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Analysis of electrical potentials and magnetic fields of the brain

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Abstract

How does the brain learn a foreign language or relearn speech after a stroke? How do changes in the brains of trauma victims lead to recurring anxiety states, and how can this condition be treated? Specialists in a variety of disciplines, including biology, linguistics, math- ematics, medicine, physics and psychology, investigate these questions using the most modern instruments available to the neurosciences. From positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) to electroencephalography (EEG) and magnetoencephalography (MEG), these instruments are yielding information on brain activity at an unprecedented rate and in previ- ously unimaginable detail. The challenge is to find analytical software that is sophisticated enough to cope with this deluge of data. Several commercial software packages are available for analyzing EEG or MEG data. However, these packages can be inadequate for researchers who wish to use nontraditional evaluation methods or develop their own. The MATLAB based analysis package ElectroMagnetic EncaphaloGraphy Software (EMEGS) developed in the Department of Clinical Psychology at the University of Constance fills this gap.

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... The real and imaginary parts of the 10 Hz Fourier component per condition resulting from the procedure mentioned above were submitted to minimum norm source estimation and subsequently recombined by taking the square root of the sum of the two squared dipole orientations. Cortical sources were estimated using the L2 minimum norm estimate (MNE), following the approach suggested by Hauk (2004) using EMEGS (Junghöfer & Peyk, 2004). The L2 minimum norm estimate enables enhanced resolution of brain activations generating the magnetic field without a priori assumptions regarding the location and number of current sources (Hämäläinen & Ilmoniemi, 1994). ...
... Using the Matlab-based software EMEGS c (Junghöfer & Peyk, 2004), the distribution of the cortical sources of neuromagnetic activity was estimated by calculating L2 minimum norm solutions that offer enhanced resolution of brain activity generated by a magnetic field without a-priori assumption regarding the location and number of current sources (Hämäläinen & Ilmoniemi, 1994). Calculation of the L2 minimum norm was based on a one-shell spherical head model with 2 (azimuth and polar direction)× 197 evenly distributed dipolar sources. ...
... Using the Matlab-based software EMEGS c (Junghöfer & Peyk, 2004) the distribution of likely generators of the neuromagnetic activity was estimated by calculating L2-minimum norm solutions (Hämäläinen & Ilmoniemi, 1994). Calculation of the L2 minimum norm was based on a one-shell spherical head model with 2 (azimuth and polar direction) × 197 evenly distributed dipolar sources. ...
Article
Posttraumatic stress disorder (PTSD) is characterized by repeated unwanted memories of the traumatic experiences, avoidance of trauma reminders, and general hyperarousal (DSM-IV, 1994). Symptoms of hyperarousal, especially the excessive reactivity to trauma reminders, indicate a dysfunctional regulation of the physiological stress system in PTSD patients (Buckley et al., 2001). Current theories of PTSD consider alterations in the processing of threat cues as a core characteristic of this disorder (Ehlers et al., 2000). Aim of the present thesis was to investigate psychophysiological correlates of the processing of threat-related stimuli in patients with PTSD. Additionally, we wanted to examine if alterations in the emotional processing could be changed through psychotherapy. Study participants (N=78) belonged to one of the three groups: Trauma-exposed refugees with or without PTSD and healthy individuals with a similar cultural background but without traumatic experiences. We presented IAPS pictures that varied in emotional content (Lang et al., 1997) and applied a visual steady-state presentation technique and recorded physiological data using magnetencephalography (MEG). We analyzed three different psychophysiological parameters of affective picture processing: Heart rate reactivity, very early cortical activity in the range of milliseconds, and the sustained cortical activity up to four seconds after stimulus onset. Analyses of the heart rate reactivity revealed that PTSD patients reacted with an immediate increase in heart rate towards aversive pictures and an absence of the orienting response. Our findings argue for a faster flight/fight’ response to threatening cues in PTSD. Immediately after having identified the threatening quality of a stimulus, PTSD patients seem to mobilize for action rather than exploring the stimulus further in a vigilant state. Examination of the first 300 milliseconds of neuronal activity during the processing of affective pictures revealed also differences between the three groups. In patients with PTSD, we found evidence for a biphasic cortical reaction pattern. In response to aversive pictures, compared to neutral or pleasant pictures, PTSD patients showed elevated activity over right prefrontal brain areas as early as 130 milliseconds after stimulus onset. This initial increased cortical activity was followed by a decrease of the affect-related response in the parieto-occipital cortex starting 200 milliseconds after stimulus onset. Our results support the idea of a very early alarm' response towards aversive stimuli in PTSD, which precedes an attentional disengagement. Thereby, our findings are consistent with the hypothesis of a vigilance-avoidance reaction pattern to threat in anxiety disorders (Mogg et al., 2004). To examine if the attentional disengagement lasts over time, we analyzed the sustained cortical activity over the entire four seconds of picture presentation. We found reduced cortical activity over occipital areas in response to aversive pictures in both PTSD patients and trauma controls in comparison to unexposed subjects. Our results indicate that the attentional disengagement from threatening cues lasts up to four seconds. PTSD seem to focus on the initiation of a rapid flight reaction rather than concentrating on the attentive evaluation of the threat cue when confronted with potential threats. Main interest of the study was to examine whether these neuropathological alterations in the emotional processing of aversive stimuli could be changed through psychotherapy. In a randomized controlled treatment trial, 34 PTSD patients were randomly assigned to either a group that was treated with Narrative Exposure Therapy (NET) or a waiting-list group. We found that parietal and occipital activity to threatening pictures, compared to neutral pictures, significantly increased after therapy in the NET group only. Given the relevance of the parietal cortex in episodic memory retrieval, the enhanced parietal activity after therapy might be linked to a voluntary top-down episodic memory search that is trained by NET. Our results indicate that NET causes a re-establishment of cortical top-down regulation of attention towards aversive pictures. The increase of attention allocation to potential threat cues in patients treated with NET might allow exploring and re-appraising the actual danger of the current situation, thereby, reducing PTSD symptoms. Conclusively, this thesis demonstrates that PTSD is characterized by a very specific pattern of physiological responses towards threatening stimuli that can be changed through psychotherapy: PTSD patients react with an immediate increase in autonomic activation indicating