Centromedial amygdala is more relevant for phobic confrontation relative to the bed nucleus of stria terminalis in patients with spider phobia

Recent studies indicate differential involvement of the centromedial amygdala (CM) and the bed nucleus of the stria terminalis (BNST) during processing (anticipation and confrontation) of threat stimuli. Here, temporal predictability was shown to be a relevant factor. In this study, we want to investigate the relevance of these effects, which were found in healthy subjects, for anxiety disorders. Therefore, we investigated the differential involvement of CM and BNST in the anticipation and confrontation of phobic stimuli under variation of temporal predictability in spider phobia. 21 patients with spider phobia and 21 healthy controls underwent a temporally predictable/unpredictable phobic and neutral anticipation and confrontation paradigm using functional magnetic resonance imaging (fMRI) and ROI analyses. During the anticipation phase, healthy controls showed higher CM and BNST activity during the predictable compared with the unpredictable condition compared with the anxiety patients. During a confrontation phase that followed the anticipation phase, CM was more activated than BNST during the phobic compared with the neutral confrontation. While this effect was independent of threat predictability in patients, healthy controls showed higher activation in the CM compared with the BNST only during the predictable spider confrontation compared with the predictable bird confrontation. The results contribute to a better understanding of the separate roles of the CM and BNST during phobic processes. The CM was found to be more relevant to phobic confrontation in patients with spider phobia compared with the BNST.

BNST and amygdala activation to threat: Effects of temporal predictability and threat mode

Recent animal and human studies highlight the uncertainty about the onset of an aversive event as a crucial factor for the involvement of the centromedial amygdala (CM) and bed nucleus of the stria terminalis (BNST) activity. However, studies investigating temporally predictable or unpredictable threat anticipation and confrontation processes are rare. Furthermore, the few existing fMRI studies analyzing temporally predictable and unpredictable threat processes used small sample sizes or limited fMRI paradigms. Therefore, we measured functional brain activity in 109 predominantly female healthy participants during a temporally predictable-unpredictable threat paradigm, which aimed to solve limited aspects of recent studies. Results showed higher BNST activity compared to the CM during the cue indicating that the upcoming confrontation is aversive relative to the cue indicating an upcoming neutral confrontation. Both the CM and BNST showed higher activity during the confrontation with unpredictable and aversive stimuli, but the reaction to aversive confrontation relative to neutral confrontation was stronger in the CM compared to the BNST. Additional modulation analyses by NPSR1 rs324981 genotype revealed higher BNST activity relative to the CM in unpredictable anticipation relative to predictable anticipation in T-carriers compared to AA carriers. Our results indicate that during the confrontation with aversive or neutral stimuli, temporal unpredictability modulates CM and BNST activity. Further, there is a differential activity concerning threat processing, as BNST is more involved when focussing on fear-related anticipation processes and CM is more involved when focussing on threat confrontation.

Distinct phasic and sustained brain responses and connectivity of amygdala and bed nucleus of the stria terminalis during threat anticipation in panic disorder

BACKGROUND

Panic disorder (PD) patients are constantly concerned about future panic attacks and exhibit general hypersensitivity to unpredictable threat. We aimed to reveal phasic and sustained brain responses and functional connectivity of the amygdala and the bed nucleus of the stria terminalis (BNST) during threat anticipation in PD.

METHODS

Using functional magnetic resonance imaging (fMRI), we investigated 17 PD patients and 19 healthy controls (HC) during anticipation of temporally unpredictable aversive and neutral sounds. We used a phasic and sustained analysis model to disentangle temporally dissociable brain activations.

RESULTS

PD patients compared with HC showed phasic amygdala and sustained BNST responses during anticipation of aversive v. neutral stimuli. Furthermore, increased phasic activation was observed in anterior cingulate cortex (ACC), insula and prefrontal cortex (PFC). Insula and PFC also showed sustained activation. Functional connectivity analyses revealed partly distinct phasic and sustained networks.

CONCLUSIONS

We demonstrate a role for the BNST during unpredictable threat anticipation in PD and provide first evidence for dissociation between phasic amygdala and sustained BNST activation and their functional connectivity. In line with a hypersensitivity to uncertainty in PD, our results suggest time-dependent involvement of brain regions related to fear and anxiety.

