Use of the KSVM-based system for the definition, validation and identification of the incisional hernia recurrence risk factors.

BACKGROUND: Incisional hernia is one of the most common complications after abdominal surgery with an incidence rate of 11 to 20% post laparotomy. Many different factors can be considered as risk factors of incisional hernia recurrence. The aim of this study is to confirm and to validate the incisional hernia recurrence risk factors and to identify and to validate new ones. METHODS: In the period from July 2007 to July 2017, 154 patients were selected and subjected to incisional hernia repair. The surgical operations were conducted under general anaesthesia. Patients received antibiotic prophylaxis when indicated, according to the hospital prophylaxis scheme. Inclusion criteria of the study were single operator case studies and open laparotomy for incisional hernia repair. The statistical analysis proposed to identify and to verify the risk factors for recurrence of incisional hernia is the Support Vector Machine (SVM). The analysis was conducted verifying 34 risk factors. RESULTS: The data analysis confirmed the known correlations showed in the international literature with a greater incidence of comorbidities such as diabetes 37%, dyslipidaemia and hypercholesterolemia with a cumulative incidence of 16%; tobacco smoke - by combining categories smokers and ex-smokers - reach 46%, COPD 16% and hypertension 51%. CONCLUSIONS: The analysis of the data therefore confirmed the correlations showed in the international literature. A KSVM-based system to classify incisional hernia recurrence has been presented. The type of prosthesis and the site of its implant also play a significant role in the development of the recurrence. Sensitivity (86,25%), Specificity (87,14%), Negative Predictive Value (84,72%), Precision (88,46%), Accuracy (86,67%), and Error (13,33%) scores obtained using the proposed technique highlight the validity for the relapse's classification methodology.

The abdominal wall incisional hernia repair in cirrhotic patients.

BACKGROUND: The incidence of abdominal wall hernia in cirrhotic patients with ascites is between 20 and 40%. Controversies regarding the treatment modality and surgical timing of abdominal wall incisional hernia repair in cirrhotic patients remain. The study proposed wants to analyze the abdominal incisional hernia repair in cirrhotic patients with ascites performed in a single center to determine post-operative morbidity, mortality and complication rate. PATIENTS AND METHODS: Cirrhotic patients with abdominal incisional hernia that underwent surgical operation for abdominal wall hernia repair at the "Policlinico Paolo Giaccone" at Palermo University Hospital between January 2015 and December 2016 were identified and the data collected were retrospectively reviewed; patients' medical and surgical records were collected from charts and the surgical and ICU registries. The degree of hepatic dysfunction was classified using Child-Pugh classification. Post-operative mortality was considered up to 30-days after surgery. A follow-up period of 6 months at least was performed to evaluate hernia recurrence and complications. RESULTS: Mortality rate is of 18.5% (p 0.002). Recurrence rate (p 0.004) and seroma formation rate (p 0.001) are most frequent in urgency group. The elevated ASA score and the prediction of a complicated post-operative course is higher in urgency group (p 0.004) as higher is the in-hospital stay (p 0.001) and the ICU stay (p 0.001). CONCLUSIONS: Elective surgery for abdominal wall hernia repair in cirrhotic patients seems to be successful and associated with lower mortality/morbidity rate and recurrence rate than urgency.

Preliminary results about a novel technique of mesh positioning in the abdominal wall hernia repair.

INTRODUCTION: The surgical techniques described to approach the incisional hernia repair are various and there is not consensus about which of them to use. The Intra-Peritoneal Onlay Technique (IPOM) with classic mesh positioning is burdened by high post-operative complication rate. The study shows the preliminary results of a novel technique of open IPOM mesh positioning with "percutaneous" approach. PATIENTS AND METHODS: From January 2010 to December 2016 patients with abdominal wall incisional hernia that underwent surgical operation via open mesh technique for abdominal wall hernia repair at the "Policlinico Paolo Giaccone" at Palermo University Hospital were identified and the data collected were retrospectively reviewed; patients' medical and surgical records were collected from charts and the surgical registries. One hundred thirty-five patients with open IPOM percutaneous mesh positioning were selected. DISCUSSION AND CONCLUSIONS: The observational study proposed showed that the technique described for the abdominal wall incisional hernia repair seems to be hopeful in order to set a post-operative course not burdened by elevated rate of post-operative complications, estimated to be near 37% vs 13% reported by our series.

