Thomas Dietl - Academia.edu (original) (raw)
Papers by Thomas Dietl
Psychoneuroendocrinology, 1995
To study whether changes in late auditory evoked potentials (AEPs) and/or in stress-sensitive hor... more To study whether changes in late auditory evoked potentials (AEPs) and/or in stress-sensitive hormones of the hypothalamic-pituitary-adrenal (HPA) system take place between a first and a second placebo experiment and if so, whether these changes are possibly related to each other, we conducted two identical placebo sessions (2 ml 0.9% saline) and one cortisol session (50 mg) with 10 subjects on three different days. Plasma cortisol concentrations were significantly higher at the beginning of the first placebo experiment than the second, with a concordant decrease of plasma adrenocorticotropin hormone (ACTH) concentrations. In the AEP domain, a consistently lower P2 amplitude was observed in the first session. Since the change in late auditory processing could not be demonstrated after exogenous administration of cortisol, a direct mediation through an elevation of plasma cortisol concentrations or indirect mediation through a decrease of plasma ACTH concentrations seems unlikely. We rather propose that other stress-sensitive mechanisms, such as CCK, might account for the novelty-induced P2 amplitude lowering.
Clinical Neurophysiology, Jul 1, 1999
Brain electric activity in the theta frequency band has been associated with the encoding of new,... more Brain electric activity in the theta frequency band has been associated with the encoding of new, and the retrieving of previously stored, information. We studied the time course of stimulus-to-stimulus changes of theta activity under repetitive somatosensory stimulation. Twelve healthy subjects participated in the study. Repetitive electric stimuli, grouped into 48 stimulus trains, were applied to the left index finger. The stimulus trains contained 27 stimuli (0.9 Hz, 2.5 times sensory threshold). Each stimulus train of 30 s was followed by a stimulus-free break of 30 s. This stimulation paradigm allowed the separate estimation of effects for each position of the stimulus in the train and an analysis of stimulus-to-stimulus changes. Multichannel EEG recordings allowed a topographic analysis of the event-related spectral perturbation effects in the theta frequency band. The brain electric novelty response triggered by the stimulus train onset was analyzed by 3 methods: (1) event-related potentials; (2) event-related power spectra for the investigation of spectral perturbation effects on theta activity; and (3) an approach to break down the stimulus-induced theta activity into phase-locked activity and effects on the spontaneous, ongoing theta activity using digital filtering. The main findings are a frontal midline activation in the theta band with the beginning of the stimulus train, which habituates during the subsequent stimulation cycles, as well as evidence that distinct effects of the first stimulus on the ongoing, non-phase-locked, theta activity exist.
Clinical Neurophysiology, Apr 1, 1998
Joint ECG and EEG measurements were performed in 22 healthy subjects under standardized laborator... more Joint ECG and EEG measurements were performed in 22 healthy subjects under standardized laboratory conditions. Averaged EEG potentials were computed using the R-peaks in the ECG as reference events. Spatio-temporal potential patterns of heart action-related EEG activity were obtained from 26 scalp channels. A heart action-related positive potential was found, peaking over the parietal scalp regions. Its independence from the cardiac electrical field, the source of an EEG artifact that may be confounded with heart action-related brain potentials, is demonstrated. The potential reaches its maximum amplitude of about 0.5 mV at a latency of about 500 ms after the R-peak. Its topography, with peak amplitudes at the parietal electrode locations, is different from the topography of potentials observed in the few comparable experimental studies published so far. This suggests the presence of somatosensory-evoked components in heart action-related potentials and indicates that a renewed discussion of the underlying neuronal processes is necessary.
Journal of Psychiatric Research, Mar 1, 2004
NeuroImage, May 1, 1998
An experimental study of somatosensory evoked potentials (SSEP) aimed at simultaneously exploring... more An experimental study of somatosensory evoked potentials (SSEP) aimed at simultaneously exploring long-term (up to I hr) and short-term (up to 30 s) habituation effects. The latency range from 18 to .t50 ms after the stimulus was investigated. Multichannel EEG recordings alloweda topographic perspective.