DTNBP1 (dysbindin) gene variants modulate prefrontal brain function in schizophrenic patients--support for the glutamate hypothesis of schizophrenias

Dysbindin (DTNBP1) is a recently characterized protein that seems to be involved in the modulation of glutamatergic neurotransmission in the human brain, thereby influencing prefrontal cortex function and associated cognitive processes. While association, neuroanatomical and cellular studies indicate that DTNBP1 might be one of several susceptibility genes for schizophrenia, the effect of dysbindin on prefrontal brain function at an underlying neurophysiological level has not yet been explored for these patients. The NoGo-anteriorization (NGA) is a topographical event-related potential measure, which has been established as a valid neurophysiological marker of prefrontal brain function. In the present study, we investigated the influence of seven dysbindin gene variants on the NGA in a group of 44 schizophrenic patients. In line with our a priori hypothesis, one DTNBP1 polymorphism previously linked to schizophrenia (rs2619528) was found to be associated with changes in the NGA; however, the direction of this association directly contrasts with our previous findings in a healthy control sample. This differential impact of DTNBP1 gene variation on prefrontal functioning in schizophrenic patients vs. healthy controls is discussed in terms of abnormal glutamatergic baseline levels in patients suffering from schizophrenic illnesses. This is the first report on a role of DTNBP1 gene variation for prefrontal functioning at a basic neurophysiological level in schizophrenic patients. An impact on fundamental processes of cognitive response control may be one mechanism by which DTNBP1 gene variants via glutamatergic transmission contribute to the pathophysiology underlying schizophrenic illnesses.

The impact of prefrontal cortex for selective attention in a visual working memory task

In this study, a variant of the n-back task was used to investigate electrophysiological correlates of top-down processes in visual-object working memory. Event-related potentials were used to replicate results concerning an attention related modulation of neural processes and to investigate the involvement of prefrontal cortex in this modulation. 16 healthy subjects executed an n-back task with sequentially presented faces and scenes. Attention was selectively directed to only one stimulus category. We found an enhancement of the N170 amplitudes for relevant stimuli compared to irrelevant or neutral stimuli. Late frontal amplitudes were stronger positive for relevant compared to neutral stimuli indicating selective attention processes of working memory. Evidence for selective inhibition was not found.

D4 receptor gene variation modulates activation of prefrontal cortex during working memory

It has been shown that dopamine (DA) influences performance on neurocognitive tests, which are thought to rely on prefrontal activity. The purpose of this study was to explore the effects of gene polymorphisms related to DA activity, namely the D4 DA receptor (DRD4) gene exon III polymorphisms, on prefrontal cortex (PFC) activation. In this study we measured the brain oxygenation of the PFC during an n-back task with near-infrared spectroscopy (NIRS). We investigated 40 young healthy subjects, 12 of which carried the DRD4 exon III 7-repeat allele (group 7). These were compared with subjects without a 7-repeat allele (n=28, group 4). Additionally, we compared good and bad performers with respect to brain activation. As expected, we found significant increases in the concentration of oxygenated haemoglobin [O2Hb] during the 1-back and 2-back condition compared with baseline, and a corresponding significant decrease of deoxyhaemoglobin concentration. As a main result of this study we also found an interaction effect between task condition and DRD4 genotype with higher increases of [O2Hb] during the 2-back version compared with the 1-back version for the subjects of the 7-repeat allele group only. The same effect was seen as a statistical trend, when we compared bad performers with good performers. Therefore, we interpret the effects of the 7-repeat allele group of DRD4 as a sign of ineffective brain activity, perhaps even as a sign of prefrontal noise.

Event-related functional near-infrared spectroscopy (fNIRS) based on craniocerebral correlations: reproducibility of activation?

The purpose of the present study was to assess the retest reliability of cortical activation detected by event-related functional near-infrared spectroscopy (fNIRS) based on craniocerebral correlations. Isolated functional activation was evoked in the motor cortex by a periodically performed finger-tapping task. During 44-channel fNIRS recording, 12 subjects performed 30 trials of right and left index finger tapping in two sessions. The retest interval was set to 3 weeks. Simple correlations of the contrast t-values supplemented by scatterplots, channel-wise intraclass correlation coefficients (ICC), as well as reproducibility indices for the size and the location of the detected activation were calculated. The results at the group level showed sufficient single measure ICCs (up to 0.80) and excellent reproducibility of the size and the location (up to 89% were reproducible). Comparisons of the intersession group amplitudes demonstrate that the fNIRS signals were stable across time in a retest study design: the number of significant differences was less than randomly occurring false-positive activated channels if an alpha level of 5% is chosen. Effect size analyses indicated that the intersession amplitude differences are small (mean < 0.25). For deoxyhemoglobin and oxyhemoglobin distinct statistical power profiles were revealed regarding the activation vs. baseline contrast as well as the intersession amplitude differences, indicating a higher sensitivity of deoxyhemoglobin for local hemodynamic changes. The results suggest that sensorimotor activation assessed by event-related fNIRS based on craniocerebral correlations is sufficiently reproducible at the group level.

