Investigating the Dependence of Spontaneous Fluctuations in Visual Cortex on Callosal Connectivity

Li-Wei Kuo¹, Zhongming Liu¹, Jacco A. de Zwart¹, Peter van Gelderen¹, Jeff H. Duyn¹

In this study, we investigated the dependence of spontaneous fMRI activity in human visual cortex on callosal connectivity. Interhemispheric correlations in fMRI studies of spontaneous activity have been partly attributed to cortico-cortical connections through the corpus callosum, suggesting these correlations may be reduced in the part of visual area V1 that lacks these connections. Using 7T fMRI, regions of interest with high and low/absent callosal V1 connectivity were identified with retinotopic mapping, after which interhemispheric correlations were calculated during rest. Our preliminary results show that interhemispheric functional connectivity is organized retinotopically, with a minimal dependence on mono-synaptic callosal connectivity. This suggests that interhemispheric functional connectivity partly arises from multi-synaptic pathways.