Clinical Autonomic Research, 1998
Electroencephalography and Clinical Neurophysiology, Jul 1, 1997
Peptides, 1995
To investigate possible influences of growth hormone-releasing hormone (GHRH) and somatostatin (S... more To investigate possible influences of growth hormone-releasing hormone (GHRH) and somatostatin (SRIF) on auditory perceptional processes, 12 subjects received either placebo (sodium chloride 0.9%), GHRH (50 micrograms), or SRIF (100 micrograms) on different days. Late auditory evoked potentials (AEP) were computed and further analyzed by using the brain electric source analysis (BESA) method. Reduced late AEP latencies were observed following GHRH administration. In contrast, SRIF had no significant effects on the AEP. The changes in late auditory processing seen after administration of GHRH were most likely induced by a direct central nervous action.
International Journal of Neuroscience, 2004
Novelty conditions may elicit stress responses. First session effects are systematic changes in p... more Novelty conditions may elicit stress responses. First session effects are systematic changes in physiological parameters, resulting from the interference of physiological processes with novelty stress. Along with endocrinological changes, these stress responses may be accompanied by alterations of sensory and attentional processes. The present study examines the impact of novelty conditions on event-related potential indicators of auditory information processing and on cortisol. Twenty-two healthy subjects participated in a series of experimental sessions. Auditory-evoked potentials were recorded, and the plasma cortisol levels were determined. The first session causes an activation of the hypothalamo-hypopituitary-adrenal axis. The auditory-evoked potentials show an additional slow negative potential component in the novelty condition. This potential component is maximal at fronto-central electrode sites and reaches its peak at about 240 ms after stimulus onset. Similarities with the processing negativity suggest alterations in attention-related auditory information-processing in the novelty condition encountered in the first session.
International Journal of Neuroscience, 2004
Novelty conditions may elicit stress responses. First session effects are systematic changes in p... more Novelty conditions may elicit stress responses. First session effects are systematic changes in physiological parameters, resulting from the interference of physiological processes with novelty stress. Along with endocrinological changes, these stress responses may be accompanied by alterations of sensory and attentional processes. The present study examines the impact of novelty conditions on event-related potential indicators of auditory information processing and on cortisol. Twenty-two healthy subjects participated in a series of experimental sessions. Auditory-evoked potentials were recorded, and the plasma cortisol levels were determined. The first session causes an activation of the hypothalamo-hypopituitary-adrenal axis. The auditory-evoked potentials show an additional slow negative potential component in the novelty condition. This potential component is maximal at fronto-central electrode sites and reaches its peak at about 240 ms after stimulus onset. Similarities with the processing negativity suggest alterations in attention-related auditory information-processing in the novelty condition encountered in the first session.
Electroencephalography and Clinical Neurophysiology/Evoked Potentials Section, 1998
Joint ECG and EEG measurements were performed in 22 healthy subjects under standardized laborator... more Joint ECG and EEG measurements were performed in 22 healthy subjects under standardized laboratory conditions. Averaged EEG potentials were computed using the R-peaks in the ECG as reference events. Spatio-temporal potential patterns of heart action-related EEG activity were obtained from 26 scalp channels. A heart action-related positive potential was found, peaking over the parietal scalp regions. Its independence from the cardiac electrical field, the source of an EEG artifact that may be confounded with heart action-related brain potentials, is demonstrated. The potential reaches its maximum amplitude of about 0.5 mV at a latency of about 500 ms after the R-peak. Its topography, with peak amplitudes at the parietal electrode locations, is different from the topography of potentials observed in the few comparable experimental studies published so far. This suggests the presence of somatosensory-evoked components in heart action-related potentials and indicates that a renewed discussion of the underlying neuronal processes is necessary.
