Impaired gist memory in patients with temporal lobe epilepsy and hippocampal sclerosis.
OBJECTIVE
Temporal lobe epilepsy (TLE) is the most common focal epilepsy and frequently causes memory problems. It is often associated with hippocampal sclerosis (HS) and is useful in exploring memory functions. We aimed to examine the effect of restricted hippocampal lesions on gist memory function in patients with TLE.


METHODS
Forty-five patients with TLE and HS (16 left, 15 right, and 14 bilateral lesions) and 22 control subjects were recruited. Patients with magnetic resonance imaging (MRI) or electroencephalography (EEG) evidence of extratemporal lesions were excluded. All participants performed a gist-based recognition task following the Deese-Roediger-McDermott paradigm and were tested for verbal IQ and memory functions. We conducted hippocampal volumetry on MRI of all the participants.


RESULTS
Patients showed multidomain memory impairments. Gist memory was impaired in patients with bilateral HS and probably in patients with right HS. Hippocampal volumetry supported such findings that total volume of hippocampi and volume of right hippocampus correlated positively with gist memory function.


CONCLUSIONS
HS has a dose effect and a probable right dominance effect on gist memory; good item memory supports gist memory performance; and a disproportionate deficit was noted in tasks with high relational demand but not in tasks with simple association. We should develop memory skills for patients with TLE by enhancing performance of gist memory related to simple association task.
Department of Neurology, National Taiwan University Hospital, College of Medicine, National Taiwan University, Taipei, Taiwan.
Ming-Jang
MJ
Chiu
Ching-Wei
CW
Lin
Chih-Chuan
CC
Chen
Ta-Fu
TF
Chen
Ya-Fang
YF
Chen
Hon-Man
HM
Liu
Chih-Pang
CP
Chu
Horng-Huei
HH
Liou
Mau-Sun
MS
Hua
D000328:Adult; D004833:Epilepsy, Temporal Lobe / Q000150:complications / Q000473:pathology* / Q000523:psychology*; D005260:Female; D006624:Hippocampus / Q000473:pathology*; D006801:Humans; D008297:Male; D008569:Memory Disorders / Q000150:complications / Q000473:pathology* / Q000523:psychology*; D008875:Middle Aged; D012598:Sclerosis; D055815:Young Adult