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Köylü B, Trinka E, Ischebeck A, Visani P, Trieb T, Kremser C, Bartha L, Schocke M, Benke T. Neural correlates of verbal semantic memory in patients with temporal lobe epilepsy. Epilepsy Res 2006; 72:178-91. [PMID: 16996717 DOI: 10.1016/j.eplepsyres.2006.08.002] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2006] [Revised: 08/01/2006] [Accepted: 08/08/2006] [Indexed: 10/24/2022]
Abstract
Functional imaging data suggest that the core network engaged in verbal semantic memory (SM) processing encompasses frontal and temporal lobe structures, with a strong left lateralization in normal right handers. The impact of long term temporal lobe epilepsy (TLE) on this network has only partly been elucidated. We studied verbal SM in 50 patients with chronic, intractable TLE (left TLE=26, right TLE=24) and 35 right handed normal controls using a verbal fMRI semantic decision paradigm. All patients had language lateralized to the left hemisphere, as verified by the intracarotid amobarbital procedure. Within and between group analyses showed remarkable, group-specific activation profiles. The control group activated frontal and temporal areas bilaterally, with a strong left predominance. Left TLE patients showed a shift of activations of left frontal and medial temporal areas to homologous regions in the right hemisphere. Furthermore, left TLE subjects utilized subcortical structures such as the thalamus and putamen to accomplish the verbal SM task. Contrastively, the activation pattern of right TLE patients resembled that of normal controls, but exhibited "hypofrontality" with a shift from frontal to posterior regions in the temporal, parietal and occipital lobe. Our results show that chronic epileptic activity originating from temporal seizure foci is associated with an alteration of neural circuits which support semantic language processing and that side of seizure focus has a specific impact on the resulting activation network. These findings presumably result from morphological changes and from functional reorganization which are both inherent to chronic TLE.
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Affiliation(s)
- Bülent Köylü
- Innsbruck Medical University, Clinic of Neurology, Anichstrasse 35, A-6020 Innsbruck, Austria
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Drane DL, Lee GP, Cech H, Huthwaite JS, Ojemann GA, Ojemann JG, Loring DW, Meador KJ. Structured cueing on a semantic fluency task differentiates patients with temporal versus frontal lobe seizure onset. Epilepsy Behav 2006; 9:339-44. [PMID: 16870509 PMCID: PMC2727920 DOI: 10.1016/j.yebeh.2006.06.010] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/03/2006] [Revised: 06/14/2006] [Accepted: 06/16/2006] [Indexed: 11/19/2022]
Abstract
Patients with frontal lobe dysfunction (e.g., Huntington's disease) reportedly benefit more from cueing on measures of semantic fluency than do patients with damage to temporal lobe structures (e.g., Alzheimer's disease). This differential benefit from cueing suggests that different neurocognitive functions are impaired in these two groups. Patients with frontal lobe dysfunction are presumed to have difficulty with the executive aspects of this generative fluency task, whereas patients with temporal lobe impairment are limited by deficits in semantic memory. We studied the performance of patients with complex partial seizures of frontal or temporal lobe onset, as determined by video/EEG monitoring, on standard and cued measures of semantic fluency administered in a counterbalanced sequence across groups. These groups did not differ significantly in terms of age, education, gender, age at seizure onset, total number of antiepileptic drugs, or IQ, and all patients subsequently underwent surgery for intractable epilepsy. Patients with frontal lobe dysfunction (FL group) performed significantly worse than patients with temporal lobe impairment (TL group) on the standard semantic fluency paradigm (TL group: M=18.4, SD=4.7; FL group: M=11.1, SD=5.3), t(27)=-3.75, P<0.001. Nevertheless, results of an ANCOVA demonstrated that the FL group showed significantly greater performance improvement than the TL group when provided with a cued semantic fluency format, even after controlling for baseline differences in ability on the standard semantic fluency task (TL group: M=0.45, SD=3.8; FL M=9.4, SD=5.1), F(1,29)=12.37, P=0.002. These findings support previous research suggesting that frontal and temporal structures contribute uniquely to semantic generative fluency and suggest that using a combination of standard and cued semantic fluency tasks may help confirm localization of seizure onset in partial epilepsy by localizing the associated cognitive dysfunction.