Journal of Psychiatric Research, 2004
Clinical Neurophysiology, 1999
Brain electric activity in the theta frequency band has been associated with the encoding of new,... more Brain electric activity in the theta frequency band has been associated with the encoding of new, and the retrieving of previously stored, information. We studied the time course of stimulus-to-stimulus changes of theta activity under repetitive somatosensory stimulation. Twelve healthy subjects participated in the study. Repetitive electric stimuli, grouped into 48 stimulus trains, were applied to the left index finger. The stimulus trains contained 27 stimuli (0.9 Hz, 2.5 times sensory threshold). Each stimulus train of 30 s was followed by a stimulus-free break of 30 s. This stimulation paradigm allowed the separate estimation of effects for each position of the stimulus in the train and an analysis of stimulus-to-stimulus changes. Multichannel EEG recordings allowed a topographic analysis of the event-related spectral perturbation effects in the theta frequency band. The brain electric novelty response triggered by the stimulus train onset was analyzed by 3 methods: (1) event-related potentials; (2) event-related power spectra for the investigation of spectral perturbation effects on theta activity; and (3) an approach to break down the stimulus-induced theta activity into phase-locked activity and effects on the spontaneous, ongoing theta activity using digital filtering. The main findings are a frontal midline activation in the theta band with the beginning of the stimulus train, which habituates during the subsequent stimulation cycles, as well as evidence that distinct effects of the first stimulus on the ongoing, non-phase-locked, theta activity exist.
Epilepsy & Behavior, Oct 1, 2003
Levetiracetam (LEV) was shown to be very efficacious and well tolerated as add-on therapy for ref... more Levetiracetam (LEV) was shown to be very efficacious and well tolerated as add-on therapy for refractory epilepsy. Here we report 33 patients with longstanding histories of epilepsy who experienced aggressive episodes during LEV therapy. This corresponds to 3.5% of LEV-treated patients as compared with less than 1% of patients not on LEV. Among these cases, 24 showed only moderate, partly transient irritability, with 10 patients requiring reduction or discontinuation of LEV. More strikingly, 9 patients displayed severe symptoms of aggression with physical violence and, in 2 cases, the need for psychiatric emergency treatment. One patient developed additional psychotic symptoms. We suggest that, specifically in patients with a previous history of aggression, behavioral tolerability of LEV should be carefully monitored.
Epilepsy Research, Feb 1, 2008
We recorded limbic event-related potentials (ERPs) with intrahippocampal depth electrodes in a mo... more We recorded limbic event-related potentials (ERPs) with intrahippocampal depth electrodes in a more demanding verbal and an easier pictorial continuous recognition task in patients undergoing presurgical evaluations of their medical refractory mesial temporal lobe epilepsies (MTLE). In all cases depth electrodes were implanted because non-invasive studies could not demonstrate unilateral seizure-onset unequivocally. For the present study we only considered 24 patients who eventually were found to suffer from unilateral MTLE, in whom hippocampal sclerosis (HS) was confirmed histologically, and who were seizure-free postoperatively. We found that the rhinal anterior medial temporal lobe N400 (AMTL-N400) to first presentations of words but not to pictures was reduced in amplitude on the side of seizure origin. Our data suggest that limbic ERPs to words are more sensitive to the epileptogenic process than those to pictures. Thus, if limbic ERPs are recorded as part of invasive presurgical evaluations, verbal instead of pictorial recognition paradigms should be employed.
