Semantic Ambiguity Resolution in Patients With Bipolar Disorder-An Event-Related Potential Study.

Deficits in inhibitory function are assumed to underlie psychopathology in bipolar disorder (BD), especially in states of mania. A subdomain of inhibition, semantic inhibition (SI), referring to the suppression of irrelevant word meanings, may underlie formal thought disorder, such as flights of ideas. In the present study, we investigated SI in patients with BD during semantic ambiguity resolution using behavioral and event-related potential (ERP) measures. We presented 14 patients with BD with current manic, hypomanic, or mixed clinical states and 28 healthy controls sequentially with word triplets containing either a homonym (e.g., "organ") or a comparable unambiguous word (e.g., "piano"). Participants were instructed to make a decision whether or not the target word was related to the meaning field of the first two words. The inappropriate homonym meaning had to be inhibited to correctly perform the target decision. In addition to reaction times (RT) and error rates (ER), the N400 ERP component to the target, an electrophysiological index of semantic processing, was analyzed as measure of the amount of SI that had taken place. Analyses of the behavioral data revealed that BD patients exhibited an overall worse performance in terms of RT and ER. In the ERP data, we found differences in N400 amplitude to ambiguous and unambiguous conditions over the right hemisphere in patients with BD depending on target congruence: In incongruent trials, N400 amplitude was smaller in ambiguous than in unambiguous words. In congruent trials, in contrast, N400 amplitude was larger in ambiguous than in unambiguous words. Such ERP differences between ambiguous and unambiguous words were absent in controls. We conclude that N400 amplitude differences in the ambiguous and unambiguous conditions of the BD group may reflect insufficient suppression of irrelevant homonym meanings in the right hemisphere. Disturbed SI processes might contribute to formal thought disorder in BD.

The modulating effect of personality traits on neural error monitoring: evidence from event-related FMRI.

The present study investigated the association between traits of the Five Factor Model of Personality (Neuroticism, Extraversion, Openness for Experiences, Agreeableness, and Conscientiousness) and neural correlates of error monitoring obtained from a combined Eriksen-Flanker-Go/NoGo task during event-related functional magnetic resonance imaging in 27 healthy subjects. Individual expressions of personality traits were measured using the NEO-PI-R questionnaire. Conscientiousness correlated positively with error signaling in the left inferior frontal gyrus and adjacent anterior insula (IFG/aI). A second strong positive correlation was observed in the anterior cingulate gyrus (ACC). Neuroticism was negatively correlated with error signaling in the inferior frontal cortex possibly reflecting the negative inter-correlation between both scales observed on the behavioral level. Under present statistical thresholds no significant results were obtained for remaining scales. Aligning the personality trait of Conscientiousness with task accomplishment striving behavior the correlation in the left IFG/aI possibly reflects an inter-individually different involvement whenever task-set related memory representations are violated by the occurrence of errors. The strong correlations in the ACC may indicate that more conscientious subjects were stronger affected by these violations of a given task-set expressed by individually different, negatively valenced signals conveyed by the ACC upon occurrence of an error. Present results illustrate that for predicting individual responses to errors underlying personality traits should be taken into account and also lend external validity to the personality trait approach suggesting that personality constructs do reflect more than mere descriptive taxonomies.

Hallucinogen-persisting perception disorder.

A 33-year-old female patient developed a hallucinogen-persisting perception disorder (HPPD) after lysergic acid diethylamide (LSD) abuse for a year at the age of 18. Specifically, she reported after images, perception of movement in her peripheral visual fields, blurring of small patterns, halo effects, and macro- and micropsia. Previous treatment with antidepressants and risperidone failed to ameliorate these symptoms. Upon commencing drug therapy with lamotrigine, these complex visual disturbances receded almost completely. Based on its hypothesized neuroprotective and mood-stabilizing effects, the antiepileptic lamotrigine may offer a promising new approach in the treatment of HPPD.

Physical fitness, but not acute exercise modulates event-related potential indices for executive control in healthy adolescents.