their readiness for a rapid flight/fight response. The cortical processing of threat cues in PTSD is characterized by a biphasic vigilance-avoidance pattern. A rapid increase in cortical activity in prefrontal areas indicates an early alarm or categorization response towards threat. This is followed by a reduced sensory processing of aversive stimuli that lasts up to several seconds after stimulus presentation and might represent a mechanism of attentional disengangement from potential threat. These alterations in the cortical processing can be changed through Narrative Exposure Therapy. After therapy, NET patients are able to reduce cognitive avoidance and increase attention allocation towards threatening pictures. Together with a successful memory search, the increase of attention allows treated patients to evaluate the current situation on the basis of previous experiences. This might be linked to a reduction of PTSD symptoms such as chronic hyperarousal and uncontrollable intrusive memories. Die Posttraumatische Belastungsstörung (PTBS) ist gekennzeichnet durch sich wiederholende, ungewollte Erinnerungen an traumatische Erlebnisse, eine Vermeidung von Erinnerungsreizen sowie eine generelle Übererregbarkeit (DSM-IV, 1994). Aktuellen Theorien zufolge stellt die Veränderung in der Verarbeitung aversiver oder trauma-assoziierter Reize ein Hauptmerkmal der PTSD dar (Ehlers et al., 2000). Ziel der vorliegenden Arbeit ist die Untersuchung psychophysiologischer Korrelate der Verarbeitung von Bedrohungsreizen bei PTBS. Darüber hinaus soll untersucht werden, ob sich diese Abweichungen durch Psychotherapie verändern lassen. Die Studienteilnehmer (N=78) gehören zu einer der drei Gruppen: Traumaüberlebende mit und ohne PTBS, oder gesunde Kontrollprobanden mit gleichem ethnischen Hintergrund, aber ohne traumatische Lebensereignisse. Wir verwendeten eine steady-state Präsentationstechnik, bei dem 75 IAPS-Bilder in einer Frequenz von 10 Hz für jeweils 4 s präsentiert wurden. Die kortikale Aktivität wurde mit Magnetenzephalographie (MEG) aufgezeichnet. Drei verschiedene psychophysiologische Parameter wurden erhoben: Herzfrequenz, frühe kortikale Aktivierung im Bereich von Millisekunden und überdauernde kortikale Aktivierung bis zu vier Sekunden nach Stimulusbeginn. Bei der Auswertung der Herzfrequenz zeigten die PTBS-Patienten einen unmittelbaren Anstieg der Herzfrequenz und einem Ausbleiben der Orientierungsreaktion gegenüber bedrohlichen Bildern. Die Ergebnisse weisen auf eine gesteigerte und schnelle Fluchtbereitschaft von PTBS-Patienten hin. Ohne den potenziell bedrohlichen Stimulus zunächst genau zu explorieren, befindet sich das autonome Nervensystem dieser Patienten innerhalb kürzester Zeit in maximaler Alarmbereitschaft. Bei der Auswertung der ersten 300 ms neuronaler Aktivität während der affektiven Bildverarbeitung zeigten Patienten mit PTBS Hinweise auf ein zweiphasisches kortikales Reaktionsmuster. PTBS-Patienten zeigten bereits in den ersten 130 ms, im Vergleich zu neutralen oder angenehmen Bildern, eine erhöhte Aktivierung in rechts präfrontalen Hirnregionen. Dieser Aktivierung folgte in zeitlicher Latenz eine Abnahme der Reaktion in parieto-okzipitalen Arealen. Die Ergebnisse unterstützen die Annahme, dass bei PTBS-Patienten ein früher Detektionsprozess von Bedrohungsreizen stattfindet, der einer Abwendung der Aufmerksamkeit vorausgeht. Insofern sind unsere Ergebnisse vereinbar mit der Hypothese eines Übererregungs-Vermeidungs-Musters gegenüber Bedrohungsreizen bei Angststörungen (Mogg et al., 2004). Um zu untersuchen, ob die frühe Abwendung der Aufmerksamkeit von Bedrohungsreizen über längere Zeit anhält, analysierten wir zusätzlich die überdauernde kortikale Reaktion auf affektive Reize. PTBS-Patienten als auch bei Traumakontrollen zeigten eine reduzierte kortikale Aktivierung in okzipitalen Regionen bei der Präsentation aversiver Bilder. Unsere Ergebnisse weisen darauf hin, dass die Vermeidung der gezielten Aufmerksamkeitslenkung auf bedrohliche Reize bis zu 4 s bestehen bleibt. Als Schwerpunkt der Arbeit wurde der Frage nachgegangen, inwieweit sich die neuropathologischen Abweichungen in der emotionalen Verarbeitung durch Psychotherapie verändern lassen. In einer randomisierten, kontrollierten Therapiestudie wurden 34 Patienten mit PTBS einer Behandlungsgruppe mit Narrativer Expositionstherapie (NET) bzw. einer Wartelisten-Kontrollgruppe zugeteilt. Die therapierten Patienten zeigten nach 4 Monaten eine signifikante Zunahme der kortikalen Aktivität gegenüber bedrohlichen Reizen in parietalen und okzipitalen Hirnregionen. In Kenntnis der hohen Relevanz parietaler Strukturen beim episodischen Gedächtnisabruf deutet die verstärkte Aktivierung in diesen Arealen auf eine willentlich gesteuerte Gedächtnissuche hin, die durch NET trainiert wurde. Unsere Ergebnisse geben Hinweise darauf, dass Narrative Expositionstherapie die kortikale top-down' Regulierung von Aufmerksamkeitsressourcen gegenüber bedrohlichen Reizen wieder herstellt und einen verbesserten Gedächtnisabruf ermöglicht. Zusammenfassend zeigt diese Arbeit, dass PTBS durch ein spezifisches physiologisches Reaktionsmuster gegenüber bedrohlichen Reizen gekennzeichnet ist, das sich durch Narrative Expositionstherapie verändern lässt: PTBS-Patienten reagieren mit einer unmittelbaren Aktivierung des autonomen Nervensystems, was ihre Bereitschaft für eine rasche Flucht/Kampf Reaktion widerspiegelt. Die kortikale Verarbeitung von Bedrohungsreizen zeichnet sich durch ein zweiphasisches Übererregungs-Vermeidungs-Muster aus. Die schnelle Zunahme der kortikalen Aktivität in präfrontalen Arealen weist auf ein frühes Alarmsystem bei potenzieller Bedrohung hin. Diese Reaktion ist gefolgt von einer reduzierten sensorischen Verarbeitung, die bis zu einigen Sekunden anhält. Dies stellt vermutlich eine Vermeidung der detaillierten Exploration potenzieller Bedrohung dar. Diese Abweichungen in der kortikalen Reaktion bei PTBS-Patienten lassen sich durch Narrative Expositionstherapie (NET) verändern. Nach der Therapie sind NET-Patienten in der Lage, kognitive Vermeidungsmechanismen gegenüber Bedrohungsreizen zu reduzieren und damit eine adäquatere Verarbeitung dieser Reize zu ermöglichen. Die Stärkung der willentlichen Gedächtnissuche durch NET ist notwendig, um die aktuelle Situation vor dem Hintergrund früherer Erlebnisse zu bewerten. Möglicherweise steht die Veränderung in der neuronalen Verarbeitung trauma-assoziierter Reize im Zusammenhang mit der Reduktion der PTBS-Symptomatik nach der Therapie.
... Using the Matlab-based software EMEGS Ó [26], the distribution of likely generators of the neuromagnetic activity was estimated by calculating L2-minimum-norm solutions [18]. Calculation of the L2-minimum-norm was based on a one-shell spherical head model with 2 (azimuth and polar direction) 9 197 evenly distributed dipolar sources. ...
... A possible explanation could be that in PTSD patients, aversive pictures with such explicit contents as war and attack scenes are immediately categorized as a threat and do not require sustained visual processing to identify further emotionally relevant information. In this regard, studies using a rapid serial visual presentation method with healthy subjects have shown that affective processing of pictures occurs with great rapidity with high-arousing emotional slides activating occipitoparietal areas as early as 150 ms after stimulus onset [25][26][27]. In the future, similar studies should be carried out with PTSD patients in order to distinguish between rapidly Fig. 3 Brain maps showing significant group differences with respect to cortical source activation towards unpleasant (left) and pleasant (right) picture content. ...
