Using Electroencephalogram-Extracted Nonlinear Complexity and Wavelet-Extracted Power Rhythm Features during the Performance of Demanding Cognitive Tasks (Aristotle's Syllogisms) in Optimally Classifying Patients with Anorexia Nervosa.

Anorexia nervosa is associated with impaired cognitive flexibility and central coherence, i.e., the ability to provide an overview of complex information. Therefore, the aim of the present study was to evaluate EEG features elicited from patients with anorexia nervosa and healthy controls during mental tasks (valid and invalid Aristotelian syllogisms and paradoxes). Particularly, we examined the combination of the most significant syllogisms with selected features (relative power of the time-frequency domain and wavelet-estimated EEG-specific waves, Higuchi fractal dimension (HFD), and information-oriented approximate entropy (AppEn)). We found that alpha, beta, gamma, theta waves, and AppEn are the most suitable measures, which, when combined with specific syllogisms, form a powerful tool for efficiently classifying healthy subjects and patients with AN. We assessed the performance of triadic combinations of "feature-classifier-syllogism" via machine learning techniques in correctly classifying new subjects in these two groups. The following triads attain the best classifications: (a) "AppEn-invalid-ensemble BT classifier" (accuracy 83.3%), (b) "Higuchi FD-valid-linear discriminant" (accuracy 75%), (c) "alpha amplitude-valid-SVM" (accuracy 83.3%), (d) "alpha RP-paradox-ensemble BT" (accuracy 85%), (e) "beta RP-valid-ensemble" (accuracy 85%), (f) "gamma RP-valid-SVM" (accuracy 85%), and (g) "theta RP-valid-KNN" (accuracy 80%). Our findings suggest that anorexia nervosa has a specific information-processing style across reasoning tasks in the brain as measured via EEG activity. Our findings also contribute to further supporting the view that entropy-oriented, i.e., information-based features (the AppEn measure used in this study) are promising diagnostic tools (biomarkers) in clinical applications related to medical classification problems. Furthermore, the main EEG-specific frequency waves are extremely enhanced and become powerful classification tools when combined with Aristotle's syllogisms.

Unravelling brain connectivity patterns in body dysmorphic disorder during decision-making on visual illusions: A graph theoretical approach.

Body dysmorphic disorder (BDD) is characterized by an excessive preoccupation with perceived defects in physical appearance, and is associated with compulsive checking. Visual illusions are illusory or distorted subjective perceptions of visual stimuli, which are induced by specific visual cues or contexts. While previous research has investigated visual processing in BDD, the decision-making processes involved in visual illusion processing remain unknown. The current study addressed this gap by investigating the brain connectivity patterns of BDD patients during decision-making about visual illusions. Thirty-six adults - 18 BDD (9 female) and 18 healthy controls (10 female) - viewed 39 visual illusions while their EEG was recorded. For each image, participants were asked to indicate (1) whether they perceived the illusory features of the images; and (2) their degree of confidence in their response. Our results did not uncover group-level differences in susceptibility to visual illusions, supporting the idea that higher-order differences, as opposed to lower-level visual impairments, can account for the visual processing differences that have previously been reported in BDD. However, the BDD group had lower confidence ratings when they reported illusory percepts, reflecting increased feelings of doubt. At the neural level, individuals with BDD showed greater theta band connectivity while making decisions about the visual illusions, likely reflecting higher intolerance to uncertainty and thus increased performance monitoring. Finally, control participants showed increased left-to-right and front-to-back directed connectivity in the alpha band, which may suggest more efficient top-down modulation of sensory areas in control participants compared to individuals with BDD. Overall, our findings are consistent with the idea that higher-order disruptions in BDD are associated with increased performance monitoring during decision-making, which may be related to constant mental rechecking of responses.

Evaluating the Modulation of the Acoustic Startle Reflex in Children and Adolescents via Vertical EOG and EEG: Sex, Age, and Behavioral Effects.

