title: Heterogeneity of functional activation during memory encoding across hippocampal subfields in temporal lobe epilepsy.
abstract: Pathology studies have shown that the anatomical subregions of the hippocampal formation are differentially affected in various neurological disorders, including temporal lobe epilepsy (TLE). Analysis of structure and function within these subregions using magnetic resonance imaging (MRI) has the potential to generate insights on disease associations as well as normative brain function. In this study, an atlas-based normalization method (Yushkevich, P.A., Avants, B.B., Pluta, J., Das, S., Minkoff, D., Mechanic-Hamilton, D., Glynn, S., Pickup, S., Liu, W., Gee, J.C., Grossman, M., Detre, J.A., 2009. A high-resolution computational atlas of the human hippocampus from postmortem magnetic resonance imaging at 9.4 T. NeuroImage 44 (2), 385-398) was used to label hippocampal subregions, making it possible to examine subfield-level functional activation during an episodic memory task in two different cohorts of healthy controls and subjects diagnosed with intractable unilateral TLE. We report, for the first time, functional activation patterns within hippocampal subfields in TLE. We detected group differences in subfield activation between patients and controls as well as inter-hemispheric activation asymmetry within subfields in patients, with dentate gyrus (DG) and the anterior hippocampus region showing the greatest effects. DG was also found to be more active than CA1 in controls, but not in patients' epileptogenic side. These preliminary results will encourage further research on the utility of subfield-based biomarkers in TLE.
authors.affiliation: Penn Image Computing and Science Laboratory (PICSL), Department of Radiology, University of Pennsylvania, PA, USA. sudas@seas.upenn.edu
authors.forename: Sandhitsu R
authors.initials: SR
authors.lastname: Das
authors.forename: Dawn
authors.initials: D
authors.lastname: Mechanic-Hamilton
authors.forename: John
authors.initials: J
authors.lastname: Pluta
authors.forename: Marc
authors.initials: M
authors.lastname: Korczykowski
authors.forename: John A
authors.initials: JA
authors.lastname: Detre
authors.forename: Paul A
authors.initials: PA
authors.lastname: Yushkevich
mesh_terms: D000465:Algorithms; D001271:Atlases as Topic; D056547:CA1 Region, Hippocampal / Q000502:physiology; D002102:Cadaver; D015331:Cohort Studies; D004833:Epilepsy, Temporal Lobe / Q000503:physiopathology* / Q000523:psychology* / Q000601:surgery; D006624:Hippocampus / Q000502:physiology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D016014:Linear Models; D008279:Magnetic Resonance Imaging; D008568:Memory / Q000502:physiology*