Article
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Posttraumatic stress disorder (PTSD) has been associated with an altered processing of threat-related stimuli. In particular, an attentional bias towards threat cues has been consistently found in behavioral studies. However, it is unclear whether increased attention towards threat cues translates into preferential processing as neurophysiological studies have yielded inconsistent findings. The aim of the present study was to investigate the neocortical activity related to the processing of aversive stimuli in patients with PTSD. 36 survivors of war and torture with PTSD, 21 Trauma Controls and 20 Unexposed Subjects participated in a visual evoked magnetic field study using flickering pictures of varying affective valence as stimulus material. Minimum norm source localization was carried out to estimate the distribution of sources of the evoked neuromagnetic activity in the brain. Statistical permutation analyses revealed reduced steady-state visual evoked field amplitudes over occipital areas in response to aversive pictures for PTSD patients and for Trauma Controls in comparison to unexposed subjects. Furthermore, PTSD patients showed a hyperactivation of the superior parietal cortex selectively in response to aversive stimuli, which was related to dissociative symptoms as well as to torture severity. The results indicate a different pattern of cortical activation driven by aversive stimuli depending on the experience of multiple traumatic events and PTSD. Whereas, a decreased visual processing of aversive stimuli seems to be associated with trauma exposure in general, the superior parietal activity might represent a specific process linked to the diagnosis of PTSD.
... Relying on EMEGS © 2.4 custom software (Junghöfer & Peyk, 2004) Adverse experiences in childhood influence brain responses to emotional stimuli in adult psychiatric patients 51 Emotion (comparing pleasant, unpleasant and neutral stimuli). This ANOVA served to verify the modulation of cortical activation by emotional stimulus content as described, for instance, by Peyk et al. (2008; see also Schupp et al., 2006). ...
Article
Over the past decades, the link between childhood adversities, brain development and various forms of psychopathology has been well established in the literature. This dissertation aims at identifying psychological functions that are altered as a consequence of early life stress (ELS) and may play a mediating role in the development of a psychiatric disorder. In a quasi-longitudinal design, the present project examined a sample of psychiatric patients that reported a particularly high or a particularly low amount of childhood adversities. Across a 1.5 years period, two groups of patients with high and low ELS as well as a low stress healthy control group were examined three times in order to assess measures of stress sensitivity (number of life events and their subjectively experienced stressfulness), negative affect and psychopathology. Moreover, cortical processing of affective pictures was evaluated with magnetoencephalographic recordings. Patients that had experienced a high amount of ELS reported the most stressful life events in the six month prior to the assessments and experienced them as more stressful than patients without a history of ELS and healthy control subjects. Moreover, they exhibited a stable disposition to high levels of negative affect and had more comorbid diagnoses. Overall cortical responses to affective stimuli were dampened in patients as compared to controls while modulation by stimulus content did not seem to be crucially affected. Dampening of cortical responses was more pronounced in high ELS patients than in low ELS patients. Effects remained stable across a period of altogheter 1.5 years. Results indicate lasting effects of ELS on psychological functions in psychiatric patients despite of clinical improvement. Findings are discussed on the basis of the current literature concerning the mediating pathways between ELS and psychopathology. In den vergangenen Jahrzehnten hat sich in der Literatur die Auffassung durchgesetzt, dass zwischen belastenden Erfahrungen in der Kindheit, Hirnentwicklung und verschiedenen Formen der Psychopathologie ein Zusammenhang besteht. Diese Dissertation hat das Ziel, psychische Funktionen zu identifizieren, die durch die Auswirkungen kindlicher Stressbelastung verändert sind und möglicherweise eine Mediatorfunktion bei der Entstehung psychiatrischer Krankheiten einnehmen. Mit einem längsschnittlichen Design untersuchte das vorliegende Projekt eine Stichprobe psychiatrischer Patient/innen, die eine besonders hohe bzw. besonders geringe kindliche Stressbelastung aufwiesen. Über einen Zeitraum von 1.5 Jahren wurden zwei Patientengruppen mit hoher und geringer kindlicher Stressbelastung sowie eine wenig belastete gesunde Kontrollgruppe dreimalig zu Maßen der Stresssensititität (Anzahl kritischer Lebensereignisse und deren subjektiv erlebte Belastung), negativem Affekt und Psychopathologie befragt. Außerdem wurde die kortikale Verarbeitung affektiver Bilder mittels Magnetenzephalographie untersucht. Patient/innen mit hoher kindlicher Stessbelastung berichteten die meisten Lebensereignisse in den sechs Montaten vor den Erhebungen und erlebten diese subjektiv belastender als wenig belastete Patient/innen und Kontrollpersonen. Darüber hinaus zeigten sie eine dauerhafte Tendenz zu erhöhter negativer Grundstimmung und wiesen eine höhere Anzahl komorbider Diagnosen auf. Kortikale Reaktionen auf affektive Reize waren in der Patientengruppe im Vergleich zur Kontrollgruppe reduziert, wobei die Modulation durch den Reizinhalt nicht wesentlich beeinträchtig schien. In der hoch belasteten Patientengruppe waren die kortikalen Reaktionen noch stärker gedämpft als in der wenig belasteten Patientengruppe. Die Effekte blieben über einen Zeitraum von insgesamt 1.5 Jahren stabil. Die Ergebnisse weisen auf einen auch bei günstigen Krankheitsverläufen anhaltenden Einfluss kindlicher Stressbelastung auf psychische Funktionen bei psychiatrischen Patienten hin. Die Befunde werden auf Grundlage der aktuellen Literatur, die sich mit den vermittelnden Pfaden zwischen kindlicher Stressbelastung und Psychopathologie beschäftigt, diskutiert.
... The data were then divided into epochs from -100 to 900 ms and averaged. Using the Matlab-based software EMEGSÓ ([25] , http://www.emegs.org) the distribution of likely generators of the neuromagnetic activity was estimated using a L2 Minimum Norm Estimate (L2- MNE; [20]). The L2-MNE served as an inverse distributed source modelling method to estimate the cortical generator structure of the magnetic field without a-priori assumptions . ...
Article
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Recently studied 'old' stimuli lead to larger frontal and parietal ERP responses than 'new' stimuli. The present experiment investigated the neuromagnetic correlates (MEG) of this 'old-new' effect and its modulation by emotional stimulus content. Highly arousing pleasant, highly arousing unpleasant and un-arousing neutral photographs were presented to the participants with the instruction to memorize them. They were later re-presented together with new photographs in an old-new decision task. In line with previous ERP studies, a long-lasting old-new effect (350-700 ms) was found. Independently, an emotion effect also occurred, as reflected in a, particularly left temporal, activity increase for emotional pictures between 450 and 580 ms. Moreover, only for the pleasant pictures did the early part of the old-new effect, which is thought to reflect familiarity based recognition processes, interact with picture content: The old-new effect for pleasant pictures in frontal regions was larger than the one for neutral or unpleasant pictures between 350 and 450 ms. In parallel, subjects' responses were accelerated towards and biased in favour of classifying pleasant pictures as old. However, when false alarm rate was taken into account, there was no significant effect of emotional content on recognition accuracy. In sum, this MEG study demonstrates an effect of particularly pleasant emotional content on recognition memory which may be mediated by a familiarity based process.
