Signal Propagation in the Human Visual Pathways: An Effective Connectivity Analysis

Vahab Youssofzadeh, Girijesh Prasad, Andrew J. Fagan, Richard B. Reilly, Sven Martens, James F. Meaney, KongFatt Wong-Lin

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)


Although the visual system has been extensively investigated, an integrated account of the spatiotemporal dynamics of long-range signal propagation along the human visual pathways is not completely known or validated. In this work, we used dynamic causal modeling approach to provide insights into the underlying neural circuit dynamics of pattern reversal visual-evoked potentials extracted from concurrent EEG-fMRI data. A recurrent forward– backward connectivity model, consisting of multiple interacting brain regions identified by EEG source localization aided by fMRI spatial priors, best accounted for the data dynamics. Sources were first identified in the thalamic area, primary visual cortex, as well as higher cortical areas along the ventral and dorsal visual processing streams. Consistent with hierarchical early visual processing, the model disclosed and quantified the neural temporal dynamics across the identified activity sources. This signal propagation is dominated by a feedforward process, but we also found weaker effective feedback connectivity. Using effective connectivity analysis, the optimal dynamic causal modeling revealed enhanced connectivity along the dorsal pathway but slightly suppressed connectivity along the ventral pathway. A bias was also found in favor of the right hemisphere consistent with functional attentional asymmetry. This study validates, for the first time, the long-range signal propagation timing in the human visual pathways. A similar modeling approach can potentially be used to understand other cognitive processes and dysfunctions in signal propagation in neurological and neuropsychiatric disorders.
Original languageEnglish
Pages (from-to)13501-13510
Number of pages10
JournalThe Journal of Neuroscience
Issue number39
Publication statusPublished (in print/issue) - 30 Sept 2015


  • Concurrent EEG-fMRI
  • dorsal pathway
  • dynamic causal modeling
  • ventral pathway
  • visual-evoked potentials


Dive into the research topics of 'Signal Propagation in the Human Visual Pathways: An Effective Connectivity Analysis'. Together they form a unique fingerprint.

Cite this