Effective Connectivity During Haptic Perception: A Study Using Granger Causality Analysis Of Functional Magnetic Resonance Imaging Data

• Type of Material: Article
• Authors: Gopikrishna Deshpande, Emory University; Xiaoping P Hu, Emory University; Randall Stilla, Emory University; Krish Sathian, Emory University
• Language: English
• Date: 2008-05-01
• Publisher: Elsevier
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: © 2008 Elsevier Inc. All rights reserved.
• License: Creative Commons Attribution-NonCommerical-NoDerivs 3.0 Unported
• Final Published Version (URL): http://dx.doi.org/10.1016/j.neuroimage.2008.01.044
• Title of Journal or Parent Work: NeuroImage
• ISSN: 1053-8119
• Volume: 40
• Issue: 4
• Start Page: 1807
• End Page: 1814
• Grant/Funding Information: This work was supported by NIH grants R01 EY12440 and K24 EY17332 to KS, and R01 EB002009 to XH.; Support to KS and RS from the Veterans Administration is also gratefully acknowledged.
• Research Categories: Biology, Neuroscience

Abstract

Although it is accepted that visual cortical areas are recruited during touch, it remains uncertain whether this depends on top-down inputs mediating visual imagery or engagement of modality-independent representations by bottom-up somatosensory inputs. Here we addressed this by examining effective connectivity in humans during haptic perception of shape and texture with the right hand. Multivariate Granger causality analysis of functional magnetic resonance imaging (fMRI) data was conducted on a network of regions that were shape- or texture-selective. A novel network reduction procedure was employed to eliminate connections that did not contribute significantly to overall connectivity. Effective connectivity during haptic perception was found to involve a variety of interactions between areas generally regarded as somatosensory, multisensory, visual and motor, emphasizing flexible cooperation between different brain regions rather than rigid functional separation. The left postcentral sulcus (PCS), left precentral gyrus and right posterior insula were important sources of connections in the network. Bottom-up somatosensory inputs from the left PCS and right posterior insula fed into visual cortical areas, both the shape-selective right lateral occipital complex (LOC) and the texture-selective right medial occipital cortex (probable V2). In addition, top-down inputs from left postero-supero-medial parietal cortex influenced the right LOC. Thus, there is strong evidence for the bottom-up somatosensory inputs predicted by models of visual cortical areas as multisensory processors and suggestive evidence for top-down parietal (but not prefrontal) inputs that could mediate visual imagery. This is consistent with modality-independent representations accessible through both bottom-up sensory inputs and top-down processes such as visual imagery.