title: Processing of bilateral versus unilateral conditions: evidence for the functional contribution of the ventral attention network.
abstract: Processing of multiple or bilateral conditions presented simultaneously in both hemifields reflects the natural mode of perception in our multi-target environment, but is not yet completely understood. While region-of-interest based studies in healthy subjects reported single cortical areas as the right inferior parietal lobe (IPL) or temporoparietal junction (TPJ) to process bilateral conditions, studies in extinction patients with reduced ability in this regard suggested the right superior temporal cortex to hold a key role. The present fMRI study on healthy subjects aimed at resolving these discrepancies by contrasting bilateral versus unilateral visual conditions in a paradigm similar to the bed-side test for patients with visual extinction on a whole brain level. Additionally, reduced attentional capacity in spatial processing was investigated in normal aging. Processing of bilateral conditions compared to unilateral ones showed to require stronger activation of not one single cortical region but the entire right-lateralized ventral attention network, bilateral parietal and visual association areas. These results might suggest a conceptual difference between unilateral and bilateral spatial processing with the latter depending on additional anatomical and functional brain resources. Reduced attentional capacity in elderly subjects was associated with compensatory recruitment of contralateral functional homologues [left IPL, TPJ, frontal eye field (FEF)]. These data reveal the functional anatomy of our ability to visually process and respond to the entity of the environment and improve our understanding of neglect and extinction. Moreover, the data demonstrate that a restriction of the attentional capacity is based on processing limitations in the network of high-level cortical areas and not due to restriction in the primary sensory ones.
authors.affiliation: Department of Neurology and Neuroscience, University Medical Centre Freiburg, Germany; Freiburg Brain Imaging Centre, University Medical Centre Freiburg, Germany; BrainLinks-BrainTools Cluster of Excellence, University Medical Centre Freiburg, Germany. Electronic address: lena.beume@uniklinik-freiburg.de.
authors.forename: Lena-Alexandra
authors.initials: LA
authors.lastname: Beume
authors.affiliation: Department of Neurology and Neuroscience, University Medical Centre Freiburg, Germany; Freiburg Brain Imaging Centre, University Medical Centre Freiburg, Germany; BrainLinks-BrainTools Cluster of Excellence, University Medical Centre Freiburg, Germany.
authors.forename: Christoph P
authors.initials: CP
authors.lastname: Kaller
authors.affiliation: Department of Neurology and Neuroscience, University Medical Centre Freiburg, Germany; Freiburg Brain Imaging Centre, University Medical Centre Freiburg, Germany; BrainLinks-BrainTools Cluster of Excellence, University Medical Centre Freiburg, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Hoeren
authors.affiliation: Department of Neurology and Neuroscience, University Medical Centre Freiburg, Germany; Freiburg Brain Imaging Centre, University Medical Centre Freiburg, Germany; BrainLinks-BrainTools Cluster of Excellence, University Medical Centre Freiburg, Germany; Department of Psychiatry and Psychotherapy, University Medical Centre Freiburg, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Klöppel
authors.affiliation: Department of Neurology and Neuroscience, University Medical Centre Freiburg, Germany; Freiburg Brain Imaging Centre, University Medical Centre Freiburg, Germany.
authors.forename: Dorothee
authors.initials: D
authors.lastname: Kuemmerer
authors.affiliation: Department of Neurology and Neuroscience, University Medical Centre Freiburg, Germany; Freiburg Brain Imaging Centre, University Medical Centre Freiburg, Germany.
authors.forename: Volkmar
authors.initials: V
authors.lastname: Glauche
authors.affiliation: Department of Neurology and Neuroscience, University Medical Centre Freiburg, Germany; Freiburg Brain Imaging Centre, University Medical Centre Freiburg, Germany; BrainLinks-BrainTools Cluster of Excellence, University Medical Centre Freiburg, Germany; Biological and Personality Psychology, Dept. of Psychology, University Medical Centre Freiburg, Germany.
authors.forename: Lena
authors.initials: L
authors.lastname: Köstering
authors.affiliation: Department of Neurology and Neuroscience, University Medical Centre Freiburg, Germany; Department of Neuroradiology, and University Medical Centre Freiburg, Germany.
authors.forename: Irina
authors.initials: I
authors.lastname: Mader
authors.affiliation: Department of Neurology and Neuroscience, University Medical Centre Freiburg, Germany; Freiburg Brain Imaging Centre, University Medical Centre Freiburg, Germany.
authors.forename: Michel
authors.initials: M
authors.lastname: Rijntjes
authors.affiliation: Department of Neurology and Neuroscience, University Medical Centre Freiburg, Germany; Freiburg Brain Imaging Centre, University Medical Centre Freiburg, Germany; BrainLinks-BrainTools Cluster of Excellence, University Medical Centre Freiburg, Germany.
authors.forename: Cornelius
authors.initials: C
authors.lastname: Weiller
authors.affiliation: Department of Neurology and Neuroscience, University Medical Centre Freiburg, Germany; Freiburg Brain Imaging Centre, University Medical Centre Freiburg, Germany; BrainLinks-BrainTools Cluster of Excellence, University Medical Centre Freiburg, Germany.
authors.forename: Roza
authors.initials: R
authors.lastname: Umarova
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D001288:Attention / Q000502:physiology*; D001921:Brain / Q000502:physiology; D001931:Brain Mapping; D005260:Female; D007839:Functional Laterality; D059907:Functional Neuroimaging; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009434:Neural Pathways / Q000502:physiology; D010296:Parietal Lobe / Q000502:physiology*; D010468:Perceptual Disorders / Q000503:physiopathology; D010775:Photic Stimulation; D013028:Space Perception / Q000502:physiology; D013702:Temporal Lobe / Q000502:physiology*; D014794:Visual Fields; D014796:Visual Perception / Q000502:physiology*; D055815:Young Adult
keywords: Bilateral visual processing; Multi-target perception; Normal aging; Visual extinction; Visual neglect