Deep SSI after mesh-mediated groin hernia repair: management and outcome in an Emergency Surgery Department.

AIM: Mesh-mediated groin hernia repair is considered the goldstandard procedure. It has low recurrence rate. Rarely a deep Surgical Site Infection (SSI) is seen when a synthetic prosthesis is used. CASE REPORT: We describe a rare case of bilateral deep SSI after mesh-mediated groin hernia repair. Diagnosis was performed through the physical examination and radiological exams. Microbiological samples identified a methicillin-resistant Staphylococcus aureus responsible of the infection. Target therapy was performed and re-operation performed in order to remove the infected prosthesis and to apply a biological one to create the fibrous scaffold. During follow-up time, right side recurrence was observed. Tru-cut biopsy of fascia was obtained in order to identify the responsible of the recurrence. CONCLUSION: Combination of antibiotic therapy and surgical reoperation seems to be the correct way to approach the deep SSI after mesh-mediated groin hernia repair. The use of biological mesh after synthetic removal seems to improve the final outcome.

Multiparametric evaluation of risk factors associated to seroma formation in abdominal wall surgery.

INTRODUCTION: Incisional hernia is one of the main topics in the general surgery since there is not a unanimous consensus concerning to the best surgical methodology to adopt. It seems that prosthetic surgery is the best technique, even if responsible for the development of periprosthetic seroma. The aim of this study is to assess whether the preoperative abnormalities of the bio-humoral parameters may be considered as risk factors for seroma. PATIENTS AND METHODS: From July 2016 to July 2017 at the "Policlinico Paolo Giaccone", Palermo, Department of Emergency Surgery, 56 patients included in this study, underwent laparotomic mesh repair. The inclusion criteria were: age > 18 years, incisional hernia W2R0 according to the Chevrel classification and a monoperator technique. The main variables were: sex, age, BMI, smoke, ASA score, and co-morbidities. Among the main serum-blood variables: natraemia, kalaemia, chloraemia, calcaemia, PCR, level of glucose, creatinine, albumin and proteins in the blood. The data were analyzed using SPSS software. RESULTS: Univariate analysis highlighted hypo- and hyper-natraemia, hyper-kalaemia, hypo-chloraemia, high levels of PCR, hyper-glycemia, low level of serum-blood albumin and proteins, as statistically significant variables. Multivariate analysis revealed a p<0.05 for PCR, hypo-albuminemia and total serum-blood-protein level. CONCLUSIONS: Alterations of pre-operative bio-humoral parameters could be associated to a greater risk of seroma development. A better understanding of such alterations may lead to more efficient risk stratification methods. This could be essential to better address the medical resources, reducing the post-operative complications and the outpatient controls as well as the risk associated to seroma.

[Are we able to measure depression?] / Peut-on mesurer la dépression ?

Etiologically and symptomatically, depression is a profoundly heterogeneous disorder. Symptoms may be classified as either emotional or cognitive. Fear, seeking and panic/grief primary emotional circuits are involved at variable intensities. Cognitive symptoms are mostly associated with executive functions' problems. Different symptoms may be linked with specific cerebral circuits dysfunctions. However, because of their heterogeneity, it seems difficult to measure depression with biological methods (cerebral imagery and evoked potentials), as if it were a one-dimensional phenomenon. Clinical impression remains the main evaluation tool for depressive patients. Psychometric scales may be useful to evaluate the efficacy of treatments and to strengthen relationship with the therapist. Hamilton Depression Scale, Montgomery and Asberg Depression Scale and Beck Depression Inventory are the most used ones. We recommend the last one, as it is reliable and easy to use in clinical settings.