The other-race effect for face perception: an event-related potential study

It is well known that a recognition bias can be observed whenever subjects have to decide whether they have seen a person before that belongs to a different ethnical group. Although this "other-race effect" is well documented on a behavioural level, its underlying mechanisms remain unclear. One plausible explanation might be that cortical areas involved in face processing are not as effective for other-race faces due to a missing experience with individuals from other ethnical groups. This interpretation is strongly supported by a functional magnetic resonance imaging study showing decreased brain activity on other-race faces. Furthermore, two event-related potential studies revealed differences in brain activity in the first 250 ms after face presentation, but with inconsistent results. Therefore, we investigated 12 Caucasian subjects, showing them faces of Asian and Caucasian subjects in a perceptual priming paradigm and measured the event-related brain potentials. On a behavioural level we found slower reaction times to Asian faces compared to Caucasian faces in the unprimed condition, reflecting a deficit for Caucasian subjects to process other-race faces. In accordance with these behavioural data we see a significantly reduced late N250r amplitude in the unprimed condition to the Asian faces compared to the Caucasian faces. These results clearly indicate that the other-race effect was present in our sample and very specific only in the unprimed condition around 350-450 ms after stimulus onset.

Event-related visual versus blocked motor task: detection of specific cortical activation patterns with functional near-infrared spectroscopy

The purpose of this study was to investigate the regional specificity of multi-channel functional near-infrared spectroscopy (fNIRS) in the detection of cortical activation in humans. Therefore, brain activation evoked by a visual as well as a motor task was examined using 52-channel fNIRS. Analyses demonstrated an isolated activation in the occipital area during visual stimulation, whereas other regions exhibited little or no activation. Analyses of the motor task data clearly identified a differential activation pattern. The observation of an extensive cortical area by multi-channel measurement during two different tasks made it possible to examine the extent to which fNIRS measurements detect regional specific activations. We conclude that fNIRS measurements can detect regionally isolated cortical activation.

Cerebral oxygenation changes in the prefrontal cortex: Effects of age and gender

Multi-channel near-infrared spectroscopy (NIRS) is an optical method, which allows non-invasive in vivo measurements of changes in the concentration of oxygenated (O(2)Hb) and deoxygenated (HHb) hemoglobin in living brain tissue, simultaneously from multiple measurement points. In the present study, 44 young and 42 elderly subjects were investigated by means of multi-channel NIRS (optical topography) during performance of the verbal fluency task (VFT). The aim of the study was to analyze the effects of the subjects' age and gender on functional brain activation during this cognitive task. In summary, the results clearly show that the VFT activated the left and right dorsolateral prefrontal cortex (increases in O(2)Hb and more localized decreases in HHb), with an obvious left-hemispheric dominance. The elderly subjects generally exhibited less activation and no left hemispheric lateralization effect. In contrast to a previous study, we did not find a clear influence of the subjects' gender on the brain activation pattern.

Event-related functional near-infrared spectroscopy (fNIRS): Are the measurements reliable?

The purpose of the present study was to investigate the retest reliability of event-related functional near-infrared spectroscopy (fNIRS). Therefore, isolated functional activation was evoked in the occipital cortex by a periodic checkerboard stimulation. During a 52-channel fNIRS recording, 12 subjects underwent 60 trials of visual stimulation in two sessions. The retest interval was set to 3 weeks. Linear correlations of the contrast t values supplemented by scatter plots, channel-wise intraclass correlation coefficients (ICC) as well as reproducibility indices for the quantity of activated channels (RQUANTITY) and the location (ROVERLAP) of the detected activation were calculated. The results at the group level showed good reliability in terms of the single measure ICCs (up to 0.84) and excellent reproducibility quantified by RQUANTITY and ROVERLAP (up to 96% of the quantity and the location were reproducible), whereas the results at the single subjects' level were mediocre. Furthermore, the reliability assessed by single measurement ICCs improved if regarded at a cluster level.

Multi-channel near-infrared spectroscopy detects specific inferior-frontal activation during incongruent Stroop trials

Near-infrared spectroscopy (NIRS) is an optical method, which allows non-invasive in vivo measurements of changes in the concentration of oxygenated (O2Hb) and deoxygenated (HHb) hemoglobin in brain tissue. In the present study we investigated 10 healthy subjects by means of multi-channel NIRS (Optical Topography; ETG-100, Hitachi Medical Co., Japan) during performance of congruent and incongruent trials of the Stroop color word task. With a similar pattern of activation for both congruent and incongruent Stroop trials in the NIRS channels located left superior-frontally, the results for O2Hb and the total amount of hemoglobin (Hb-tot) indicate specific activation for interference trials in inferior-frontal areas of the left hemisphere. This result is in line with several neuroimaging studies (fMRI, PET) that have already investigated the frontal activation related to Stroop interference, which further supports the assumption that multi-channel NIRS is sensitive enough to detect spatially specific activation during the performance of cognitive tasks.

