Rightward shift in temporal order judgements in the wake of the attentional blink

Cambio hacia la derecha en los juicios de orden temporal durante el
 parpadeo atencional. El orden temporal de dos eventos, cada uno de ellos
 presentado en un hemicampo visual diferente, puede ser juzgado
 correctamente por observadores típicos inclusive cuando la diferencia de
 tiempo entre las presentaciones sea muy pequeña. El presente trabajo analiza
 la influencia de un proceso endógeno sobre el juicio de orden temporal
 (JOT) y nos muestra que la percepción del orden temporal está también
 afectada cuando los recursos atencionales disponibles son reducidos
 mediante un paradigma de parpadeo atencional (PA). A los participantes se
 les presentaron los siguientes estímulos: un primer estímulo visual (T1) en el
 centro de fijación y luego de un intervalo de tiempo variable (280 ó 1030
 ms), un par de estímulos lateralizados (T2). Para la tarea dual con el
 intervalo de tiempo de 280 ms entre T1 y T2, la precisión en el JOT se
 deterioró, evidenciando un PA. Sin embargo, durante el PA en lugar de la
 asimetría favorable al lado izquierdo, aparece un significativo sesgo en
 contra de ese lado

Asynchronous presentation of global and local information reveals effects of attention on brain electrical activity specific to each level

The neural basis of selective attention within hierarchically organized Navon figures has been extensively studied with event related potentials (ERPs), by contrasting responses obtained when attending the global and the local echelons. The findings are inherently ambiguous because both levels are always presented together. Thus only a mixture of the brain responses to two levels can be observed. Here, we use a method that allows unveiling of global and local letters at distinct times, enabling estimation of separate ERPs related to each level. Two interspersed oddball streams were presented, each using letters from one level and comprised of frequent distracters and rare targets. Previous work and our Experiment 1 show that it is difficult to divide attention between two such streams of stimuli. ERP recording in Experiment 2 evinced an early selection negativity (SN, with latencies to the 50% area of about 266 ms for global distracters and 276 ms for local distracters) that was larger for attended relative to unattended distracters. The SN was larger over right posterior occipito-temporal derivations for global stimuli and over left posterior occipito-temporal derivations for local stimuli (although the latter was less strongly lateralized). A discrimination negativity (DN, accompanied by a P3b) was larger for attended targets relative to attended distracters, with latencies to the 50% area of about 316 ms for global stimuli and 301 ms for local stimuli, which presented a similar distribution for both levels over left temporo-parietal electrodes. The two negativities apparently index successive stages in the processing of a selected level within a compound figure. By resolving the ambiguity of traditional designs, our method allowed us to observe the effects of attention for each hierarchical level on its own

Brain Signals of Face Processing as Revealed by Event-Related Potentials

We analyze the functional significance of different event-related potentials (ERPs) as electrophysiological indices of face perception and face recognition, according to cognitive and neurofunctional models of face processing. Initially, the processing of faces seems to be supported by early extrastriate occipital cortices and revealed by modulations of the occipital P1. This early response is thought to reflect the detection of certain primary structural aspects indicating the presence grosso modo of a face within the visual field. The posterior-temporal N170 is more sensitive to the detection of faces as complex-structured stimuli and, therefore, to the presence of its distinctive organizational characteristics prior to within-category identification. In turn, the relatively late and probably more rostrally generated N250r and N400-like responses might respectively indicate processes of access and retrieval of face-related information, which is stored in long-term memory (LTM). New methods of analysis of electrophysiological and neuroanatomical data, namely, dynamic causal modeling, single-trial and time-frequency analyses, are highly recommended to advance in the knowledge of those brain mechanisms concerning face processing

Numerical capacities as domain-specific predictors beyond early mathematics learning: a longitudinal study.

The first aim of the present study was to investigate whether numerical effects (Numerical Distance Effect, Counting Effect and Subitizing Effect) are domain-specific predictors of mathematics development at the end of elementary school by exploring whether they explain additional variance of later mathematics fluency after controlling for the effects of general cognitive skills, focused on nonnumerical aspects. The second aim was to address the same issues but applied to achievement in mathematics curriculum that requires solutions to fluency in calculation. These analyses assess whether the relationship found for fluency are generalized to mathematics content beyond fluency in calculation. As a third aim, the domain specificity of the numerical effects was examined by analyzing whether they contribute to the development of reading skills, such as decoding fluency and reading comprehension, after controlling for general cognitive skills and phonological processing. Basic numerical capacities were evaluated in children of 3(rd) and 4(th) grades (n=49). Mathematics and reading achievements were assessed in these children one year later. Results showed that the size of the Subitizing Effect was a significant domain-specific predictor of fluency in calculation and also in curricular mathematics achievement, but not in reading skills, assessed at the end of elementary school. Furthermore, the size of the Counting Effect also predicted fluency in calculation, although this association only approached significance. These findings contrast with proposals that the core numerical competencies measured by enumeration will bear little relationship to mathematics achievement. We conclude that basic numerical capacities constitute domain-specific predictors and that they are not exclusively "start-up" tools for the acquisition of Mathematics; but they continue modulating this learning at the end of elementary school