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Affiliation(s)
- Daniel L Drane
- Department of Neurology, University of Washington School of Medicine, Seattle, WA, USA.
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McDonald CR, Delis DC, Norman MA, Tecoma ES, Iragui VJ. Discriminating patients with frontal-lobe epilepsy and temporal-lobe epilepsy: utility of a multilevel design fluency test. Neuropsychology 2006; 19:806-13. [PMID: 16351356 DOI: 10.1037/0894-4105.19.6.806] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Patients with frontal-lobe epilepsy (FLE) or temporal-lobe epilepsy (TLE) and matched control participants were given a design fluency test that assessed nonverbal fluency and switching ability. Patients with FLE generated fewer designs in the switching condition relative to the TLE patients and controls, whereas group differences did not emerge in the basic fluency conditions. When the side of the seizure focus and the presence or absence of a structural lesion were considered in patients with FLE, only those with left-lesional FLE generated fewer designs than controls did in the switching condition. Furthermore, patients with left-lesional and nonlesional FLE produced a greater proportion of set-loss errors than did controls. These results indicate that patients with FLE are impaired when they must simultaneously generate new designs and engage in cognitive switching; however, the pattern of impairment may depend on the side of the seizure focus and the presence of a structural lesion.
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Affiliation(s)
- Carrie R McDonald
- Veterans Administration San Diego Healthcare System, La Jolla, CA 92611, and Department of Psychiatry, University of California, San Diego, CA, USA.
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Vannucci M, Grunwald T, Pezer N, Dietl T, Helmstaedter C, Schaller C, Viggiano MP, Elger CE. Hippocampus proper distinguishes between identified and unidentified real-life visual objects: an intracranial ERP study. Neurosci Lett 2006; 401:165-70. [PMID: 16567041 DOI: 10.1016/j.neulet.2006.03.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2005] [Revised: 02/22/2006] [Accepted: 03/06/2006] [Indexed: 11/16/2022]
Abstract
Converging evidence indicates that the medial temporal lobe participates not only in memory but also in visual object processing. We investigated hippocampal contributions to visual object identification by recording event-related potentials directly from within the hippocampus during a visual object identification task with spatially filtered pictures of real objects presented at different levels of filtering. Hippocampal responses differentiated between identified and unidentified visual objects within a time window of 200-900 ms after stimulus presentation: identified objects elicited a small negative component peaking around 300 ms (hippocampal-N300) and a large positive component, around 650 ms (hippocampal-P600), while the N300 was increased and the P600 was reduced in amplitude in response to unidentified objects. These findings demonstrate that the hippocampus proper contributes to the identification of visual objects discriminating from the very early between identified and unidentified meaningful visual objects.
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Affiliation(s)
- Manila Vannucci
- Department of Epileptology, Bonn University Medical Center, Germany.
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Van der Elst W, Van Boxtel MPJ, Van Breukelen GJP, Jolles J. Normative data for the Animal, Profession and Letter M Naming verbal fluency tests for Dutch speaking participants and the effects of age, education, and sex. J Int Neuropsychol Soc 2006; 12:80-9. [PMID: 16433947 DOI: 10.1017/s1355617706060115] [Citation(s) in RCA: 212] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2005] [Revised: 08/05/2005] [Accepted: 08/12/2005] [Indexed: 11/05/2022]
Abstract
Previous research has indicated that performance on verbal fluency tests (VFTs) is influenced by language and/or culture. Consequently, normative VFT data for English-speaking people cannot be used for people for whom English is not their first language. The aim of the present study was to provide normative data for the Animal Naming, Profession Naming, and Letter M Naming (four-letter words beginning with the letter M) VFTs for Dutch-speaking populations, based on a large sample (N = 1856) of healthy men and women aged 24-81 years of different educational levels. The results showed that age affected the performance of all VFTs profoundly, but the age effect was not uniform: in the Profession and Letter M Naming VFTs, performance was stable in young adulthood but declined strongly after age 50. In contrast, in the Animal Naming VFT, performance appeared to decline linearly, starting early in life. Furthermore, males had higher scores than females on the Profession Naming VFT, and higher educated participants outperformed their lower educated counterparts on all three VFTs. Regression-based normative data were prepared for the 3 VFTs, and the advantages of using a regression-based normative approach instead of a traditional normative approach are discussed.