... EGI: Electrical Geodesics, Inc., Eugene, OR), on line bandpass filtered from 0.01 100 Hz, and sampled at 250 Hz using Netstation acquisition software and EGI amplifiers. Data editing and artifact rejection were based on an elaborate method for statistical control of artifacts, specifically tailored for the analysis of dense sensor ERP recordings (Junghöfer et al., 2000; Junghöfer and Peyk, 2004). The reported data were baseline adjusted and converted to an average reference. ...
Article
Humans are the only species known to use symbolic gestures for communication. This affords a unique medium for nonverbal emotional communication with a distinct theoretical status compared to facial expressions and other biologically evolved nonverbal emotion signals. While a frown is a frown all around the world, the relation of emotional gestures to their referents is arbitrary and varies from culture to culture. The present studies examined whether such culturally based emotion displays guide visual attention processes. In two experiments, participants passively viewed symbolic hand gestures with positive, negative and neutral emotional meaning. In Experiment 1, functional magnetic resonance imaging (fMRI) measurements showed that gestures of insult and approval enhance activity in selected bilateral visual-associative brain regions devoted to object perception. In Experiment 2, dense sensor event-related brain potential recordings (ERP) revealed that emotional hand gestures are differentially processed already 150 ms poststimulus. Thus, the present studies provide converging neuroscientific evidence that emotional gestures provoke the cardinal signatures of selective visual attention regarding brain structures and temporal dynamics previously shown for emotional face and body expressions. It is concluded that emotionally charged gestures are efficient in shaping selective attention processes already at the level of stimulus perception.
... These calculations were done using EMEGS (ElectroMagnetic-EncephaloGraphy Software; http://www.emegs.org/), a tool for analyzing neuroscientific data developed in MATLAB [45]. The 275 channels of the MEG system were fragmented into 10 channel groups, frontal, central, parietal, temporal and occipital channels in each hemisphere. ...
Article
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Dysphagia is a leading complication in stroke patients causing aspiration pneumonia, malnutrition and increased mortality. Current strategies of swallowing therapy involve on the one hand modification of eating behaviour or swallowing technique and on the other hand facilitation of swallowing with the use of pharyngeal sensory stimulation. Thermal tactile oral stimulation (TTOS) is an established method to treat patients with neurogenic dysphagia especially if caused by sensory deficits. Little is known about the possible mechanisms by which this interventional therapy may work. We employed whole-head MEG to study changes in cortical activation during self-paced volitional swallowing in fifteen healthy subjects with and without TTOS. Data were analyzed by means of synthetic aperture magnetometry (SAM) and the group analysis of individual SAM data was performed using a permutation test. Compared to the normal swallowing task a significantly increased bilateral cortical activation was seen after oropharyngeal stimulation. Analysis of the chronological changes during swallowing suggests facilitation of both the oral and the pharyngeal phase of deglutition. In the present study functional cortical changes elicited by oral sensory stimulation could be demonstrated. We suggest that these results reflect short-term cortical plasticity of sensory swallowing areas. These findings facilitate our understanding of the role of cortical reorganization in dysphagia treatment and recovery.
... These calculations were done using EMEGS (ElectroMagnetic-EncephaloGraphy Software; http://www.emegs.org), a tool for analyzing neuroscientific data developed in MATLAB [45]. The 275 channels of the MEG system were fragmented into 10 channel groups, frontal, central, parietal, temporal and occipital channels in each hemisphere. ...
Article
Full-text available
Dysphagia is a major complication of different diseases affecting both the central and peripheral nervous system. Pharyngeal sensory impairment is one of the main features of neurogenic dysphagia. Therefore an objective technique to examine the cortical processing of pharyngeal sensory input would be a helpful diagnostic tool in this context. We developed a simple paradigm to perform pneumatic stimulation to both sides of the pharyngeal wall. Whole-head MEG was employed to study changes in cortical activation during this pharyngeal stimulation in nine healthy subjects. Data were analyzed by means of synthetic aperture magnetometry (SAM) and the group analysis of individual SAM data was performed using a permutation test. Our results revealed bilateral activation of the caudolateral primary somatosensory cortex following sensory pharyngeal stimulation with a slight lateralization to the side of stimulation. The method introduced here is simple and easy to perform and might be applicable in the clinical setting. The results are in keeping with previous findings showing bihemispheric involvement in the complex task of sensory pharyngeal processing. They might also explain changes in deglutition after hemispheric strokes. The ipsilaterally lateralized processing is surprising and needs further investigation.
... The real and imaginary parts of the 10 Hz Fourier component per condition resulting from the procedure mentioned above were submitted to minimum norm source estimation and subsequently recombined by taking the square root of the sum of the two squared dipole orientations . Cortical sources were estimated using the L2 minimum norm estimate (MNE), following the approach suggested by Hauk et al. [26] using EMEGS [27] . The L2- minimum-norm estimate enables enhanced resolution of brain activations generating the magnetic field without a priori assumptions regarding the location and number of current sources [21]. ...
Article
Full-text available
The affective and motivational relevance of a stimulus has a distinct impact on cortical processing, particularly in sensory areas. However, the spatial and temporal dynamics of this affective modulation of brain activities remains unclear. The purpose of the present study was the development of a paradigm to investigate the affective modulation of cortical networks with a high temporal and spatial resolution. We assessed cortical activity with MEG using a visual steady-state paradigm with affective pictures. A combination of a complex demodulation procedure with a minimum norm estimation was applied to assess the temporal variation of the topography of cortical activity. Statistical permutation analyses of the results of the complex demodulation procedure revealed increased steady-state visual evoked field amplitudes over occipital areas following presentation of affective pictures compared to neutral pictures. This differentiation shifted in the time course from occipital regions to parietal and temporal regions. It can be shown that stimulation with affective pictures leads to an enhanced activity in occipital region as compared to neutral pictures. However, the focus of differentiation is not stable over time but shifts into temporal and parietal regions within four seconds of stimulation. Thus, it can be crucial to carefully choose regions of interests and time intervals when analyzing the affective modulation of cortical activity.
... All channels were bandpass filtered online from 0.1 to 100 Hz. Off-line analysis was performed using EMEGS (Junghöfer and Peyk, 2004), a MATLAB based program. Continuous EEG data were low pass filtered at 40 Hz using digital filtering before stimulus synchronized epochs were extracted from 100 ms before to 1200 ms after picture onset and baseline corrected for pre-stimulus (100 ms) ERP activity. ...
