title: Metabolic evidence for episodic memory plasticity in the nonepileptic temporal lobe of patients with mesial temporal epilepsy.
abstract: OBJECTIVE
  Metabolic changes have been described in the nonepileptic temporal lobe of patients with unilateral mesiotemporal lobe epilepsy (MTLE) associated with hippocampal sclerosis (HS). To better understand the functional correlate of this metabolic finding, we have sought to characterize brain regions in patients with MTLE that show correlation between unilateral episodic memory performances, as assessed by intracarotid amobarbital test (IAT), and interictal regional cerebral metabolism measured by [(18) F]-fluorodeoxyglucose positron emission tomography (FDG-PET).
  
  
  METHODS
  Resting FDG-PET was performed interictally in 26 patients with unilateral MTLE caused by HS (16 female, mean age: 36 years; 16 left HS). Using statistical parametric mapping (SPM8), we performed a group comparison analysis comparing brain metabolism in the patients and in 54 adult controls (27 female, mean age: 32 years), with FDG-PET data of right HS patients being flipped. IAT scores of nonepileptic hemisphere functions (amobarbital injection ipsilateral to HS) were used as covariates of interest in a correlation analysis with regional brain metabolism.
  
  
  RESULTS
  The group comparison analysis revealed significant hypometabolic areas in a widespread temporofrontal network ipsilateral to HS. In addition, a significant increase in metabolism was found in mesial and lateral temporal regions contralateral to HS. Significant positive correlations were found between IAT scores of nonepileptic hemisphere functions and mesial temporal metabolism in this hemisphere.
  
  
  CONCLUSIONS
  This study demonstrates the existence of significant increase in relative regional cerebral glucose metabolism in mesial and lateral temporal regions contralateral to the epileptic focus in patients with unilateral MTLE associated with HS. The positive correlation in these brain regions between IAT scores and metabolism supports the role of disease-induced plasticity mechanisms contralateral to HS in the preservation of episodic memory processes.
authors.affiliation: Laboratoire de Cartographie Fonctionnelle du Cerveau, Hpital Erasme, Université Libre de Bruxelles, Brussels, Belgium. ntrotta@ulb.ac.be
authors.forename: Nicola
authors.initials: N
authors.lastname: Trotta
authors.forename: Serge
authors.initials: S
authors.lastname: Goldman
authors.forename: Benjamin
authors.initials: B
authors.lastname: Legros
authors.forename: Noémie
authors.initials: N
authors.lastname: Ligot
authors.forename: Nathalie
authors.initials: N
authors.lastname: Guerry
authors.forename: Kristof
authors.initials: K
authors.lastname: Baete
authors.forename: Koen
authors.initials: K
authors.lastname: Van Laere
authors.forename: Patrick
authors.initials: P
authors.lastname: Van Bogaert
authors.forename: Xavier
authors.initials: X
authors.lastname: De Tiège
mesh_terms: D000293:Adolescent; D000328:Adult; D001921:Brain / Q000378:metabolism; D002648:Child; D004833:Epilepsy, Temporal Lobe / Q000378:metabolism* / Q000523:psychology; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000378:metabolism; D005947:Glucose / Q000378:metabolism; D006801:Humans; D008297:Male; D061212:Memory, Episodic; D008875:Middle Aged; D009473:Neuronal Plasticity; D049268:Positron-Emission Tomography; D013702:Temporal Lobe / Q000378:metabolism*; D055815:Young Adult
chemical_list: D019788:Fluorodeoxyglucose F18; D005947:Glucose