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Affiliation(s)
- Wim Van der Elst
- Maastricht Brain and Behavior Institute, European Graduate School of Neuroscience (EURON), Department of Psychiatry and Neuropsychology, Maastricht University, Maastricht, The Netherlands
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Abstract
OBJECTIVE To evaluate interictal language functions in patients with medically intractable left and right sided mesial temporal lobe epilepsy (TLE). METHODS Spontaneous speech, language comprehension, confrontation naming, repetition, reading, writing, and word fluency were examined in 12 patients with left sided TLE and 11 patients with right sided TLE. RESULTS Four patients out of 23 displayed language deficits in more than one language domain. Three further patients exhibited isolated language deficits. Linguistic deficits were observed in both left TLE and right TLE. In quantitative analyses left and right TLE only differed in spontaneous speech (p = 0.02); no difference was found in other language functions, laterality quotient of Wada test, or overall IQ. Qualitative error analysis of object naming, however, showed typical errors associated only with left TLE. Patients with linguistic deficits were older at testing compared to patients without linguistic deficits (p = 0.003), whereas other factors including side of TLE, handedness, educational level, age at epilepsy onset, and duration of epilepsy did not differ between groups. CONCLUSIONS Possible explanations for these findings include neuronal cell loss and deafferentiation in cortical areas, and disruption of the basal temporal language area pathways. Our study suggests that some patients with chronic mesial TLE exhibit linguistic deficits when specifically tested, and underlines the need to routinely investigate linguistic functions in TLE.
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Affiliation(s)
- L Bartha
- Innsbruck Medical University, Clinical Department of Neurology, Austria.
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Bartha L, Trinka E, Ortler M, Donnemiller E, Felber S, Bauer G, Benke T. Linguistic deficits following left selective amygdalohippocampectomy: a prospective study. Epilepsy Behav 2004; 5:348-57. [PMID: 15145305 DOI: 10.1016/j.yebeh.2004.02.004] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/26/2003] [Revised: 02/11/2004] [Accepted: 02/11/2004] [Indexed: 11/20/2022]
Abstract
Language deficits in 10 patients with medically intractable left-sided temporal lobe epilepsy prior to and following selective amygdalohippocampectomy are described. Preoperatively, a pattern of minor linguistic deficits was observed in three patients; isolated minor naming deficits were detectable in one additional patient. Three months after surgery, six patients' linguistic functions were unchanged, whereas in four patients, a significant decline in linguistic functions could be observed. All four patients revealed a very similar language syndrome characterized by reduced language comprehension and fluency, well-articulated speech, frequent word-finding difficulties, circumlocutions, and semantic paraphasias in the absence of any phonological disorder. These deficits remained stable during the 12-month follow-up period. However, magnetic resonance imaging did not show any neocortical lesions outside the resection area. Possible explanations for these findings include neuronal cell loss and deafferentiation in cortical areas, disruption of the basal temporal language area pathways, reorganization of the language network in chronic temporal lobe epilepsy, and neocortical lesions due to the surgical intervention. Furthermore, correlations between linguistic and demographic data for our patients suggest that patients older at epilepsy onset are at greater risk for developing postoperative language deficits.
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Affiliation(s)
- Lisa Bartha
- Department of Neurology, University of Innsbruck, Anichstrasse 35, A-6020 Innsbruck, Austria.
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Lespinet-Najib V, N'Kaoua B, Sauzéon H, Bresson C, Rougier A, Claverie B. Levels of processing with free and cued recall and unilateral temporal lobe epilepsy. BRAIN AND LANGUAGE 2004; 89:83-90. [PMID: 15010240 DOI: 10.1016/s0093-934x(03)00303-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 07/28/2003] [Indexed: 05/24/2023]
Abstract
This study investigates the role of the temporal lobes in levels-of-processing tasks (phonetic and semantic encoding) according to the nature of recall tasks (free and cued recall). These tasks were administered to 48 patients with unilateral temporal epilepsy (right "RTLE"=24; left "LTLE"=24) and a normal group (n=24). The results indicated that LTLE patients were impaired for semantic processing (free and cued recall) and for phonetic processing (free and cued recall), while for RTLE patients deficits appeared in free recall with semantic processing. It is suggested that the left temporal lobe is involved in all aspects of verbal memory, and that the right temporal lobe is specialized in semantic processing. Moreover, our data seem to indicate that RTLE patients present a retrieval processing impairment (semantic condition), whereas the LTLE group is characterized by encoding difficulties in the phonetic and semantic condition.
