title: Top-down and bottom-up neurodynamic evidence in patients with tinnitus.
abstract: Although a peripheral auditory (bottom-up) deficit is an essential prerequisite for the generation of tinnitus, central cognitive (top-down) impairment has also been shown to be an inherent neuropathological mechanism. Using an auditory oddball paradigm (for top-down analyses) and a passive listening paradigm (for bottom-up analyses) while recording electroencephalograms (EEGs), we investigated whether top-down or bottom-up components were more critical in the neuropathology of tinnitus, independent of peripheral hearing loss. We observed significantly reduced P300 amplitudes (reflecting fundamental cognitive processes such as attention) and evoked theta power (reflecting top-down regulation in memory systems) for target stimuli at the tinnitus frequency of patients with tinnitus but without hearing loss. The contingent negative variation (reflecting top-down expectation of a subsequent event prior to stimulation) and N100 (reflecting auditory bottom-up selective attention) were different between the healthy and patient groups. Interestingly, when tinnitus patients were divided into two subgroups based on their P300 amplitudes, their P170 and N200 components, and annoyance and distress indices to their tinnitus sound were different. EEG theta-band power and its Granger causal neurodynamic results consistently support a double dissociation of these two groups in both top-down and bottom-up tasks. Directed cortical connectivity corroborates that the tinnitus network involves the anterior cingulate and the parahippocampal areas, where higher-order top-down control is generated. Together, our observations provide neurophysiological and neurodynamic evidence revealing a differential engagement of top-down impairment along with deficits in bottom-up processing in patients with tinnitus but without hearing loss.
authors.affiliation: Department of Brain and Cognitive Engineering, Korea University, Seoul 02841, Republic of Korea; Department of Otolaryngology, Hallym University College of Medicine, Anyang 14068, Republic of Korea.
authors.forename: Sung Kwang
authors.initials: SK
authors.lastname: Hong
authors.affiliation: Department of Computer Science and Engineering, Korea University, Seoul 02841, Republic of Korea.
authors.forename: Sejik
authors.initials: S
authors.lastname: Park
authors.affiliation: Department of Brain and Cognitive Engineering, Korea University, Seoul 02841, Republic of Korea.
authors.forename: Min-Hee
authors.initials: MH
authors.lastname: Ahn
authors.affiliation: Department of Brain and Cognitive Engineering, Korea University, Seoul 02841, Republic of Korea. Electronic address: min_bk@korea.ac.kr.
authors.forename: Byoung-Kyong
authors.initials: BK
authors.lastname: Min
mesh_terms: D000161:Acoustic Stimulation; D000293:Adolescent; D000328:Adult; D001288:Attention / Q000502:physiology; D001307:Auditory Perception / Q000502:physiology; D016022:Case-Control Studies; D004569:Electroencephalography; D005072:Evoked Potentials, Auditory / Q000502:physiology; D005260:Female; D006179:Gyrus Cinguli / Q000503:physiopathology; D006624:Hippocampus / Q000503:physiopathology; D006801:Humans; D008297:Male; D014012:Tinnitus / Q000209:etiology / Q000503:physiopathology* / Q000523:psychology*; D055815:Young Adult
keywords: Attention; Causality; Electroencephalogram; Tinnitus; Top-down