La dépression est un trouble profondément hétérogène, tant dans ses causes que dans sa présentation clinique. Les symptômes qui la caractérisent peuvent être sommairement classés en émotionnels d'une part et cognitifs d'autre par t. Les principaux circuits émotionnels impliqués sont ceux de la peur, de la tristesse et du désir. Les perturbations cognitives sont pour leur part associées principalement à des troubles des fonctions exécutives. Les différentes catégories de symptômes renvoient à des perturbations de circuits cérébraux spécifiques, mais du fait de leur hétérogénéité, il semble difficile de pouvoir mesurer la dépression par des méthodes biologiques (imagerie cérébrale et potentiels évoqués cognitifs) comme s'il s'agissait d'un phénomène unidimensionnel. L'examen clinique reste l'outil principal d'évaluation du patient dépressif. Les échelles psychométriques sont une aide précieuse pour suivre l'évolution des résultats d'un traitement et pour renforcer l'alliance thérapeutique. Les 3 échelles les plus uti lisées sont cel les d'Hamilton, de Montgomery-Asberg et de Beck. Nous recommandons plus particulièrement cette dernière échelle en raison de sa fiabilité et de sa facilité d'utilisation en pratique clinique.

Mannheim Peritonitis Index (MPI) and elderly population: prognostic evaluation in acute secondary peritonitis.

INTRODUCTION: Acute Secondary Peritonitis due to abdominal visceral perforation is characterized by high mortality and morbidity risk. Risk stratification allows prognosis prediction to adopt the best surgical treatment and clinical care support therapy. In Western countries elderly people represent a significant percentage of population Aim. Evaluation of Mannheim Peritonitis Index (MPI) and consideration upon old people. PATIENTS AND METHODS: Retrospective study on 104 patients admitted and operated for "Acute Secondary Peritonitis due to visceral perforation". MPI was scored. In our study we want to demonstrate efficacy of MPI and the possibility to consider older age an independent prognostic factor. RESULTS: Mortality was 25.96%. Greatest sensitivity and specificity for the MPI score as a predictor of mortality was at the score of 20. MPI score of <16 had 0.15 times lower risk of mortality compared to patients with MPI score 17 - 21 and 0.61 lower than patients with MPI >22. Patients with MPI score 17-21 had 0.46 times lower risk of mortality compared to patients with MPI score >21. In the group of patients with MPI score of >20 the mortality rate was 48.5% for patients older than 80 years old and 12.1% for younger patients (p < 0.005); in the group with MPI score of < 20 mortality rate was respectively 8.4% and 1.4% (p < 0.005). DISCUSSION AND CONCLUSIONS: Data confirm the accuracy of the test. MPI score and age over 80 years old resulted independent predictors of mortality at multivariate analysis.

Abdominal wall incisional hernia repair improves respiratory function: results after 3 years of follow-up.

PURPOSE: Hernias severely impact patient quality of life (QoL), and 80% of patients require a surgical operation. Moreover, hernias are responsible for respiratory function alterations. This study aims to investigate the postoperative alterations in respiratory function after open ventral hernia repair in patients with incisional hernia. METHODS: Patients operated on at the Policlinico "Paolo Giaccone" at Palermo University Hospital between January 2015 and December 2016 were identified in a prospective database. Fifty-one patients were enrolled in the study. The respiratory outcome measures used were forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), FEV1/FVC ratio, peak expiratory flow (PEF) and PEF percentage (%PEF). The timepoints at which the parameters listed were assessed were t0, 1 week before the surgical operation; t1, 12 months later; and t2, 3 years later. RESULTS: The difference between mean preoperative and postoperative PEF was significant [t0 4.32 (4.03-7.92), t1 6.7 (4.27-8.24) with p = 0.012 and t2 6.5 (4.25-8.21) with p = 0.026]. The %PEF increased from 75% preoperatively to 87% at t1 (p = 0.009) and to 85% at t2 (p = 0.03). No differences were found in the comparison of pre- and postoperative FVC, FEV1 or FEV1/FVC ratio. CONCLUSION: The improvement in respiratory measures suggests the importance of abdominal wall restoration to recover functional activity of respiratory function.

