The insula function via epilepsy-SEEG pattern and fMRI

1802 

Abstract Submission 

Yi-Hsiu Chen¹, Cheng-Chia Lee^2,3,4, Cheng-Chen Chou⁵, YI-HSUAN LIU¹, Pei-Lin Lee⁶, Kun-Hsien Chou^1,4, Ching-Po Lin^1,6,7

¹Institute of Neuroscience, National Yang Ming Chiao Tung University, Taipei, Taiwan, ²Department of Neurosurgery, Neurological Institute, Taipei Veteran General Hospital, Taipei, Taiwan, ³School of Medicine, National Yang Ming Chiao Tung University,, Taipei, Taiwan, ⁴Brain Research Center, National Yang Ming Chiao Tung University, Taipei, Taiwan, ⁵Department of Neurology, Neurological Institute,Taipei Veterans General Hospital, Taipei, Taiwan, ⁶Center for Healthy Longevity and Aging Sciences, National Yang Ming Chiao Tung University, Taipei, Taiwan, ⁷Department of Education and Research, Taipei City Hospital, Taipei, Taiwan

Yi-Hsiu Chen  
Institute of Neuroscience, National Yang Ming Chiao Tung University
Taipei, Taiwan

Cheng-Chia Lee  
Department of Neurosurgery, Neurological Institute, Taipei Veteran General Hospital|School of Medicine, National Yang Ming Chiao Tung University,|Brain Research Center, National Yang Ming Chiao Tung University
Taipei, Taiwan|Taipei, Taiwan|Taipei, Taiwan

Cheng-Chen Chou  
Department of Neurology, Neurological Institute,Taipei Veterans General Hospital
Taipei, Taiwan

YI-HSUAN LIU  
Institute of Neuroscience, National Yang Ming Chiao Tung University
Taipei, Taiwan

Pei-Lin Lee  
Center for Healthy Longevity and Aging Sciences, National Yang Ming Chiao Tung University
Taipei, Taiwan

Kun-Hsien Chou  
Institute of Neuroscience, National Yang Ming Chiao Tung University|Brain Research Center, National Yang Ming Chiao Tung University
Taipei, Taiwan|Taipei, Taiwan

Ching-Po Lin  
Institute of Neuroscience, National Yang Ming Chiao Tung University|Center for Healthy Longevity and Aging Sciences, National Yang Ming Chiao Tung University|Department of Education and Research, Taipei City Hospital
Taipei, Taiwan|Taipei, Taiwan|Taipei, Taiwan

The insular cortex, with its concealed location and broad connections to other brain regions, plays a complex role in the spread of epileptic discharges. These discharges often extend from the insula to other lobes, leading to a range of symptoms that can obscure the correct diagnosis of insular epilepsy. Advances in intracranial technology now allow clinicians to precisely identify the epileptogenic zone, including in insular epilepsy cases. Recent clinical reports show a burgeoning interest in the functional mapping of the insula, which is associated not only with visceral-somatic processing but also with a spectrum of sensations such as pain, speech disturbances, and oropharyngeal responses. Specific clinical responses have been correlated with distinct insular subregions [1,2]. A meta-analysis has proposed a functional subdivision of the insula into different four parcellation [3]. In summary, the insula is a multifaceted region whose significance is much greater than previously appreciated. The current study, therefore, aims to utilize a combination of neurophysiological and neuroimaging techniques to explore the FC of the insula.

We collected electrophysiological mapping data from 42 patients with drug-resistant epilepsy of non-insular origin who had undergone Stereo-encephalography (SEEG). We compiled their electrical stimulation reports to understand the functional characteristics of different subregions within the insular cortex. Additionally, we analyzed rs-fMRI data from 20 control subjects and 16 epilepsy patients with non-insular onset. The rs-fMRI data was used to calculate the functional connectivity (FC) between the insular cortex and other cortical areas. This served to validate the electrical stimulation results and to delineate distinct functional subregions. We defined the motor-premotor (MOT), occipital-parietal (OCC), prefrontal (PRE), somatosensory (SOM), and temporal (TEM) cortical Regions of Interest (ROI) in standard MNI space by combining associated masks from the Harvard-Oxford cortical atlas [4]. The insula mask was derived from the AAL atlas. To compute FC between the left and right cortex and the insular regions, we calculated the Pearson correlation coefficient between the average BOLD time series from each cortical seed and all corresponding insular target voxels. The one-sample t test was done to produce insular-cortical connectivity maps for each group. Lastly, we conducted a nonparametric statistical comparison (P < 0.05) between the control group and epilepsy patients, applying a false discovery rate for multiple comparisons

According to our electrophysiological mapping results, insular functions mainly correlated with motor, somatosensory, temporal, oro-pharyngearl responses, which can be corresponded to our FC results. Furthermore, the results demonstrated significantly higher FC in the patient group compared to the normal control group within the insular subregion correlated with the temporal lobe and motor function on both the two sides of the insula. However, there was no statistical difference between groups in the PRE, MOT, SOM, and OCC regions. These findings suggest that epilepsy with a non-insular onset may still affect the FC of the insula, particularly in areas related to the temporal lobe and motor cortex. According to our mapping results, motor responses were primarily associated with the posterior insula, while somatosensory responses were distributed throughout the insula. Temporal lobe functions were mostly mapped to the middle short gyrus and the posterior long gyrus, and oro-pharyngeal responses were asymmetrically localized to the right insula

Our study combined electrophysiological patterns with FC revealing functions of the insula. Epilepsy with a non-insular onset still influences the epileptic network, including the insula, as evidenced by increased FC within the insula between the temporal lobe and motor cortex.

Direct Electrical/Optogenetic Stimulation ²

Connectivity (eg. functional, effective, structural)

fMRI Connectivity and Network Modeling ¹

Electroencephaolography (EEG)

Epilepsy

FUNCTIONAL MRI