Higher media multi-tasking activity is associated with smaller gray-matter density in the anterior cingulate cortex

Media multitasking, or the concurrent consumption of multiple media forms, is increasingly prevalent in today’s society and has been associated with negative psychosocial and cognitive impacts. Individuals who engage in heavier media-multitasking are found to perform worse on cognitive control tasks and exhibit more socio-emotional difficulties. However, the neural processes associated with media multi-tasking remain unexplored. The present study investigated relationships between media multitasking activity and brain structure. Research has demonstrated that brain structure can be altered upon prolonged exposure to novel environments and experience. Thus, we expected differential engagements in media multitasking to correlate with brain structure variability. This was confirmed via Voxel-Based Morphometry (VBM) analyses: Individuals with higher Media Multitasking Index (MMI) scores had smaller gray matter density in the anterior cingulate cortex (ACC). Functional connectivity between this ACC region and the precuneus was negatively associated with MMI. Our findings suggest a possible structural correlate for the observed decreased cognitive control performance and socio-emotional regulation in heavy media-multitaskers. While the cross-sectional nature of our study does not allow us to specify the direction of causality, our results brought to light novel associations between individual media multitasking behaviors and ACC structure differences

L'organisation anatoma-fonctionnelle du contrôle adaptatif des réponses manuelles, orofaciales et vocales dans le cortex frontal humain

This thesis primarily investigated how the human frontal cortex is organised to learn and use conditional rules linking contextual stimuli with manual, vocal and orofacial actions. My first study demonstrated that in humans: 1) the posterior lateral frontal cortex (pLFC) is organized along a dorso-ventral gradient, where the dorsal premotor cortex and ventral area 44 are involved in manual and vocal-orofacial conditional associations respectively, and 2) the anterior-most cingulate motor area (RCZa) within the mid-cingulate cortex (MCC), contributes to the evaluation of auditory feedback during the trial-and-error learning of the conditional associations. My second study showed that within the MCC, the three CMAs are functionally coupled with the lateral frontal cortex along a rostral-caudal gradient where more rostral regions are implicated in more abstracted levels of behavioral control. These findings provided important contributions to current theories about frontal cortical organization for behavioural control. Lastly, through an extensive review, I revealed that, within the pLFC-MCC network, area 44 and RCZa are part of a homologous brain network that might play a similar role in cognitive vocal/orofacial control across primates. My hypothesized role of this network in the adaptive control of vocal/orofacial actions based on auditory feedback monitoring had been validated, in humans, from my first study. Thus, my thesis had also revealed an important starting point - the area 44-RCZa, for future investigations into the potential neural changes that occurred across primate evolution to support the emergence of human speech abilitiesCe travail de thèse explore l'organisation fonctionnelle du cortex frontal chez l'homme lors de l'apprentissage et l'utilisation de règles conditionnelles associées à des stimuli contextuels et demandant la réalisation d'actions manuelles, vocales et orofaciales. Ma première étude a démontré chez l'homme que 1) le cortex frontal latéral postérieur (pLFC) est organisé selon un gradient dorso-ventral, où le cortex prémoteur dorsal (PMd) et le cortex préfrontal dorsal (BA 44) sont impliqués respectivement dans les associations conditionnelles manuelles et vocal-orofaciales, et 2) que l'aire motrice cingulaire antérieure (RCZa) au sein du cortex cingulaire moyen (MCC), contribue à l'évaluation des feedback auditifs durant l'apprentissage par essai-erreur de ces associations. Ma seconde étude a révélé qu'au sein du MCC, les trois CMAs sont fonctionnellement couplées avec le cortex préfrontal latéral le long du gradient rostro- caudal où les régions les plus rostrales sont impliqués dans un contrôle comportemental de plus haut niveau. Ces résultats apportent de nouveaux éclaircissements aux théories actuelles concernant l'organisation cortico-frontal du contrôle comportemental. En réalisant une revue de la littérature, j'ai montré qu'au sein du réseau pLFD-MCC les aires BA 44 et RCZa font partie d'un réseau cérébral homologue qui pourrait jouer un rôle similaire dans le contrôle cognitif vocal/orofacial chez les primates - le contrôle adaptatif des actions vocales/orofaciales basés sur l'évaluation des feedback auditifs. Cette hypothèse a été validé chez l'homme dans ma première étude. Cette thèse a mis en évidence un important réseau neural aidant à comprendre comment le contrôle du langage a évolué au cours de l'évolution des primates. Pour finir, j'ai présenté des résultats préliminaires qui montre que la correspondance des profils de connectivité en état de repos est une approche prometteuse pour comparer l'organisation fonctionnelle cérébrale inter-espèce

Brain regions exhibiting functional connectivity with ACC ROI.