Physical activity and aerobic exercise in particular, promotes health and effective cognitive functioning. To elucidate mechanisms underlying the beneficial effects of physical fitness and acute exercise, behavioral and electrophysiological indices of task preparation and response inhibition as a part of executive functions were assessed in a modified version of an Eriksen flanker task subsequent to an acute bout of aerobic exercise and a period of rest, respectively. 35 higher- and lower-fit adolescents between 13 and 14 years of age participated in a controlled cross-over study design. Results indicate that higher-fit individuals show significantly greater CNV amplitudes, reflecting enhanced task preparation processes, as well as decreased amplitudes in N2, indexing more efficient executive control processes. P3 amplitudes associated with the allocation of attentional and memory control neither showed influences of physical fitness nor the acute bout of exercise. Furthermore, acute aerobic exercise was not related to any of the dependent measures. The current findings suggest that physical fitness, but not an acute bout of aerobic exercise enhances cognitive processing by increasing attentional allocation to stimulus encoding during task preparation.

Neural correlates of attachment trauma in borderline personality disorder: a functional magnetic resonance imaging study.

Functional imaging studies have shown that individuals with borderline personality disorder (BPD) display prefrontal and amygdala dysfunction while viewing or listening to emotional or traumatic stimuli. The study examined for the first time the functional neuroanatomy of attachment trauma in BPD patients using functional magnetic resonance imaging (fMRI) during the telling of individual stories. A group of 11 female BPD patients and 17 healthy female controls, matched for age and education, told stories in response to a validated set of seven attachment pictures while being scanned. Group differences in narrative and neural responses to "monadic" pictures (characters facing attachment threats alone) and "dyadic" pictures (interaction between characters in an attachment context) were analyzed. Behavioral narrative data showed that monadic pictures were significantly more traumatic for BPD patients than for controls. As hypothesized BPD patients showed significantly more anterior midcingulate cortex activation in response to monadic pictures than controls. In response to dyadic pictures patients showed more activation of the right superior temporal sulcus and less activation of the right parahippocampal gyrus compared to controls. Our results suggest evidence for potential neural mechanisms of attachment trauma underlying interpersonal symptoms of BPD, i.e. fearful and painful intolerance of aloneness, hypersensitivity to social environment, and reduced positive memories of dyadic interactions.

Impulsiveness and ERP components in a Go/Nogo task.

Impulsiveness has been linked to fast guesses and premature responses in reaction time tasks like the Eriksen flanker task or the Go/Nogo task. In the present study, healthy subjects without history of DSM-IV Axis I or II psychopathology were examined. Impulsiveness was determined by calculating individual reaction times (as a function of general response speed) in order to split the entire group (n = 26) in a subgroup with a more controlled response style (low impulsiveness [LI] group; n = 13) and a subgroup with a more impulsive response style (high impulsiveness [HI] group; n = 13). Subjects performed a Go/Nogo task while a multi-channel EEG was recorded. Two event-related potentials (ERP) were of special interest: the Nogo-N2 and -P3 component. HI subjects had significantly reduced (less positive) Nogo-P3 amplitudes compared to LI subjects whereas groups did not differ with regard to the Nogo-N2. These results corroborate previous findings of reduced Nogo-P3 amplitudes in samples with enhanced levels of impulsiveness. Moreover, present data suggest that there is a broader range of impulsiveness even in healthy subjects which might mask or pronounce between-group differences in clinical studies. Therefore, different levels of impulsiveness in control groups should be carefully taken into account in further ERP studies.

Electrophysiological evidence for reduced inhibitory control in depressed patients in partial remission: a Go/Nogo study.

Major depressive disorder (MDD) can be characterized by a wide-ranging profile of cognitive deficits including attention, memory, and executive functions which is possibly due to reduced volumes and a hypometabolism of the anterior cingulate cortex, orbitofrontal, and dorsolateral prefrontal cortex. We examined 21 patients with MDD in partial remission and 21 age-, sex-, and education matched healthy controls using event-related potentials (ERPs). Participants performed a hybrid flanker Go/Nogo task while multichannel EEG was recorded. Two ERP components were of interest which repeatedly have been linked to response inhibition: the Nogo-N2 and the Nogo-P3 which can be observed in Nogo trials of a Go/Nogo task. MDD patients showed a specifically reduced Nogo-P3 while the Nogo-N2 and the P3b in Go trials were unaffected. These results provide further evidence of impaired response monitoring and control processes in patients with MDD.

Measuring attachment representation in an FMRI environment: a pilot study.