Article
Evidence from both animal and human research suggests that the formation of emotional memories is triggered by the beta-adrenergic system. To confirm whether modulation of central beta-adrenergic transmission is specifically involved in the neural signature of memory performance, the pre-encoding effect of propranolol (80 mg) on event-related potentials (ERPs) was measured in a placebo-controlled, double-blind, parallel-group study in 46 male healthy subjects using high density EEG and source imaging analysis during encoding and retrieval (after 1 week) of IAPS pictures of unpleasant, neutral and pleasant contents; for recognition 90 old pictures were randomly mixed with 90 new pictures. During retrieval correctly remembered old pictures elicited a significantly larger positive voltage change over the centro-parietal cortex than new pictures. Propranolol significantly reduced this old/new difference of the mean ERP amplitudes (500-800 ms) for unpleasant but not for neutral and pleasant memories. This effect correlated with salivary alpha-amylase activity, a surrogate for central adrenergic stimulation. In conclusion, propranolol selectively blocked the neural signature of unpleasant memories by mechanisms in which the parietal cortex seems to be specifically involved.
... 3 Both primes and targets were evaluated for their prototypicality of the underlying domains of shape/weight/ eating concerns (primes) and of performance/interpersonal SE (targets) by n=15 members of the Department of Clinical Psychology, who all had considerable experience with ED. 4 EMEGS (Junghofer & Peyk, 2004) was used to generate the figures, based on the average waveforms calculated in AVG-Q. 5 An omnibus ANOVA contained parietal (P3, Pz, P4), central (C3, Cz, C4) and frontal (F3, Fz, F4) electrodes coded by the region (parietal, central, frontal) and laterality (left, midline, right) factors in addition to congruence (congruent, incongruent), SE domain (performance, interpersonal) and group (AN, BN, HC) factors to confirm the frontal location of the N400 and its modulation by group. ...
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Current theories and nosology assume that the self-evaluation (SE) of individuals with eating disorders (EDs) is unduly influenced by body shape and weight. However, experimental data supporting this link are scarce, and it is not specified which subdomains of SE might be affected. We studied patients with anorexia nervosa (AN), bulimia nervosa (BN) and healthy controls (HC) with an affective priming (AP) procedure (Study 1) to unveil explicit and implicit associations between shape/weight and SE. We used weight/shape-related prime sentences, complemented by affectively congruent and incongruent target words from two SE domains. AP effects were assessed by event-related potentials (ERPs), reaction times (RTs) and subjective ratings. The ratings were also assessed (Study 2) in undergraduate restrained (RES) and unrestrained eaters (UNRES). Study 1 demonstrated stronger AP effects in both ED groups compared to HC on RTs and subjective ratings. ERPs showed AP effects only in the BN group. Restrained eaters showed similar, albeit less pronounced, priming effects on subjective ratings. ED patients associate shape/weight concerns with the non-appearance-related SE domains of interpersonal relationships and achievement/performance. These associations seem to be encoded deeper in BN patients relative to the other groups. Links between shape/weight and SE explain how body dissatisfaction impacts on self-esteem and mood in ED. The existence of similar associations in restrained eaters supports a continuum model according to which increasing associations between shape/weight and SE go along with increasing levels of ED symptoms.
... The L2 minimum-norm was calculated based on a one-shell spherical head model with evenly distributed 2 (azimuthal and polar direction) × 350 dipoles as a source model using the MATLAB-based software EMEGS© [38]. The L2 minimum-norm estimate enables an enhanced resolution of brain activations generating the magnetic field without a priori assumptions regarding the location and number of current sources [39]. ...
Article
Objective: Dysfunctional emotion processing has been discussed as a contributing factor to functional neurological symptoms (FNS) in the context of conversion disorder, and refers to blunted recognition and the expression of one's own feelings. However, the emotion processing components characteristic for FNS and/or relevant for conversion remain to be specified. With this goal, the present study targeted the initial, automatic discrimination of emotionally salient stimuli. Methods: The magnetoencephalogram (MEG) was monitored in 21 patients with functional weakness and/or sensory disturbance subtypes of FNS and 21 healthy comparison participants (HC) while they passively watched 600 emotionally arousing, pleasant, unpleasant or neutral stimuli in a rapid serial visual presentation (RSVP) design. Neuromagnetic activity was analyzed 110-330ms following picture onset in source space for prior defined posterior and central regions of interest. Results: As early as 110ms and across presentation interval, posterior neural activity modulation by picture category was similar in both groups, despite smaller initial (110-150ms) overall and posterior power in patients with FNS. The initial activity modulation by picture category was also evident in the left sensorimotor area in patients with FNS, but not significant in HC. Conclusions: Similar activity modulation by emotional picture category in patients with FNS and HC suggests that the fast, automatic detection of emotional salience is unchanged in patients with FNS, but involves an emotion-processing network spanning posterior and sensorimotor areas.
... With the Matlab-based software EMEGS (25), the distribution of the cortical sources of neuromagnetic activity was estimated by calculating L2-minimum-norm solutions that offer enhanced resolution of brain activity generated by a magnetic field without a priori assumption regarding the location and number of current sources (26; Supplement 1). Calculation of the L2-minimumnorm was based on a one-shell spherical head model with 2 (azimuth and polar direction) ϫ 197 evenly distributed dipolar sources. ...
Article
The present study investigated the influence of posttraumatic stress disorder (PTSD) on early visual processing of affective stimuli in survivors of war and torture. Trauma-exposed refugees with (n = 36) and without (n = 21) PTSD as well as unexposed control subjects (n = 16) participated in a magnetoencephalography study with pictures that varied in emotional content. We found evidence for a biphasic cortical response in patients with PTSD in comparison with the two control groups. In response to aversive (relative to neutral or positive) pictures, PTSD patients showed elevated cortical activity over right prefrontal areas as early as 130-160 msec after stimulus onset followed by a decrease of the affect-related response in the parieto-occipital cortex at 206-256 msec. The increased early activity in the right prefrontal cortex most likely represents an enhanced alarm response or the fear network toward aversive stimuli in PTSD, whereas the subsequent decreased activation in right parieto-occipital areas in response to aversive pictures seems to reflect the tendency to disengage from emotional content. This finding is consistent with the hypothesis of a vigilance-avoidance reaction pattern to threat in anxiety disorders and helps to reconcile contradicting results of over- and under-responsiveness in the sensory processing of threatening stimuli in PTSD.
... The data were topographically visualized and statistically analyzed using EMEGS 2.4 (Elec-troMagnetic EncephaloGraphy Software, <http://www.emegs.de>, Junghöfer and Peyk 2004 Weymar et al. 2009, 2013 for a similar approach). ...
Article
Language can serve to constrain cognitive and emotional representations. Here, we investigate to what extent linguistic emotional information alters processing of faces with neutral expressions. Previous studies have shown that cortical processing of emotional faces differs from that of neutral faces. Electroencephalography (EEG) has revealed emotion effects for early and late event-related potentials (ERPs) such as the N1, the Early Posterior Negativity (EPN) and the Late Positive Potential (LPP). In order to study the effect of language information on face processing, 30 negative and 30 neutral descriptive phrases were presented, each followed by a neutral expression face. Participants were instructed to remember the association. We analyzed the immediate effect of information type on face processing during encoding as well as delayed effects during subsequent recognition. During encoding, faces following negative language information elicited a larger left frontal positivity between 500–700 ms after stimulus onset. During recognition, a left centro-parietal LPP was likewise increased for faces previously associated with a negative description. In addition, the parietal old/new effect was significantly increased for faces with negative information compared to new ones, while no significant effect was observed for faces with neutral information. No information effects on early perceptual ERPs (N1, EPN) were found. Reaction times (RTs) for source memory decisions (negative versus neutral) were significantly shorter for faces with negative versus neutral information. In sum, ERP results indicate that emotional significance can be linguistically induced in faces on a cortical level and, at least in an explicit memory task, this information modulates later stages of face processing and memory. Implications for cognitive effects of public media design are discussed.
