title: Scalp topography and intracerebral sources for ERPs recorded during auditory target detection.
abstract: The goal of this study was to measure the scalp topography of the event-related potentials (ERPs) during the detection of improbable auditory targets and to determine the intracerebral sources of these potentials. ERPs were recorded when subjects listened to a sequence of spoken words and detected occasional (p = 0.2) targets defined either by the gender of the speaker (male/female) or the meaning of the word (animate/inanimate). Waveforms were evaluated in relation to category (target versus standard) and task (voice versus semantic). Dipole source analysis was performed using locations obtained from fMRI. Fronto-central negative waves (N450 and N600 ms) generated by sources in both the auditory cortex and frontal regions were larger for semantic tasks and larger over the left hemisphere. A large parieto-occipital positive wave (P700) occurring with a peak latency about 150 ms before the reaction time was mainly generated in the left temporo-parietal regions for the semantic task and bilaterally for the voice task. About 300 ms after the P700, a highly lateralized right temporo-parietal positive wave P1000r occurred with a source in the right temporo-parietal area. These results indicate three distinct physiological processes underlie the detection of auditory targets. Perceptual discrimination is related to interactions between the frontal and temporal regions, stimulus-response association occurs in the temporo-parietal regions and post-perceptual processing in the right temporo-parietal region.
authors.affiliation: Center for Mind and Brain, University of California-Davis, Davis, CA, USA. ajshahin@ucdavis.edu
authors.forename: Antoine J
authors.initials: AJ
authors.lastname: Shahin
authors.forename: Claude
authors.initials: C
authors.lastname: Alain
authors.forename: Terence W
authors.initials: TW
authors.lastname: Picton
mesh_terms: D000161:Acoustic Stimulation; D000328:Adult; D001931:Brain Mapping; D018913:Event-Related Potentials, P300 / Q000502:physiology; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D005260:Female; D007839:Functional Laterality; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D010296:Parietal Lobe / Q000502:physiology; D011930:Reaction Time / Q000502:physiology; D012535:Scalp; D012660:Semantics; D012737:Sex Factors; D013067:Speech Perception / Q000502:physiology*; D013702:Temporal Lobe / Q000502:physiology