This exploratory study is the first to examine the neural correlates of attachment status in adults. The study examined the feasibility of assessing attachment narratives in the functional magnetic resonance imaging (fMRI) environment by challenging subjects to tell attachment stories to specific attachment pictures from the Adult Attachment Projective (AAP) while being scanned. We investigated theoretically derived hypotheses regarding predicted differences in the brain activation patterns of individuals whose attachment status was organized (resolved) versus disorganized (unresolved) with respect to attachment trauma (e.g., as associated with loss through death, abuse, threat of abandonment). Adult attachment was assessed using the AAP, a new representational attachment measure that we thought might be suitable for use in the fMRI environment. This measure was used to obtain a preliminary picture of the neural processes associated with the activation of attachment in 11 healthy female adults. Results are reported from a second-level analysis (p < 0.001 uncorrected) and confirm that the AAP is a feasible measure for use in a neuroimaging environment. Cerebral activation during continuous speech yielded results consistent with the literature. Brain activation was demonstrated in expected visual and semantic brain regions. Furthermore, we found that the rate of articulation was positively correlated with activation in the right superior temporal gyrus. The results of theoretically derived attachment hypotheses showed no differences at the chosen level of significance when comparing the 'all attachment pictures' effect between both groups (resolved vs. unresolved). More interestingly, we found a significant interaction effect between the sequence of pictures and attachment category. Only the unresolved participants showed increasing activation of medial temporal regions, including the amygdala and the hippocampus, in the course of the AAP task. This pattern was demonstrated especially at the end of the AAP task where the pictures are drawn to portray traumatic situations. We interpret these results as confirming our hypothesis, linking unresolved attachment to emotional dysregulation of the attachment system. These results are discussed in relation to assessing attachment in an fMRI environment and future research in this area.

Error processing in major depressive disorder: evidence from event-related potentials.

In a previous study we showed that errors following errors activate a strategic (prefrontal) mechanism. In an error trial (trial n) following an erroneous previous trial (trial n - 1) healthy control subjects were found to have enlarged (more negative) amplitudes of the error related negativity (ERN)/error negativity (Ne), an electrophysiological correlate of response monitoring, in response to a negative feedback signal. Contrary to that, patients with major depressive disorder showed smaller (less negative) ERN/Ne amplitudes. It has been discussed controversially whether errors of choice (e.g., pressing an incorrect response button in an Eriksen flanker task) and errors of commission (e.g., pressing a button when one is not supposed to in a Go/Nogo task) are related to different ERN/Ne mechanisms. In the present study, we examined whether our previous result only holds for errors of choice in an Eriksen flankers task or extends to errors of commission in a Go/Nogo task, as well. Ten patients with DSM-IV major depressive disorder and 10 matched controls participated in a Go/Nogo task with performance feedback which signaled monetary reward. Patients with major depressive disorder again showed a less negative ERN/Ne amplitude in error trials following error trials. This result might reflect impaired response monitoring processes in major depressive disorder resulting from an impaired activation of a central reward pathway and/or a deficit in strategic reasoning.

Electrophysiological correlates of error processing in borderline personality disorder.

The electrophysiological correlates of error processing were investigated in patients with borderline personality disorder (BPD) using event-related potentials (ERP). Twelve patients with BPD and 12 healthy controls were additionally rated with the Barratt impulsiveness scale (BIS-10). Participants performed a Go/Nogo task while a 64 channel EEG was recorded. Three ERP components were of special interest: error-related negativity (ERN)/error negativity (Ne), early error positivity (early Pe) reflecting automatic error processing, and the late Pe component which is thought to mirror the awareness of erroneous responses. We found smaller amplitudes of the ERN/Ne in patients with BPD compared to controls. Moreover, significant correlations with the BIS-10 non-planning sub-score could be demonstrated for both the entire group and the patient group. No between-group differences were observed for the early and late Pe components. ERP measures appear to be a suitable tool to study clinical time courses in BPD.

Error processing and impulsiveness in normals: evidence from event-related potentials.

Electrophysiological correlates of impulsiveness were investigated in thirty-two healthy subjects using event-related potentials (ERP). Impulsiveness was determined by calculating individual reaction times (as a function of general response speed) in order to split the entire group into two subgroups with a more controlled (n = 16) and less controlled (n = 16) response style. Participants performed a Go/Nogo task while a 64 channel EEG was recorded. Artifact-free EEG segments were used to compute ERPs on correct Go trials and incorrect Nogo trials, separately. Three ERP components were of special interest: the error-related negativity (ERN)/error negativity (Ne) and the "early" error positivity (Pe) reflecting automatic error processing and the "late" error positivity (Pe) which is thought to mirror the awareness of erroneous responses. Subjects with higher impulsiveness showed smaller amplitudes than subjects with lower impulsiveness for the ERN/Ne component and the "early" Pe component. With regard to the "late" Pe groups did not differ. Hence, ERP measures appear suitable for detailed analyses of impulsiveness in healthy participants. Moreover, present results argue for the necessity of careful control of impulsiveness when including normal comparison groups in the context of clinical studies.

