Functional neuroanatomy of the insular lobe

Abstract

The insula is the fifth lobe of the brain and it is the least known. Hidden under the temporal, frontal and parietal opercula, as well as under dense arterial and venous vessels, its accessibility is particularly restricted. Functional data on this region in humans, therefore, are scarce and the existing evidence makes conclusions on its functional and somatotopic organization difficult. 5 patients with intractable epilepsy underwent an invasive presurgical evaluation with implantation of diagnostic invasive-depth electrodes, including insular electrodes that were inserted using a mesiocaudodorsal to laterorostroventral approach. Altogether 113 contacts were found to be in the insula and were stimulated with alternating currents during preoperative monitoring. Different viscerosensitive and somatosensory phenomena were elicited by stimulation of these electrodes. A relatively high density of electrode contacts enabled us to delineate several functionally distinct areas within the insula. We found somatosensory symptoms to be restricted to the posterior insula and a subgroup of warmth or painful sensations in the dorsal posterior insula. Viscerosensory symptoms were elicited by more anterior electrode contacts with a subgroup of gustatory symptoms occurring after stimulation of electrode contacts in the central part of the insula. The anterior insula did not show reproducible responses to stimulation. In line with previous studies, we found evidence for somato- and viscerosensory cortex in the insula. In addition, our results suggest that there is a predominantly posterior and central distribution of these functions in the insular lobe.Electronic supplementary materialThe online version of this article (doi:10.1007/s00429-010-0296-3) contains supplementary material, which is available to authorized users.

Vascular consequences of operculoinsular corticectomy for refractory epilepsy

“…Surgery of the insular area is known to be challenging because of its close relationship with vascular structures. 8,15,26,36,[38][39][40] Immediate postoperative deficits have been previously reported with incidence rates between 9.2% and 74% in the literature. Comparison in incidence rate of transient or permanent complications is difficult considering that these series have mostly dealt with patients with tumors or vascular malformations often extending outside the insula both to surrounding lobes and in deeper subcortical structures.…”

Connectivity of the frontal and anterior insular network: a cortico-cortical evoked potential study

“…15 The central sulcus of the insula was used to divide the insula into anterior and posterior parts. 26 …”

“…2 These networks may be involved in the anterior insular functions relevant for homeostasis or emotional processing. 26 Posterior insular was not examined in the present study due to the limitations of electrode coverage. It is an interesting consideration for future analysis.…”

Molecular, Functional, and Structural Imaging of Major Depressive Disorder

“…The anterior insula connects to the inferior frontal cortex and to the ACC [44]. It is thought to be involved in social-emotional and cognitive networks [45], and thus may play a crucial role in the neurobiology of MDD [42]. Similarly, given that the thalamus is connected to the cortex and to negative emotion-generating limbic structures such as the amygdala [38], the anomalous thalamic structure may account for deficits in the top-down regulation of negative affect in individuals with MDD.…”