Acoustic startle reflex (ASR) constitutes a reliable, cross-species indicator of sensorimotor and inhibitory mechanisms, showing distinct signature in cognitive aging, sex, and psychopathological characterization. ASR can be modulated by the prepulse inhibition (PPI) paradigm, which comprises the suppression of reactivity to a startling stimulus (pulse) following a weak prepulse (30- to 500-ms time difference), being widely linked to inhibitory capabilities of the sensorimotor system. If the prepulse-pulse tones are more clearly separated (500-2,000 ms), ASR amplitude is enhanced, termed as prepulse facilitation (PPF), reflecting sustained or selective attention. Our study aimed to investigate early-life sensorimotor sex/age differences using Electroencephalographic recordings to measure muscular and neural ASR in a healthy young population. Sixty-three children and adolescents aged 6.2-16.7 years (31 females) took part in the experiment. Neural ASR was assessed by two different analyses, namely, event-related potentials (ERPs) and first-derivative potentials (FDPs). As expected, PPF showed enhanced responses compared with PPI, as indicated by eyeblink, ERP and FDP measures, confirming the gating effect hypothesis. Sex-related differences were reflected in FDPs, with females showing higher ASR than males, suggesting increased levels of poststartle excitability. Intragroup age effects were evaluated via multipredictor regression models, noticing positive correlation between age versus eyeblink and ERP responses. Attention-related ERPs (N100 and P200) showed distinct patterns in PPI versus PPF, potentially indicative for alternative attentional allocation and block-out of sensory overload. Screening measures of participants' neurodevelopmental (assessed by Wechsler Intelligence Scale for Children) and behavioral (assessed by Child Behavior Checklist) markers were also associated with increased N100/P200 responses, presumably indexing synergy between perceptual consistency, personality profiling, and inhibitory performance. Conclusively, modulation of ASR by PPI and PPF is associated with biological sex and internal/external personality traits in childhood and adolescence, potentially useful to guide symptomatology and prevention of psychopathology.

Deciding on Optical Illusions: Reduced Alpha Power in Body Dysmorphic Disorder.

BACKGROUND: Body dysmorphic disorder (BDD) is a psychiatric disorder characterized by excessive preoccupation with imagined defects in appearance. Optical illusions induce illusory effects that distort the presented stimulus, thus leading to ambiguous percepts. Using electroencephalography (EEG), we investigated whether BDD is related to differentiated perception during illusory percepts. METHODS: A total of 18 BDD patients and 18 controls were presented with 39 optical illusions together with a statement testing whether or not they perceived the illusion. After a delay period, they were prompted to answer whether the statement was right/wrong and their degree of confidence in their answer. We investigated differences of BDD patients on task performance and self-reported confidence and analyzed the brain oscillations during decision-making using nonparametric cluster statistics. RESULTS: Behaviorally, the BDD group exhibited reduced confidence when responding incorrectly, potentially attributed to higher levels of doubt. Electrophysiologically, the BDD group showed significantly reduced alpha power at the fronto-central and parietal scalp areas, suggesting impaired allocation of attention. Interestingly, the lower the alpha power of the identified cluster, the higher the BDD severity, as assessed by BDD psychometrics. CONCLUSIONS: Results evidenced that alpha power during illusory processing might serve as a quantitative EEG biomarker of BDD, potentially associated with reduced inhibition of task-irrelevant areas.

Instantaneous radiated power of brain activity: application to prepulse inhibition and facilitation for body dysmorphic disorder.

