Early Visually Evoked Electrophysiological Responses Over the Human Brain (P1, N170) Show Stable Patterns of Face-Sensitivity from 4 years to Adulthood

Whether the development of face recognition abilities truly reflects changes in how faces, specifically, are perceived, or rather can be attributed to more general perceptual or cognitive development, is debated. Event-related potential (ERP) recordings on the scalp offer promise for this issue because they allow brain responses to complex visual stimuli to be relatively well isolated from other sensory, cognitive and motor processes. ERP studies in 5- to 16-year-old children report large age-related changes in amplitude, latency (decreases) and topographical distribution of the early visual components, the P1 and the occipito-temporal N170. To test the face specificity of these effects, we recorded high-density ERPs to pictures of faces, cars, and their phase-scrambled versions from 72 children between the ages of 4 and 17, and a group of adults. We found that none of the previously reported age-dependent changes in amplitude, latency or topography of the P1 or N170 were specific to faces. Most importantly, when we controlled for age-related variations of the P1, the N170 appeared remarkably similar in amplitude and topography across development, with much smaller age-related decreases in latencies than previously reported. At all ages the N170 showed equivalent face-sensitivity: it had the same topography and right hemisphere dominance, it was absent for meaningless (scrambled) stimuli, and larger and earlier for faces than cars. The data also illustrate the large amount of inter-individual and inter-trial variance in young children's data, which causes the N170 to merge with a later component, the N250, in grand-averaged data. Based on our observations, we suggest that the previously reported “bi-fid” N170 of young children is in fact the N250. Overall, our data indicate that the electrophysiological markers of face-sensitive perceptual processes are present from 4 years of age and do not appear to change throughout development

Are Pyogenic Liver Abscesses Still a Surgical Concern? A Western Experience

Backgrounds. Pyogenic liver abscess is a rare disease whose management has shifted toward greater use of percutaneous drainage. Surgery still plays a role in treatment, but its indications are not clear. Method. We conducted a retrospective study of pyogenic abscess cases admitted to our university hospital between 1999 and 2010 and assessed the factors potentially associated with surgical treatment versus medical treatment alone. Results. In total, 103 liver abscess patients were treated at our center. The mortality was 9%. The main symptoms were fever and abdominal pain. All of the patients had CRP > 6 g/dL. Sixty-nine patients had a unique abscess. Seventeen patients were treated with antibiotics alone and 57 with percutaneous drainage and antibiotics. Twenty-seven patients who were treated with percutaneous techniques required surgery, and 29 patients initially received it. Eventually, 43 patients underwent abscess surgery. The factors associated with failed medical treatment were gas-forming abscess (P = 0.006) and septic shock at the initial presentation (P = 0.008). Conclusion. Medical and percutaneous treatment constitute the standard management of liver abscess cases. Surgery remains necessary after failure of the initial treatment but should also be considered as an early intervention for cases presenting with gas-forming abscesses and septic shock and when treatment of the underlying cause is immediately required

Late relapse after hematopoietic stem cell transplantation for acute leukemia: a retrospective study by SFGM-TC.

peer reviewedLate relapse (LR) after allogeneic hematopoietic stem cell transplantation (AHSCT) for acute leukemia is a rare event (nearly 4.5%) and raises the questions of prognosis and outcome after salvage therapy. We performed a retrospective multicentric study between January 1, 2010, and December 31, 2016, using data from the French national retrospective register ProMISe provided by the SFGM-TC (French Society for Bone Marrow Transplantation and Cellular Therapy). We included patients presenting with LR, defined as a relapse occurring at least 2 years after AHSCT. We used the Cox model to identify prognosis factors associated with LR. During the study period, a total of 7582 AHSCTs were performed in 29 centers, and 33.8% of patients relapsed. Among them, 319 (12.4%) were considered to have LR, representing an incidence of 4.2% for the entire cohort. The full dataset was available for 290 patients, including 250 (86.2%) with acute myeloid leukemia and 40 (13.8%) with acute lymphoid leukemia. The median interval from AHSCT to LR was 38.2 months (interquartile range [IQR], 29.2 to 49.7 months), and 27.2% of the patients had extramedullary involvement at LR (17.2% exclusively and 10% associated with medullary involvement). One-third of the patients had persistent full donor chimerism at LR. Median overall survival (OS) after LR was 19.9 months (IQR, 5.6 to 46.4 months). The most common salvage therapy was induction regimen (55.5%), with complete remission (CR) obtained in 50.7% of cases. Ninety-four patients (38.5%) underwent a second AHSCT, with a median OS of 20.4 months (IQR, 7.1 to 49.1 months). Nonrelapse mortality after second AHSCT was 18.2%. The Cox model identified the following factors as associated with delay of LR: disease status not in first CR at first HSCT (odds ratio [OR], 1.31; 95% confidence interval [CI], 1.04 to 1.64; P = .02) and the use of post-transplantation cyclophosphamide (OR, 2.23; 95% CI, 1.21 to 4.14; P = .01). Chronic GVHD appeared to be a protective factor (OR, .64; 95% CI, .42 to .96; P = .04). The prognosis of LR is better than in early relapse, with a median OS after LR of 19.9 months. Salvage therapy associated with a second AHSCT improves outcome and is feasible, without creating excess toxicity

Décours temporel de la perception visuelle des visages : de la catégorisation faciale à l'encodage d'une représentation individuelle

