Patients
Drug resistant MTLE-HS patients (n = 55) underwent standard presurgical workups which include video electroencephalogram (vEEG), epilepsy protocol MRI, interictal fluoro-2-deoxyglucose positron emission tomography (FDG-PET), ictal single photon emissioncomputer tomography (SPECT) and magnetoencephalography (MEG) [22]. Patient details were discussed weekly at epilepsy surgery meeting attended by epileptologists, epilepsysurgeon, neuroradiologists and nuclear-medicine specialists where patients were selected for surgery based on concordance of above-mentioned diagnostic procedures. Surgical resection involves anterior temporal lobectomy with amygdalohippocampectomy. A portion of resected hippocampus was analysed by neuropathologist for confirmation of the diagnosis of MTLE-HS. All these patients were seizure-free post-operatively (class I Engel outcome) (Supplementary Table 1) (Engel, 1983). Resected hippocampal tissues from patients who underwent autopsies and devoid of any history of brain pathology were collected within 12h of death and used as autopsy controls (n= 15) (Supplementary Table 2). For experiments involving cellular electrophysiological studies resected cortical tissues obtained from surrounding areas of brain tumours during surgical resection, which was also a part of planned surgical resection, in patients with glioma without any history of seizures were considered as non-seizure controls (n = 20) molecular as autopsy control samples were not suitable for these experiments (Supplementary Table 3) (Banerjee et al., 2015; 2017; 2020). Samples were collected from 2015 to 2019 at the All India Institute of Medical Sciences in New Delhi, which is the referral center for epilepsy surgery in northern India. All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.
The study was ethically approved by the Institutional Ethics Committee, All India Institute of Medical Sciences, New Delhi, India (IECPG/-38/27.11.2015, RT-4/30.12.2015). Informed consent was obtained from all patients or their legally authorized representatives prior to inclusion in this study.
A small portion of resected tissue was stored for fixation in 0.1M phosphate buffer containing 4% paraformaldehyde, pH 7.4 for 72 hours. Post fixation, the tissues were dehydrated, embedded and cut into 6µM thick sections with a microtome and collected on poly L-lysine coated slides. Haematoxylin-eosin stained sections were used for cytoarchitecture. Immunohistochemistry was performed using with anti-GFAP (1:1000; Cat# ab7260, RRID: AB_305808), or with anti-NeuN (1:1000; Cat# ab104225, RRID: AB_10711153) primary antibodies. Secondary antibody was Biotinylated Goat Anti-Rabbit IgG antibody (1:1000; Vector Laboratories Cat# BA-1000, RRID: AB_2313606)