The Brain and Mind Institute, The University of Western Ontario, London, Ontario, Canada N6A 5B7.
Department of Psychology, University of Nevada, Reno, NV 89557, USA.
Cereb Cortex. 2018 Apr 1;28(4):1117-1131. doi: 10.1093/cercor/bhx017.
Images of tools induce stronger activation than images of nontools in a left-lateralized network that includes ventral-stream areas implicated in tool identification and dorsal-stream areas implicated in tool manipulation. Importantly, however, graspable tools tend to be elongated rather than stubby, and so the tool-selective responses in some of these areas may, to some extent, reflect sensitivity to elongation rather than "toolness" per se. Using functional magnetic resonance imaging, we investigated the role of elongation in driving tool-specific activation in the 2 streams and their interconnections. We showed that in some "tool-selective" areas, the coding of toolness and elongation coexisted, but in others, elongation and toolness were coded independently. Psychophysiological interaction analysis revealed that toolness, but not elongation, had a strong modulation of the connectivity between the ventral and dorsal streams. Dynamic causal modeling revealed that viewing tools (either elongated or stubby) increased the connectivity from the ventral- to the dorsal-stream tool-selective areas, but only viewing elongated tools increased the reciprocal connectivity between these areas. Overall, these data disentangle how toolness and elongation affect the activation and connectivity of the tool network and help to resolve recent controversies regarding the relative contribution of "toolness" versus elongation in driving dorsal-stream "tool-selective" areas.
工具图像在一个左侧化网络中比非工具图像引起更强的激活，该网络包括涉及工具识别的腹侧流区域和涉及工具操作的背侧流区域。然而，重要的是，可抓握的工具往往是细长的而不是粗短的，因此这些区域中的一些工具选择性反应可能在某种程度上反映了对细长而不是“工具性”本身的敏感性。使用功能磁共振成像，我们研究了伸长在驱动 2 个流及其连接中的工具特异性激活中的作用。我们表明，在一些“工具选择性”区域中，工具性和伸长的编码共存，但在其他区域中，伸长和工具性是独立编码的。心理生理交互分析显示，工具性而不是伸长对腹侧和背侧流之间的连接具有强烈的调制作用。动态因果建模显示，观看工具（无论是细长的还是粗短的）都会增加从腹侧流到背侧流工具选择性区域的连接，但只有观看细长的工具会增加这些区域之间的相互连接。总体而言，这些数据阐明了工具性和伸长如何影响工具网络的激活和连接，并有助于解决关于“工具性”与伸长在驱动背侧“工具选择性”区域中的相对贡献的最近争议。