<p><i>p_{FWE-corrected}</i><0.05.</p><p>Brain regions exhibiting functional connectivity with ACC ROI.</p

Datafiles for Loh and Kanai (2014)

<p><strong>Datafiles for Research Study:</strong></p> <p>Loh and Kanai (2014) Higher media multi-tasking activity is associated with decreased gray-matter density in the anterior cingulate cortex.</p> <p><strong>Files Included:</strong></p> <p>1. Processed Structural Images for VBM Regressions (<em>smwc...nii files</em>)</p> <p>2. Template File for VBM (<em>Template_6.nii</em>)</p> <p>3. Spreadsheet with Variables for VBM regression (<em>Variables for VBM regressions.xlx</em>)</p> <p>4. Processed Beta images showing correlated activity with ACC region of interest for functional connectivity regression (<em>BETA....nii files</em>)</p> <p>5. Spreadsheet with Variables for functional connectivity regressions (<em>Variables for Resting State Functional Connectivity Regressions.xlx</em>)</p> <p> </p

Regression analyses revealed that connectivity between the ACC ROI and the Precuneus (intersection of blue lines) was negatively associated with MMI scores (Precuneus; t(40) = 5.22, P_{FWE-uncorrected}<0.001, Cluster size = 159 mm³; Peak MNI coordinate: x = 10, y = −50, z = 18).

<p>There was a negative relationship (<i>r</i> = −0.68, <i>p</i><0.001) between adjusted Z-transformed ACC-Precuneus correlations (Y-axis) and MMI scores (X-axis).</p

VBM regression analyses revealed that MMI scores were significantly associated with gray matter density in the ACC (t(70) = 5.16, P_{FWE-corrected} <0.05, Cluster size = 158 voxels x 1.5³ = 533 mm³; peak MNI coordinate: x = 12, y = 41, z = 3).

<p>Adjusted gray matter density in the peak voxel (Y-axis) was negatively correlated (<i>r</i> = −0.54, <i>p</i><0.001) with MMI scores (X-axis).</p

Correlations between Media multitasking index scores and Big Five Inventory scores.

<p>Correlations between Media multitasking index scores and Big Five Inventory scores.</p

Comparisons between demographic characteristics and MMI scores of participants involved in VBM analyses and functional connectivity analyses.

a<p>Mean (standard deviation) for age and MMI scores.</p><p>Comparisons between demographic characteristics and MMI scores of participants involved in VBM analyses and functional connectivity analyses.</p

The Arcuate Fasciculus and language origins: Disentangling existing conceptions that influence evolutionary accounts

The Arcuate Fasciculus (AF) is of considerable interdisciplinary interest, because of its major implication in language processing. Theories about language brain evolution are based on anatomical differences in the AF across primates. However, changing methodologies and nomenclatures have resulted in conflicting findings regarding interspecies AF differences: Historical knowledge about the AF originated from human blunt dissections and later from monkey tract-tracing studies. Contemporary tractography studies reinvestigate the fasciculus’ morphology, but remain heavily bound to unclear anatomical priors and methodological limitations. First, we aim to disentangle the influences of these three epistemological steps on existing AF conceptions, and to propose a contemporary model to guide future work. Second, considering the influence of various AF conceptions, we discuss four key evolutionary changes that propagated current views about language evolution: 1) frontal terminations, 2) temporal terminations, 3) greater Dorsal- versus Ventral Pathway expansion, 4) lateralisation. We conclude that new data point towards a more shared AF anatomy across primates than previously described. Language evolution theories should incorporate this continuous AF evolution across primates

The Arcuate Fasciculus and language origins: Disentangling existing conceptions that influence evolutionary accounts

International audienceThe Arcuate Fasciculus (AF) is of considerable interdisciplinary interest, because of its major implication in language processing. Theories about language brain evolution are based on anatomical differences in the AF across primates. However, changing methodologies and nomenclatures have resulted in conflicting findings regarding interspecies AF differences: Historical knowledge about the AF originated from human blunt dissections and later from monkey tract-tracing studies. Contemporary tractography studies reinvestigate the fasciculus’ morphology, but remain heavily bound to unclear anatomical priors and methodological limitations. First, we aim to disentangle the influences of these three epistemological steps on existing AF conceptions, and to propose a contemporary model to guide future work. Second, considering the influence of various AF conceptions, we discuss four key evolutionary changes that propagated current views about language evolution: 1) frontal terminations, 2) temporal terminations, 3) greater Dorsal- versus Ventral Pathway expansion, 4) lateralisation. We conclude that new data point towards a more shared AF anatomy across primates than previously described. Language evolution theories should incorporate this more continuous AF evolution across primates