Evaluation of Fmri Analysis for Localization of Hippocampus Activation During Episodic Encoding Memory Task Publisher



Gholami S¹ ; Oghabian MA¹ ; Barekatain M² ; Fesharaki SH³ ; Hafizi S⁴ ; Hasani N¹ Show Affiliations
Source: IFMBE Proceedings Published:2013

Abstract

Functional Magnetic Resonance Imaging (fMRI) is a promising technique to examine brain cognitive functions such as memory. In patients with refractory Temporal Lobe Epilepsy (TLE) evaluation of memory function is important before the surgery. This is due to the fact that anterior temporal lobe resection may result in memory impairment. It has been shown that verbal memory declines following left anterior temporal lobe resection, and visual memory declines after right anterior temporal lobe resection. Although previously many studies used fMRI to localize brain memory regions, the approached used in this study aimed to design an optimal fMRI protocol for hippocampus activation to be used in clinical settings. In this study, episodic memory task with nonverbal stimulus which previously has been shown that can activate Medial Temporal Lobe (MTL) and particularly the right hippocampus in normal group was employed. Twenty healthy adults participated in this study. During functional imaging, subjects were presented with 60 unfamiliar faces as the face-encoding memory task. An event-related data analysis was used to map brain activation related to successful encoding. fMRI data analysis was carried out using FLAME (FMRIB's Local Analysis of Mixed Effects), to obtain mean activation across the normal groups (one-sample t-test). Z>2.0 was utilized for cluster statistics and a (corrected) cluster significance threshold of P<0.05. Results of data analysis showed that successful face encoding is associated with activation in right hippocampus in the normal subjects. The results presented here indicated that our fMRI protocol was successful in activating MTL and hippocampus due to episodic encoding in normal subjects. © 2013 Springer-Verlag.