Near-infrared optical topography to assess activation of the parietal cortex during a visuo-spatial task

Multi-channel near-infrared spectroscopy (NIRS) is a relatively new method to investigate the brain activation, based on changes in oxygenated haemoglobin (O2Hb) and deoxygenated haemoglobin (HHb). Recently, it has been shown that NIRS seems to be able to detect even small changes in O2Hb and HHb concentration due to cognitive demands. This study aimed at investigating the changes in O2Hb and HHb concentrations of the parietal cortex during a spatial task, a modified version of the Benton Line Orientation Task [Gur, R. C., Alsop, D., Glahn, D., Petty, R., Swanson, C. L., Maldjian, J. A., et al. (2000). An fMRI study of sex differences in regional activation to a verbal and a spatial task. Brain & Language, 74(2), 157-170.]. Twenty-four subjects were measured with NIRS while they had to estimate the orientation of a given line or to name the colour of the line in the control condition. Both conditions consisted of three activation phases each lasting 30 s, with a 10 s baseline and a 20 s post resting period. For assessing the changes in O2Hb and HHb concentrations, we measured with 24 NIRS channels over the parietal cortex using the NIRS apparatus ETG-100 (Hitachi Medical Ltd.). O2Hb concentration significantly increased during the active phase compared to the baseline for both conditions, but was significantly higher in the active phase for the line orientation condition compared to the colour naming condition bilaterally parieto-occipital. For the HHb concentrations, we only found significant decreases for both conditions but no differences between the conditions. The results of our study underscore the value of multi-channel NIRS for assessing cortical activation during cognitive tasks.

Early stages (P100) of face perception in humans as measured with event-related potentials (ERPs)

According to current ERP literature, face specific activity is reflected by a negative component over the inferior occipito-temporal cortex between 140 and 180 ms after stimulus onset (N170). A recently published study (Liu et al., 2002) using magnetoencephalography (MEG) clearly indicated that a face-selective component can be observed at 100 ms (M100) which is about 70 ms earlier than reported in most previous studies. Here we report these early differences at 107 ms between the ERPs of faces and buildings over the occipito-temporal cortex using electroencephalography. To exclude contrast differences as the main factor for this P100 differences we replicated this study using pictures of faces and scrambled faces. Both studies indicated that face processing starts already at approximately 100 ms with an initial stage which can be measured not only with MEG but also with ERPs.

Reduced prefrontal response control in patients with schizophrenias: a subgroup analysis

We investigated the function of the anterior cingulate cortex (ACC) with the continuous performance test (CPT) in patients with chronic schizophrenias. We had previously shown that the NoGo anteriorisation (NGA), which consists of a more anterior center of gravity (centroid) of the event-related potentials during the inhibition of a prepared motor response, correlates with physiological activation of the ACC in healthy probands. However, in patients with schizophrenias, the event-related potentials are located more anteriorly in the Go condition and more posteriorly in the NoGo condition, which leads to a decreased NGA reflecting reduced activation of the ACC. We now extend our observations to a larger number of patients with different subgroups of chronic schizophrenias according to Leonhard's classification system. While the schizophrenic patients as a group showed only a trend towards a decreased NGA, there was a significant reduction of the NGA in patients with systematic schizophrenias but not in those with unsystematic schizophrenias. Our results show that a subclassification of "schizophrenic" patients is useful to detect differences between subgroups, which may reflect differences in pathophysiology.

Nah-Infrarot-Spektroskopie in der Psychiatrie

Near-infrared spectroscopy (NIRS) is a noninvasive optical method for in vivo measurement of regional brain tissue oxygenation. Light from the near-infrared spectrum can penetrate the skull and is mainly absorbed by oxyhaemoglobin (O(2)Hb) and desoxyhaemoglobin (HHb). From the amount of reflected near-infrared light in relation to the amount absorbed by brain tissue, regional changes in O(2)Hb and HHb concentrations can be calculated spectrophotometrically. It has been shown that NIRS is not only able to measure massive disturbances in cerebral blood circulation due to serious neurological diseases, but that it also is sensitive enough to assess task-specific patterns of activation in healthy subjects during circumscribed cognitive processes. Preliminary investigations indicate altered regional brain tissue oxygenation in psychiatric patients during cognitive activation tasks. The NIRS outmatches other functional imaging methods in that it has no side effects and is well tolerated by psychiatric patients. Furthermore, it can be applied quickly and easily. Thus, NIRS is a potential screening method in psychiatric settings, provided that robust parameters of reliable diagnostic and/or prognostic value can be developed for individual psychiatric illnesses. However, this will depend on broader application of the method combined with established neurophysiological procedures and functional imaging techniques in psychiatric research.