... Brain readings of buyer's option Data pre-processing, inverse modeling, statistical analysis, and visualization were accomplished using ElectroMagneticEncephaloGraphy Software (Junghöfer and Peyk, 2004 3 ). ...
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Emotional stimuli guide selective visual attention and receive enhanced processing. Previous event-related potential studies have identified an early (>120 ms) negative potential shift over occipito-temporal regions (early posterior negativity, EPN) presumed to indicate the facilitated processing of survival-relevant stimuli. The present study investigated whether this neural signature of motivated attention is also responsive to the intrinsic significance of man-made objects and consumer goods. To address this issue, we capitalized on gender differences towards specific man-made objects, shoes and motorcycles, for which the Statistical Yearbook 2005 of Germany's Federal Statistical Office (Statistisches Bundesamt, 2005) revealed pronounced differences in consumer behavior. In a passive viewing paradigm, male and female participants viewed pictures of motorcycles and shoes, while their magnetoencephalographic brain responses were measured. Source localization of the magnetic counterpart of the EPN (EPNm) revealed pronounced gender differences in picture processing. Specifically, between 130 and 180 ms, all female participants generated stronger activity in occipito-temporal regions when viewing shoes compared to motorcycles, while all men except one showed stronger activation for motorcycles than shoes. Thus, the EPNm allowed a sex-dimorphic classification of the processing of consumer goods. Self-report data confirmed gender differences in consumer behavior, which, however, were less distinct compared to the brain based measure. Considering the latency of the EPNm, the reflected automatic emotional network activity is most likely not yet affected by higher cognitive functions such as response strategies or social expectancy. Non-invasive functional neuroimaging measures of early brain activity may thus serve as objective measure for individual preferences towards consumer goods.
... Continuous EEG data were low pass-filtered at 40 Hz using digital filtering before stimulus synchronized epochs from 100 ms before to 1,200 ms after picture onset were extracted and baseline-corrected (100 ms prior to stimulus onset). For data editing and artifact rejection, a two-step procedure was used for statistical control of artifacts, specifically tailored for the analysis of dense sensor recordings [Junghö fer et al., 2000; Junghö fer and Peyk, 2004]. The raw EEG epochs were first passed through a computerized artifact detection algorithm that uses statistical parameters (e.g., absolute value over time, standard deviation over time, etc.) to determine and reject channels and trials with artifacts. ...
Article
Emotional memories can be extremely robust and long-lasting and can contribute to the development of anxiety disorders. Despite tremendous work on neural responses underlying the memory formation of emotional events, less is known about long-term retention. In the present study, behavioral and electrophysiological measures were used to investigate long-term recognition memory for emotional (unpleasant and pleasant) and neutral pictures after two retention intervals (1 week vs. 1 year) in 21 male subjects. The results show enhanced recognition performance for emotional relative to neutral pictures for both test delays. On the neural side, the retrieval of emotional pictures compared to neutral pictures was accompanied after 1 week by an enhanced old/new effect (500-800 ms), originating in the parietal cortex. After 1-year retention delay, only unpleasant but not pleasant pictures were different from neutral pictures in the recollection-sensitive ERP component. Analysis of the subjective awareness (confidence ratings) during recognition indicated that behavioral and electrocortical response patterns were exclusively driven by high confidence responses, an indication for recollection-based recognition. These results suggest that high arousing emotional memories were highly consistent over time relative to neutral memories.
... Impedances were kept below 50 kΩ, as recommended for this type of amplifier. Electromagnetic Encephalography Software (EMEGS) (Junghöfer & Peyk, 2004) software was used for analysis. Data editing and artifact rejection were based on a method for the statistical control of artifacts specifically devised for analyzing dense sensor EEG recordings (Junghöfer, Elbert, Tucker, & Rockstroh, 2000). ...
... Impedances were kept below 50 k , as recommended for this type of amplifier. Electromagnetic Encephalography Software (EMEGS; Junghöfer and Peyk, 2004) software was used for analysis. Data editing and artifact rejection were based on a method for the statistical control of artifacts specifically devised for analyzing dense sensor EEG recordings (Junghöfer et al., 2000). ...
Article
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Field studies on HIV risk perception suggest that people may rely on impressions they have about the safety of their partner. Previous studies show that individuals perceived as "risky" regarding HIV elicit a differential brain response in both earlier (~200-350 ms) and later (~350-700 ms) time windows compared to those perceived as safe. This raises the question whether this event-related brain potential (ERP) response is specific to contagious life-threatening diseases or a general mechanism triggered by life-threatening but non-contagious diseases. In the present study, we recorded dense sensor EEG while participants (N = 36) evaluated photographs of unacquainted individuals for either HIV or leukemia risk. The ERP results replicated previous findings revealing earlier and later differential brain responses towards individuals perceived as high risk for HIV. However, there were no significant ERP differences for high vs. low leukemia risk. Rather than reflecting a generic response to disease, the present findings suggest that intuitive judgments of HIV risk are at least in part specific to sexually transmitted diseases.
... By experimental measures, we refer to any measures other than self-report, for example reaction times or biosignals. 2 Of the 22 AN and the 21 BN patients who participated in this study, two AN patients and one BN patient had to be excluded because of excessive noise on the electroencephalography (EEG) signals or incorrect understanding of the instructions. 3 Both primes and targets were evaluated for their prototypicality of the underlying domains of shape/weight/ eating concerns (primes) and of performance/interpersonal SE (targets) by n=15 members of the Department of Clinical Psychology, who all had considerable experience with ED. 4 EMEGS (Junghofer & Peyk, 2004) was used to generate the figures, based on the average waveforms calculated in AVG-Q. 5 An omnibus ANOVA contained parietal (P3, Pz, P4), central (C3, Cz, C4) and frontal (F3, Fz, F4) electrodes coded by the region (parietal, central, frontal) and laterality (left, midline, right) factors in addition to congruence (congruent, incongruent), SE domain (performance, interpersonal) and group (AN, BN, HC) factors to confirm the frontal location of the N400 and its modulation by group. ...
Article
Implicit self-esteem and its link to body shape and weight concerns were examined among restrained (n=32) and unrestrained eaters (n=39). Implicit self-esteem was assessed in an Implicit Association Test before and after increasing the participants' awareness of their own body shape and weight. The results showed a differential direction of change of implicit self-esteem in both groups: Whereas implicit self-esteem increased for unrestrained eaters, it decreased descriptively for restrained eaters. This suggests that restrained eating status and/or initial level of body dissatisfaction might determine whether implicit self-esteem decreases or increases as a result of an activation of body schema.