Etude de la dynamique temporelle de la catégorisation faciale depuis la détection d'un visage dans le champ visuel jusqu'a l'encodage d'une représentation individuelle du visage. Investigation de cette dynamique temporelle via l'électrophysiologie chez le sujet humain (potentiels évoqués). / Temporal dynamics of face visual categorization : an electrophysiological (event-related potentials) approach(PSY 3) -- UCL, 200

The time course of visual competition to the presentation of centrally fixated faces

A recent event-related potential (ERP) study showed that the occipitotemporal component N170 recorded to a face stimulus appearing in the peripheral visual field is strongly reduced when subjects are concurrently fixating another face stimulus. This suggests that concurrently presented face stimuli compete for neural representation in the occipitotemporal cortex between 100 and 200 ms following stimulus onset. We tested whether this competition can be observed for a foveally presented face stimulus appearing next to either two peripheral face pictures or two peripheral control stimuli. The N170 in response to the fixated central face stimulus was substantially reduced (approximately 20% of signal) when it was presented next to peripheral face stimuli. The response suppression was smaller in magnitude than in a previous study where the competing stimulus was fixated and the target stimulus appeared in the periphery. Besides providing a better control for attentional and eye movement confounds, the concurrent stimulation paradigm for fixated face stimuli in ERPs offers a powerful tool to investigate the time course and the nature of the interactions between face and nonface object representations

The speed of individual face categorization.

How fast does the human visual system discriminate individual faces? To address this question, we used a continuous-stimulation paradigm in which event-related potentials (ERPs) to a face stimulus are recorded with respect to another face stimulus, rather than to a preceding blank-screen baseline epoch. Following the shift between two face stimuli, posterior sites showed an early negative ERP deflection that started at 130 ms and peaked at 160 ms, the latency of the N170, an ERP component associated with discriminating faces from objects. The ERP we recorded was larger in amplitude when the preceding stimulus was perceived as a different individual face rather than the same individual face, although face pairs were of equal physical distance in the two conditions. These findings provide direct evidence that individual face discrimination in humans can take place as early as 130 ms following stimulus onset, during the same time window as face detection

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Misaligning face halves increases and delays the N170 specifically for upright faces : implications for the nature of early face representations

The N170 is an occipito-temporal visual event-related potential that is larger in response to faces than other nonface object categories and has been associated with the early activation of visual face representations in the human brain. It has been recently showed that spatially misaligning the bottom and top halves of a face stimulus-a manipulation used in behavioural studies to disrupt the processing of the whole face configuration (i.e. holistic processing)increases the latency and the amplitude of the N170, particularly in the right hemisphere. Here we show that these observations cannot be accounted for by a general effect of spatial misalignment of visual patterns. A first experiment showed that the effect of misalignment on the N170 was larger when both top and bottom halves of the stimulus were made of face parts (i.e. a full face) compared to when one of the two halves was made of visual noise. The N170 delay and increase for misaligned faces is similar to the effect of upside-down face inversion, a manipulation thought to disrupt holistic processing. Supporting this view, in a second experiment in which we presented upside-down versions of the stimuli used in the first experiment, we did not observe such a larger effect of misalignment on the N170 for a full face compared to the control conditions. These observations support the view that the early face representation activated in the human brain at the level of the N170, is that of a global upright face pattern. Specifically, when the global configuration of a face is modified by inverting it or spatially misaligning its top and bottom halves, the activation of its representation is delayed in cortical areas coding preferentially for faces. Moreover, when the global face configuration is disrupted, the face stimulus appears to recruit additional neural processes compared to normal face processing, leading to an increase of the N170 amplitude on the scalp. (C) 2009 Elsevier B.V. All rights reserved

Does physical interstimulus variance account for early electrophysiological face sensitive responses in the human brain? : Ten lessons on the N170

A recent event-related potential (ERP) study (Thierry G., Martin, C.D., Downing, P., Pegna, A.J. 2007. Controlling for interstimulus perceptual variance abolishes N170 face selectivity. Nature Neuroscience, 10, 505-11) claimed that the larger occipito-temporal N170 response to pictures of faces than other categories -- the N170 effect -- is due to a methodological artifact in stimulus selection, specifically, a greater interstimulus physical variance between pictures of objects than faces in previous ERP studies which, when controlled, eliminates this N170 effect. This statement casts doubts on the validity of the conclusions reached by a whole tradition of electrophysiological experiments published over the past 15 years and questions the very interest of using the N170 to probe the time course of face processes in the human brain. Here we claim that this physical variance factor is ill-defined by Thierry et al. and cannot account for previous observations of a smaller N170 amplitude to nonface objects than faces without latency increase and component "smearing". Most importantly, this factor was controlled in previous studies that reported robust N170 effects. We demonstrate that the absence of N170 effect in the study of Thierry et al. is due to methodological flaws in the reported experiments, most notably measuring the N170 at the wrong electrode sites. Moreover, the authors attributed a modulation of N170 amplitude in their study to a differential interstimulus physical variance while it probably reflects a biased comparison of different quality sets of individual images. Here, by taking Thierry et al.'s study as an exemplar case of what should not be done in ERP research of visual categorization processes, we provide clarifications on a number of methodological and theoretical issues about the N170 and its largest amplitude to faces. More generally, we discuss the potential role of differential visual homogeneity of object categories as well as low-level visual properties versus high-level visual processes in accounting for early face-preferential responses and the question of the speed at which visual stimuli are categorized as faces. This survey of the literature points to the N170 as a critical event in the time course of face processes in the human brain