Karlsson Emma M, Carey David P
Institute of Cognitive Neuroscience, School of Psychology and Sport Science, Bangor University, Bangor, UK; Department of Experimental Clinical and Health Psychology, Ghent University, Ghent, Belgium.
Institute of Cognitive Neuroscience, School of Psychology and Sport Science, Bangor University, Bangor, UK.
Neuropsychologia. 2024 Apr 15;196:108837. doi: 10.1016/j.neuropsychologia.2024.108837. Epub 2024 Feb 29.
Regions in the brain that are selective for images of hands and tools have been suggested to be lateralised to the left hemisphere of right-handed individuals. In left-handers, many functions related to tool use or tool pantomime may also depend more on the left hemisphere. This result seems surprising, given that the dominant hand of these individuals is controlled by the right hemisphere. One explanation is that the left hemisphere is dominant for speech and language in the majority of left-handers, suggesting a supraordinate control system for complex motor sequencing that is required for skilled tool use, as well as for speech. In the present study, we examine if this left-hemispheric specialisation extends to perception of hands and tools in left- and right-handed individuals. We, crucially, also include a group of left-handers with right-hemispheric language dominance to examine their asymmetry biases. The results suggest that tools lateralise to the left hemisphere in most right-handed individuals with left-hemispheric language dominance. Tools also lateralise to the language dominant hemisphere in right-hemispheric language dominant left-handers, but the result for left-hemispheric language dominant left-handers are more varied, and no clear bias towards one hemisphere is found. Hands did not show a group-level asymmetry pattern in any of the groups. These results suggest a more complex picture regarding hemispheric overlap of hand and tool representations, and that visual appearance of tools may be driven in part by both language dominance and the hemisphere which controls the motor-dominant hand.
大脑中对手部和工具图像具有选择性的区域，被认为在右利手个体中偏向于左半球。在左利手个体中，许多与工具使用或工具模仿相关的功能可能也更多地依赖于左半球。鉴于这些个体的优势手由右半球控制，这一结果似乎令人惊讶。一种解释是，在大多数左利手个体中，左半球在言语和语言方面占主导地位，这表明存在一个用于复杂运动序列的上级控制系统，该系统对于熟练使用工具以及言语来说都是必需的。在本研究中，我们考察这种左半球特化是否延伸至左利手和右利手个体对手部和工具的感知。至关重要的是，我们还纳入了一组右半球语言占主导地位的左利手个体，以考察他们的不对称偏向。结果表明，在大多数左半球语言占主导地位的右利手个体中，工具偏向于左半球。在右半球语言占主导地位的左利手个体中，工具也偏向于语言占主导地位的半球，但左半球语言占主导地位的左利手个体的结果更为多样，未发现对某一个半球的明显偏向。在任何一组中，手部都未呈现出组水平的不对称模式。这些结果表明，关于手部和工具表征的半球重叠情况，存在更为复杂的图景，并且工具的视觉外观可能部分地由语言占主导地位以及控制运动优势手的半球所驱动。
