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We examined the slowing in vocal reaction times shown by dyslexic (compared to control) children with that of older (compared to younger) adults using an approach focusing on the detection of global, non-task-specific components. To address this aim, data were analyzed with reference to the difference engine (DEM) and rate and amount (RAM) models. In Experiment 1, typically developing children, children with dyslexia (both attending sixth grade), younger adults and older adults read words and non-words and named pictures. In Experiment 2, word and picture conditions were presented to dyslexic and control children attending eighth grade. In both experiments, dyslexic children were delayed in reading conditions, while they were unimpaired in naming pictures (a finding which indicates spared access to the phonological lexicon). The reading difficulty was well accounted for by a single multiplicative factor while only the residual effect of length (but not frequency and lexicality) was present after controlling for over-additivity using a linear mixed effects model with random slopes on critical variables. Older adults were slower than younger adults across reading and naming conditions. This deficit was well described by a single multiplicative factor. Thus, while slowing of information processing is limited to orthographic stimuli in dyslexic children, it cuts across verbal tasks in older adults. Overall, speed differences in groups such as dyslexic children and older adults can be effectively described with reference to deficits in domains encompassing a variety of experimental conditions rather than deficits in single specific task/conditions. The DEM and RAM prove effective in teasing out global vs. specific components of performance.

The omissions are infrequent errors consisting in missing responses to the target stimuli. This is the first study aimed at investigating the brain activities associated with omissions in a decision-making task. We recorded event-related potentials (ERPs) in 12 subjects which reported a suitable number of omissions in a visual go/no-go task. We investigated both the pre- and post-stimulus brain activities associated with correct and omitted trials. The electrical neuroimaging technique (BESA) was adopted to extract the anterior insula (aIns) activity associated with the prefrontal P2 component (pP2) peaking about 300 ms after the stimulus and reflecting the stimulus-response mapping process. We found that omissions were predicted by a delayed onset (about half a second) of two pre-stimulus components, i.e. the prefrontal negativity (pN) and the Bereitschaftspotential (BP) associated with the top-down control and the motor preparation, respectively. Further, at the post-stimulus stage the omission trials were characterized by the suppression of the pP2 (and the aIns activity as measured by BESA). No differences between omission and correct trials were detected at the level of the P1 and N1 visual components, as well as the P3. These findings would suggest that omissions are attentional lapsebased errors, as indicated by the delayed brain preparation before the stimulus onset. The reduced cortical activity during the preparation phase did not affect the visual processing; in contrast the stimulus categorization process at the level of the anterior insula did not start at all, resulting in the inability to reach a decision.

Recent evidence suggests that ongoing brain oscillations may be instrumental in binding and integrating multisensory signals. In this experiment, we investigated the temporal dynamics of visual-motor integration processes. We show that action modulates sensitivity to visual contrast discrimination in a rhythmic fashion at frequencies of about 5 Hz (in the theta range), for up to 1 s after execution of action. To understand the origin of the oscillations, we measured oscillations in contrast sensitivity at different levels of luminance, which is known to affect the endogenous brain rhythms, boosting the power of alpha-frequencies. We found that the frequency of oscillation in sensitivity increased at low luminance, probably reflecting the shift in mean endogenous brain rhythm towards higher frequencies. Importantly, both at high and at low luminance, contrast discrimination showed a rhythmic motor-induced suppression effect, with the suppression occurring earlier at low luminance. We suggest that oscillations play a key role in sensory-motor integration, and that the motor-induced suppression may reflect the first manifestation of a rhythmic oscillation., (© 2016 The Author(s).)

Objective: The aim of the present study was to investigate the cortical correlates of the intraindividual coefficient of variation (ICV) in a go/no-go task, focusing on the prefrontal cortex (PFC) contribution and evaluating both pre- and poststimulus brain activity., Method: We recorded event-related potentials (ERPs) in 40 subjects, arranged a posteriori in 2 groups on the basis of their ICV values. By this method, we formed the consistent (low ICV; n = 20) and inconsistent (high ICV; n = 20) group: the age, speed, and accuracy performance of the 2 groups were matched., Results: The prestimulus anticipatory PFC activity, as reflected by the prefrontal negativity (pN) wave, and the poststimulus P3 component were larger in the consistent than in the inconsistent group. In contrast, no differences were observed between groups in the brain activities associated to motor preparation and early sensory processing., Conclusions: Data are interpreted as an enhanced top-down control in consistent performers, likely characterized by a greater sustained attention on the task., ((c) 2015 APA, all rights reserved).)