NeuroImage, May 1, 2013
Corrigendum to “Processing of famous faces and medial temporal lobe event-related potentials: A d... more Corrigendum to “Processing of famous faces and medial temporal lobe event-related potentials: A depth electrode study” [Neuroimage 25/2 (2005) 401–407] T. Dietl ⁎, P. Trautner, M. Staedtgen, M. Vannucci, A. Mecklinger, T. Grunwald, H. Clusmann, C.E. Elger, M. Kurthen a Department of Epileptology, University of Bonn, Sigmund-Freud-Strasse, 25, D-53115 Bonn, Germany b Department of Psychology, University of Florence, Florence, Italy c Department of Psychology, Saarland University, Saarbrücken, Germany d Swiss Epilepsy Center, Zurich, Switzerland e Department of Neurosurgery, University of Bonn, Bonn, Germany
NeuroImage, 2005
The present study aims at analyzing the modulation of two types of event-related potentials origi... more The present study aims at analyzing the modulation of two types of event-related potentials originating from the human medial temporal lobe, the rhinal AMTL-N400 and the hippocampal P600 by the processing of famous faces. Therefore, we used a face recognition paradigm in which subjects had to discriminate the faces of famous persons from the faces of non-famous persons. Eleven patients with unilateral medial temporal lobe epilepsy undergoing intrahippocampal depth electrode recording for presurgical evaluation participated in this study. Event-related potentials (ERP) were recorded while a sequence of famous and non-famous faces was presented to the patients. The presentation of each face was repeated. The faces evoked N400-like potentials (anterior medial temporal lobe N400, AMTL-N400) in the rhinal cortex and P600-like potentials in the hippocampus. ERPs elicited by famous faces were contrasted with ERPs elicited by non-famous faces. The first presentation of famous faces elicited an enhanced AMTL-N400 and an enhanced hippocampal P600 in comparison to the second presentations of the famous faces or the (first and second presentation of the) non-famous faces. This findings are discussed in terms of associative semantic memory processes and the retrieval of person-specific information from long-term memory stores triggered by the processing of famous faces.
Hippocampus, 2005
However, the neural correlates of this effect are poorly understood. Here, we investigated the ef... more However, the neural correlates of this effect are poorly understood. Here, we investigated the effect of imageability on brain activity in the medial temporal lobe (MTL) processes underlying recognition memory. We recorded eventrelated potentials (ERPs) via depth electrodes from within the MTL in 14 patients with drug-resistant epilepsy. Patients performed a continuous word recognition task with words of high and low imageability (controlled for word frequency). Behaviorally, recognition performance was better for high, compared to low, imageable words. Two ERP components associated with recognition memory, the AMTL-N400 and the hippocampal late negative component, showed an old/new effect, but only the hippocampal P600 showed a main effect of imageability. We suggest that the hippocampal effect of imageability in recognition memory may be associated with conceptual or pictorial information processing of concrete words. V
Psychoneuroendocrinology, 1995
To study whether changes in late auditory evoked potentials (AEPs) and/or in stress-sensitive hor... more To study whether changes in late auditory evoked potentials (AEPs) and/or in stress-sensitive hormones of the hypothalamic-pituitary-adrenal (HPA) system take place between a first and a second placebo experiment and if so, whether these changes are possibly related to each other, we conducted two identical placebo sessions (2 ml 0.9% saline) and one cortisol session (50 mg) with 10 subjects on three different days. Plasma cortisol concentrations were significantly higher at the beginning of the first placebo experiment than the second, with a concordant decrease of plasma adrenocorticotropin hormone (ACTH) concentrations. In the AEP domain, a consistently lower P2 amplitude was observed in the first session. Since the change in late auditory processing could not be demonstrated after exogenous administration of cortisol, a direct mediation through an elevation of plasma cortisol concentrations or indirect mediation through a decrease of plasma ACTH concentrations seems unlikely. We rather propose that other stress-sensitive mechanisms, such as CCK, might account for the novelty-induced P2 amplitude lowering.
Clinical Neurophysiology, Jul 1, 1999
Brain electric activity in the theta frequency band has been associated with the encoding of new,... more Brain electric activity in the theta frequency band has been associated with the encoding of new, and the retrieving of previously stored, information. We studied the time course of stimulus-to-stimulus changes of theta activity under repetitive somatosensory stimulation. Twelve healthy subjects participated in the study. Repetitive electric stimuli, grouped into 48 stimulus trains, were applied to the left index finger. The stimulus trains contained 27 stimuli (0.9 Hz, 2.5 times sensory threshold). Each stimulus train of 30 s was followed by a stimulus-free break of 30 s. This stimulation paradigm allowed the separate estimation of effects for each position of the stimulus in the train and an analysis of stimulus-to-stimulus changes. Multichannel EEG recordings allowed a topographic analysis of the event-related spectral perturbation effects in the theta frequency band. The brain electric novelty response triggered by the stimulus train onset was analyzed by 3 methods: (1) event-related potentials; (2) event-related power spectra for the investigation of spectral perturbation effects on theta activity; and (3) an approach to break down the stimulus-induced theta activity into phase-locked activity and effects on the spontaneous, ongoing theta activity using digital filtering. The main findings are a frontal midline activation in the theta band with the beginning of the stimulus train, which habituates during the subsequent stimulation cycles, as well as evidence that distinct effects of the first stimulus on the ongoing, non-phase-locked, theta activity exist.
