Le 15/10/2021 de 13:30 à 15:30

Retour Session


La connectivité fonctionnelle au sein du réseau du modèle interne de verticalité

Camille Lemaire (Grenoble, France), Assia Jaillard (Grenoble, France), Irina Gornushkina (Grenoble, France), Céline Piscicelli (Grenoble, France), Shenhao Dai (Grenoble, France), Cédric Pichat (Grenoble, France), Olivier Detante (Grenoble, France), Marc Hommel (Grenoble, France), Monica Baciu (Grenoble, France), Dominic Perennou (Grenoble, France)

Objective : The construction of an internal model of verticality from a normal multisensory integration is critical for postural control. After hemispheric stroke, the existence of lateropulsion is a marker of an abnormal internal model of verticality. The neural correlates of the internal model of verticality are well known and are : parietal operculum, posterior insula and postero-lateral thalamus. However, how these structures interact within a network has never been investigated. This is the aim of this pilot study.

Material / Patients and Methods : rs-fMRI was evaluated in 5 patients with unilateral hemispheric stroke and 10 healthy participants. Data analysis involved a region of interest (ROI)-based approach. Outside the MRI machine, stroke individuals performed a visual vertical (verticality perception). 

Results : First, we assessed functional connectivity between the different seeds (ROIs) of the verticality core network separately in the healthy and stroke groups.
Second, we compared the strength of these connections of healthy and stroke participants, using one-tailed two-sample t-test. Several connections were weaker in stroke than healthy participants and one connection stronger (in the side opposite the stroke), showing plasticity.
Third, we analysed the relationship between VV estimates and connectivity parameters for the projections between the posterolateral thalamus and the posterior insula.We found that the weaker the connection linking the posterior parts of the thalamus and the insula, the more VV was biased.

Discussion - Conclusion : This study is the first showing that core structures involved in verticality perceptionare functionally connected, at intra- and interhemispheric levels and that, after stroke, the more disrupted the thalamo-insular projections, the more biased the verticality perception.

Keywords : stroke, spatial cognition, verticality perception, fMRI, functionnal connectivity