BACKGROUND: Global measures of neuronal activity embrace the advantage of a univariate, holistic and unique description of brain activity, reducing the spatial dimensions of electroencephalography (EEG) analysis at the cost of lower precision in localizing effects. In this work, the instantaneous radiated power (IRP) is proposed as a new whole-brain descriptor, reflecting the cortical activity from an exclusively electromagnetic perspective. Considering that the brain consists of multiple elementary dipoles, the whole-brain IRP takes into account the radiational contribution of all cortical sources. Unlike conventional EEG analyses that evaluate a large number of scalp or source locations, IRP reflects a whole-brain, event-related measure and forces the analysis to focus on a single time-series, thus efficiently reducing the EEG spatial dimensions and multiple comparisons. RESULTS: To apply the developed methodology in real EEG data, two groups (25 controls vs 30 body dysmorphic disorder, BDD, patients) were matched for age and sex and tested in a prepulse inhibition (PPI) and facilitation (PPF) paradigm. Two global brain descriptors were extracted for between-groups and between-conditions comparison purposes, namely the global field power (GFP) and the whole-brain IRP. Results showed that IRP can replicate the expected condition differences (with PPF being greater than PPI responses), exhibiting also reduced levels in BDD compared to control group overall. There were also similar outcomes using GFP and IRP, suggesting consistency between the two measures. Finally, regression analysis showed that the PPI-related IRP (during N100 time-window) is negatively correlated with BDD psychometric scores. CONCLUSIONS: Investigating the brain activity with IRP significantly reduces the data dimensionality, giving insights about global brain synchronization and strength. We conclude that IRP can replicate the existing evidence regarding sensorimotor gating effects, revealing also group electrophysiological alterations. Finally, electrophysiological IRP responses exhibited correlations with BDD psychometrics, potentially useful as supplementary tool in BDD symptomatology.

Early auditory-evoked potentials in body dysmorphic disorder: An ERP/sLORETA study.

Body dysmorphic disorder (BDD) is characterized by excessive preoccupation with imagined or slight physical defects in appearance. BDD is associated with cognitive impairments (attention, visual processing). Our study aims to evaluate the early neural responses (N100, P200) to prepulse inhibition (PPI) and prepulse facilitation (PPF), to investigate attentional processing of BDD in the auditory domain. Fifty-five adults took part: 30 BDD patients and 25 healthy controls. We compared their brain responses to PPI and PPF by analyzing global field power (GFP), event-related potentials (ERPs) and their respective sources. BDD exhibited reduced N100 amplitudes compared to healthy controls in response to the startle tone elicited by both PPI and PPF, potentially suggesting impaired allocation of attention. Interestingly, the lower the GFP at the N100, the higher the BDD severity. Source reconstruction analysis showed reduced activation for BDD during the N100 time window in PPI. Scalp responses and source activations in PPI were decreased overall compared to PPF, confirming the gating effect of PPI. We provided evidence that the N100 may serve as an electrophysiological marker of BDD, predicting its severity. Our study demonstrated the potential of using ERPs combined with behavioural PPI and PPF protocols to advance our understanding of BDD pathophysiology.

Gender-dependent variations in optical illusions: evidence from N400 waveforms.

OBJECTIVE: The cognitive mechanisms (especially the gender-related ones) underlying optical illusion processing remain elusive. Since the N400 component of event-related potentials (ERPs) is an index of the semantic integration of information processing tasks, the present study focuses on gender-related differences in N400 waveforms elicited during the reasoning process applied to reach a valid conclusion of optical illusions engaging working memory (WM). APPROACH: Fifty-one healthy participants (28 males, age = 34.25 years ± 10.25, years of education = 16.00 years ± 1.78; and 23 females, age = 33.43 ± 7.93, years of education = 15.56 ± 1.82) were measured. The N400 ERP component was evoked by 39 optical illusions adjusted to induce WM. We compared brain activation patterns while participants maintained conclusions of the optical illusions in WM. The N400 of ERPs was recorded during the WM phase, during which participants were required to draw a logical conclusion regarding the correctness of the optical illusions. MAIN RESULTS: Analysis revealed that females compared to males exhibited significantly increased N400 amplitudes located at parietal and occipital sites, whereas males exhibited significantly higher N400 amplitudes located at frontal areas. Furthermore, females compared to males demonstrated significantly prolonged latencies of the N400 component located at right frontotemporal abductions. SIGNIFICANCE: These results suggest that coupling of optical illusions with WM engages distinct gender-related variations of brain semantic processing as reflected by the N400 ERP component. Based on the dual process account, our study gives support to the notion that women tend to employ a more deliberate and slower semantic reasoning than the men who tend to employ an automatic and fast one. Topographically, within the network sub-serving the semantic operation, the posterior brain areas responsible for sensorimotor integration-related processes elicit a greater brain activation among females while the anterior brain areas responsible for control and storage/retrieval operation elicit a greater brain activation among males.

