REPRESENTATION OF TIME IN THE BRAIN

众所周知，大脑可以分辨出两个刺激的顺序，这两个刺激在时间上相隔仅30毫秒。然而，对于这种歧视是如何以及在哪里做出的，几乎没有达成共识。为了阐明大脑如何对感觉信号进行排序，我们对人类和动物受试者进行了一系列实验。1)我们之前报道过，两个连续刺激传递到每只手持棒的尖端，通过交叉棒而不改变手的位置来改变时间顺序判断。先前的报告提供了将触觉信号引用到手中实际工具的尖端的证据。在本研究中，我们考察了参照是否发生在具有反作用力的虚拟现实中操纵物体的虚拟工具的尖端或作用点。结果表明，体感信号可以参考虚拟工具的作用点，该虚拟工具没有任何刚体连接作用点和手。2)阐明Whe…为了更多地了解感觉信号在大脑中的顺序，研究人员使用了事件相关功能磁共振成像(FMRI)，而右撇子受试者则判断两个连续刺激的时间顺序，每只手一个。在双侧颞中回后部(BA37)、双侧运动前皮质(BA6)、双侧额下回(BA44)、双侧顶下皮质(BA40)以及左侧初级和次级躯体感觉皮质中，在时间顺序判断时比在数量判断时激活更多。颞中回的激活与MT/V5.3的前部重叠)为了研究体感刺激在小鼠大脑中的排列顺序，我们检测了C57BL/6N小鼠c-Fos的产生，这些小鼠接受了判断向右和向左胡须传递两个喷气刺激的顺序的训练。与对照组相比，任务组大鼠双侧初级躯体感觉皮质(桶状皮质)、丘脑室旁核、下丘脑和脾后无颗粒皮质c-Fos表达增强。C-Fos在筒状皮质表达最明显的部位是第2、3层，其起始部位为胼胝体纤维。综上所述，我们推断触觉信号的时间顺序在时间上是有序的，这是通过将时间多模区中的运动表示与额叶和顶叶皮质中刺激的空间表示相结合来实现的。较少

It is known that the brain can resolve the order of two stimuli that are separated in time by as little as 30 ms. However, there is little consensus on how and where such discriminations are made. To elucidate how the brain orders sensory signals, we carried out a series of experiments with human and animal subjects. 1)We previously reported that temporal order judgment of two successive stimuli, delivered to the tips of sticks held in each hand, was altered by crossing the sticks without changing the positions of the hands. The previous report provided evidence for the referral of tactile signals to the tip of an actual tool in hand. In this study, we examined whether the referral occur to the tip, or action point, of a virtual tool for manipulating objects in the virtual reality with reaction force. The results suggest that somatosensory signals can be referred to the action point of a virtual tool that lacks any rigid body connecting the action point and the hand. 2)To elucidate whe … More re and how sensory signals are ordered in the brain, event-related functional magnetic resonance imaging (fMRI) was used while right-handed subjects judged the temporal order of two successive stimuli delivered one to each hand. Greater activation was elicited during the temporal order judgment than during the numerosity judgment in the following areas : bilateral posterior part of the middle temporal gyri (BA 37), bilateral premotor cortices (BA 6), bilateral inferior frontal gyri (BA 44), bilateral inferior parietal cortices (BA 40), and the left primary and secondary somatosensory cortices. The activation in the middle temporal gyri overlapped with the anterior part of the MT/V5.3) To study how somatosensory stimuli are ordered in the mouse brain, c-Fos production was examined in C57BL/6N mice that were trained to judge the order of two air-puff stimuli that were delivered to the right and the left whiskers. c-Fos expression was enhanced bilaterally in the task group as compared to the control group in the primary somatosensory cortex (barrel cortex), the paraventricular thalamic nucleus, the hypothalamus and the retrosplenial agranular cortex. c-Fos expression in the barrel cortex was most evident in the layers II and III, where callosal fibers originate from. Taken together, we infer that temporal order of tactile signals are ordered in time by combining representation of 'motion' in the temporal multimodal areas with the spatial representation of the stimuli in the frontal and parietal cortices. Less