Bilaterally reduced frontal activation during a verbal fluency task in depressed patients as measured by near-infrared spectroscopy

The present study investigated functional changes of brain oxygenation in prefrontal brain areas of nine depressed patients and nine age- and sex-matched healthy comparison subjects by using near-infrared spectroscopy. During a verbal fluency task, the healthy subjects exhibited the typical activation pattern, with a significant increase in oxyhemoglobin and a decrease in deoxyhemoglobin, as compared to a resting baseline condition. Patients had significantly lower activation bilaterally during the cognitive task, with no significant differences in behavioral performance. The results underscore the hypothesis of a functional deficit in prefrontal cortex in depression and confirm the feasibility of near-infrared spectroscopy in measuring functional brain activation.

Prefrontal activation through task requirements of emotional induction measured with NIRS

The medial prefrontal cortex is believed to be involved in emotional experiences, but also in situations in which attention and self-monitoring is required. Therefore, it might be that the medial prefrontal cortex is not only activated by the emotional state per se, but rather through the task requirements that were used to induce emotions in the laboratory. The present study investigated the change of oxygenation in the left and right prefrontal cortex measured with near-infrared spectroscopy (NIRS) from 14 subjects during two kinds of emotional induction, which differed in the self-monitoring requirements. The task with the higher self-monitoring requirements resulted in an increased concentration of oxygenated hemoglobin (O(2)HB). This activation pattern was not observed during the emotional induction with the fewer self-monitoring requirements, although the subjective ratings indicated that both tasks induced comparable emotional states. The results indicate that task requirements should be taken into account when investigating the neural substrate of emotions.

Far field potentials from the brain stem after transcutaneous vagus nerve stimulation

Recently, the vagus nerve has gained particular interest in neuropsychiatry, as neurodegenerative diseases like Alzheimer's and Parkinson's disease are supposed to affect the brainstem nuclei of the vagus nerve early in their course. In addition, electric stimulation of the vagus nerve has therapeutic effects in otherwise therapy-refractory epilepsies and depressions. So far, no method is available to assess vagus nerve function in this context. On this background and based on the established techniques of early acoustic evoked potentials we investigated if a transcutaneous electric stimulation of the sensory auricular branch of the vagus nerve innervating parts of the outer ear is feasible in healthy subjects using this hypothesis-generated approach. We were able to record a clear, reproducible Vagus Sensory Evoked Potential (VSEP) measured as far field potential probably originating in vagus nuclei in the brainstem. Further studies are needed to test the interindividual stability and test-retest reliability of this new method before potential diagnostic and therapeutic applications might be evaluated.

Dopamine D2 (DAD2) and dopamine D3 (DAD3) receptor gene polymorphisms and treatment outcome in alcohol dependence

The dopaminergic system is critically involved in reward mechanisms mediating the reinforcing effects of alcohol. The intention of this study was to investigate the genotypic frequencies of the -141C Ins/Del polymorphism of the DAD2 receptor gene as well as the Bal I polymorphism of the DAD3 receptor and their potential association with treatment outcome in alcoholism. Therefore, individuals suffering from primary alcohol dependence were clinically and genetically characterized and followed prospectively over a period of one year after inpatient treatment. No association was found between DAD2 or DAD3 receptor gene variants and treatment outcome as reflected by abstinence/relapse after one year. Taking into account potential stratification effects, such as family history, gender, age of onset, or severity of the disease an association with DAD2 or DAD3 gene variants could neither be found. In conclusion, we found no evidence that the DAD2 or DAD3 gene variants investigated have a major influence on treatment outcome in primary alcohol dependence.

Frontal activation during a verbal-fluency task as measured by near-infrared spectroscopy

Near-infrared spectroscopy (NIRS) is an optical method which allows non-invasive in vivo measurements of concentration changes of oxygenated hemoglobin (O(2)Hb) and deoxygenated hemoglobin (HHb) in brain tissue. The present study investigated the blood oxygenation changes that were associated with the execution of the Verbal-Fluency Test (VFT) in left and right prefrontal brain areas of 14 healthy subjects by means of NIRS. During the VFT, subjects were required to pronounce as many nouns as possible beginning with the letters "A," "F," and "S." Compared to a baseline resting condition, we found a significant increase of O2Hb (left hemisphere: baseline, 1.2+/-1.1microm; VFT(letterS), 3.56+/-2.02microm; right hemisphere: baseline, 1.26+/-1.08microm; VFT(letterS), 3.67+/-2.03microm) and a significant decrease of HHb (left hemisphere: baseline, -0.21+/-0.59microm; VFT(letterS), -0.67+/-0.60microm; right hemisphere: baseline, -0.29+/-0.53microm; VFT(letterS), -0.68+/-0.44microm) during the execution of the VFT over both hemispheres. No lateralization effects were observed. The results confirm that NIRS is suitable for the measurement of blood oxygenation changes in frontal brain areas that are associated with cognitive tasks.

