Do focal brain lesions have distant effects on intact neural tissue?

Abstract

Event Abstract Back to Event Do focal brain lesions have distant effects on intact neural tissue? Yuan Tao1* and Brenda Rapp1 1 Johns Hopkins University, Cognitive Science Department, United States Introduction. The remote effects of focal brain lesions (“diaschisis”) have long been of interest for clinical reasons and for understanding neural connectivity and modularity. Recent computer simulation work in connectomics predicts that lesions affecting highly connected brain areas within the frontal and parietal lobes and midline structures should have effects on the functioning of distant, intact cortical areas in both hemispheres (Honey & Sporns, 2008). However, these predictions have not been evaluated with neuroimaging data from individuals with brain lesions. In this study, we examined individuals with acquired dysgraphia as a result of left hemisphere stroke. Their lesions affected left frontal, parietal or superior temporal areas that have been predicted should produce diaschisis. Using fMRI, we evaluated activation patterns during two tasks: spelling and face processing. These tasks were selected because the brain-lesioned individuals had spelling deficits but normal performance in face processing. Furthermore, both tasks involve key brain regions in ventral occipito-temporal cortices that were preserved in the brain-lesioned participants. This allowed to us to examine whether or not focal brain lesions necessarily produce disruption in neural activation in distant, intact neural substrates. Methods and Results. The dysgraphic participants (n=18) had a mean age of 63, and had suffered a single left hemisphere stroke, at least one year before the investigation. The neurotypical participants (n=30) ranged in age from 30 to 69. All participants carried out spelling and face processing tasks during fMRI scanning. In the spelling task, on each trial participants were asked to judge if a visually presented letter was in the spelling of a heard word. In the face processing task, participants viewed blocks of faces, object, scenes, and scrambled images. Group-level GLM analyses for spelling indicated that the dysgraphic group failed to show the activation in left mid-fusiform gyrus exhibited by the control group (Fig.1). In contrast, the dysgraphic group exhibited similar face processing activation patterns as control participants in bilateral occipital and fusiform areas. Comparable results were observed when individual participant activation patterns were evaluated. Discussion. Our findings suggest that non-local, distant disruption of BOLD response is not a necessary consequence of focal brain lesions, supporting the notion of a significant degree of modular neural organization. Furthermore, the results suggest that distant disruption may be “context dependent”, in that it is modulated by the functional relationships between lesioned and intact substrates. However, firm conclusions will require more detailed analysis of neural responsivity in distant, intact areas, including measures of functional and structure network connectivity. Acknowledgements The research reported here was part of a larger, multi-site NIH-funded P50 project examining the neurobiology of language recovery in people with aphasia (DC 012283). We thank all of the research participants, and Jennifer Shea and Donna Gotsch for data collection. References Honey, C. & Sporns, O. (2008). Dynamical consequences of lesions in cortical networks. Human Brain Mapping, 29, 802-809. Keywords: dysgraphia, lesion, face processing, VWFA, diaschisis Conference: Academy of Aphasia 55th Annual Meeting , Baltimore, United States, 5 Nov - 7 Nov, 2017. Presentation Type: poster presentation Topic: General Submission Citation: Tao Y and Rapp B (2019). Do focal brain lesions have distant effects on intact neural tissue?. Conference Abstract: Academy of Aphasia 55th Annual Meeting . doi: 10.3389/conf.fnhum.2017.223.00016 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 04 May 2017; Published Online: 25 Jan 2019. * Correspondence: Dr. Yuan Tao, Johns Hopkins University, Cognitive Science Department, Baltimore, MD, 21210, United States, yuan.tao@jhu.edu Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Yuan Tao Brenda Rapp Google Yuan Tao Brenda Rapp Google Scholar Yuan Tao Brenda Rapp PubMed Yuan Tao Brenda Rapp Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.