral gyrus. We investigated previous claims about the existence of somatotopic motor maps in the human lateral occipitotemporal cortex (LOTC) and the precuneus, in comparison to known maps in the precentral and postcentral gyri. Consistent with previous findings, we identified clear somatotopic motor maps in the latter two regions. With multiple quantitative measures of activity and connectivity, however, we found no evidence for a map in the LOTC and limited evidence for a map in the precuneus.
人体运动由位于中央前回的躯体运动定位图谱——初级运动皮层（M1）支持。最近的证据表明，还有另外两张运动图谱，分别跨越外侧枕颞叶皮层（LOTC）和楔前叶。这些图谱的确认很重要，因为它们会影响我们对运动行为组织的理解，例如通过揭示视觉相关活动和运动相关活动是如何相互作用的。然而，这些最近提出的图谱的证据有限。我们分析了一个开放的功能磁共振成像（fMRI）数据集，该数据集包含62名参与者，他们进行了12种不同身体部位的运动。我们用新的定量指标分析了运动诱发反应的幅度，这些指标用于测试图谱样的组织。我们发现了中央前回和中央后回中双侧躯体运动定位图谱的有力证据。在LOTC中，我们发现对运动的反应要弱得多，几乎没有躯体定位的证据。在楔前叶中，我们仅发现了有限的躯体定位证据。我们还采用了背景连接性方法来检查剩余时间序列数据中M1、LOTC和楔前叶之间的相关性。这揭示出楔前叶和M1之间的连接存在腹侧-后部/背侧-前部差异，分别有利于头部和手臂。右侧半球后部的LOTC显示出一些与M1的手臂选择性区域优先连接的证据。总体而言，我们的结果不支持LOTC中存在躯体运动定位图谱，但为楔前叶中的粗略图谱提供了一些支持，特别是在连接模式中所揭示的。这些发现有助于阐明中央前回以外的人类运动表征的组织。我们调查了先前关于人类外侧枕颞叶皮层（LOTC）和楔前叶中存在躯体运动定位图谱的说法，并与中央前回和中央后回中已知的图谱进行了比较。与先前的发现一致我们在后面这两个区域中识别出了清晰的躯体运动定位图谱。然而，通过对活动和连接性的多种定量测量，我们没有发现LOTC中存在图谱的证据，而楔前叶中存在图谱的证据也很有限。
