NeuroImage
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Comparative Study
Significant correlation between a set of genetic polymorphisms and a functional brain network revealed by feature selection and sparse Partial Least Squares.
Brain imaging is increasingly recognised as an intermediate phenotype to understand the complex path between genetics and behavioural or clinical phenotypes. In this context, a first goal is to propose methods to identify the part of genetic variability that explains some neuroimaging variability. Classical univariate approaches often ignore the potential joint effects that may exist between genes or the potential covariations between brain regions. ⋯ We estimate the generalisability of the multivariate association with a cross-validation scheme and demonstrate the significance of this link, using a permutation procedure. Univariate selection appears to be necessary to reduce the dimensionality. However, the significant association uncovered by this two-step approach combining univariate filtering and L1-regularised PLS suggests that discovering meaningful genetic associations calls for a multivariate approach.
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The specific neural processes underlying vicarious pain perception are not fully understood. In this functional imaging study, 20 participants viewed pain-evoking or neutral images displaying either sensory or emotional-communicative information. The pain images displayed nociceptive agents applied to the hand or the foot (sensory information) or facial expressions of pain (emotional-communicative information) and were matched with their neutral counterparts. ⋯ However, greater pain-related activity was observed in the rostral IPL when images depicted a hand or foot compared to a facial expression of pain, suggesting a more specific involvement in the coding of somato-motor information. Posterior probability maps enabling Bayesian inferences further showed that the anterior IFG (BA 45 and 47) was the only region showing no intrinsic probability of activation by the neutral images, consistent with a role in the extraction of the meaning of pain-related visual cues. Finally, inter-individual empathy traits correlated with responses in the supracallosal mid/anterior cingulate cortex and the anterior insula when pain-evoking images of body limbs or facial expressions were presented, suggesting that these regions regulated the observer's affective-motivational response independent from the channels from which vicarious pain is perceived.
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The brain is organized into a set of widely distributed networks. Therefore, although structural damage from stroke is focal, remote dysfunction can occur in regions connected to the area of lesion. Historically, neuroscience has focused on local processing due in part to the absence of tools to study the function of distributed networks. ⋯ Early results suggest that disruption of inter-hemispheric connectivity in the somatomotor network and the dorsal attention network is more strongly associated with behavioral impairment in those domains than is intra-hemispheric connectivity within either the lesioned or unaffected hemisphere. We also observe in the somatomotor network an interesting interaction between corticospinal tract damage and decreased inter-hemispheric connectivity that suggests that both processes combine to contribute to neuromotor impairment after stroke. A connectivity-based approach will provide greater insight into network reorganization in the acute and chronic phases after stroke and will contribute to improving prognostic ability and the development of therapeutic interventions.