Interhemispheric Dynamics of the Insular Processing of Nociceptive and non-Nociceptive Stimuli (e-poster)

Background and aims. The human insula is a main target of ascending nociceptive inputs and is thought to play an important role in pain perception. A large number of studies using fMRI, PET, EEG and intracerebral EEG have shown that nociceptive stimuli elicit similar responses in the ipsilateral and contralateral insulae. Other studies have distinguished the functional contributions of its posterior and anterior portions in nociception. In this setting, our goal was to characterize the interhemispheric dynamics of ongoing and nociception-evoked activity in the posterior and anterior portions of the human insula. Methods. We had the unique opportunity to record intracerebral EEG signals from the anterior and posterior parts of the left and right insulae simultaneously in a patient implanted bilaterally using depth electrodes for a presurgical evaluation of partial epilepsy. The fine spatiotemporal resolution of these recordings allowed us to study the interhemispheric dynamics of intrinsic insular activity and evoked insular activity elicited by painful (heat) and non-painful (auditory, visual and vibrotactile) stimuli. Results. We show that local-field potentials (LFPs) recorded in the right and left insulae are highly cross-correlated both in resting-state and in response to a stimulus. LFPs elicited by a stimulus on the same insular gyrus in both hemispheres present a very small time lag. Conclusions. Our results highlight the bilateral activation of the insula to both nociceptive and non-nociceptive stimuli, with similar time lags