Changes in effective connectivity of human superior parietal lobule under multisensory and unisensory stimulation

R J Moran, S Molholm, R B Reilly, J J Foxe

Research output: Contribution to journalArticle (Academic Journal)

21 Citations (Scopus)

Abstract

Previous event-related potential (ERP) studies have identified the superior parietal lobule (SPL) as actively multisensory. This study compares effective, or contextually active, connections to this region under unisensory and multisensory conditions. Effective connectivity, the influence of one brain region over another, during unisensory visual, unisensory auditory and multisensory audiovisual stimulation was investigated. ERPs were recorded from subdural electrodes placed over the parietal lobe of three patients while they conducted a rapid reaction-time task. A generative model of interacting neuronal ensembles for ERPs was inverted in a scheme allowing investigation of the connections from and to the SPL, a multisensory processing area. Important features of the ensemble model include inhibitory and excitatory feedback connections to pyramidal cells and extrinsic input to the stellate cell pool, with extrinsic forward and backward connections delineated by laminar connection differences between ensembles. The framework embeds the SPL in a plausible connection of distinct neuronal ensembles mirroring the integrated brain regions involved in the response task. Bayesian model comparison was used to test competing feed-forward and feed-backward models of how the electrophysiological data were generated. Comparisons were performed between multisensory and unisensory data. Findings from three patients show differences in summed unisensory and multisensory ERPs that can be accounted for by a mediation of both forward and backward connections to the SPL. In particular, a negative gain in all forward and backward connections to the SPL from other regions was observed during the period of multisensory integration, while a positive gain was observed for forward projections that arise from the SPL.

Original languageEnglish
Pages (from-to)2303-12
Number of pages10
JournalEuropean Journal of Neuroscience
Volume27
Issue number9
DOIs
Publication statusPublished - May 2008

Keywords

  • Acoustic Stimulation
  • Adult
  • Brain Mapping
  • Electroencephalography
  • Epilepsy
  • Evoked Potentials
  • Humans
  • Male
  • Middle Aged
  • Models, Theoretical
  • Neural Pathways
  • Parietal Lobe
  • Photic Stimulation
  • Reaction Time

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