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Affiliation(s)
- Véronique Lespinet-Najib
- Laboratoire de Neuropsychologie Expérimentale, Université Victor Segalen Bordeaux 2, Bordeaux, France.
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Bastiaansen MCM, van Berkum JJA, Hagoort P. Syntactic processing modulates the theta rhythm of the human EEG. Neuroimage 2002; 17:1479-92. [PMID: 12414287 DOI: 10.1006/nimg.2002.1275] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Changes in oscillatory brain dynamics can be studied by means of induced band power (IBP) analyses, which quantify event-related changes in amplitude of frequency-specific EEG rhythms. Such analyses capture EEG phenomena that are not part of traditional event-related potential measures. The present study investigated whether IBP changes in the delta, theta, and alpha frequency ranges are sensitive to syntactic violations in sentences. Subjects read sentences that either were correct or contained a syntactic violation. The violations were either grammatical gender agreement violations, where a prenominal adjective was not appropriately inflected for the head noun's gender, or number agreement violations, in which a plural quantifier was combined with a singular head noun. IBP changes of the concurrently measured EEG were computed in five frequency bands of 2-Hz width, individually adjusted on the basis of subjects' alpha peak, ranging approximately from 2 to 12 Hz. Words constituting a syntactic violation elicited larger increases in theta power than the same words in a correct sentence context, in an interval of 300-500 ms after word onset. Of all the frequency bands studied, this was true for the theta frequency band only. The scalp topography of this effect was different for different violations: following number violations a left-hemispheric dominance was found, whereas gender violations elicited a right-hemisphere dominance of the theta power increase. Possible interpretations of this effect are considered in closing.
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Affiliation(s)
- Marcel C M Bastiaansen
- Max Planck Institute for Psycholinguistics, P.O. Box 310, 6500 AH Nijmegen, The Netherlands
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Helmstaedter C. Effects of chronic epilepsy on declarative memory systems. PROGRESS IN BRAIN RESEARCH 2002; 135:439-53. [PMID: 12143363 DOI: 10.1016/s0079-6123(02)35041-6] [Citation(s) in RCA: 146] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
Memory is systematically affected by temporal lobe epilepsy. Since surgery is a promising alternative to pharmacological treatment the questions which memory system is affected and what the long-term prognosis of memory is are more relevant than ever. We address these issues by cross-sectional and longitudinal analysis of memory performance in large series of patients with temporal lobe epilepsy (TLE). The findings indicate that episodic memory rather than semantic memory is impaired in TLE, in particular in TLE with mesial temporal pathology. With the exception that mesial functions appear increasingly affected by chronic non-mesial TLE, memory decline in TLE is not different from that observed in healthy control subjects. However, since patients perform poorer than controls at any age, normal senescence brings patients to mnesic disability at a younger age. Semantic memory seems unaffected by this process but early cortical lesions appear to interfere with knowledge acquisition. Longitudinal data come to a different conclusion regarding the contribution of epilepsy/seizures to memory decline. Conservative treatment is associated with significant decline in figural memory and 37% of the patients experience some memory decline in the long run. Surgery partly anticipates the decline observed with conservative treatment, but losses are most marked after left temporal lobe surgery. After surgery, quite stable memory or even late recovery from surgery is indicated. Leaving aside the surgical intervention, the data provide evidence that the longitudinal memory outcome in TLE is determined by seizure control, seizure severity, mental reserve capacities, and the retest interval. Thus early and efficient seizure control and the prevention of any cerebral damage from the beginning of epilepsy are demanded.
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Affiliation(s)
- C Helmstaedter
- Department of Epileptology, University of Bonn, 53105 Bonn, Germany.
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