Clinical Neurophysiology, Apr 1, 1998
Joint ECG and EEG measurements were performed in 22 healthy subjects under standardized laborator... more Joint ECG and EEG measurements were performed in 22 healthy subjects under standardized laboratory conditions. Averaged EEG potentials were computed using the R-peaks in the ECG as reference events. Spatio-temporal potential patterns of heart action-related EEG activity were obtained from 26 scalp channels. A heart action-related positive potential was found, peaking over the parietal scalp regions. Its independence from the cardiac electrical field, the source of an EEG artifact that may be confounded with heart action-related brain potentials, is demonstrated. The potential reaches its maximum amplitude of about 0.5 mV at a latency of about 500 ms after the R-peak. Its topography, with peak amplitudes at the parietal electrode locations, is different from the topography of potentials observed in the few comparable experimental studies published so far. This suggests the presence of somatosensory-evoked components in heart action-related potentials and indicates that a renewed discussion of the underlying neuronal processes is necessary.
Journal of Psychiatric Research, Mar 1, 2004
NeuroImage, May 1, 1998
An experimental study of somatosensory evoked potentials (SSEP) aimed at simultaneously exploring... more An experimental study of somatosensory evoked potentials (SSEP) aimed at simultaneously exploring long-term (up to I hr) and short-term (up to 30 s) habituation effects. The latency range from 18 to .t50 ms after the stimulus was investigated. Multichannel EEG recordings alloweda topographic perspective.
Clinical Autonomic Research, 1998
Electroencephalography and Clinical Neurophysiology, Jul 1, 1997
Peptides, 1995
To investigate possible influences of growth hormone-releasing hormone (GHRH) and somatostatin (S... more To investigate possible influences of growth hormone-releasing hormone (GHRH) and somatostatin (SRIF) on auditory perceptional processes, 12 subjects received either placebo (sodium chloride 0.9%), GHRH (50 micrograms), or SRIF (100 micrograms) on different days. Late auditory evoked potentials (AEP) were computed and further analyzed by using the brain electric source analysis (BESA) method. Reduced late AEP latencies were observed following GHRH administration. In contrast, SRIF had no significant effects on the AEP. The changes in late auditory processing seen after administration of GHRH were most likely induced by a direct central nervous action.
International Journal of Neuroscience, 2004
Novelty conditions may elicit stress responses. First session effects are systematic changes in p... more Novelty conditions may elicit stress responses. First session effects are systematic changes in physiological parameters, resulting from the interference of physiological processes with novelty stress. Along with endocrinological changes, these stress responses may be accompanied by alterations of sensory and attentional processes. The present study examines the impact of novelty conditions on event-related potential indicators of auditory information processing and on cortisol. Twenty-two healthy subjects participated in a series of experimental sessions. Auditory-evoked potentials were recorded, and the plasma cortisol levels were determined. The first session causes an activation of the hypothalamo-hypopituitary-adrenal axis. The auditory-evoked potentials show an additional slow negative potential component in the novelty condition. This potential component is maximal at fronto-central electrode sites and reaches its peak at about 240 ms after stimulus onset. Similarities with the processing negativity suggest alterations in attention-related auditory information-processing in the novelty condition encountered in the first session.
