Dyna Delle-Vigne

Greater sensitivity of the P300 component to bimodal stimulation in an event-related potentials oddball task

OBJECTIVE Studies that explore neurophysiological correlates of psychiatric disorders have commonly used event-related potentials during a visual or an auditory oddball task with the main results being changes in the P300 component. In the present study, a bimodal oddball design with synchronized pairs of audio-visual stimuli was used to further improve the clinical sensitivity of the P300. METHODS Two groups of healthy participants, one consisting of students displaying anxious-depressive tendencies and the other of control students, completed visual, auditory and two kinds of audio-visual oddball task (one using emotional stimuli and the other using geometrical figures and simple sounds), in which they had to detect deviant rare stimuli among more frequently presented standard stimuli as quickly as possible. Behavioral performance and P300 data were analyzed. RESULTS The subjects with anxious and depressive tendencies had lower P300 amplitudes than controls, but only in the bimodal tasks. CONCLUSIONS Although the two groups differed in their levels of anxiety and depression, only the bimodal tasks were able to identify these differences. SIGNIFICANCES These results suggest that a bimodal oddball design should be used in future studies to increase the sensitivity of P300 differences for differentiating between healthy participants and those with clinical symptoms.

Subclinical alexithymia modulates early audio-visual perceptive and attentional event-related potentials

Introduction: Previous studies have highlighted the advantage of using audio–visual oddball tasks (instead of unimodal ones) in order to electrophysiologically index subclinical behavioral differences. Since alexithymia is highly prevalent in the general population, we investigated whether the use of various bimodal tasks could elicit emotional effects in low- vs. high-alexithymic scorers. Methods: Fifty students (33 females and 17 males) were split into groups based on low and high scores on the Toronto Alexithymia Scale (TAS-20). During event-related potential (ERP) recordings, they were exposed to three kinds of audio–visual oddball tasks: neutral-AVN—(geometrical forms and bips), animal-AVA—(dog and cock with their respective shouts), or emotional-AVE—(faces and voices) stimuli. In each condition, participants were asked to quickly detect deviant events occurring amongst a train of repeated and frequent matching stimuli (e.g., push a button when a sad face–voice pair appeared amongst a train of neutral face–voice pairs). P100, N100, and P300 components were analyzed: P100 refers to visual perceptive and attentional processing, N100 to auditory ones, and the P300 relates to response-related stages, involving memory processes. Results: High-alexithymic scorers presented a particular pattern of results when processing the emotional stimulations, reflected in early ERP components by increased P100 and N100 amplitudes in the emotional oddball tasks [P100: F(2, 48) = 20,319, p < 0.001; N100: F(2, 96) = 8,807, p = 0.001] as compared to the animal or neutral ones. Indeed, regarding the P100, subjects exhibited a higher amplitude in the AVE condition (8.717 μV), which was significantly different from that observed during the AVN condition (4.382 μV, p < 0.001). For the N100, the highest amplitude was found in the AVE condition (−4.035 μV) and the lowest was observed in the AVN condition (−2.687 μV, p = 0.003). However, no effect was found on the later P300 component. Conclusions: Our findings suggest that high-alexithymic scorers require heightened early attentional resources in comparison to low scorers, particularly when confronted with emotional bimodal stimuli.

Conditional Reasoning in Schizophrenic Patients.

Conditional reasoning (if p then q) is used very frequently in everyday situations. Conditional reasoning is impaired in brain-lesion patients, psychopathy, alcoholism, and polydrug dependence. Many neurocognitive deficits have also been described in schizophrenia. We assessed conditional reasoning in 25 patients with schizophrenia, 25 depressive patients, and 25 controls, using the Wason selection task in three different domains: social contracts, precautionary rules, and descriptive rules. Control measures included depression, anxiety, and severity of schizophrenia measures as a Verbal Intelligence Scale. Patients with schizophrenia were significantly impaired on all conditional reasoning tasks compared to depressives and controls. However, the social contract and precautions tasks yielded better results than the descriptive tasks. Differences between groups disappeared for social contract but remained for precautions and descriptive tasks when verbal intelligence was used as a covariate. These results suggest that domain-specific reasoning mechanisms, proposed by evolutionary psychologists, are relatively resilient in the face of brain network disruptions that impair more general reasoning abilities. Nevertheless, patients with schizophrenia could encounter difficulties understanding precaution rules and social contracts in real-life situations resulting in unwise risk-taking and misunderstandings in the social world.

Conditional Reasoning Difficulties in Polysubstance-Dependent Patients

Polysubstance dependence has been associated with many neurocognitive impairments. The present study explored one of these deficits, namely conditional reasoning, using the Wason selection task. In healthy individuals, social contract and precautionary content improve conditional reasoning performance compared with descriptive or abstract content. Twenty-two recently detoxified polysubstance-dependent patients were compared with 22 controls matched for sex, age, and education level on their performance on the Wason selection task across problems involving social contract, precautionary, and descriptive conditional rules, controlling for depression, anxiety levels, and verbal intelligence. Conditional reasoning on descriptive and social contract rules was severely impaired in polysubstance-dependent patients. Precautionary reasoning was also impaired, but to a lesser degree than the other modalities of conditional reasoning. These results may reflect a toxic effect of chronic multiple-drug consumption on the prefrontal areas of the brain. Alternatively, conditional reasoning difficulties could be present, at least partially, before polysubstance dependence onset. This population may have difficulties properly understanding social contracts in real-life settings, suggesting a potential target for clinical intervention.

Searching for a Greater Sensitivity of Cognitive Event-Related Potentials Through a Crossmodal Procedure for a Better Clinical Use in Psychiatry

Psychiatry has never been able to satisfactorily respond to the delicate question of differential diagnosis, both in theory as well as in practice, which creates a more fundamental question: what about the discrimination between normality and pathology (e.g. Canguilhem, 1972; Duyckarts, 1964; Wakefield, 2007)? Patient’s subjectivity will add some complexity to this concern, as attempts to standardize such diagnosis tools have been made.