Literature on mirror neurons has shown that seeing someone preparing to move generates in the motor areas of the observers a brain activity similar to that generated when the subject prepares his own actions. Thus, the 'mirroring' of action would not be limited to the execution phase but also involves the preparation process. Here we confirm and extend this notion showing that, just as different brain activities prepare different voluntary actions, also different brain activities prepare to observe different predictable actions. Videos of two different actions from egocentric point of view were presented in separate blocks: (i) grasping of a cup and (ii) impossible grasping of a cup. Subjects had to passively observe the videos showing object-directed hand movements. Through the use of the event-related potentials, we found a cortical activity before observing the actions, which was very similar to the one recorded prior to the actual execution of that same action, in terms of both topography and latency. This anticipatory activity does not represent a general preparation state but an action-specific state, because being dependent on the specific meaning of the forthcoming action. These results reinforce our knowledge about the correspondence between action, perception and cognition., (© The Author (2014). Published by Oxford University Press. For Permissions, please email: journals.permissions@oup.com.)

This work explores, for the first time, the electro-cortical activity related to the preparation of bimanual incompatible actions. To accomplish this aim, we recorded motor-related cortical potentials (MRCPs) in 16 healthy subjects, who were asked to draw lines and/or circles during three experimental conditions: Unimanual, Bimanually Compatible (either lines or circles with both hands) and Bimanually Incompatible (a line with one hand and a circle with the other hand). We show that the electro-cortical activity recorded during the preparation of the bimanually incompatible actions included a central positivity (CP) that began approximately 2.5s before movement onset and was localized in medial frontal areas. We then recorded a later (ca. 700ms before movement onset) negative activity in the supplementary motor area (consistent with Bereitschaftspotential). Finally, a strong frontal lateral positivity (FLP) emerged ca. 1.8s before the initiation of drawing that was localized in the dorsolateral prefrontal cortex. All components were bilateral. The CP component has not been described before. These data are discussed with regard to the "interference network" theory., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Visual-evoked potentials (VEPs) were recorded in seventeen patients with unilateral lesions of the right hemisphere (RH) and visuospatial neglect. Hemispheric differences were detected for VEP components in the time window from 130 to 280 msec; this result replicates data from a previous study using a larger group of patients (Di Russo et al., 2008). Three patients were tested twice; their hemispheric differences, i.e., the differences in latency and amplitude of VEPs to ipsilesional and contralesional stimuli, were evaluated at the beginning and end of visuospatial rehabilitation training for neglect. The hemispheric differences were limited to components anterior N1 (N1a), posterior N1 (N1p) and P2 (not C1 and P1) and showed a significant decrease after training; amelioration at the behavioural level was also observed. Fourteen patients were tested only once, at different steps of their training. For the overall group, we determined the correlation between VEP hemispheric differences and the number of sessions attended by the patients at the time of VEP recording. The correlation was negative, the higher the number of sessions, the lower the hemispheric asymmetry, and high, ranging from .45 to .64, for both the latency and amplitude of the N1p and P2 components, and for the amplitude of the N1a component. The correlation between VEP hemispheric differences and time from onset (TFO) of the pathological event was not significant. Overall, the hemispheric differences between specific components of the VEP responses to lateralised stimuli appear to be a good marker of recovery from neglect., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Purpose: Open-skill sports require high levels of visual attention and fast and flexible decision making and action execution. We evaluated whether these sports may counteract the well-known age-related declines in executive processing., Methods: Young and middle-age fencers and nonathletes were studied. Participants (N = 40) performed visual motor tasks while reaction times (RTs) and event-related potentials were recorded., Results: RTs were slower for the older subjects, but accuracy was not impaired. At event-related potential level, the late P3 component was delayed in older subjects, but those who participated in sports showed less delay. The RTs of middle-age and young fencers were comparable; the P1 latency of middle-age fencers was similar to that of the younger subjects; the N1 was enhanced in older, as well as younger, fencers; the N2 component of fencers had shorter latencies and larger amplitudes than nonathletes; and in no-go trials, the P3 component was enhanced in fencers independent of age., Conclusions: Overall, the practice of open-skill sports was associated with improvement of the executive functions that are already degraded at middle age.