Test-retest reliability of brain oscillations in a prepulse inhibition and facilitation paradigm: effects of gender in healthy humans.

There is a growing interest in assessing the reliability of electroencephalographic (EEG) measures in clinical and research settings. Prepulse inhibition (PPI: representing attentional modulation) and facilitation (PPF: reflecting selective attention) paradigms have been used to study inhibitory function and selective attention, respectively. However, to date, little has been known with regards to the stability of brain oscillatory activity during PPI and PPF. We investigated the stability of event-related EEG oscillations during PPI and PPF in healthy humans over two monthly sessions. Power spectral densities were analysed at traditional frequency bands (delta, alpha, beta sub-bands, and gamma). We assessed test-retest reliability by calculating intraclass correlation coefficients (ICCs, absolute agreement definition) and examined potential effects of gender. The results showed good-to-excellent reproducibility of EEG power (both in PPI and PPF) over all frequency bands (ICCs > 0.75), except for delta (ICCs < 0.75), with alpha exhibiting the highest repeatability performance. In addition, females showed reduced reliability compared to males in both PPI and PPF, possibly attributed to menstrual cycle phase across our female participants. Overall, our findings suggest that brain oscillatory activity can be test-retest reliable, while gender needs to be controlled with caution. Finally, event-related EEG oscillations during both PPI and PPF could provide a complementary tool to study psychopathology in clinical practice.

Event-related EEG oscillations in body dysmorphic disorder.

BACKGROUND: Patients with body dysmorphic disorder (BDD) exhibit differential attentional mechanisms compared to healthy subjects. The exact nature of this differentiation is unclear. To this end, EEG (electrophysiological) responses to prepulse inhibition (PPI: reflecting attentional modulation) and prepulse facilitation (PPF: indicating orienting activation) were recorded and analysed. The aim of this study was to compare the respective neural oscillations associated with PPI and PPF in BDD vs healthy controls. MATERIALS AND METHODS: Event-related EEG oscillations elicited by PPI and PPF (26 and 25 trials, respectively, randomly presented) were explored in a sample of patients with BDD (N = 30) vs healthy controls (N = 25). The Yale-Brown Obsessive-Compulsive Scale for BDD (BDD-YBOCS), the Body Dysmorphic Disorder Examination, the Dysmorphic Concern Questionnaire (DCQ) and the Brown Assessment of Belief Scale (BABS) were also administered. RESULTS: Analysis of the power spectrum in response to PPI and PPF revealed that the BDD patient group compared to healthy controls exhibited higher theta-1 oscillations (potentially indicative of disrupted thalamo-cortical activation) and reduced beta-1 oscillations (potentially indicative of reduced top-down-controlled processing during attentional orienting). CONCLUSION: These findings offer novel contributions with regards to the neural mechanisms underlying attention processes in BDD patients, and demonstrate the potential of event-related EEG oscillations as a tool to better understand body dysmorphic disorder.

Aristotle Meets Zeno: Psychophysiological Evidence.

This study, a tribute to Aristotle's 2400 years, used a juxtaposition of valid Aristotelian arguments to the paradoxes formulated by Zeno the Eleatic, in order to investigate the electrophysiological correlates of attentional and /or memory processing effects in the course of deductive reasoning. Participants undertook reasoning tasks based on visually presented arguments which were either (a) valid (Aristotelian) statements or (b) paradoxes. We compared brain activation patterns while participants maintained the premises / conclusions of either the valid statements or the paradoxes in working memory (WM). Event-related brain potentials (ERPs), specifically the P300 component of ERPs, were recorded during the WM phase, during which participants were required to draw a logical conclusion regarding the correctness of the valid syllogisms or the paradoxes. During the processing of paradoxes, results demonstrated a more positive event-related potential deflection (P300) across frontal regions, whereas processing of valid statements was associated with noticeable P300 amplitudes across parieto-occipital regions. These findings suggest that paradoxes mobilize frontal attention mechanisms, while valid deduction promotes parieto-occipital activity associated with attention and/or subsequent memory processing.

Atrioventricular nodal reentrant tachycardia associated with idiopathic ventricular tachycardia: clinical and electrophysiologic characteristics.

