Magnocellular Bias in Exogenous Attention to Biologically Salient Stimuli as Revealed by Manipulating Their Luminosity and Color.

Exogenous attention is a set of mechanisms that allow us to detect and reorient toward salient events-such as appetitive or aversive-that appear out of the current focus of attention. The nature of these mechanisms, particularly the involvement of the parvocellular and magnocellular visual processing systems, was explored. Thirty-four participants performed a demanding digit categorization task while salient (spiders or S) and neutral (wheels or W) stimuli were presented as distractors under two figure-ground formats: heterochromatic/isoluminant (exclusively processed by the parvocellular system, Par trials) and isochromatic/heteroluminant (preferentially processed by the magnocellular system, Mag trials). This resulted in four conditions: SPar, SMag, WPar, and WMag. Behavioral (RTs and error rates in the task) and electrophysiological (ERPs) indices of exogenous attention were analyzed. Behavior showed greater attentional capture by SMag than by SPar distractors and enhanced modulation of SMag capture as fear of spiders reported by participants increased. ERPs reflected a sequence from magnocellular dominant (P1p, ≃120 msec) to both magnocellular and parvocellular processing (N2p and P2a, ≃200 msec). Importantly, amplitudes in one N2p subcomponent were greater to SMag than to SPar and WMag distractors, indicating greater magnocellular sensitivity to saliency. Taking together, results support a magnocellular bias in exogenous attention toward distractors of any nature during initial processing, a bias that remains in later stages when biologically salient distractors are present.

Suppression of alpha-band power underlies exogenous attention to emotional distractors.

Alpha-band oscillations (8-14 Hz) are essential for attention and perception processes by facilitating the selection of relevant information. Directing visuospatial endogenous (voluntary) attention to a given location consistently results in a power suppression of alpha activity over occipito-parietal areas contralateral to the attended visual field. In contrast, the neural oscillatory dynamics underlying the involuntary capture of attention, or exogenous attention, are currently under debate. By exploiting the inherent capacity of emotionally salient visual stimuli to capture attention, we aimed to investigate whether exogenous attention is characterized by either a reduction or an increase in alpha-band activity. Electroencephalographic activity was recorded while participants completed a Posner visuospatial cueing task, in which a lateralized image with either positive, negative, or neutral emotional content competed with a target stimulus presented in the opposite hemifield. Compared with trials with no distractors, alpha power was reduced over occipital regions contralateral to distracting images. This reduction of alpha activity turned out to be functionally relevant, as it correlated with impaired behavioral performance on the ongoing task and was enhanced for distractors with negative valence. Taken together, our results demonstrate that visuospatial exogenous attention is characterized by a suppression of alpha-band activity contralateral to distractor location, similar to the oscillatory underpinnings of endogenous attention. Further, these results highlight the key role of exogenous attention as an adaptive mechanism for the efficient detection of biologically salient stimuli.

Response inhibition in borderline personality disorder: Neural and behavioral correlates.

Although response inhibition is thought to be important in borderline personality disorder (BPD), little is known about its neurophysiological basis. This study aimed to provide insight into this issue by capitalizaing on the high temporal resolution of electroencephalography and information provided by source localization methods. To this end, twenty unmedicated patients with BPD and 20 healthy control subjects performed a modified go/no-go task designed to better isolate the brain activity specifically associated with response inhibition. Event-related potentials (ERP) were measured and further analyzed at the scalp and source levels. Patients with BPD made more commission errors (failed inhibitions) than control subjects. Scalp ERP data showed that both groups displayed greater frontocentral P3 amplitude for no-go (response inhbition) than for go trials (response execution). However, source reconstruction data revealed that patients with BPD activated posterior parietal regions (precuneus) to inhibit their responses, whereas controls activated prefrontal regions (presupplementary motor area, preSMA). This dissociation was supported by a significant Region (precuneus, preSMA) x Trial Type (no-go, go) x Group (BPD, control) interaction. These findings extend our understanding of the neurophysiological basis of abnormal response inhibition in BPD, suggesting that patients with BPD recruit different brain regions for inhibiting prepotent responses compared to controls. Future research in larger, medication-naïve samples of patients with BPD is required to confirm and extend these findings.