... All channels were bandpass filtered online from .1 to 48 Hz. Off-line reduction was performed using Electro-Magnetic EncaphaloGraphy Software (EMEGS) (Junghöfer and Peyk, 2004) and included low-pass filtering at 40 Hz, artifact detection, sensor interpolation, baseline correction, and conversion to an average reference (Junghöfer et al., 2000). Stimulus-synchronized epochs were extracted from 100 msec before to 1200 msec after picture onset and baseline corrected (100 msec prior to stimulus onset). ...
... All channels were bandpass filtered online from 0.1 to 100 Hz. Off-line analyses were performed using EMEGS (Junghöfer and Peyk, 2004) including low-pass filtering at 40 Hz, artefact detection, sensor interpolation, baseline correction, and conversion to an average reference (Junghöfer et al., 2000). Stimulus-synchronized epochs were extracted from 100 ms before to 800 ms after picture onset and baseline corrected (100 ms prior to stimulus onset). ...
... Data were recorded continuously applying band-pass filtering from 0.1 to 200 Hz. MEG analysis were conducted with the Matlab-based EMEGS software [17] (www.emegs.org). The method for statistical control of artifacts was used for data editing and artifact rejection [16]. ...
Article
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Recent functional magnetic resonance imaging (fMRI) and event-related brain potential (ERP) studies provide empirical support for the notion that emotional cues guide selective attention. Extending this line of research, whole head magneto-encephalogram (MEG) was measured while participants viewed in separate experimental blocks a continuous stream of either pleasant and neutral or unpleasant and neutral pictures, presented for 330 ms each. Event-related magnetic fields (ERF) were analyzed after intersubject sensor coregistration, complemented by minimum norm estimates (MNE) to explore neural generator sources. Both streams of analysis converge by demonstrating the selective emotion processing in an early (120-170 ms) and a late time interval (220-310 ms). ERF analysis revealed that the polarity of the emotion difference fields was reversed across early and late intervals suggesting distinct patterns of activation in the visual processing stream. Source analysis revealed the amplified processing of emotional pictures in visual processing areas with more pronounced occipito-parieto-temporal activation in the early time interval, and a stronger engagement of more anterior, temporal, regions in the later interval. Confirming previous ERP studies showing facilitated emotion processing, the present data suggest that MEG provides a complementary look at the spread of activation in the visual processing stream.
... The magnetoencephalogram was recorded continuously at a sampling rate of 1200 Hz and filtered on-line with a hardware low-pass filter of 300 Hz. For preprocessing and statistical analysis of MEG data, the Matlab-based (The MathWorks) EMEGS software (Junghöfer and Peyk, 2004) (freely available at http://www. emegs.org/) ...
Article
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Emotionally significant objects and events in our environment attract attention based on their motivational relevance for survival. Such kind of emotional attention is thought to lead to affect-specific amplified processing that closely resembles effects of directed attention. Although there has been extensive research on prioritized processing of visual emotional stimuli, the spatio-temporal dynamics of motivated attention mechanisms in auditory processing are less clearly understood. We investigated modulatory effects of emotional attention at early auditory processing stages using time-sensitive whole-head magnetoencephalography. A novel associative learning procedure involving multiple conditioned stimuli (CSs) per affective category was introduced to specifically test whether affect-specific modulation can proceed in a rapid and highly differentiating fashion in humans. Auditory evoked fields (AEFs) were recorded in response to 42 different ultrashort, click-like sounds before and after affective conditioning with pleasant, unpleasant, or neutral auditory scenes. As hypothesized, emotional attention affected neural click tone processing at time intervals of the P20-50m (20-50 ms) and the N1m (100-130 ms), two early AEF components sensitive to directed selective attention (Woldorff et al., 1993). Distributed source localization revealed amplified processing of tones associated with aversive or pleasant compared with neutral auditory scenes at auditory sensory, frontal and parietal cortex regions. Behavioral tests did not indicate any awareness for the contingent CS-UCS (unconditioned stimulus) relationships in the participants, suggesting affective associative learning in absence of contingency awareness. Our findings imply early and highly differentiating affect-specific modulation of auditory stimulus processing supported by neural mechanisms and circuitry comparable with those reported for directed auditory attention.
... Impedances were kept below 50 kΩ, as recommended for this type of amplifier. Off-line analyses were performed using EMEGS (Junghöfer and Peyk, 2004) and EEGLAB (Delorme and Makeig, 2004) software packages. Data editing and artifact rejection were based on a method for statistical control of artifacts specifically devised for the analysis of dense sensor EEG recordings (Junghöfer et al., 2000). ...
Article
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Field studies on HIV risk suggest that people may rely on impressions they have about the safety of their partner at the dispense of more objective risk protection strategies. In this study, ERP recordings were used to investigate the brain mechanisms that give rise to such impressions. First, in an implicit condition, participants viewed a series of photographs of unacquainted persons while performing a task that did not mention HIV risk. Second, in an explicit condition, participants estimated the HIV risk for each presented person. Dense sensor EEG was recorded during the implicit and explicit conditions. In the analysis, explicit risk ratings were used to categorize ERP data from the implicit and explicit conditions into low and high HIV risk categories. The results reveal implicit ERP differences on the basis of subsequent ratings of HIV risk. Specifically, the processing of risky individuals was associated with an early occipital negativity (240-300 ms) and a subsequent central positivity between 430 and 530 ms compared to safe. A similar ERP modulation emerged in the explicit condition for the central positivity component between 430 and 530 ms. A subsequent late positive potential component between 550 and 800 ms was specifically enhanced for risky persons in the explicit rating condition while not modulated in the implicit condition. Furthermore, ratings of HIV risk correlated substantially with ratings of trustworthiness and responsibility. Taken together, these observations provide evidence for theories of intuitive risk perception, which, in the case of HIV risk, seem to operate via appearance-based stereotypic inferences.
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Research indicates that many people do not use condoms consistently but rather rely on illusory control strategies for avoiding an infection with HIV. Preliminary evidence suggests that people form impressions of a partner’s HIV risk based on his or her physical appearance. To examine the neural correlates of such appearance-based HIV risk impressions, event-related potentials were recorded while participants viewed portraits of unacquainted persons. Participants’ explicit HIV risk ratings for each of the presented unacquainted persons were used to form categories of low and high HIV risk persons. Results showed that risky, compared to safe persons elicited distinct event-related potential (ERP) modulations. Viewing risky persons was associated with an increased positivity over right frontal regions between 180 and 240 ms. This suggests that impressions related to HIV risk occur rapidly, presumably reflecting automatic person evaluations eluding introspection. In a time window between 450 and 600 ms, risky persons elicited an increased late positive potential. Consistent with previous findings reporting augmented late positive potentials (LPP) amplitudes to affectively significant stimuli, the results support the assumption that risky faces draw more attention resources. These findings are in accordance with the ‘risk as feeling’ notion.
Article
Restrained eating is a pattern of chronic dietary restriction interspersed with episodes of disinhibited overeating. The present study investigated whether this eating pattern is related to altered electrocortical processing of appetitive food stimuli in two different motivational contexts. Restrained (n=19) and unrestrained eaters (n=21) passively viewed high-caloric food pictures, along with normative emotional pictures in a first block. In a second block, food availability was manipulated: participants were told that half of the food items should later be eaten (available food items), whereas the other half of food items was said to be unavailable. While no group differences were obtained during the first block, restrained eaters' event-related potentials (ERPs) were significantly modulated by the availability manipulation: ERPs for available food cues were significantly less positive than ERPs to unavailable food cues. Restrained eaters might down-regulate their reactivity to available food cues to maintain their dietary rules.