How clinical neurophysiology may contribute to the understanding of a psychiatric disease such as schizophrenia.

INTRODUCTION: The increasing knowledge about anatomical structures and cellular processes underlying psychiatric disorders may help bridge the gap between clinical manifestations and basic physiological processes. Accordingly, important insights have been brought these last years into a main psychiatric affection, i.e. schizophrenia. MATERIAL AND METHODS: Here we reviewed and described, by comparison to healthy people, different physiological parameters - oculomotor measures, startle response, and cognitive event related potentials, which are altered in schizophrenia, in order to link these physiological parameters to dysfunctional cognitive processes and specific clinical symptoms. RESULTS: Schizophrenic patients displayed: (1) abnormalities in smooth pursuit eye movements and saccadic inhibition during antisaccade tasks that may stem from the same prefrontal "inhibitory" cortical dysfunction; (2) deficits in prepulse inhibition and facilitation suggesting disturbed attentional modulations, which seem also correlated to abnormal patterns of prefrontal activation; and (3) decreased amplitude for cognitive ERP situated all along the continuum of the information processing, suggesting that schizophrenia shows neurophysiological deficits since the level of the sensory cortex and not only disturbances involving associative cortices and limbic structures. DISCUSSION: The heterogeneity of schizophrenic disorders regarding symptomatology, course, and outcome is underlain by various pathophysiological processes that physiological parameters may help define. These alterations may be related to precise cognitive processes that are easily neurophysiologically monitored in order to create more homogeneous subgroups of schizophrenic patients.

Face processing in chronic alcoholism: a specific deficit for emotional features.

BACKGROUND: It is well established that chronic alcoholism is associated with a deficit in the decoding of emotional facial expression (EFE). Nevertheless, it is still unclear whether this deficit is specifically for emotions or due to a more general impairment in visual or facial processing. This study was designed to clarify this issue using multiple control tasks and the subtraction method. METHODS: Eighteen patients suffering from chronic alcoholism and 18 matched healthy control subjects were asked to perform several tasks evaluating (1) Basic visuo-spatial and facial identity processing; (2) Simple reaction times; (3) Complex facial features identification (namely age, emotion, gender, and race). Accuracy and reaction times were recorded. RESULTS: Alcoholic patients had a preserved performance for visuo-spatial and facial identity processing, but their performance was impaired for visuo-motor abilities and for the detection of complex facial aspects. More importantly, the subtraction method showed that alcoholism is associated with a specific EFE decoding deficit, still present when visuo-motor slowing down is controlled for. CONCLUSION: These results offer a post hoc confirmation of earlier data showing an EFE decoding deficit in alcoholism by strongly suggesting a specificity of this deficit for emotions. This may have implications for clinical situations, where emotional impairments are frequently observed among alcoholic subjects.

Visual processing of emotional expressions in mixed anxious-depressed subclinical state: an event-related potential study on a female sample.

AIMS: Controversy remains about the existence and the nature of a specific bias in emotional facial expression processing in mixed anxious-depressed state (MAD). MATERIAL AND METHODS: Event-related potentials were recorded in the following three types of groups defined by the Spielberger state and trait anxiety inventory (STAI) and the Beck depression inventory (BDI): a group of anxious participants (n=12), a group of participants with depressive and anxious tendencies (n=12), and a control group (n=12). Participants were confronted with a visual oddball task in which they had to detect, as quickly as possible, deviant faces amongst a train of standard neutral faces. Deviant stimuli changed either on identity, or on emotion (happy or sad expression). RESULTS: Anxiety facilitated emotional processing and the two anxious groups produced quicker responses than control participants; these effects were correlated with an earlier decisional wave (P3b) for anxious participants. Mixed anxious-depressed participants showed enhanced visual processing of deviant stimuli and produced higher amplitude in attentional complex (N2b/P3a), both for identity and emotional trials. P3a was also particularly increased for emotional faces in this group. CONCLUSION: Anxious state mainly influenced later decision processes (shorter latency of P3b), whereas mixed anxious-depressed state acted on earlier steps of emotional processing (enhanced N2b/P3a complex). Mixed anxious-depressed individuals seemed more reactive to any visual change, particularly emotional change, without displaying any valence bias.

