Lilianne Manning

Remote Memory in Temporal Lobe Epilepsy

Summary:  Purpose: The present study aims at characterizing remote memory in patients with temporal lobe epilepsy (TLE); it also considers the impact of its most important variables (lateralization of the lesion, duration of epilepsy, age at onset, and seizure frequency) on remote memory.

Acute limbic encephalitis and glutamic acid decarboxylase antibodies: A reality?

Limbic encephalitis (LE) associated with glutamic acid decarboxylase antibodies (GAD-Ab) is rare. We describe a 30-year-old male with acute LE and GAD-Ab, with follow-up during 2 years of cognitive status including verbal episodic memory, number of seizures recorded by high-resolution video-EEG, brain MRI, 2-[18F]-fluoro-2-deoxyglucose PET and GAD-Ab titres. Treatment with corticosteroids, IV immunoglobulins, immunosuppressors and antiepileptic drugs resulted in improved memory status, disappearance of seizures and decreased GAD-Ab titres. Review of the other cases of literature and this case is in favour of the existence of autoimmune LE associated with GAD-Ab and supports the link between memory, temporal seizures and possibly GAD-Ab titres.

Pure retrograde amnesia following a mild head trauma: a neuropsychological and metabolic study.

After a minor closed head injury, a 33-year-old man acquired extensive retrograde amnesia (RA) covering the previous ten years and concerning autobiographical, semantic and procedural memories. The patients learning abilities remained excellent and he recovered considerable information from his wife, the media and personal documents. This relearned information did not, however, provide a sense of personal experience in the first weeks. CT and MRI failed to show brain damage, but EEG and SPECT examination showed a marked right temporal dysfunction. After three months the patient had almost completely recovered from RA. Interestingly, a parallel recovery was observed in the second SPECT obtained at this period. There was clearly a blockade of retrieval, while the stored engrams were probably intact. The mechanisms underlying such a functional amnesia are discussed in the light of previous reports of amnesia without brain lesions.

The neural bases of the constructive nature of autobiographical memories studied with a self-paced fMRI design.

In Conway and Pleydell-Pearces model (2000), autobiographical memories are viewed as transitory mental representations, more often generated in an effortful way. An important claim of the model concerns the dynamic process that evolves over time, from the left prefrontal areas to posterior regions, to retrieve specific memories. The present work aims at investigating, using fMRI, the temporal distribution of effortful autobiographical memory construction. In addition, a self-paced design was implemented to elucidate the question of the timing window required to evoke recollections. The results showed a large pattern of brain regions, which included the two major poles of activation predicted by Conway and Pleydell-Pearces model. Likewise, we were able to detect the earlier implication of the left dorso-lateral prefrontal cortex, by comparison with posterior structures, which seemed to confirm its involvement in the effortful retrieval process. Finally, the self-paced procedure allowed us to refine the timing window necessary to construct past events.

One-Year Postoperative Autobiographical Memory Following Unilateral Temporal Lobectomy for Control of Intractable Epilepsy

Summary:  Purpose: To examine the effects of temporal lobectomy (TL), particularly concerning its lateralization.

Déficit sélectif de la mémoire des faits publics associé à un oubli accéléré chez un patient atteint d’épilepsie du lobe temporal gauche

Resume Introduction La memoire du passe, contrairement a la memoire anterograde, rarement ete examinee dans l’epilepsie du lobe temporal et jamais avant et apres traitement chirurgical. Par ailleurs, les etudes de cas rapportant un deficit de la memoire des faits publics avec une preservation de la memoire autobiographique sont tres rares. Methodes Nous presentons le cas d’un patient atteint d’une epilepsie temporale pharmacoresistante en rapport avec une sclerose hippocampique gauche. Des examens neuropsychologiques complets ont ete realises avant et apres lobectomie temporale, avec un interet particulier pour la memoire du passe, evaluee exhaustivement au moyen de tests standardises, mais egalement d’epreuves adaptees au patient. Resultats Le patient presentait une memoire preservee pour les faits et episodes autobiographiques, mais des scores deficients aux tests de faits publics, dans un contexte de capacites cognitives generales normales. De plus, un oubli accelere pour du materiel verbal et non verbal etait mis en evidence. Conclusion Les resultats suggerent que le trouble de consolidation a long terme pourrait avoir contribue au deficit de la memoire des faits publics. Nous discutons les caracteristiques specifiques du traitement des faits publics en essayant d’expliquer sa plus grande vulnerabilite par rapport a la memoire autobiographique, dans le cas de l’oubli accelere.

MRI-based volumetry correlates of autobiographical memory in Alzheimer's disease.

The aim of the present volumetric study was to explore the neuro-anatomical correlates of autobiographical memory loss in Alzheimers patients and healthy elderly, in terms of the delay of retention, with a particular interest in the medial temporal lobe structures. Fifteen patients in early stages of the disease and 11 matched control subjects were included in the study. To assess autobiographical memory and the effect of the retention delay, a modified version of the Crovitz test was used according to five periods of life. Autobiographical memory deficits were correlated to local atrophy via structural MRI using Voxel Based Morphometry. We used a ‘lateralized index’ to compare the relative contribution of hippocampal sub-regions (anterior vs posterior, left vs right) according to the different periods of life. Our results confirm the involvement of the hippocampus proper in autobiographical memory retrieval for both recent and very remote encoding periods, with larger aspect for the very remote period on the left side. Contrary to the prominent left-sided involvement for the young adulthood period, the implication of the right hippocampus prevails for the more recent periods and decreases with the remotness of the memories, which might be associated with the visuo-spatial processing of the memories. Finally, we suggest the existence of a rostrocaudal gradient depending on the retention duration, with left anterior aspects specifically related to retrieval deficits of remote memories from the young adulthood period, whereas posterior aspects would result of simultaneous encoding and/or consolidation and retrieval deficit of more recent memories.

Material-independent cerebral network of re-experiencing personal events: evidence from two parallel fMRI experiments.

Two parallel fMRI experiments were conducted with the aim to clarify the lateralisation issue of the cerebral network underlying autobiographical memory retrieval independently of the stimulus material and the refreshment of the memory trace. The verbal experiment required a pre-scanning interview, while the nonverbal version tested the subjects directly during the fMRI session. Both experiments were constructed using the same experimental design to eliminate methodological variables in order to render comparisons possible. We found a predominantly left-lateralised cerebral network independently of material and regardless of whether or not memory traces were reactivated prior to the scanning session. We discuss the results in the context of neuroimaging studies of autobiographical memory (AbM).

Psychogenic Memory Deficits Associated with Functional Cerebral Changes: An fMRI Study

We studied a case of psychogenic amnesia by means of a functional magnetic resonance imaging (fMRI) experiment involving the retrieval of autobiographical memories. The 38-year-old patient was unable to access most of her autobiographical memories from her childhood up to 16 years of age. Compared with the forgotten period, evocation of the normally retrieved memories elicited increased activity in medial temporal and dorso–lateral frontal regions. Evocation of the preserved scattered recollections was associated with bilaterally distributed temporo-parieto-occipital loci of activations. These functional changes seem to support the idea of common mechanisms involved in both organic and psychogenic amnesias.

Selective memory impairment for public events in a patient with left temporal lobe epilepsy

Highly selective memory impairment for public events was demonstrated in a patient (JR), who suffered from temporal lobe epilepsy (TLE). We successfully trained JRs memory for a set of news events and discuss, on those bases, the characteristics of news events processing that may have contributed to its increased vulnerability relative to autobiographical memory (AbM).