Graduate School of Frontier Biosciences, Osaka University


Brain Alpha rhythm controlling signal traffics in the brain

Journal J Neurosci 37, 5298-5308 (2017)
Authors Takahashi T (1, 2), Kitazawa S (1, 2, 3).
  1. Dynamic Brain Network Laboratory, Graduate School of Frontier Biosciences, Osaka University, Osaka, 565-0871, Japan.
  2. Department of Brain Physiology, Graduate School of Medicine, Osaka University, Osaka, 565-0871 Japan.
  3. Center for Information and Neural Networks, National Institute of Information and Communications Technology, and Osaka University, Osaka, 565-0871, Japan.
Title Modulation of Illusory Reversal in Tactile Temporal Order by the Phase of Posterior α Rhythm
PubMed 28450538
Laboratory Dynamic Brain Network Laboratory 〈Prof. Kitazawa〉
Abstract The subjective temporal order of tactile stimuli, delivered sequentially to each hand with an interval of 100-300 ms, is often inverted when the arms are crossed. Based on data from behavioral and neuroimaging studies, it has been proposed that the reversal is due to a conflict between anatomical and spatial representations of the tactile signal or to the production of an inverted apparent motion signal. Because the α rhythms, which consist of a few distinct components, reportedly modulate tactile perception and apparent motion and serve as a 10 Hz timer, we hypothesized that the illusory reversal would be regulated by some of the α rhythms. To test this hypothesis, we conducted magnetoencephalographic recordings in both male and female participants during the tactile temporal order judgment task. We decomposed the α rhythms into five independent components and discovered that the illusory reversal was modulated by the phase of one independent component with strong current sources near the parieto-occipital (PO) sulcus (peri-PO component). As expected, the estimated current sources distributed over the human MST implicated to represent tactile apparent motion, in addition to the intraparietal region implicated in mapping tactile signals in space. However, the strongest source was located in the precuneus that occupies a central hub region in the cortical networks and receives tactile inputs through a tecto-thalamic pathway. These results suggest that the peri-PO component plays an essential role in regulating tactile temporal perception by modulating the thalamic nuclei that interconnect the superior colliculus with the cortical networks.
Description In spite of a long-held hypothesis that the posterior alpha rhythm serves as a 10 Hz timer that regulates human temporal perception, the contribution of the alpha rhythms in temporal perception is still unclear. We examined how the alpha rhythms influence tactile temporal order judgment. Judgment reversal depended on the phase of one particular alpha rhythm with its source near the parieto-occipital sulcus. The peri-PO alpha rhythm may play a crucial role in organizing tactile temporal perception.

Figure: A "precuneus" component of the alpha rhythms altered subjective temporal order.
Successive taps, delivered one to the crossed hands, were often perceived in the inverted order when they were delivered at the peaks of a 10-Hz alpha rhythm (red) whose major source is located in the precuneus. When delivered at the troughs, they were judged correctly.