Alcoholism leads to early perceptive alterations, independently of comorbid depressed state: an ERP study.

INTRODUCTION: Alcoholism is associated with a deficit in the processing of emotional facial expressions (EFE) and with a delayed P3b component, partially mediated by earlier perceptive deficits (P100, N170). Since alcohol dependence often occurs with depression, we aim at investigating whether classical event-related potentials (ERP) alterations observed in alcoholism are modulated or not by depression. METHODS: Four groups (controls; alcoholics; depressed; alcoholics-depressed) of 12 participants performed two different discrimination tasks, a gender and an emotional one. They had to decide as quickly as possible about the gender or the emotion displayed by facial stimuli during an ERP recording session (32 channels). Reaction times (RTs), P100, N100, N170 and P3b were recorded. RESULTS: At the behavioural level, control participants discriminated EFE (but not gender) more rapidly than the three other groups. At the ERP level, the differences observed on RTs for emotional task were neurophysiologically indexed by a delayed P3b component. This delay was associated with earlier ERP alterations (P100, N100, N170), but only in participants suffering from alcohol dependence, in association or not with depression. DISCUSSION: On the one hand, individuals with alcoholism, associated or not with a comorbid depression, were impaired in the processing of EFE. This deficit was neurophysiologically indexed by early perceptive (P100, N100, N170) and decisional (P3b) alterations. On the other hand, non-alcoholic patients with depression only exhibited P3b impairment. These results lead to potential implications concerning the usefulness of the ERP for the differential diagnosis in psychiatry, notably concerning the comorbidities in alcoholism.

Is the P300 deficit in alcoholism associated with early visual impairments (P100, N170)? An oddball paradigm.

OBJECTIVE: Studies exploring chronic alcoholism with event-related potentials (ERPs) have shown delayed latency and reduced amplitude of the P300, a long-lasting positive potential reflecting decisional processing. This P300 deficit in alcoholism is generally interpreted as a disturbance in central nervous system inhibition or in memory/attention. The present study aimed at identifying if this electrophysiological deficit is already present on earlier components, and advances a new hypothesis concerning the interpretation of the P300 alteration. METHODS: Patients suffering from alcoholism and matched healthy controls had to detect, in an oddball paradigm, emotional faces among a succession of neutral faces. Behavioral performance and ERP data (recorded from 32 electrodes) were analyzed. RESULTS: In line with previous studies, data showed that alcoholism led to a P300 deficit. Moreover, we observed for the first time that this deficit begins at earlier visual (P100) and face-processing (N170) stages, and we found high positive correlations between P100, N170 and P300 for amplitude and latency values, suggesting cumulative deficits on the cognitive continuum. CONCLUSIONS: We suggest that the P300 deficit observed in chronic alcoholism could be linked to earlier visuo-spatial deficits rather than being an impairment of the specific processes linked to the P300. SIGNIFICANCE: These results call for reconsidering the interpretation of P300 impairments at a fundamental and clinical level, and shows that earlier ERP components must be taken into account in future studies.

The crossmodal facilitation effect is disrupted in alcoholism: a study with emotional stimuli.

AIMS: Chronic alcoholism is classically associated with major deficits in the visual and auditory processing of emotions. However, the crossmodal (auditory-visual) processing of emotional stimuli, which occurs most frequently in everyday life, has not yet been explored. The aim of this study was to explore crossmodal processing in alcoholism, and specifically the auditory-visual facilitation effect. METHODS: Twenty patients suffering from alcoholism, and 20 matched healthy controls had to detect the emotion (anger or happiness) displayed by auditory, visual or auditory-visual stimuli. The stimuli were designed to elicit a facilitation effect (namely, faster reaction times (RTs) for crossmodal condition than for unimodal ones). RTs and performance were recorded. RESULTS: While the control subjects elicited a significant facilitation effect, alcoholic individuals did not present this effect, as no significant differences between RTs according to the modality were shown. This lack of facilitation effect is the marker of an impaired auditory-visual processing. CONCLUSIONS: Crossmodal processing of complex social stimuli (such as faces and voices) is crucial for interpersonal relations. This first evidence for a crossmodal deficit in alcoholism contribute in explaining the contrast observed between experimental results describing, up to now, mild impairments in emotional facial expression (EFE) recognition in alcoholic subjects (e.g. Oscar-Berman et al.,1990), and the many clinical observations suggesting massive problems.

