Is That within Reach? fMRI Reveals That the Human Superior Parieto-Occipital Cortex Encodes Objects Reachable by the Hand
Is That within Reach? fMRI Reveals That the Human Superior Parieto-Occipital Cortex Encodes Objects Reachable by the Hand
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DOI：
10.1523/jneurosci.0377-09.2009
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发表时间：
2009-04-08
影响因子：
5.3
通讯作者：
Culham, Jody C.
中科院分区：
文献类型：
--
作者：
Gallivan, Jason P.;Cavina-Pratesi, Cristiana;Culham, Jody C.
猕猴神经生理学和人类神经心理学结果表明，顶叶皮层编码了手臂可及范围内空间的独特表示。在这里，我们使用慢事件相关的功能磁共振成像（fMRI）来研究人类大脑中涉及伸手的区域是否更容易被触及范围内的物体激活，而不是被触及范围之外的物体激活。在实验 1 中，可抓取的物体被放置在平台上的三个可能的位置：两个可到达的位置和一个不可到达的位置。在一些试验中，参与者伸手触摸或抓住可触及位置的物体；在其他试验中，参与者被动地观察三个地点之一的物体。上顶枕皮质（SPOC）中与触及相关的区域对于触及范围内的目标比触及范围之外的目标更活跃。在实验 2 中，我们研究了当视觉和运动混杂受到控制时是否会发生这种 SPOC 反应，以及当工具扩展手臂的有效范围时是否会调节这种 SPOC 反应。在一些试验中，参与者仅使用手或工具对可触及的物体位置进行抓握和到达动作；在其他试验中，参与者被动地查看可到达和不可到达的物体位置。无论是否有工具可用，SPOC 对于被动观察手可及范围内的物体与手无法触及的物体的主动性明显更高。有趣的是，这些发现表明，编码动作的大脑区域内的神经反应（例如用于伸手的 SPOC）可能反映了运动可供性（例如手的可达性）的自动处理。
Macaque neurophysiology and human neuropsychology results suggest that parietal cortex encodes a unique representation of space within reach of the arm. Here, we used slow event-related functional magnetic resonance imaging (fMRI) to investigate whether human brain areas involved in reaching are more activated by objects within reach versus beyond reach. In experiment 1, graspable objects were placed at three possible locations on a platform: two reachable locations and one beyond reach. On some trials, participants reached to touch or grasp objects at the reachable location; on other trials participants passively viewed objects at one of the three locations. A reach-related area in the superior parieto-occipital cortex (SPOC) was more activated for targets within reach than beyond. In experiment 2, we investigated whether this SPOC response occurred when visual and motor confounds were controlled and whether it was modulated when a tool extended the effective range of the arm. On some trials, participants performed grasping and reaching actions to a reachable object location using either the hand alone or a tool; on other trials, participants passively viewed reachable and unreachable object locations. SPOC was significantly more active for passively viewed objects within reach of the hand versus beyond reach, regardless of whether or not a tool was available. Interestingly, these findings suggest that neural responses within brain areas coding actions ( such as SPOC for reaching) may reflect automatic processing of motor affordances (such as reachability with the hand).