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Previous results suggest that early life stress (ELS) may be related to altered cortical responses to emotional stimuli. In a previous study, we found suppressed cortical responses to emotional pictures in psychiatric patients with high-ELS. The present study explored the stability of this effect across time and stimulation conditions. In addition, the relationship between ELS and current life stress was examined, and we probed whether this current life stress was related to the cortical responses. Fifteen patients with high, 16 patients with low-ELS and 15 psychiatrically healthy subjects with low-ELS participated in two sessions 8 months apart. Subjects monitored a rapid serial presentation of pleasant, neutral and unpleasant pictures during magnetoencephalographic recording. In both sessions, estimated neural activity in occipital-parietal-temporal regions between 70 and 250 ms after picture onset was smaller in patients, particularly in those with high-ELS, compared to healthy subjects. Modulation of activity by arousing (pleasant and unpleasant) compared to neutral stimuli around 200 ms post-stimulus did not differ between groups, whereas around 300 ms, patients did not show the pronounced cortical response to pleasant stimuli exhibited by healthy subjects. Results suggest that ELS and psychiatric disorder (1) diminish early perceptual processing (<200 ms) of emotional stimuli without substantially affecting activity modulation by stimulus arousal value, (2) diminish later attention allocation processes (>300 ms), and (3) are related to more recent life stress. High intraindividual correlations of activity patterns between sessions suggest lasting effects of ELS on processing modes.
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The present study used event-related brain potentials to examine deprivation effects on visual attention to food stimuli at the level of distinct processing stages. Thirty-two healthy volunteers (16 females) were tested twice 1 week apart, either after 24 h of food deprivation or after normal food intake. Participants viewed a continuous stream of food and flower images while dense sensor ERPs were recorded. As revealed by distinct ERP modulations in relatively earlier and later time windows, deprivation affected the processing of food and flower pictures. Between 300 and 360 ms, food pictures were associated with enlarged occipito-temporal negativity and centro-parietal positivity in deprived compared to satiated state. Of main interest, in a later time window (∼ 450–600 ms), deprivation increased amplitudes of the late positive potential elicited by food pictures. Conversely, flower processing varied by motivational state with decreased positive potentials in the deprived state. Minimum-Norm analyses provided further evidence that deprivation enhanced visual attention to food cues in later processing stages. From the perspective of motivated attention, hunger may induce a heightened state of attention for food stimuli in a processing stage related to stimulus recognition and focused attention.
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The present study examined the interaction of anticipatory anxiety and selective emotion processing. Toward this end, a rapid stream of pleasant, neutral, and unpleasant pictures was presented in alternating blocks of threat-of-shock or safety, which were signaled by colored picture frames. The main finding is that pleasant pictures elicited a sustained negative difference potential over occipital regions during threat as compared to safety periods. In contrast, unpleasant and neutral picture processing did not vary as a function of threat-of-shock. Furthermore, in both the safety and threat-of-shock conditions, emotional pictures elicited an enlarged early posterior negativity and late positive potential. These data show that the activation of the fear/anxiety network exerts valence-specific effects on affective picture processing. Pleasant stimuli mismatching the current state of anticipatory anxiety apparently draw more attentional resources.
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A subset of German function verbs can be used either in a full, concrete, 'heavy' ("take a computer") or in a more metaphorical, abstract or 'light' meaning ("take a shower", no actual 'taking' involved). The present magnetoencephalographic (MEG) study explored whether this subset of 'light' verbs is represented in distinct cortical processes. A random sequence of German 'heavy', 'light', and pseudo verbs was visually presented in three runs to 22 native German speakers, who performed lexical decision task on real versus pseudo verbs. Across runs, verbs were presented (a) in isolation, (b) in minimal context of a personal pronoun, and (c) 'light' verbs only in a disambiguating context sentence. Central posterior activity 95-135 ms after stimulus onset was more pronounced for 'heavy' than for 'light' uses, whether presented in isolation or in minimal context. Minimal context produced a similar heavy>light differentiation in the left visual word form area at 160-200 ms. 'Light' verbs presented in sentence context allowing only for a 'heavy reading' evoked larger left-temporal activation around 270-340 ms than the corresponding 'light reading'. Across runs, real verbs provoked more pronounced activation than pseudo verbs in left-occipital regions at 110-150 ms. Thus, 'heavy' versus 'light readings' of verbs already modulate early posterior visual evoked response even when verbs are presented in isolation. This response becomes clearer in the disambiguating contextual condition. This type of study shows for the first time that language processing is sensitive to representational differences between two readings of one and the same verb stem.
Article
In the present study, we examined stimulus-driven neuromagnetic activity in a delayed Pavlovian aversive conditioning paradigm using steady state visual evoked fields (SSVEF). Subjects showing an accelerative heart rate (HR) component to the CS+ during learning trials exhibited an increased activation in sensory and parietal cortex due to CS+ depiction in the extinction block. This was accompanied by a selective orientation response (OR) to the CS+ during extinction as indexed by HR deceleration. However, they did not show any differential cortical activation patterns during acquisition. In contrast, subjects not showing an accelerative HR component but rather unspecific HR changes during learning were characterized by greater activity in left orbito-frontal brain regions in the acquisition block but did not show differential SSVEF patterns during extinction. The results suggest that participants expressing different HR responses also differ in their stimulus-driven neuromagnetic response pattern to an aversively conditioned stimulus.
Article
Objective To compare the electrocortical processing of food pictures in participants with anorexia nervosa (n = 21), bulimia nervosa (n = 22), and healthy controls (HCs) (n = 32) by measuring the early posterior negativity, an event-related potential that reflects stimulus salience and selective attention. Methods We exposed these three groups to a rapid stream of high- and low-calorie food pictures, as well as standard emotional and neutral pictures. Results Event-related potentials in the time range of 220 milliseconds to 310 milliseconds on posterior electrodes differed between groups: patients with eating disorders showed facilitated processing of both high- and low-calorie food pictures relative to neutral pictures, whereas HC participants did so only for the high-calorie pictures. Subjective palatability of the pictures was rated highest by patients with anorexia nervosa, followed by the HC and bulimia nervosa groups. Conclusions Patients with eating disorders show a generalized attentional bias for food images, regardless of caloric value. This might explain the persistent preoccupation with food in these individuals.
Article
Altered affective processing has been proposed as mediating between early life stress (ELS) and subsequent psychopathology. The present study examined whether ELS influences affective cortical processing differently in psychiatric patients and healthy subjects. The number of stressful experiences before onset of puberty was assessed in 50 inpatients with diagnoses of Major Depressive Disorder, schizophrenia, drug addiction, or Borderline Personality Disorder and in 20 healthy comparison subjects. Subjects monitored pleasant, neutral, and unpleasant pictures during magnetoencephalographic recording. Suppression of right-posterior activity 160-210 ms after stimulus onset was associated with certain diagnoses and high ELS. Results confirmed specific contributions of ELS versus adult stress, comorbid posttraumatic stress disorder, or depression.
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