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Investigating Neuromagnetic Brain Responses against Chromatic Flickering Stimuli by Wavelet Entropies

Bhagat, Mayank and Bhushan, Chitresh and Saha, Goutam and Shimojo, Shinsuke and Watanabe, Katsumi and Bhattacharya, Joydeep (2009) Investigating Neuromagnetic Brain Responses against Chromatic Flickering Stimuli by Wavelet Entropies. PLoS ONE, 4 (9). Art. No. e7173. ISSN 1932-6203. PMCID PMC2747006.

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Background: Photosensitive epilepsy is a type of reflexive epilepsy triggered by various visual stimuli including colourful ones. Despite the ubiquitous presence of colorful displays, brain responses against different colour combinations are not properly studied. Methodology/Principal Findings: Here, we studied the photosensitivity of the human brain against three types of chromatic flickering stimuli by recording neuromagnetic brain responses (magnetoencephalogram, MEG) from nine adult controls, an unmedicated patient, a medicated patient, and two controls age-matched with patients. Dynamical complexities of MEG signals were investigated by a family of wavelet entropies. Wavelet entropy is a newly proposed measure to characterize large scale brain responses, which quantifies the degree of order/disorder associated with a multi-frequency signal response. In particular, we found that as compared to the unmedicated patient, controls showed significantly larger wavelet entropy values. We also found that Renyi entropy is the most powerful feature for the participant classification. Finally, we also demonstrated the effect of combinational chromatic sensitivity on the underlying order/disorder in MEG signals. Conclusions/Significance: Our results suggest that when perturbed by potentially epileptic-triggering stimulus, healthy human brain manages to maintain a non-deterministic, possibly nonlinear state, with high degree of disorder, but an epileptic brain represents a highly ordered state which making it prone to hyper-excitation. Further, certain colour combination was found to be more threatening than other combinations.

Item Type:Article
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URLURL TypeDescription CentralArticle
Shimojo, Shinsuke0000-0002-1290-5232
Bhattacharya, Joydeep0000-0003-3443-9049
Additional Information:© 2009 Bhagat et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Received: July 4, 2009; Accepted: August 23, 2009; Published: September 25, 2009. The research was partially supported by Shimojo Implicit Brain Function Project, JST.ERATO (Japan Science & Technology Agency), Japan, Hokuriku Innovation Cluster for Health Science, MEXT Knowledge Custer Initiative Toyama/Ishikawa Region, Japan, and CP-STIO (Department of Science & Technology, Government of India). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Author Contributions: Conceived and designed the experiments: SS KW. Performed the experiments: KW. Analyzed the data: MB CB JB. Contributed reagents/materials/analysis tools: MB CB GS JB. Wrote the paper: MB CB GS JB. The authors have declared that no competing interests exist.
Funding AgencyGrant Number
Japan Science and Technology AgencyUNSPECIFIED
Ministry of Education, Culture, Sports, Science and Technology (MEXT)UNSPECIFIED
Department of Science and Technology (India)UNSPECIFIED
Issue or Number:9
PubMed Central ID:PMC2747006
Record Number:CaltechAUTHORS:20200218-151249731
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Official Citation:Citation: Bhagat M, Bhushan C, Saha G, Shimjo S, Watanabe K, Bhattacharya J (2009) Investigating Neuromagnetic Brain Responses against Chromatic Flickering Stimuli by Wavelet Entropies. PLoS ONE 4(9): e7173.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:101346
Deposited By: George Porter
Deposited On:18 Feb 2020 23:47
Last Modified:03 Aug 2020 22:47

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