Differential neural mechanisms underlying exogenous attention to peripheral and central distracters.

Mechanisms underlying exogenous attention to central and peripheral distracters were temporally and spatially explored while 30 participants performed a digit categorization task. Neural (event-related potentials-ERPs-, analyzed both at the scalp and at the voxel level) and behavioral indices of exogenous attention were analyzed. Distracters were either biologically salient or neutral, in order to test whether the exogenous attention bias to the former observed in previous studies is independent of, or interacts with, distracter eccentricity. Two subcomponents of the N2 component of the ERPs, N2olp and N2ft, reflected processes related to peripheral distracters processing. N2olp effects, located in the dorsal attention network (supplementary motor area), were probably related to covert reorientation to peripheral distracters. N2ft effects, located in the default mode network (posterior cingulate cortex), appeared to reflect less effort in the ongoing task when peripheral distracters were presented. N2ft also showed a biological saliency effect which was independent of eccentricity and was located in the polar/ventral prefrontal cortex. P3 showed greater amplitudes to centrally presented distracters. These latter effects were located in TEO (visual cortex), and would be functionally associated with spatial interference between the target and central distracters. Behavior showed the relevance of both central and peripheral distracters in exogenous attention. These results indicate that exogenous attention to peripheral distracters differed in temporal and spatial terms from exogenous attention to central distracters and that it is biased towards biologically salient events irrespective of their eccentricity.

Características de las personas gestantes con COVID-19 residentes de la provincia de Buenos Aires e inequidades en el acceso a los servicios de salud. Periodo marzo-septiembre del año 2020 / Characteristics of pregnant people with COVID-19 residing in the province of Buenos Aires and inequities in access to health services. Period March-September 2020

El COVID-19 fue declarado como pandemia por la OMS en marzo de 2020. A pesar de que inicialmente las personas gestantes no fueron consideradas población de riesgo, paulatinamente fueron apareciendo evidencias que mostraron mayor frecuencia de eventos clínicos, obstétricos y perinatales adversos; mayor ingreso a UTI, preeclampsia, mayor tasa de cesáreas, prematurez y muertes perinatales. La provincia de Buenos Aires, compuesta por 135 municipios y 12 Regiones Sanitarias, concentra el 39,0% de la población, 36,6% de los nacimientos y la mayor cantidad de casos COVID-19 del país. Los casos se concentraron, al inicio de la pandemia, en el AMBA. Es un territorio que presenta profundas desigualdades socioeconómicas que podrían relacionarse con inequidades en el acceso a los servicios de salud. Este es un estudio cuantitativo, observacional, descriptivo, transversal y retrospectivo, realizado con fuentes secundarias, sobre 2412 casos de 15 a 49 años, entre marzo y septiembre de 2020. Tiene por objetivo analizar las características sociosanitarias, del proceso de gestación y resultados clínicos, obstétricos y perinatales de las personas gestantes con COVID-19 residentes en la provincia; compararlas con la población del año anterior sin COVID-19; y observar además si las diferencias encontradas en los distintos territorios y sectores de atención de la salud pueden analizarse como inequidades de acceso a los servicios. Se encontraron diferencias significativas al comparar la población gestante COVID-19 con la población de 2019 en complicaciones de la hipertensión gestacional, cesáreas, prematurez, muerte fetal, ingreso a UTI y ARM. También se observó que el sector público dió respuesta a un mayor volumen de población gestante que el que habitualmente atiende (158,4% más), logrando brindar acceso al diagnóstico en tiempos similares que el sector privado y de obra social. El 73% de las personas gestantes fallecidas por COVID-19 residían en municipios caracterizados como de peor situación socioeconómica