Early visual components (P100, N170) are disrupted in chronic schizophrenic patients: an event-related potentials study.

INTRODUCTION: On the basis of the Positive and Negative Syndrome Scale (PANSS), fourteen schizophrenic patients and 7 normal controls were confronted with pictures from the Ekman & Friesen series in an event-related potentials study. PROCEDURE: Participants were confronted with a visual face-detection task, in which they had to detect, as quickly as possible, deviant faces amongst a train of standard stimuli (neutral faces). Deviant faces changed either on identity (different identity, neutral expression), or on emotion (same identity, happy, fearful or sad expression). RESULTS: Schizophrenics exhibited a decrease in amplitude of the face N170, recorded around 170 ms at occipito-temporal sites; this was observed as well for emotional as for identity faces, which suggests a global involvement of face processing. Moreover, this decrease of the face-N170 was positively correlated to positive, but not negative, symptoms of schizophrenia. Finally, the amplitude of P100 was also decreased, which suggests that the N170 decrement would result from a more global deficit in visual processing deficit. DISCUSSION: It is suggested that, in schizophrenics, an involvement of early visual processing might underlie the decreased amplitudes and the higher onset latencies of later P300 and N400 components.

Emotional deficit in subjects with psychopathic tendencies as assessed by the Minnesota Multiphasic Personality Inventory-2: an event-related potentials study.

On the basis of the Minnesota Multiphasic Personality Inventory-2 (MMPI-2), 20 male students were separated in low (LP) versus high (HP) subjects with psychopathic tendencies. Pictures from the Ekman and Friesen series were used in an event-related potentials study to investigate the neurophysiological correlates of the emotional deficit described in psychopathy. Subjects were confronted with a visual oddball design, in which they had to detect, as quickly as possible, deviant happy, sad or fearful faces amongst a train of standard stimuli (neutral faces). Behavioral results suggest that LP subjects are more efficient in the detection of emotional deviant faces. This emotional deficit was neurophysiologically indexed, in HP subjects, by a decreased N300 component, which is supposed to be particularly sensitive to affective features of stimuli rather than to physical characteristics. Moreover, independently of the nature of the deviant faces, the P3a component shows an earlier latency in the HP group as compared to the LP group, whereas the reversed pattern was shown for the P3b component. Implications of these results were discussed.

The perception of fearful and happy facial expression is modulated by anxiety: an event-related potential study.

Anxiety is supposed to interfere with cognitive and emotional processing and high level of trait-anxiety has been associated with an attentional bias for fearful faces, even in sub-clinical anxiety. On the basis of the Spielberger State and Trait Anxiety Inventory (STAI), twenty students were grouped as low vs. high anxious. Pictures from the Ekman and Friesen series were used in an event-related potentials study to investigate the neurophysiological correlates of the emotional processing of fear and happiness in sub-clinical anxiety. Subjects were confronted with a visual oddball design, in which they had to detect, as quickly as possible, deviant happy or fearful faces amongst a train of standard stimuli (neutral faces). Anxiety does not modify early perceptual (N100, P100, N170, VPP) or attentional (N2b) component, but later components are affected. Indeed, high anxious subjects are faster to detect deviant faces as suggested by earlier reaction times and P3b component. However, they show a reduced ability to process the emotional content of faces, this deficit being indexed by a decreased N300 component. Indeed, N300 is supposed to be particularly sensitive to affective features of stimuli rather than to physical characteristics. We propose that the earlier P3b observed in high anxious subjects could be interpreted as a way to overcome the deficient emotional appraisal by a more salient conscious processing.

