title: Right hemisphere dominance for auditory attention and its modulation by eye position: an event related fMRI study.
abstract: OBJECTIVE
  Previous neuroimaging studies of oddball tasks and other paradigms measuring attention processes support right hemisphere dominance for attentional processes. Using an auditory selective attention task, we studied the functional asymmetry of the human brain in response to attended or unattended deviant tones. Secondly, we examined whether a congruency or a discrepancy between audio-spatial and visuo-spatial cued attentional resources may influence the activity elicited by an auditory selective attention task.
  
  
  METHODS
  We used event-related functional magnetic resonance imaging (fMRI) to study healthy adults as they performed an auditory oddball task in which a spatial-cued instruction indicated the ear to attend a monaural deviant tone. We addressed the question of congruency/discrepancy between attentional resources by using three different eye positions during the performance of the auditory oddball task.
  
  
  RESULTS
  Relative to standard tones, both attended and unattended deviant tones (DTs) presented to either ear elicit the activation of a widespread bilaterally distributed cortical and subcortical network. A subset of this network, essentially frontal and temporal areas, showed not only greater right than left activity but an enhancement of this rightward asymmetry in response to attended DTs. The only cortical region that showed a leftward asymmetry in response to attended DTs overlapped Heschl gyrus and planum temporale, unmasking a left hemisphere preference of both primary and secondary auditory cortex for processing simple attended monaural stimuli. Questioning the impact of eye position during auditory oddball task, we observed a lesser activity in right integrative crossmodal areas (superior temporal sulcus, opercular part of the inferior frontal gyrus, pre-SMA) when the eye positions were contralateral to detected DTs. These regions may be tuned to best respond when both visuo-spatial and audio-spatial attentional resources work together.
  
  
  CONCLUSIONS
  These results support the assumption that the right hemisphere is preferentially engaged in processing audio-spatial attentional resources and underline the interest to study the crossmodal integration of attentional resources by the mean of the detection of DTs in different eye positions.
authors.affiliation: Groupe d'Imagerie Neurofonctionnelle, UMR 6194 CNRS - CEA - University of Caen and University Paris Descartes, GIP Cyceron, Bd. H. Becquerel, BP 5229, 14074 Caen Cedex, France. lpetit@cyceron.fr
authors.forename: Laurent
authors.initials: L
authors.lastname: Petit
authors.forename: Grégory
authors.initials: G
authors.lastname: Simon
authors.forename: Marc
authors.initials: M
authors.lastname: Joliot
authors.forename: Frédéric
authors.initials: F
authors.lastname: Andersson
authors.forename: Thomas
authors.initials: T
authors.lastname: Bertin
authors.forename: Laure
authors.initials: L
authors.lastname: Zago
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Mellet
authors.forename: Nathalie
authors.initials: N
authors.lastname: Tzourio-Mazoyer
mesh_terms: D000161:Acoustic Stimulation; D000293:Adolescent; D000328:Adult; D001288:Attention / Q000502:physiology*; D001307:Auditory Perception / Q000502:physiology*; D001931:Brain Mapping; D003463:Cues; D003627:Data Interpretation, Statistical; D004292:Dominance, Cerebral / Q000502:physiology*; D005071:Evoked Potentials / Q000502:physiology; D005133:Eye Movements / Q000502:physiology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009415:Nerve Net / Q000502:physiology; D010775:Photic Stimulation; D013028:Space Perception / Q000502:physiology; D013702:Temporal Lobe / Q000502:physiology