title: Difficulty-related changes in inter-regional neural synchrony are dissociated between target and non-target processing.
abstract: The major purpose of this study was to explore the changes in the local/global gamma-band neural synchronies during target/non-target processing due to task difficulty under an auditory three-stimulus oddball paradigm. Multichannel event-related potentials (ERPs) were recorded from fifteen healthy participants during the oddball task. In addition to the conventional ERP analysis, we investigated the modulations in gamma-band activity (GBA) and inter-regional gamma-band phase synchrony (GBPS) for infrequent target and non-target processing due to task difficulty. The most notable finding was that the difficulty-related changes in inter-regional GBPS (33-35 Hz) at P300 epoch (350-600 ms) completely differed for target and non-target processing. As task difficulty increased, the GBPS significantly reduced for target processing but increased for non-target processing. This result contrasts with the local neural synchrony in gamma-bands, which was not affected by task difficulty. Another major finding was that the spatial patterns of functional connectivity were dissociated for target and non-target processing with regard to the difficult task. The spatial pattern for target processing was compatible with the top-down attention network, whereas that for the non-target corresponded to the bottom-up attention network. Overall, we found that the inter-regional gamma-band neural synchronies during target/non-target processing change significantly with task difficulty and that this change is dissociated between target and non-target processing. Our results indicate that large-scale neural synchrony is more relevant for the difference in information processing between target and non-target stimuli.
authors: Department of Biomedical Engineering, College of Health Science, Yonsei University, 234 Maeji-ri, Heungup-myun, Wonju, Gangwon-do 220-710, South Korea.
authors: Jeong Woo
authors: JW
authors: Choi
authors: Department of Biomedical Engineering, College of Health Science, Yonsei University, 234 Maeji-ri, Heungup-myun, Wonju, Gangwon-do 220-710, South Korea.
authors: Kwang Su
authors: KS
authors: Cha
authors: Department of Biomedical Engineering, College of Health Science, Yonsei University, 234 Maeji-ri, Heungup-myun, Wonju, Gangwon-do 220-710, South Korea.
authors: Jong Doo
authors: JD
authors: Choi
authors: Department of Neurology, Seoul National University College of Medicine, 101 Daehak-Ro, Jongno-Gu, Seoul 110-744, South Korea.
authors: Ki-Young
authors: KY
authors: Jung
authors: Department of Biomedical Engineering, College of Health Science, Yonsei University, 234 Maeji-ri, Heungup-myun, Wonju, Gangwon-do 220-710, South Korea. Electronic address: khkim0604@yonsei.ac.kr.
authors: Kyung Hwan
authors: KH
authors: Kim
mesh_terms: D000161:Acoustic Stimulation; D001288:Attention / Q000502:physiology; D001307:Auditory Perception / Q000502:physiology*; D001611:Beta Rhythm; D001921:Brain / Q000502:physiology*; D004192:Discrimination, Psychological / Q000502:physiology; D004569:Electroencephalography; D018913:Event-Related Potentials, P300; D005260:Female; D065818:Gamma Rhythm; D006801:Humans; D008297:Male; D009483:Neuropsychological Tests; D046709:Pattern Recognition, Physiological / Q000502:physiology; D011930:Reaction Time; D055815:Young Adult
keywords: Attention network; Gamma-band activity (GBA); Gamma-band phase sychrony (GBPS); P300; Task difficulty; Three-stimulus oddball task