Electrophysiological measurements of anterior cingulate function

Based on recent findings from various areas of brain research the anterior cingulate cortex (ACC) within the prefrontal cortex is increasingly considered as a brain region activated during tasks requiring conflict-monitoring and allocation of attention. In the present study with event-related potentials (ERPs) the question has been addressed, whether the NoGo-condition of the Continuous Performance Test is associated with enough conflict-monitoring and allocation of attention in order to activate the ACC in healthy controls. Low Resolution Electromagnetic Tomography (LORETA), a new three-dimensional source localization method, revealed significantly increased brain electrical activity during the NoGo-ERP as compared to the Go-ERP with its maximum located exactly within the ACC in four independent samples of healthy subjects. These results relate the conflict-monitoring requirements associated with inhibition of a prepared motor response (NoGo-condition) to a powerful brain electrical ACC-activity. This non-invasive, easy to perform and inexpensive electrophysiological measurement, therefore, provides a new method for the assessment of ACC-function in healthy subjects.

Long-term reliability of electrophysiologic response control parameters

The execution (Go) and the inhibition (NoGo) of a motor response are basic cognitive processes that can be assessed by means of a simple neuropsychological Go-NoGo task: the Continuous Performance Test (CPT). Simultaneous electrophysiologic investigations revealed that the NoGo condition of the CPT is associated with a clearly more anterior brain electrical activity compared with the Go condition. Recently, it has been shown that this NoGo anteriorization effect during a response control paradigm can be measured quantitatively with the electrophysiologic centroid method. The objective of the current study, therefore, was to determine the long-term reliability of the topographic measures of cognitive response control (i.e., location of the Go and the NoGo centroid and the NoGo anteriorization). For this purpose, a 21-channel EEG was recorded twice from 13 healthy volunteers during their execution of a cued CPT (O-X version). The time interval between test and retest was 2.74 years (range, 2.41 to 2.97 years). Statistical analysis of the event-related Go and NoGo potentials revealed an excellent test-retest reliability, as expressed by Pearson's product moment correlation coefficients of more than 0.85 (P < or = 0.0005) and intraclass correlation coefficients of more than 0.90 (P </= 0.0005) for all three topographic measures. These results indicate that these electrophysiologic parameters present with superior long-term reliability and that they may be applied as electrophysiologic trait markers of response control mechanisms in the human brain.

Americans' health priorities: curing cancer and controlling costs

In this paper we provide a comprehensive examination of Americans' priorities within both health and health care. We find that Americans do have a clear set of priorities in each of these areas. Americans rated cancer, human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome (AIDS), and heart disease, and medical research to address these conditions, as top priorities among eighty health problems. However, they did not rank many leading causes of death very high as serious problems. On the issue of health care, problems of costs, prescription drugs, and the uninsured top the list. Americans are very concerned about emerging international infectious diseases that they believe threaten their health.

Alcohol cue-reactivity in heavy and light social drinkers as revealed by event-related potentials

An elevated cue-reactivity evoked by alcohol-related stimuli (cues) in alcohol-dependent patients has been described for different physiological variables, including electrophysiological measures, such as event-related potentials (ERPs). Cue-reactivity has, however, also been reported for social drinkers. The aim of this study is to assess the effect of the drinking behaviours of social drinkers on cue-reactivity as measured with ERPs. Forty alcohol-related and 40 neutral pictures were presented to 15 heavy and 15 light drinkers (all males). ERPs were recorded using 21 scalp electrodes. Stimuli were presented for 500 ms with an inter-stimulus interval of 2000 ms. Heavy social drinkers displayed a cue-reactivity of significantly higher amplitude at the frontal electrode location Fz, elicited by alcohol-related, as compared to neutral, pictures. This effect was not found in light social drinkers. The results indicate that the cue-reactivity previously found in alcohol-dependent patients is also present in social drinkers, and that electrophysiological cue-reactivity is associated with alcohol consumption.

Cognitive response control in writer's cramp

Disturbances of the motor and sensory system as well as an alteration of the preparation of movements have been reported to play a role in the pathogenesis of dystonias. However, it is unclear whether higher aspects of cortical - like cognitive - functions are also involved. Recently, the NoGo-anteriorization (NGA) elicited with a visual continuous performance test (CPT) during recording of a 21-channel electroencephalogram has been proposed as an electrophysiological standard-index for cognitive response control. The NGA consists of a more anterior location of the positive area of the brain electrical field associated with the inhibition (NoGo-condition) compared with that of the execution (Go-condition) of a prepared motor response in the CPT. This response control paradigm was applied in 16 patients with writer's cramp (WC) and 14 age matched healthy controls. Topographical analysis of the associated event-related potentials revealed a significant (P < 0.05) NGA effect for both patients and controls. Moreover, patients with WC showed a significantly higher global field power value (P < 0.05) in the Go-condition and a significantly higher difference-amplitude (P < 0.05) in the NoGo-condition. A source location analysis with the low resolution electromagnetic tomography (LORETA) method demonstrated a hypoactivity for the Go-condition in the parietal cortex of the right hemisphere and a hyperactivity in the NoGo-condition in the left parietal cortex in patients with WC compared with healthy controls. These results indicate an altered response control in patients with WC in widespread cortical brain areas and therefore support the hypothesis that the pathogenesis of WC is not restricted to a pure sensory-motor dysfunction.

