Advanced lesion symptom mapping analyses and implementation as BCBtoolkit

Abstract

BackgroundPatients with brain lesions provide a unique opportunity to understand the functioning of the human mind. However, even when focal, brain lesions have local and remote effects that impact functionally and structurally connected circuits. Similarly, function emerges from the interaction between brain areas rather than their sole activity. For instance, category fluency requires the associations between executive, semantic, and language production functions.FindingsHere, we provide, for the first time, a set of complementary solutions for measuring the impact of a given lesion on the neuronal circuits. Our methods, which were applied to 37 patients with a focal frontal brain lesions, revealed a large set of directly and indirectly disconnected brain regions that had significantly impacted category fluency performance. The directly disconnected regions corresponded to areas that are classically considered as functionally engaged in verbal fluency and categorization tasks. These regions were also organized into larger directly and indirectly disconnected functional networks, including the left ventral fronto-parietal network, whose cortical thickness correlated with performance on category fluency.ConclusionsThe combination of structural and functional connectivity together with cortical thickness estimates reveal the remote effects of brain lesions, provide for the identification of the affected networks, and strengthen our understanding of their relationship with cognitive and behavioral measures. The methods presented are available and freely accessible in the BCBtoolkit as supplementary software [1].

White matter tracts lesions and decline of verbal fluency after deep brain stimulation in Parkinson's disease

“…We fixed 50% of probability to consider a tract as disconnected, as previously used in literature (Foulon et al, 2018). Then, we calculated the percentage of subjects with a disconnected tract.…”

“…The second methodological limitation of the study is the lack of an accurate quantification of the severity of the fiber tracts disconnection. Notably, we fixed 50% of probability to consider a tract as disconnected, as previously used in literature (Foulon et al, ). Moreover, we used as a surrogate measure of tract damage the proportion of the tract that was intersected by the electrodes trajectory.…”

“…The second methodological limitation of the study is the lack of an accurate quantification of the severity of the fiber tracts disconnection. Notably, we fixed 50% of probability to consider a tract as disconnected, as previously used in literature (Foulon et al, 2018).…”

“…Then, the lesion mask along the electrode trajectory transformed into the MNI 152 coordinate system was compared with white matter tract atlas in Tractotron software, which provides a probability and proportion of fibers disconnection. A tract with a probability of >50% value is considered as disconnected in accordance with tractotron method paper (Foulon et al, ). The proportion fibers disconnection was calculated by dividing the number of damaged voxels in the ROI by the total volume of the tract.…”

“…Tractotron software provides a file containing probability and proportion of any tract, ready to be analyzed with statistical software. We fixed 50% of probability to consider a tract as disconnected, as previously used in literature (Foulon et al, ). Then, we calculated the percentage of subjects with a disconnected tract.…”