A Combined Dynamic Causal Modeling & Functional MRI Study to Assess Visuospatial Symmetry Judgment in Healthy Subjects

Manisha Bhattacharya¹, Shilpi Modi¹, Memita Devi¹, Namita Singh Saini¹, Rajendra Prasad Tripathi¹, Subash Khushu¹

Dynamic Causal Modeling along with fMRI was used to quantify effective connectivity within a visuospatial symmetry processing network in each cerebral hemisphere. Twelve different models consisting of Occipital Gyrus, Superior Parietal Lobule (SPL(7A)) and Middle Frontal Gyrus (BA6) were defined. Our results provide evidence in support of the direct effect of the task on SPL and its modulatory effect on the connectivity between SPL and BA6 for both hemispheres. However, SPL is excitatory in its action on BA6 in the left hemisphere while it is inhibitory in the right hemisphere demonstrating the greater role of left hemisphere in symmetry processing.