Macaluso E, Frith C D, Driver J
Neuroimaging Laboratory, Fondazione Santa Lucia, Via Ardeatina, 306-00179 Roma, Italy.
J Neurophysiol. 2007 Nov;98(5):3081-94. doi: 10.1152/jn.00192.2007. Epub 2007 Sep 26.
To perform eye or hand movements toward a relevant location, the brain must translate sensory input into motor output. Recent studies revealed segregation between circuits for translating visual information into saccadic or manual movements, but less is known about translation of tactile information into such movements. Using human functional magnetic resonance imaging (fMRI) in a delay paradigm, we factorially crossed sensory modality (vision or touch) and motor effector (eyes or hands) for lateralized movements (gaze shifts to left or right or pressing a left or right button with the corresponding left or right hand located there). We investigated activity in the delay-period between stimulation and response, asking whether the currently relevant side (left or right) during the delay was encoded according to sensory modality, upcoming motor response, or some interactive combination of these. Delay activity mainly reflected the motor response subsequently required. Irrespective of visual or tactile input, we found sustained activity in posterior partial cortex, frontal-eye field, and contralateral visual cortex when subjects would later make an eye movement. For delays prior to manual button-press response, activity increased in contralateral precentral regions, again regardless of stimulated modality. Posterior superior temporal sulcus showed sustained delay activity, irrespective of sensory modality, side, and response type. We conclude that the delay activations reflect translation of sensory signals into effector-specific motor circuits in parietal and frontal cortex (plus an impact on contralateral visual cortex for planned saccades), regardless of cue modality, whereas posterior STS provides a representation that generalizes across both sensory modality and motor effector.
为了朝着相关位置进行眼部或手部运动，大脑必须将感觉输入转化为运动输出。最近的研究揭示了将视觉信息转化为眼球跳动或手部运动的神经回路之间的分离，但对于将触觉信息转化为这类运动的了解较少。在一个延迟范式中使用人类功能磁共振成像（fMRI），我们将感觉模态（视觉或触觉）和运动效应器（眼睛或手）进行析因交叉，以进行侧向运动（向左或向右的注视转移，或者用位于相应位置的左手或右手按下左边或右边的按钮）。我们研究了刺激与反应之间延迟期的活动，探究延迟期间当前相关的一侧（左或右）是根据感觉模态、即将到来的运动反应还是它们的某种交互组合进行编码的。延迟期活动主要反映了随后所需的运动反应。无论视觉或触觉输入如何，当受试者随后进行眼球运动时，我们在顶叶后部皮质、额眼区和对侧视觉皮质中发现了持续活动。对于手动按钮按压反应之前的延迟，对侧中央前区的活动增加，同样与刺激模态无关。颞上沟后部显示出持续的延迟期活动，与感觉模态、方向和反应类型无关。我们得出结论，延迟激活反映了感觉信号向顶叶和额叶皮质中效应器特异性运动神经回路的转化（对于计划中的眼球跳动，还对侧视觉皮质有影响），与线索模态无关，而颞上沟后部提供了一种跨感觉模态和运动效应器的表征。