International Journal of Neuroscience, 2004
Novelty conditions may elicit stress responses. First session effects are systematic changes in p... more Novelty conditions may elicit stress responses. First session effects are systematic changes in physiological parameters, resulting from the interference of physiological processes with novelty stress. Along with endocrinological changes, these stress responses may be accompanied by alterations of sensory and attentional processes. The present study examines the impact of novelty conditions on event-related potential indicators of auditory information processing and on cortisol. Twenty-two healthy subjects participated in a series of experimental sessions. Auditory-evoked potentials were recorded, and the plasma cortisol levels were determined. The first session causes an activation of the hypothalamo-hypopituitary-adrenal axis. The auditory-evoked potentials show an additional slow negative potential component in the novelty condition. This potential component is maximal at fronto-central electrode sites and reaches its peak at about 240 ms after stimulus onset. Similarities with the processing negativity suggest alterations in attention-related auditory information-processing in the novelty condition encountered in the first session.
Electroencephalography and Clinical Neurophysiology/Evoked Potentials Section, 1998
Joint ECG and EEG measurements were performed in 22 healthy subjects under standardized laborator... more Joint ECG and EEG measurements were performed in 22 healthy subjects under standardized laboratory conditions. Averaged EEG potentials were computed using the R-peaks in the ECG as reference events. Spatio-temporal potential patterns of heart action-related EEG activity were obtained from 26 scalp channels. A heart action-related positive potential was found, peaking over the parietal scalp regions. Its independence from the cardiac electrical field, the source of an EEG artifact that may be confounded with heart action-related brain potentials, is demonstrated. The potential reaches its maximum amplitude of about 0.5 mV at a latency of about 500 ms after the R-peak. Its topography, with peak amplitudes at the parietal electrode locations, is different from the topography of potentials observed in the few comparable experimental studies published so far. This suggests the presence of somatosensory-evoked components in heart action-related potentials and indicates that a renewed discussion of the underlying neuronal processes is necessary.
Journal of Psychiatric Research, 2004
Clinical Neurophysiology, 1999
Brain electric activity in the theta frequency band has been associated with the encoding of new,... more Brain electric activity in the theta frequency band has been associated with the encoding of new, and the retrieving of previously stored, information. We studied the time course of stimulus-to-stimulus changes of theta activity under repetitive somatosensory stimulation. Twelve healthy subjects participated in the study. Repetitive electric stimuli, grouped into 48 stimulus trains, were applied to the left index finger. The stimulus trains contained 27 stimuli (0.9 Hz, 2.5 times sensory threshold). Each stimulus train of 30 s was followed by a stimulus-free break of 30 s. This stimulation paradigm allowed the separate estimation of effects for each position of the stimulus in the train and an analysis of stimulus-to-stimulus changes. Multichannel EEG recordings allowed a topographic analysis of the event-related spectral perturbation effects in the theta frequency band. The brain electric novelty response triggered by the stimulus train onset was analyzed by 3 methods: (1) event-related potentials; (2) event-related power spectra for the investigation of spectral perturbation effects on theta activity; and (3) an approach to break down the stimulus-induced theta activity into phase-locked activity and effects on the spontaneous, ongoing theta activity using digital filtering. The main findings are a frontal midline activation in the theta band with the beginning of the stimulus train, which habituates during the subsequent stimulation cycles, as well as evidence that distinct effects of the first stimulus on the ongoing, non-phase-locked, theta activity exist.
Epilepsy & Behavior, Oct 1, 2003
Levetiracetam (LEV) was shown to be very efficacious and well tolerated as add-on therapy for ref... more Levetiracetam (LEV) was shown to be very efficacious and well tolerated as add-on therapy for refractory epilepsy. Here we report 33 patients with longstanding histories of epilepsy who experienced aggressive episodes during LEV therapy. This corresponds to 3.5% of LEV-treated patients as compared with less than 1% of patients not on LEV. Among these cases, 24 showed only moderate, partly transient irritability, with 10 patients requiring reduction or discontinuation of LEV. More strikingly, 9 patients displayed severe symptoms of aggression with physical violence and, in 2 cases, the need for psychiatric emergency treatment. One patient developed additional psychotic symptoms. We suggest that, specifically in patients with a previous history of aggression, behavioral tolerability of LEV should be carefully monitored.
