Poster Session E, Monday, March 25, 2:30 – 4:30 pm, Pacific Concourse
Involvement of the Insula in Top-Down Attentional Processing: An Intracranial EEG Study
Daphné Citherlet1,2, Olivier Boucher1,2,3, Julie Tremblay4, Manon Robert1, Anne Gallagher2,4, Alain Bouthillier3, Franco Lepore2, Dang Khoa Nguyen1,2,3; 1Centre de Recherche du Centre Hospitalier de l'Université de Montréal, CRCHUM, 2University of Montreal, 3Centre Hospitalier de l'Université de Montréal, CHUM, 4Centre de Recherche du CHU Sainte-Justine, Montréal
The insula is a paralimbic structure localized deep in the Sylvian fissure. Whereas the posterior insula (pI) is thought to be involved in primary sensory processing, the anterior insula (aI) is more involved in attentional processes, playing a crucial role in the “salience network”. However, its specific role in attentional processing remains unclear, especially due to the limited temporal resolution of neuroimaging techniques. Our study examines the spatio-temporal dynamics of visual target processing using intracranial EEG recorded directly from the insula. During the extraoperative invasive intracranial EEG monitoring of their drug-resistant seizures, eight epileptic patients completed a three-stimulus visual oddball task involving standard, target, and novel stimuli. A total of 59 electrode contacts in the insula were recorded. Permutation analyses were performed to compare event-related potentials (ERPs) across different conditions during the P300 (225-400 ms) interval, and modulations of gamma band responses (GBRs; 70-150 Hz) were analyzed across different conditions using non-parametric Wilcoxon test from 0 to 1,000 ms post-stimuli. We found that target stimulus detection was associated with a P300 component for 39 % of contacts implanted in the aI, reflecting voluntary attentional processing. In the pI, only 16 % of contacts showed responses to target stimulus in the P300 interval. Increased GBRs in response to targets were observed in 53 % of aI contacts (from ≈ 200-300 ms). Results suggest that visual targets elicit a P300 and GBRs in the aI, suggesting that this region is involved in top-down attentional processing of task-relevant information.
Topic Area: ATTENTION: Other