Research group identifies the parts of the brain that can distinguish a time interval of 0.05 seconds
A KUT research group has elucidated the parts of the brain related to perception of the extremely short time interval of 0.05 seconds. The group, consisting of Professor Makoto Iwata, Associate Professor Hiroshi Kadota, and Visiting Associate Professor Takahiro Kimura (Kanazawa University), all of the Research Center for Brain Communication (BrainCom) at KUT's Research Institute, conducted joint research with Professor Makoto Miyazaki (Shizuoka University) and Dr. Takanori Kochiyama (researcher at Advanced Telecommunications Research Institute International) et al.
Our ability to perceive time is an important support for various actions in our daily life, but there is no sensory organ for time. Not only that: the detection, evaluation, and generation of time are performed in the brain and it is known that the perceptions of different lengths of time, such as hours, minutes, and seconds, involve different parts of the brain. The perception of tiny time differences between events is a neural function required to achieve precise behaviors in music, sports and manufacturing.
(Graphic representation of experimentation details)
The research group conducted a brain activity measurement experiment using functional magnetic resonance imaging (fMRI)*1 and found out that the right inferior parietal lobule is active when we try to detect whether the tactile stimuli received by the left and right hands were simultaneous (time difference: 0 second) or whether there was a short time difference (0.05 seconds). The times of 0 second and 0.05 seconds are the shortest that have been examined in studies of brain activity related to time perception. In particular, this research on tactile stimulation was the first such attempt in the world.
The parts of the brain that showed stronger activity when a subject was performing simultaneity judgment than performing number judgement.
This research outcome is expected to be part of the foundation knowledge needed for elucidating the mechanism of the brain that produces superlative skills and ingenuity and for the development of a method for training and the succession method. It is expected that, as this research develops further, the knowledge acquired in this study will be applied to robot control sufficient for imitation of human skill.
Associate Professor Kadota said, "We started this research in 2014 and have been designing experiments, implementing our findings, and analyzing our MRI data. I am very happy that we have been able to report our results in a paper. Given this outcome, there is a possibility that we can improve humans' ability to detect and evaluate the difference between stimulation times by applying transcranial direct current stimulation (tDCS)*2 to the inferior parietal lobule. I would like to pursue research from various related perspectives."
The outcomes of this research were published in the online science journal Scientific Reports, published by Nature Publishing Group in the UK.
*1 Functional magnetic resonance imaging (fMRI)
A method that uses magnetic resonance imaging (MRI) to visualize areas where the brain is active. The method is based on the fact that when we see or touch something, or move our body, the associated neurons in the brain area activate and consume oxygen. The blood then collects around the active neurons to supplement the oxygen consumed. Those changes in blood flow and in oxygen metabolism can be detected by fMRI, so we can identify active brain regions. Currently, fMRI is one of the best methods for identifying the active areas of the human brain.
*2 Transcranial direct current stimulation (tDCS)
This method modulates brain activity by inducing a weak direct current via an electrode attached to the head. For example, it has been reported that placing an anode on the head just above the primary motor area and flowing a 1 mA current for several to 10 minutes produces an enhancement effect, whereas doing the same with a cathode produces a suppression effect.
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