Epilepsy Research, Feb 1, 2008
We recorded limbic event-related potentials (ERPs) with intrahippocampal depth electrodes in a mo... more We recorded limbic event-related potentials (ERPs) with intrahippocampal depth electrodes in a more demanding verbal and an easier pictorial continuous recognition task in patients undergoing presurgical evaluations of their medical refractory mesial temporal lobe epilepsies (MTLE). In all cases depth electrodes were implanted because non-invasive studies could not demonstrate unilateral seizure-onset unequivocally. For the present study we only considered 24 patients who eventually were found to suffer from unilateral MTLE, in whom hippocampal sclerosis (HS) was confirmed histologically, and who were seizure-free postoperatively. We found that the rhinal anterior medial temporal lobe N400 (AMTL-N400) to first presentations of words but not to pictures was reduced in amplitude on the side of seizure origin. Our data suggest that limbic ERPs to words are more sensitive to the epileptogenic process than those to pictures. Thus, if limbic ERPs are recorded as part of invasive presurgical evaluations, verbal instead of pictorial recognition paradigms should be employed.
NeuroImage, May 1, 2013
Corrigendum to “Processing of famous faces and medial temporal lobe event-related potentials: A d... more Corrigendum to “Processing of famous faces and medial temporal lobe event-related potentials: A depth electrode study” [Neuroimage 25/2 (2005) 401–407] T. Dietl ⁎, P. Trautner, M. Staedtgen, M. Vannucci, A. Mecklinger, T. Grunwald, H. Clusmann, C.E. Elger, M. Kurthen a Department of Epileptology, University of Bonn, Sigmund-Freud-Strasse, 25, D-53115 Bonn, Germany b Department of Psychology, University of Florence, Florence, Italy c Department of Psychology, Saarland University, Saarbrücken, Germany d Swiss Epilepsy Center, Zurich, Switzerland e Department of Neurosurgery, University of Bonn, Bonn, Germany
NeuroImage, 2005
The present study aims at analyzing the modulation of two types of event-related potentials origi... more The present study aims at analyzing the modulation of two types of event-related potentials originating from the human medial temporal lobe, the rhinal AMTL-N400 and the hippocampal P600 by the processing of famous faces. Therefore, we used a face recognition paradigm in which subjects had to discriminate the faces of famous persons from the faces of non-famous persons. Eleven patients with unilateral medial temporal lobe epilepsy undergoing intrahippocampal depth electrode recording for presurgical evaluation participated in this study. Event-related potentials (ERP) were recorded while a sequence of famous and non-famous faces was presented to the patients. The presentation of each face was repeated. The faces evoked N400-like potentials (anterior medial temporal lobe N400, AMTL-N400) in the rhinal cortex and P600-like potentials in the hippocampus. ERPs elicited by famous faces were contrasted with ERPs elicited by non-famous faces. The first presentation of famous faces elicited an enhanced AMTL-N400 and an enhanced hippocampal P600 in comparison to the second presentations of the famous faces or the (first and second presentation of the) non-famous faces. This findings are discussed in terms of associative semantic memory processes and the retrieval of person-specific information from long-term memory stores triggered by the processing of famous faces.
Hippocampus, 2005
However, the neural correlates of this effect are poorly understood. Here, we investigated the ef... more However, the neural correlates of this effect are poorly understood. Here, we investigated the effect of imageability on brain activity in the medial temporal lobe (MTL) processes underlying recognition memory. We recorded eventrelated potentials (ERPs) via depth electrodes from within the MTL in 14 patients with drug-resistant epilepsy. Patients performed a continuous word recognition task with words of high and low imageability (controlled for word frequency). Behaviorally, recognition performance was better for high, compared to low, imageable words. Two ERP components associated with recognition memory, the AMTL-N400 and the hippocampal late negative component, showed an old/new effect, but only the hippocampal P600 showed a main effect of imageability. We suggest that the hippocampal effect of imageability in recognition memory may be associated with conceptual or pictorial information processing of concrete words. V