Division of Integrative Physiology, Department of System Neuroscience, National Institute for Physiological Sciences, Okazaki, Japan; Department of Physiological Sciences, School of Life Science, The Graduate University for Advanced Studies (SOKENDAI), Okazaki, Japan.
Division of Integrative Physiology, Department of System Neuroscience, National Institute for Physiological Sciences, Okazaki, Japan; Brain and Mind Research Center, Nagoya University, Nagoya, Japan; Japan Society for the Promotion of Science, Tokyo, Japan.
Neuroimage. 2018 Oct 1;179:373-384. doi: 10.1016/j.neuroimage.2018.06.063. Epub 2018 Jun 22.
Previous studies have demonstrated the cortical mechanisms for the gradient of spatial attention in vision and audition, whereas those for touch have yet to be elucidated in detail. In order to examine the within-hand gradient of tactile spatial attention in the cerebral cortex, we used magnetoencephalography (MEG) to record cortical responses to an electrocutaneous stimulation presented randomly to any of the five fingers of the right hand at a random interstimulus interval (750-1250 ms). Participants attended to the index finger, ring finger, or both to detect a rare target stimulus in a sequence of frequent standard stimuli presented to the attended finger(s) by silent counting. Neuromagnetic responses around the contralateral primary and secondary somatosensory cortices (SIc and SIIc) at 50-70 ms and 80-100 ms, respectively, for the stimulation of the index or ring finger were stronger when that finger was attended than when the distant finger was attended or at rest. The amplitude of the SIIc response was also intermediate when the index and ring fingers were simultaneously attended. The SIIc response to the task-irrelevant stimulation of the thumb or little finger increased when the index or ring finger was attended, respectively, suggesting an across-finger gradient of tactile attention. Simultaneous attention to the index and ring fingers decreased the SIIc response to the task-irrelevant stimulation of the intervening middle finger more than that with attention to either one of the two fingers. The earliest attentional sign was observed for the SI M40c response, with the amplitude increasing with the stimulation of the unattended finger. Furthermore, late responses in the temporo-parietal junction (TPJ) and prefrontal cortex (PFC) were stronger with the stimulation of the unattended finger than with that of the attended finger. Thus, the present study provides cortical evidence for the adaptive control of the within-hand, across-finger gradient of tactile attention that depends on whether attention is focused on a single finger or divided into non-adjacent different fingers.
先前的研究已经证明了视觉和听觉中空间注意力梯度的皮质机制，而触觉的皮质机制尚未详细阐明。为了研究手内触觉空间注意力的梯度，我们使用脑磁图（MEG）记录了对右手 5 个手指中任意一个手指的电触觉刺激的皮质反应，刺激的随机间隔为 750-1250ms。参与者专注于食指、无名指或同时专注于检测在被注意的手指（通过无声计数）呈现的频繁标准刺激序列中的罕见目标刺激。当刺激食指或无名指时，在对侧初级和次级体感皮层（SIc 和 SIIc）周围分别在 50-70ms 和 80-100ms 处的神经磁响应更强，而当注意力集中在远处的手指或休息时则较弱。当同时关注食指和无名指时，SIIc 响应的幅度也处于中间。当食指或无名指被关注时，拇指或小指的任务无关刺激的 SIIc 响应增加，表明存在跨手指的触觉注意力梯度。当同时关注食指和无名指时，与只关注两个手指之一相比，对中间手指的任务无关刺激的 SIIc 响应减少更多。最早的注意力迹象出现在 SI M40c 响应中，其幅度随着未受刺激手指的刺激而增加。此外，颞顶联合区（TPJ）和前额叶皮层（PFC）的晚期反应在未受刺激手指的刺激下比在受刺激手指的刺激下更强。因此，本研究为手内跨手指触觉注意力梯度的自适应控制提供了皮质证据，这取决于注意力是否集中在单个手指上还是分散在不相邻的不同手指上。