Repeated exposure of flight phobics to flights in virtual reality

The present study examined the effects of repeated exposure of flight phobics to flights in virtual reality (VR). Flight phobics were randomly assigned either to complete one VR test flight followed by four VR exposure flights (VR group; N=15) in one lengthy session or to complete one VR test flight followed by a lengthy relaxation training session (relaxation group; N=15). All participants completed a second VR test flight at the end of the session. Fear reports and physiological fear reactions (heart rate, skin conductance level) during VR exposures were registered, and fear of flying was assessed psychometrically from 3 weeks before to 3 months after exposure. Exposure to VR flights elicited subjective and physiological fear responses in flight phobics, and these responses attenuated within and across VR flights. Fear reduction associated with repeated VR exposure was greater than fear reduction caused by relaxation training. Fear of flying improved in both treatment groups, but several outcome measures indicated greater effects in the VR treated group than in the relaxation group. These findings indicate that exposure in virtual reality may offer a new and promising approach for the treatment of fear of flying.

Electrophysiological assessment of impulsive behavior in healthy subjects

The different concepts of impulsivity cover a wide range of divergent behaviors. In clinical terms, aspects of impulsivity are both an important feature in several psychiatric conditions related to a low central serotonergic neurotransmission like aggressive behavior and suicidality, and a core symptom of frontal lobe syndromes of various etiologies. Assessment of the different forms of impulsivity so far relies on clinical observations and self-rating questionnaires. Measurements of a distinct brain function associated with impulsive behavior are not available yet, however, electrophysiological parameters of cognitive response control elicited with the execution (Go-condition) and the inhibition (NoGo-condition) of a prepared motor response within the Continuous Performance Test (CPT) might be suitable candidates. By means of a spatial analysis method the centers of gravity (centroids) of the brain electrical fields evoked with Go- and NoGo-responses can be localized and quantified. In the present study, the Go- and NoGo-centroids and the impulsivity score in Eysenck's I(7)-scale were determined in 22 healthy subjects (10 women, 12 men, mean age 42.0+/-10.1 years). Impulsivity was correlated with both, a more anterior location of the Go- (r=0.58, P<0.01) and the NoGo-centroid (r=0.53, P=0.01). These results indicate, that in healthy subjects the amount of I(7)-impulsivity is associated with differences in the prefrontal brain activation pattern during cognitive response control. However, a replication study with a larger sample and an investigation of psychiatric patients with pathological levels of impulsivity are necessary to qualify these topographical ERP-parameters of cognitive response control as valid measures of the brain electrical basis of impulsive behavior.

Stability of late event-related potentials: topographical descriptors of motor control compared with the P300 amplitude

The P300-amplitude evoked with an acoustic oddball-paradigm is considered the most stable late event-related potential (ERP). This amplitude-index has become a standard parameter in electrophysiology. Recently, a robust ERP-parameter (NoGo-anteriorization, NGA) has been introduced, which reflects spatial brain electrical changes in relation to execution and inhibition of a motor response elicited with a Continuous Performance Test (CPT). The current study refers to the stability of this new topographical ERP-parameter compared to the stability of the classical P300-amplitude. For that purpose, 12 healthy subjects were investigated with both paradigms during recording of a 21-channel EEG. Analysis of the resulting ERPs revealed a very high stability for both, topographical and amplitude index: In every single subject, the brain electrical fields were characterized by a more anterior location in the NoGo- compared to the Go-condition (=NGA) and by higher amplitudes after target compared to distractor condition. T-tests, analyses of the effect size and of the power revealed equivalent differences between the two contrasting conditions for the topographical compared to the amplitude index. These results indicate that the stability of the topographical ERP-parameters elicited with the CPT is sufficient for an electrophysiological standard-index. The possibility to elicit a robust and specific spatial brain activation with the CPT is an ideal completion to the classical P300 amplitude effect and, therefore, hopefully will be a useful expansion of the standard paradigms in electrophysiological laboratories.

