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Spatiotemporal brain dynamics of auditory temporal assimilation. Sci Rep 2017; 7:11400. [PMID: 28900289 PMCID: PMC5595862 DOI: 10.1038/s41598-017-11631-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2017] [Accepted: 08/29/2017] [Indexed: 12/27/2022] Open
Abstract
Time is a fundamental dimension, but millisecond-level judgments sometimes lead to perceptual illusions. We previously introduced a “time-shrinking illusion” using a psychological paradigm that induces auditory temporal assimilation (ATA). In ATA, the duration of two successive intervals (T1 and T2), marked by three auditory stimuli, can be perceived as equal when they are not. Here, we investigate the spatiotemporal profile of human temporal judgments using magnetoencephalography (MEG). Behavioural results showed typical ATA: participants judged T1 and T2 as equal when T2 − T1 ≤ +80 ms. MEG source-localisation analysis demonstrated that regional activity differences between judgment and no-judgment conditions emerged in the temporoparietal junction (TPJ) during T2. This observation in the TPJ may indicate its involvement in the encoding process when T1 ≠ T2. Activation in the inferior frontal gyrus (IFG) was enhanced irrespective of the stimulus patterns when participants engaged in temporal judgment. Furthermore, just after the final marker, activity in the IFG was enhanced specifically for the time-shrinking pattern. This indicates that activity in the IFG is also related to the illusory perception of time-interval equality. Based on these observations, we propose neural signatures for judgments of temporal equality in the human brain.
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Nagaike A, Mitsudo T, Nakajima Y, Ogata K, Yamasaki T, Goto Y, Tobimatsu S. 'Time-shrinking perception' in the visual system: a psychophysical and high-density ERP study. Exp Brain Res 2016; 234:3279-3290. [PMID: 27401472 DOI: 10.1007/s00221-016-4726-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Accepted: 07/06/2016] [Indexed: 11/26/2022]
Abstract
'Time-shrinking perception (TSP)' is a unique perceptual phenomenon in which the duration of two successive intervals (T1 and T2) marked by three auditory stimuli is perceived as equal even when they are physically different. This phenomenon provides a link between time and working memory; however, previous studies have mainly been performed on the auditory modality but not the visual modality. To clarify the neural mechanism of visual TSP, we performed a psychophysical experiment and recorded event-related potentials (ERPs) under different T1/T2 combinations. Three successive black/white sinusoidal gratings (30 ms duration) were presented to the participants. In the psychophysical experiment, either T1 or T2 was varied from 240 to 560 ms in 40-ms steps, while T2 or T1 was fixed at 400 ms. Participants judged whether T1 and T2 were equal or not by pressing a button. ERPs were recorded from 128 scalp electrodes, while T1 was varied from 240, 320, and 400 ms with the 400 ms T2 duration, and vice versa. Behavioral data showed asymmetrical assimilation: When -80 ms ≤ (T1 - T2) ≤ +120 ms, TSP was observed in the T1-varied condition. When -120 ms ≤ (T1 - T2) ≤ +80 ms, it was also observed in the T2-varied condition. These asymmetric time ranges in vision were different from those in the auditory modality. ERP data showed that contingent negative variation (CNV) appeared in the fronto-central region at around 300-500 ms during T2 presentation in the T1 < T2 condition. In the /240/400/ pattern, the CNV amplitude was decreased at around 350 ms. In contrast, P3 appeared at the parietal region about 450-650 ms after T2 in the T1 > T2 condition. In the /400/240/ pattern, P3 amplitude was greater than those of other temporal patterns. These neural responses corresponded to participants' perception that T1 and T2 were not equal. The neural responses in the fronto-central region were involved with endogenous temporal attention for discrimination. Moreover, neural responses in the parietal region were engaged in exogenous temporal attention. Therefore, fronto-parietal neural responses underlie temporal perception in vision.
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Affiliation(s)
- Atsushi Nagaike
- Department of Clinical Neurophysiology, Neurological Institute, Faculty of Medicine, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-Ku, Fukuoka, 812-8582, Japan
| | - Takako Mitsudo
- Department of Informatics, Faculty of Information Science and Electrical Engineering, Kyushu University, Fukuoka, Japan
| | - Yoshitaka Nakajima
- Department of Acoustic Design, Faculty of Design, Kyushu University, Fukuoka, Japan
| | - Katsuya Ogata
- Department of Clinical Neurophysiology, Neurological Institute, Faculty of Medicine, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-Ku, Fukuoka, 812-8582, Japan
| | - Takao Yamasaki
- Department of Clinical Neurophysiology, Neurological Institute, Faculty of Medicine, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-Ku, Fukuoka, 812-8582, Japan
| | - Yoshinobu Goto
- Department of Occupational Therapy, Faculty of Rehabilitation, International University of Health and Welfare, Fukuoka, Japan
| | - Shozo Tobimatsu
- Department of Clinical Neurophysiology, Neurological Institute, Faculty of Medicine, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-Ku, Fukuoka, 812-8582, Japan.
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