title: Decreased entropy modulation of EEG response to novelty and relevance in schizophrenia during a P300 task.
abstract: The analysis of the interaction between novelty and relevance may be of interest to test the aberrant salience hypothesis of schizophrenia (SCH). In comparison with other neuroimaging techniques, such as functional magnetic resonance imaging, electroencephalography (EEG) provides high temporal resolution. Therefore, EEG is useful to analyze transient dynamics in neural activity, even in the range of milliseconds. In this study, EEG activity from 31 patients with SCH and 38 controls was analyzed using Shannon spectral entropy (SE) and median frequency (MF). The aim of the study was to quantify differences between distractor (i.e., novelty) and target (i.e., novelty and relevance) tones in an auditory oddball paradigm. Healthy controls displayed a larger SE decrease in response to target stimulus than in response to distractor tones. SE decrease was accompanied by a significant and widespread reduction of MF (i.e., a significant slowing of EEG activity). In comparison with controls, patients showed a significant reduction of changes in SE in response to both target and distractor tones. These differences were also observed in patients that only received a minimal treatment prior to EEG recording. Furthermore, significant changes in SE were inversely correlated to positive and total symptoms severity for SCH patients. Our findings support the notion that SCH is associated with a reduced response to both novelty and relevance during an auditory P300 task.
authors.affiliation: Biomedical Engineering Group, Department T.S.C.I.T., E.T.S. Ingenieros de Telecomunicación, University of Valladolid, Paseo Belén, 15, CP 47011, Valladolid, Spain.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Bachiller
authors.forename: Alba
authors.initials: A
authors.lastname: Lubeiro
authors.forename: Álvaro
authors.initials: Á
authors.lastname: Díez
authors.forename: Vanessa
authors.initials: V
authors.lastname: Suazo
authors.forename: Cristina
authors.initials: C
authors.lastname: Domínguez
authors.forename: José A
authors.initials: JA
authors.lastname: Blanco
authors.forename: Marta
authors.initials: M
authors.lastname: Ayuso
authors.forename: Roberto
authors.initials: R
authors.lastname: Hornero
authors.forename: Jesús
authors.initials: J
authors.lastname: Poza
authors.forename: Vicente
authors.initials: V
authors.lastname: Molina
mesh_terms: D000328:Adult; D001307:Auditory Perception / Q000502:physiology; D004569:Electroencephalography / Q000379:methods*; D019277:Entropy; D018913:Event-Related Potentials, P300 / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011597:Psychomotor Performance / Q000502:physiology*; D012559:Schizophrenia / Q000503:physiopathology*