Prediction of Postoperative Seizure Control by Hippocampal Event‐Related Potentials

Grünwald, Thomas; Lehnertz, Klaus; Pezer, Nico; Kurthen, Martin; Roost, Dirk Van; Schramm, Johannes; Elger, Christian E.

doi:10.1111/j.1528-1157.1999.tb00708.x

Cited by 31 publications

(31 citation statements)

References 22 publications

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“…Slopes were more negative in the controls than the patients. Furthermore, using hippocampal depth electrodes in patients with temporal lobe epilepsy, Grunwald et al (1999) found that medial temporal N400 responses to items decreased with repetition in the intact hippocampus but not in the epileptic hippocampus. These data suggest that an economic use of learning-related neural resources characterizes a well functioning memory system.…”

Section: Discussionmentioning

confidence: 96%

Better Memory and Neural Efficiency in Young Apolipoprotein E 4 Carriers

Mondadori¹,

Quervain²,

Buchmann³

et al. 2006

Cerebral Cortex

238

218

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The apolipoprotein E (APOE) e4 allele is the major genetic risk factor for Alzheimer's disease, but an APOE effect on memory performance and memory-related neurophysiology in young, healthy subjects is unknown. We found an association of APOE e4 with better episodic memory compared with APOE e2 and e3 in 340 young, healthy persons. Neuroimaging was performed in a subset of 34 memory-matched individuals to study genetic effects on memory-related brain activity independently of differential performance. E4 carriers decreased brain activity over 3 learning runs, whereas e2 and e3 carriers increased activity. This smaller neural investment of e4 carriers into learning reappeared during retrieval: e4 carriers exhibited reduced retrieval-related activity with equal retrieval performance. APOE isoforms had no differential effects on cognitive measures other than memory, brain volumes, and brain activity related to working memory. We suggest that APOE e4 is associated with good episodic memory and an economic use of memory-related neural resources in young, healthy humans.

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Section: Discussionmentioning

confidence: 96%

Better Memory and Neural Efficiency in Young Apolipoprotein E 4 Carriers

Mondadori¹,

Quervain²,

Buchmann³

et al. 2006

Cerebral Cortex

238

218

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“…Our findings thus show that separate analysis of event-related power and phase effects can reveal additional information compared with conventional ERP evaluation. The averaged AMTL-N400 recorded from within the rhinal cortex showed a newminus-old repetition effect (Smith et al, 1986;Nobre and McCarthy, 1995;Grunwald et al, 1998aGrunwald et al, , 1999) which would Power/phase modulation in the rhinal cortex (upper row) and hippocampus (lower row) for hits (correctly identified repeated words; left) and correct rejections (correctly identified new words; right) in a continuous recognition paradigm (grand average). The plots show color-coded synchronization values between the mean-wavelet phases (Figs.…”

Section: Discussionmentioning

confidence: 99%

Phase/amplitude reset and theta–gamma interaction in the human medial temporal lobe during a continuous word recognition memory task

et al. 2005

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We analyzed intracranial electroencephalographic (EEG) recordings from the medial temporal lobes of 12 epilepsy patients during a continuous word recognition paradigm, contrasting trials of correctly recognized repeated words (hits) and correctly identified new words (correct rejections). Using a wavelet-based analysis, we investigated how power changes and phase clustering in different frequency bands contribute to the averaged event-related potentials (ERPs). In addition, we analyzed the actual mean phases of the different oscillations. Our analyses yielded the following results: (1) power changes contributed significantly only to the late components of the ERPs (>400 ms) (2) earlier ERP components were produced by a stimulus-related broad-band phase and amplitude reset of ongoing oscillatory activity about 190 ms after stimulus onset that involved not only the theta band, but also covered alpha and lower beta band frequencies (3) phase and amplitude reset occurred during an epoch of increased phase entrainment over time that lasted for about two oscillation periods for all involved frequencies and was more pronounced for correct rejections than for hits. The broad-band phase and amplitude reset was observed for both hits and correct rejections, and therefore, did not appear to support a specific cognitive function, but rather to act as a general facilitating factor for the processes involved in this memory task. Further analyses of synchronization between oscillations and power changes in different frequency bands revealed a task-dependent modulation of gamma activity by the entrained theta cycle, a mechanism potentially related to memory encoding and retrieval in the rhinal cortex and hippocampus, respectively.

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“…Because seizure onset could not be determined unequivocally by noninvasive investigations, electrodes were implanted according to clinical requirements. The ERP investigation, employing a continuous visual word recognition paradigm [Rugg and Nagy, 1989], is part of our presurgical work-up, providing predictors of seizure control and verbal memory performance after temporal lobe surgery [Grunwald et al, 1998b;1999a]. All patients were right hand dominant (selfreported) and native German speakers.…”

Section: Patientsmentioning

confidence: 99%

Inferior temporal stream for word processing with integrated mnemonic function

Fernández

Heitkemper

Grünwald

et al. 2001

Human Brain Mapping

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The participation of the inferior temporal cortex in visual word perception and recognition raises several questions: Is there a directed processing stream proceeding anteriorly by continuous cortical processing? How fast are words processed within such an inferior temporal stream? Does this stream support implicit or explicit memory? To answer these questions, we analyzed the spatio-temporal relationship of event-related potentials, recorded directly from the inferior temporal cortex in epilepsy patients performing a continuous visual word recognition paradigm. Event-related potentials elicited an inferior temporal positivity in a strip along the left collateral sulcus. This potential exhibited a linear (r = 0.74) peak latency progression from posterior to anterior inferior temporal regions (approximately 15 cm/sec), indicating a directed, intracortical processing stream. Peak amplitudes and latencies showed reliable old/new effects with smaller amplitudes and shorter latencies for old as opposed to new words. Although the amplitude-old/new-effect occurred for all repeated words (e.g., implicit memory), the latency-old/new-effect occurred for correctly recognized old words only (e.g., explicit recognition). These results seem to dissociate two distinct mnemonic processes. The graded decrease of mean ITP peak amplitudes and latencies, however, does not allow us to exclude a single trace model as assumed for explicit recognition memory based on familiarity (Mandler [1980]: Psychol Rev 87:252-271). Regardless whether there is a dissociation between implicit and explicit memory in inferior temporal cortex or not, our findings are in accordance with an integrated inferior temporal processing stream for words that performs continuously semantic and mnemonic operations supporting both implicit and explicit memory.

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Prediction of Postoperative Seizure Control by Hippocampal Event‐Related Potentials

Cited by 31 publications

References 22 publications

Better Memory and Neural Efficiency in Young Apolipoprotein E 4 Carriers

Better Memory and Neural Efficiency in Young Apolipoprotein E 4 Carriers

Phase/amplitude reset and theta–gamma interaction in the human medial temporal lobe during a continuous word recognition memory task

Inferior temporal stream for word processing with integrated mnemonic function

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