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Past selection experience greatly affects the deployment of attention such that targets are more readily selected if their features or locations were more frequently selected in the past. Crucially, recent studies have shown similar experience-dependent effects also for salient task irrelevant stimuli: distractors exerted less interference if they appeared at a location where they were presented more often, relatively to other possible locations. Here we investigated the effects of such suppression history on the immediate behavioural correlates of attentional deployment, i.e., eye movements. Participants were to make saccadic eye movements to a target stimulus, while ignoring a highly distracting irrelevant visual onset appearing abruptly on the screen in a proportion of trials. Crucially, this irrelevant onset occurred more frequently in two locations on the visual display and our results showed that, relatively to distractors elsewhere, onsets presented at these locations became easier to ignore, giving rise to reduced oculomotor capture. Consistent with the notion that experience can alter attentional deployment towards spatial locations, these findings indicate that, through learning, the priority of high frequency locations becomes suppressed, attenuating the intrinsic saliency of distractors appearing therein. Traces left by individual events of attentional suppression decrease the processing priority of coordinates within topographic maps of the visual space.

Recent findings suggest that attentional and oculomotor control is heavily affected by past experience, giving rise to selection and suppression history effects, so that target selection is facilitated if they appear at frequently attended locations, and distractor filtering is facilitated at frequently ignored locations. While selection history effects once instantiated seem to be long-lasting, whether suppression history is similarly durable is still debated. We assessed the permanence of these effects in a unique experimental setting investigating eye-movements, where the locations associated with statistical unbalances were exclusively linked with either target selection or distractor suppression. Experiment 1 and 2 explored the survival of suppression history in the long and in the short term, respectively, revealing that its lingering traces are relatively short lived. Experiment 3 showed that in the very same experimental context, selection history effects were long lasting. These results seem to suggest that different mechanisms support the learning-induced plasticity triggered by selection and suppression history. Specifically, while selection history may depend on lasting changes within stored representations of the visual space, suppression history effects hinge instead on a functional plasticity which is transient in nature, and involves spatial representations which are constantly updated and adaptively sustain ongoing oculomotor control.

Electroencephalography (EEG) is useful to objectively diagnose/grade hepatic encephalopathy (HE) across its spectrum of severity. However, it requires expensive equipment, and hepatogastroenterologists are generally unfamiliar with its acquisition/interpretation. Recent technological advances have led to the development of low-cost, user-friendly EEG systems, allowing EEG acquisition also in settings with limited neurophysiological experience. The aim of this study was to assess the relationship between EEG parameters obtained from a standard-EEG system and from a commercial, low-cost wireless headset (light-EEG) in patients with cirrhosis and varying degrees of HE. Seventy-two patients (58 males, 61 6 9 years) underwent clinical evaluation, the Psychometric Hepatic Encephalopathy Score (PHES), and EEG recording with both systems. Automated EEG parameters were calculated on two derivations. Strong correlations were observed between automated parameters obtained from the two EEG systems. Bland and Altman analysis indicated that the two systems provided comparable automated parameters, and agreement between classifications (normal versus abnormal EEG) based on standard-EEG and light-EEG was good (0.6 < j < 0.8). Automated parameters such as the mean dominant frequency obtained from the light-EEG correlated significantly with the Model for End-Stage Liver Disease score (r 5 20.39, P < 0.05), fasting venous ammonia levels (r 5 20.41, P < 0.01), and PHES (r 5 20.49, P < 0.001). Finally, significant differences in light-EEG parameters were observed in patients with varying degrees of HE. Conclusion: Reliable EEG parameters for HE diagnosing/ grading can be obtained from a cheap, commercial, wireless headset; this may lead to more widespread use of this patientindependent tool both in routine liver practice and in the research setting. (HEPATOLOGY 2016;63:1651-1659 H epatic encephalopathy (HE) is a neuropsychiatric syndrome caused by liver disease and/or portal-systemic shunting, which manifests as a wide spectrum of mental and motor dysfunction.Patients with cirrhosis and HE exhibit electroencephalographic (EEG) alterations. These were first identified in 1950 by Foley and colleagues, who described highvoltage, slow waves in patients with hepatic coma.(1) A few years later, Parsons-Smith and colleagues reported that EEG alterations in patients with cirrhosis were related to the severity of overt HE (i.e., the more severe the clinical picture, the slower the EEG).(2) The same authors highlighted how mild EEG slowing could also be detected in patients without overt HE, thus already introducing the concept of latent or subclinical HE.(2) The visual classification of EEG changes proposed by ParsonsSmith and colleagues was descriptive in nature and thus prone to interobserver variability. In 1977, Conn and coworkers proposed a semiquantitative classification based Abbreviations: EEG, electroencephalography; HE, hepatic encephalopathy; MDF, mean dominant frequency; MELD, Model for End-Stage Liver Disease; MPZS, mean PHES z ...

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