Anterior limbic alpha-like activity: a low resolution electromagnetic tomography study with lorazepam challenge.

OBJECTIVE: To verify findings of an independently regulated anterior limbic alpha band source. METHODS: In a randomised cross-over study, the spontaneous EEG was recorded in nine healthy subjects after i.v. lorazepam or placebo. Intracerebral current densities within classical frequency bands were estimated with low resolution electromagnetic tomography [LORETA] and compared between groups with t-statistical parametric mapping [SPM[t]]. A region-of-interest [ROI] based method was used to compare frontal and occipital alpha band activity changes. RESULTS: Irrespective of treatment group, local maxima of alpha band power were localised both in the occipital lobe, Brodman area [BA] 18, and in the anterior cingulate cortex [ACC], BA 32. Statistical parametric mapping showed reduced parieto-occipital, but unaltered frontal alpha band power after lorazepam. This result was confirmed by ROI-based comparison of BA 18 and BA 32. CONCLUSIONS: There was an anterior limbic maximum of alpha band activity which, unlike occipital alpha, was not suppressed by lorazepam. SIGNIFICANCE: The well-known anterior alpha band components may originate from a narrowly circumscribed source, located in the ACC. Frontal and occipital alpha band activities appear to be independently regulated.

The effect of erroneous responses on response monitoring in patients with major depressive disorder: a study with event-related potentials.

Perceived failure is reported to have detrimental effects on subsequent performance in patients with major depressive disorder. We investigated the error-related negativity (ERN)/error negativity (Ne), an electrophysiological correlate of response monitoring, using a 64-channel EEG. Sixteen patients with DSM-IV major depressive disorder and 16 matched controls participated in an Eriksen flanker task with continuous performance feedback that signaled monetary reward. Compared to controls, patients with major depressive disorder showed a less negative ERN/Ne in error trials following error trials. This result might reflect impaired response monitoring processes in major depressive disorder resulting from an underactivity in a central reward pathway and/or a deficit in strategic reasoning.

Semantic and syntactic processes during sentence comprehension in patients with schizophrenia: evidence from event-related potentials.

Language and thought disorders are core symptoms in schizophrenia. We therefore studied language comprehension processes in patients with schizophrenia and control subjects during a sentence processing paradigm using event-related potentials (ERPs). In the ERP, assignment of syntactic structure to a string of words is reflected by an early left anterior negativity (ELAN) at about 80 ms after stimulus onset. Integration of syntactic and semantic information into a coherent representation is indexed by a positive potential at 600 ms (P600). Amplitudes of the ELAN and the P600 components are higher for grammatically incorrect sentences. Semantic processes are associated with a negative deflection peaking at 400 ms (N400). N400 amplitude is higher in semantically incongruent sentences. Nineteen patients with DSM IV schizophrenia and 19 healthy controls were presented with correct, semantically incorrect (semantic mismatch) and grammatically incorrect sentences (syntactic mismatch). Syntactic mismatch elicited an ELAN component in both subject groups. However, only controls but not patients with schizophrenia exhibited a P600 syntactic mismatch effect. Semantic mismatch was associated with a larger N400 potential which did not differ between groups. These results suggest that patients with schizophrenia are not impaired in syntactic structure assignment as reflected by the ELAN, but show deficits in semantic-syntactic integration processes underlying the P600.

Human anterior cingulate cortex is activated by negative feedback: evidence from event-related potentials in a guessing task.

It has been controversially discussed whether the error-related negativity (ERN) or error negativity (N(e)), an electrophysiological index of anterior cingulate activation, reflects response conflict or response evaluation subserving error monitoring processes. We investigated event-related potentials (ERPs) in a guessing task which did not induce response conflict. Subjects had to guess which of the four aces of a French card play would be presented next and received feedback at random. We observed a negative ERP deflection in trials following negative feedback which was identified as ERN/N(e). Dipole analysis of scalp potentials indicated sources in the anterior cingulate and left inferior prefrontal cortex. The observation of the ERN/N(e) following negative feedback during guessing suggests that this ERP component mirrors response evaluation processes comparing expected and actual response outcome rather than response conflict.