Brain and behaviour in post-acute stroke: Reduction in seeking and posterior cingulate neuronal variability.

Introduction: Stroke is a complex event on both behavioral and neuronal grounds. Recent investigations evidence the central role of subcortical damage on the post-stroke brain and behavior reorganization. We have conducted an exploratory study combining anatomical lesion analysis, functional analysis of resting state fMRI, and behavioral assessment with focus on exploration as represented by SEEKING. Method: 24 stroke inpatients were studied immediately after their clinical stabilization post-stroke; neuronal variability in fMRI along with behavioral outcomes were assessed. These outcomes were compared with a control group of 22 healthy subjects. Results: First, we observed predominant subcortical lesions in our sample with all stroke patients showing subcortical lesions and only some exhibiting additional cortical lesions. Second, we observed significantly reduced neuronal variability in the posterior cingulate cortex (PCC) that did not show any structural damage. Third, our stroke subjects showed reduced SEEKING which was related to reduced PCC neuronal variability in an abnormal way (compared to healthy subjects). This last outcome was assessed by considering the subset of 11 stroke subjects for which fMRI and behavioral outcomes were jointly measured. Conclusions: Taken together, our findings suggest that damage in subcortical regions may play a central role in abnormalities in both cortical activity (PCC) and associated behavior of post-stroke reorganization. Accounting for these aspects may have significant implications to optimize multidisciplinary rehabilitation processes, particularly during the early steps of recovery, reducing the impact of stroke on the patient and caregiver quality of life.