This study evaluated letter recognition processing in Italian developmental dyslexics and its potential contribution to word reading. Letter/bigram recognition (naming and matching) and reading of words and non-words were examined. A group of developmental dyslexics and a chronologically age-matched group of skilled readers were examined. Dyslexics were significantly slower than skilled readers in all tasks. The rate and amount model (RAM, Faust et al., 1999) was used to detect global and specific factors in the performance differences controlling for the presence of over-additivity effects. Two global factors emerged. One ("letter-string" factor) accounted for the performance in all (and only) word and non-word reading conditions, indicating a large impairment in dyslexics (more than 100% reaction time - RT increase as compared to skilled readers). All the letter/bigram tasks clustered on a separate factor ("letter" factor) indicating a mild impairment (ca. 20% RT increase as compared to skilled readers). After controlling for global factor influences by the use of the z-score transformation, specific effects were detected for the "letter-string" (but not the "letter") factor. Stimulus length exerted a specific effect on dyslexics' performance, with dyslexics being more affected by longer stimuli; furthermore, dyslexics showed a stronger impairment for reading words than non-words. Individual differences in the "letter" and "letter-string" factors were uncorrelated, pointing to the independence of the impairments. The putative mechanisms underlying the two global factors and their possible relationship to developmental dyslexia are discussed., (Copyright © 2009 Elsevier Srl. All rights reserved.)

Background: The aim of this study was to examine longitudinally the acquisition of reading fluency in a shallow orthography from the very beginning using eye movement recordings. The development of reading fluency is easier to examine in shallow (such as German, Finnish, or Italian) rather than in opaque (such as English or French) orthographies because the former limit the presence of speed-accuracy trade-offs at early stages of acquisition. To date, only cross-sectional eye movement studies of reading development are available., Material/methods: One normally developing child was assessed at the very beginning of first grade and at the end of the first, second, and fifth grades. Eye movement parameters during reading, reading speed and accuracy in a standard reading test, and vocal reaction time at onset to single words varying in length were measured., Results: Reading fluency improved dramatically during the first grade and progressively less thereafter: the word-length effect decreased abruptly by the end of the first grade and then less onwards. The rate of improvement closely followed a power function. This pattern held for standard reading tests, various eye movement parameters during reading, and vocal reaction times to single word onset., Conclusions: These longitudinal observations indicate the rapid acquisition of reading fluency in a transparent orthography showing that the largest changes occurred within the first year of education.

We tested the hypothesis that crowding effects are responsible for the reading slowness characteristic of developmental dyslexia. A total of twenty-nine Italian dyslexics and thirty-three age-matched controls participated in various parts of the study. In Experiment 1, we measured contrast thresholds for identifying letters and words as a function of stimulus duration. Thresholds were higher in dyslexics than controls for words (at a limited time exposure) but not for single letters. Adding noise to the stimuli produced comparable effects in dyslexics and controls. At the long time exposure thresholds were comparable in the two groups. In Experiment 2, we measured the spacing between a target letter and two flankers at a fixed level of performance as a function of eccentricity and size. With eccentricity, the critical spacing (CS) scaled in the control group with 0.62 proportionality (a value of b close to Bouma's law, 0.50) and with a greater proportionality (0.95) in the dyslexic group. CS was independent of size in both groups. In Experiment 3, we examined the critical print size (CPS), that is, the increase in reading rate up to a critical character size (S. T. Chung, J. S. Mansfield, & G. E. Legge, 1998). CPS of dyslexic children was greater than that of controls. Individual maximal reading speed was predicted by individual bs (from Experiment 2). The maximal reading rate achieved by dyslexics at CPS (and also for larger print sizes) was below the values observed in controls. We conclude that word analysis in dyslexics is slowed because of greater crowding effects, which limit letter identification in multi-letter arrays across the visual field. We propose that the peripheral reading of normal readers might constitute a model for dyslexic reading. The periphery model accounts for 60% of dyslexics' slowness. After compensating for crowding, the dyslexics' reading rate remains slower than that of proficient readers. This failure is discussed in terms of a developmental learning effect.

Fixation disparity, that is, misalignment of the gaze direction of both eyes, may be observed in static conditions (through standard optometric evaluation) and dynamic conditions (through eye movement recording). A computation method is presented to determine vergence angles and fixation disparity from gaze positions as commonly recorded by infrared eye-trackers when a participant looks at a personal computer (PC) screen. Eye-tracking devices provide gaze position in coordinates relative to the bidimensional screen surface. From these data, vergence angles can be calculated by trigonometric triangulations; fixation disparity is then calculated from the vergence angles. The application of the procedure to the recordings of one participant is described. To control for the effective alignment of the two eyes on the target during binocular calibration, a procedure based on the dichoptic presentation of nonius lines was used. The recordings confirm that computation and the dichoptic calibration procedures ensure reliable measures of vergence and fixation disparity. The usefulness of this approach with infrared recording of eye position is discussed.