BACKGROUND: Case reports have described the coexistence of ventricular tachycardia (VT) and supraventricular tachycardia in the same patient. This study examines the frequency of dual atrioventricular nodal (AVN) physiology, AVN echo beats, and atrioventricular nodal reentrant tachycardia (AVNRT) in patients with VT. METHODS: Programmed atrial and ventricular stimulation was performed in 132 consecutive patients referred for electrophysiologic study of symptomatic VT. Of the 132, 99 patients had structural heart disease, and 33 patients had idiopathic ventricular tachycardia (IVT). RESULTS: Among the 33 patients with IVT, 23 had dual AVN physiology. Compared with patients with structural heart disease undergoing VT ablation, dual AVN pathways (70% vs 27%, P < .0001), dual AVN pathways with echo beats (24% vs 8%, P = 0.03), and AVNRT (21% vs 1%, P = .0002) were more common in patients with IVT. CONCLUSION: Dual AVN physiology and AVNRT appear to be associated with IVT. This finding suggests that patients with IVT should undergo a complete electrophysiologic evaluation, and the diagnosis of coexistent AVNRT should be considered in this population.

Standard right atrial ablation is effective for atrioventricular nodal reentry with earliest activation in the coronary sinus.

INTRODUCTION: Reports suggest that coronary sinus (CS) or left atrial ablations may be necessary for treatment of AV nodal reentrant tachycardia (AVNRT) with earliest retrograde atrial activation in the CS. We assessed the efficacy of standard right atrial catheter ablation approaches in these tachycardias and determined the incidence of earliest activation in the CS in AVNRT. METHODS AND RESULTS: We retrospectively evaluated intracardiac recordings from 225 consecutive patients who underwent electrophysiologic studies and radiofrequency (RF) ablation for AVNRT in two institutions. Atrial activation during AVNRT was evaluated using multiple catheters according to standard protocol used in our laboratories. RF ablations in the triangle of Koch were performed in all patients. Eighteen of 225 patients (8%) had earliest activation in one of the CS poles. The demographics and AVNRT characteristics of these 18 patients were similar to those of the other 207 patients who did not have CS as earliest activation site and included both typical and atypical AVNRT. Following RF ablation, none of the 18 patients had inducible AVNRT. CONCLUSION: Successful RF ablation can be performed at standard sites in the triangle of Koch regardless of earliest site of atrial activation. The incidence of CS as earliest retrograde atrial activation site in AVNRT is 8%.

Variable electrocardiographic characteristics of isthmus-dependent atrial flutter.

OBJECTIVES: The purpose of this study was to characterize variations in flutter-wave (F-wave) morphology among patients with clockwise isthmus-dependent (CWID) and counterclockwise isthmus-dependent (CCWID) right atrial flutter (AFL) and to attempt to correlate F-wave morphology with echocardiographic data and clinical patient characteristics. BACKGROUND: Variations in F-wave morphology on surface electrocardiogram (ECG) during CCWID and CWID flutter have been reported but never systematically characterized. METHODS: Over a four-year period, 139 patients with AFL on ECG underwent electrophysiologic study and echocardiography at our institution. Electrocardiographic data, intracardiac recordings, echocardiographic data, and patient characteristics were reviewed retrospectively. RESULTS: Of 156 AFLs evaluated, 130 were CCWID, 26 were CWID. Three types of CCWID flutter were observed: type 1 had purely negative F-waves inferiorly, types 2 and 3 had F-waves inferiorly with small (type 2) or broad (type 3) positive terminal deflections; CCWID flutter types 2 and 3 were associated with higher incidence of left atrial (LA) enlargement, heart disease, and atrial fibrillation (Afib) than type 1. Two types of CWID flutter were observed: type 1 had notched positive F-waves with a distinct isoelectric segment inferiorly. Type 2 had broader F-waves inferiorly with positive and negative components and a short isoelectric segment. CONCLUSIONS: Variable ECG patterns for CCWID and CWID AFL exist. A positive component of the F-wave in the inferior leads during CCWID flutter is associated with an increased likelihood of heart disease, Afib, and LA enlargement.