Test-retest reliability of electrophysiological parameters related to cognitive motor control

Previously, the continuous performance test was demonstrated to elicit distinct electrophysiological correlates of cognitive response during execution (Go) and inhibition (NoGo) of an anticipated motor response. A robust method for topographical quantification of these brain electrical microstates has been established recently. Test reliability is crucial to allow application in the assessment of neuropsychiatric disorders. The present study evaluates the reliability of the Go and NoGo centroid locations as well as the NoGo anteriorisation (NGA) in 23 healthy individuals. Our results show supreme test-alternate retest reliabilities of Pearson's product moment correlations and intraclass correlation coefficients of r> or =0.63 (P< or =0.001) for these parameters which assert a quality well within the range reported for those of other electrophysiological standard paradigms. Go and NoGo centroid locations as well as the NGA are, therefore, reliable correlates of prefrontal motor control and may contribute to the understanding of disorders with allied impairments.

[Reliability of electrophysiological measurements of motor control]

OBJECTIVES

The aim of the study was the short term test-retest-reliability of electrophyisiological correlates of simple processes of the motor control, i.e. the execution (go) and the inhibition (no go) of a prepared motor response, evoked during the Continuous Performance Test (CPT). Our interest was centered in the reliability of the topographical P300-parameters described in previous studies, i.e. the localizations of the go and no go centroids and the no go anteriorization (NGA), which is the difference between the two centroid locations. A sufficient reliability is a basic requirement for the application of these new topographical parameters for the investigation of different psychiatric illnesses with suspected dysfunctions of prefrontal motor control, e.g. schizophrenias and affective illnesses, obsessive-compulsive disorders, personality disorders with deficits in impulse control, and in children with attention deficit hyperactivity disorder.

PATIENTS AND METHODS

We examined 23 healthy subjects who executed two versions of the CPT with an interval of 30 minutes. After averaging the obtained evoked potentials of each subject, we determined the latencies, amplitudes and positive centroids, at the moment of the peak of the Global Field Power in a P300 time window.

RESULTS

Statistical analysis revealed sufficient test-retest-reliabilities in comparison to other electrophysiological paradigms, mainly for the localizations of the go (r = 0.93; p = 10(-10)) and no go centroid (r = 0.85; p = 10(-4)), as well as for the no go anteriorization (r = 0.63; p = 10(-3)).

CONCLUSION

These results are a prerequisite for the application of these topographical parameters as measures of the prefrontal motor control in different healthy and psychiatric populations.

Event-related potentials and cue-reactivity in alcoholism

BACKGROUND

Relapse is a major problem in the treatment of addictive behaviors. Conditioning models of alcohol addiction suggest that stimuli associated with previous drug use (cues) may initiate relapse in a definite group of alcoholics. Event-related potentials (ERPs) might be useful to reveal the brain functional substrates of cue-reactivity.

METHODS

In a preliminary investigation, 11 alcohol-dependent patients who did not take part in the electrophysiological study completed a structured interview to rate 80 words as to the degree of relatedness to alcohol. Based on these results, cue-reactivity for 15 alcohol-related and 15 unrelated word cues, each repeated eight times, was investigated in 19 alcohol-dependent men (44.2 +/- 8.5 years) and 19 healthy control men (42.5 +/- 12.5 years).

RESULTS

A cue-reactivity that consisted of significantly higher amplitudes in the ERPs after alcohol-related words compared with unrelated words was found in alcohol-dependent patients, but not in controls, at the electrode location Pz [F(1,36) = 5.2,p < 0.05].

CONCLUSIONS

Consistent with the hypothesis, only alcohol-dependent patients were characterized by signs of increased cerebral activity associated with alcohol-related compared with unrelated cues. Therefore, the results support the concept of cue-reactivity in alcoholism based on a neurobiological measurement. Future investigations will show whether this cue-reactivity can be applied to assess the risk of relapse in individual alcohol-dependent patients.

Prevention of graft-versus-host disease in allogeneic bone marrow transplantation by pretreatment with 2'-deoxycoformycin

Germ-free mice were used as a model for acute graft-versus-host disease (GVHD) in allogeneic bone marrow transplantation (BMT). C3H/He recipients of DBA/2 cells showed typical symptoms of acute GVHD and died within 8 days. Incubation of the cells with 10 microM 2'-deoxycoformycin (2dCF) + 100 microM deoxyadenosine (dAdo) for 1 h inhibited all T-cell functions as well as T-cell-dependent B-cell functions, but had no effect on B-cell functions that are T-cell independent, nor on the hemopoietic stem cells (CFU-S). Recipients of allogeneic cells that had been incubated with 2dCF + dAdo for 1 h prior to inoculation showed no signs, gross or histological, of acute or chronic GVHD up to 15 months after transplantation. The recovery patterns of the blood and bone marrow were not affected by the treatment, and were similar to those of recipients of treated and untreated syngeneic cells.