Testing the connections within face processing circuitry in Capgras delusion with diffusion imaging tractography

Although Capgras delusion (CD) patients are capable of recognizing familiar faces, they present a delusional belief that some relatives have been replaced by impostors. CD has been explained as a selective disruption of a pathway processing affective values of familiar faces. To test the integrity of connections within face processing circuitry, diffusion tensor imaging was performed in a CD patient and 10 age-matched controls. Voxel-based morphometry indicated gray matter damage in right frontal areas. Tractography was used to examine two important tracts of the face processing circuitry: the inferior fronto-occipital fasciculus (IFOF) and the inferior longitudinal (ILF). The superior longitudinal fasciculus (SLF) and commissural tracts were also assessed. CD patient did not differ from controls in the commissural fibers, or the SLF. Right and left ILF, and right IFOF were also equivalent to those of controls. However, the left IFOF was significantly reduced respect to controls, also showing a significant dissociation with the ILF, which represents a selective impairment in the fiber-tract connecting occipital and frontal areas. This suggests a possible involvement of the IFOF in affective processing of faces in typical observers and in covert recognition in some cases with prosopagnosia

Scatterplot showing significant correlation between mathematics fluency and the size of the subitizing effect.

<p>The solid line represents the linear regression for this relationship.</p

Flowchart of participant´s selection.

PurposeThis study aimed to identify the most effective summary cognitive index predicted from spatio-temporal gait features (STGF) extracted from gait patterns.MethodsThe study involved 125 participants, including 40 young (mean age: 27.65 years, 50% women), and 85 older adults (mean age: 73.25 years, 62.35% women). The group of older adults included both healthy adults and those with Mild Cognitive Impairment (MCI). Participant´s performance in various cognitive domains was evaluated using 12 cognitive measures from five neuropsychological tests. Four summary cognitive indexes were calculated for each case: 1) the z-score of Mini-Mental State Examination (MMSE) from a population norm (MMSE z-score); 2) the sum of the absolute z-scores of the patients’ neuropsychological measures from a population norm (ZSum); 3) the first principal component scores obtained from the individual cognitive variables z-scores (PCCog); and 4) the Mahalanobis distance between the vector that represents the subject’s cognitive state (defined by the 12 cognitive variables) and the vector corresponding to a population norm (MDCog). The gait patterns were recorded using a body-fixed Inertial Measurement Unit while participants executed four walking tasks (normal, fast, easy- and hard-dual tasks). Sixteen STGF for each walking task, and the dual-task costs for the dual tasks (when a subject performs an attention-demanding task and walks at the same time) were computed. After applied Principal Component Analysis to gait measures (96 features), a robust regression was used to predict each cognitive index and individual cognitive variable. The adjusted proportion of variance (adjusted-R2) coefficients were reported, and confidence intervals were estimated using the bootstrap procedure.ResultsThe mean values of adjusted-R2 for the summary cognitive indexes were as follows: 0.0248 for MMSE z-score, 0.0080 for ZSum, 0.0033 for PCCog, and 0.4445 for MDCog. The mean adjusted-R2 values for the z-scores of individual cognitive variables ranged between 0.0009 and 0.0693. Multiple linear regression was only statistically significant for MDCog, with the highest estimated adjusted-R2 value.ConclusionsThe association between individual cognitive variables and most of the summary cognitive indexes with gait parameters was weak. However, the MDCog index showed a stronger and significant association with the STGF, exhibiting the highest value of the proportion of the variance that can be explained by the predictor variables. These findings suggest that the MDCog index may be a useful tool in studying the relationship between gait patterns and cognition.</div

Plots of the best models for the four summary cognitive indexes.

Plots of the best models for the four summary cognitive indexes.</p

Performance of the multiple linear regression models for the summary cognitive indexes.

Performance of the multiple linear regression models for the summary cognitive indexes.</p