Task-Residual Effective Connectivity of Motor Network in Transient Ischemic Attack and its Association with Risk Factor of Stroke

Transient ischemic attack (TIA) is a transient episode of neurological dysfunction caused by focal brain ischemia. Although TIA symptoms are quickly resolved, patients with TIA have a high risk of stroke and persistent impairments in multiple domains of cognitive and motor functions. In this study, using spectral dynamic causal modelling, we investigated the changes in task-residual effective connectivity of patients with TIA during fist-closing movements and associated them with risk factors of stroke. 28 healthy participants and 15 age-matched patients with TIA underwent functional magnetic resonance imaging at 7T. Our results showed that during motor movement, patients with TIA had significantly higher effective connectivity toward the ipsilateral primary motor cortex and lower connectivity to the supplementary motor area than healthy controls. These changes in connectivity strength were positively correlated with ABCD2 scores indicating higher risk of stroke. The leave-on-out cross-validation analysis further confirmed the reliability of using effective connectivity in prediction of stroke risk after TIA. Our results imply that (i) TIA patients have disrupted connections among motor regions that are closely related to the risk of stroke, and (ii) these changes may reflect the neural dedifferentiation in the motor system.