Event-related potentials (ERPs) in ecstasy (MDMA) users during a visual oddball task.

Ecstasy is the common name for a drug mainly containing a substance identified as 3,4-methylenedioxymethamphetamine (MDMA). It has become popular with participants in "raves", because it enhances energy, endurance and sexual arousal, together with the widespread belief that MDMA is a safe drug [Byard, R.W., Gilbert, J., James, R., Lokan, R.J., 1998. Amphetamine derivative fatalities in South Australia. Is "ecstasy" the culprit? Am. J. Forensic Med. Pathol. 19, 261-265]. However, it is suggested that this drug causes a neurotoxicity to the serotonergic system that could lead to permanent physical and cognitive problems. In order to investigate this issue, and during an ERP recording with 32 channels, we used a visual oddball design, in which subjects (14 MDMA abusers and 14 paired normal controls) saw frequent stimuli (neutral faces) while they had to detect as quickly as possible rare stimuli with happy or fearful expression. At a behavioral level, MDMA users imply longer latencies than normal controls to detect rare stimuli. At the neurophysiological level, ERP data suggest as main result that the N200 component, which is involved in attention orienting associated to the detection of stimulus novelty (e.g. [Campanella, S., Gaspard, C., Debatisse, D., Bruyer, R., Crommelinck, M., Guerit, J.M., 2002. Discrimination of emotional facial expression in a visual oddball task: an ERP study. Biol. Psychol. 59, 171-186]), shows shorter latencies for fearful rare stimuli (as compared to happy ones), but only for normal controls. This absence of delay was interpreted as an attentional deficit due to MDMA consumption.

Task modulation of brain activity related to familiar and unfamiliar face processing: an ERP study.

In order to investigate stimulus-related and task-related electrophysiological activity relevant for face processing, event-related potentials (ERPs) from 58 electrodes at standard EEG sites were recorded while subjects performed a simple visual discrimination (control) task, in addition to various face processing tasks: recognition of previously learned faces and gender decision on familiar and unfamiliar faces. Three electrophysiological components or dipolar complex were recorded in all subjects: an occipital early component (P1, around 110 ms); a vertex positive potential (VPP; around 158 ms) which appeared to be specific to faces; and a negative central component, N2 (around 230 ms). Parametric analysis and source localization were applied to these components by means of a single-subject analysis methodology. No effect of familiarity was observed on any of these early component. While the VPP appears to be independent of the kind of processing performed, face task modulations of the early P1 and the N2 were observed, with a higher amplitude for the recognition than for the gender discrimination task. An attentional modulation of early visual areas is proposed for the first effect (P1 modulation), while the N2 seems to be related to general visual memory processing. This study strongly suggests that the VPP reflects an early visual stage of face processing in the fusiform gyrus that is strictly stimulus-related and independent of familiarity. It also shows that source localization algorithms may give reliable solutions on single subject averages for early visual components despite high inter-subject variability of the surface characteristics of ERPs.

When audition alters vision: an event-related potential study of the cross-modal interactions between faces and voices.

Ten healthy volunteers took part in this event-related potential (ERP) study aimed at examining the electrophysiological correlates of the cross-modal audio-visual interactions in an identification task. Participants were confronted either to the simultaneous presentation of previously learned faces and voices (audio-visual condition; AV), either to the separate presentation of faces (visual, V) or voices (auditive, A). As expected, an interference effect of audition on vision was observed at a behavioral level, as the bimodal condition was performed more slowly than the visual condition. At the electrophysiological level, the subtraction (AV - (A + V)) gave prominence to three distinct cerebral activities: (1) a central positive/posterior negative wave around 110 ms, (2) a central negative/posterior positive wave around 170 ms, AND (3) a central positive wave around 270 ms. These data suggest that cross-modal cerebral interactions could be independent of behavioral facilitation or interference effects. Moreover, the implication of unimodal and multisensory convergence regions in these results, as suggested by a source localization analysis, is discussed.