Effective connectivity reveals right-hemisphere dominance in audiospatial perception: implications for models of spatial neglect.
Detecting the location of salient sounds in the environment rests on the brain's ability to use differences in sounds arriving at both ears. Functional neuroimaging studies in humans indicate that the left and right auditory hemispaces are coded asymmetrically, with a rightward attentional bias that reflects spatial attention in vision. Neuropsychological observations in patients with spatial neglect have led to the formulation of two competing models: the orientation bias and right-hemisphere dominance models. The orientation bias model posits a symmetrical mapping between one side of the sensorium and the contralateral hemisphere, with mutual inhibition of the ipsilateral hemisphere. The right-hemisphere dominance model introduces a functional asymmetry in the brain's coding of space: the left hemisphere represents the right side, whereas the right hemisphere represents both sides of the sensorium. We used Dynamic Causal Modeling of effective connectivity and Bayesian model comparison to adjudicate between these alternative network architectures, based on human electroencephalographic data acquired during an auditory location oddball paradigm. Our results support a hemispheric asymmetry in a frontoparietal network that conforms to the right-hemisphere dominance model. We show that, within this frontoparietal network, forward connectivity increases selectively in the hemisphere contralateral to the side of sensory stimulation. We interpret this finding in light of hierarchical predictive coding as a selective increase in attentional gain, which is mediated by feedforward connections that carry precision-weighted prediction errors during perceptual inference. This finding supports the disconnection hypothesis of unilateral neglect and has implications for theories of its etiology.
Centre for Functionally Integrative Neuroscience, Institute of Clinical Medicine, Aarhus University, 8000 Aarhus C, Denmark, Wellcome Trust Centre for Neuroimaging, University College London, London WC1N 3BG, United Kingdom, Queensland Brain Institute and Australian Research Council Centre of Excellence for Integrative Brain Function and School of Psychology, The University of Queensland, St Lucia 4072, Brisbane, Australia.
Martin J
MJ
Dietz
Karl J
KJ
Friston
Jason B
JB
Mattingley
Andreas
A
Roepstorff
Marta I
MI
Garrido
D000161:Acoustic Stimulation; D000328:Adult; D001306:Auditory Pathways / Q000502:physiology*; D001307:Auditory Perception / Q000502:physiology*; D001499:Bayes Theorem; D001931:Brain Mapping; D004292:Dominance, Cerebral / Q000502:physiology*; D004569:Electroencephalography; D005072:Evoked Potentials, Auditory; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D015225:Magnetoencephalography; D008297:Male; D008959:Models, Neurological; D017711:Nonlinear Dynamics; D009949:Orientation; D013028:Space Perception / Q000502:physiology*; D055815:Young Adult
Bayesian; DCM; EEG; audiospatial; connectivity; neglect