133 research outputs found
Procedimento e processo nel consolidato fiscale
No full textI profili procedurali del consolidato fiscale: premesse. Il procedimento nel consolidato fiscale nazionale. Il processo nel consolidato fiscale nazionale. Il procedimento e il processo nel consolidato fiscale mondiale.I profili procedurali del consolidato fiscale: premesse. Il procedimento nel consolidato fiscale nazionale. Il processo nel consolidato fiscale nazionale. Il procedimento e il processo nel consolidato fiscale mondiale.LUISS PhD Thesi
Object-centred neglect: Simulation with head-centred coding based on Gaussian gaze-dependent units
No full textRight brain damaged patients affected by contralesional object-centred neglect are able to process all objects around them but systematically omit the left part of these objects. We show that pure object-centred neglect can be simulated by a basis function neural network in which the activity of units allowing head-centred coding of space is based on the activity of gaze-dependent units with no lateral gradient of preferred eye positions along the horizontal space. This type of network simulates complete dissociation between object-centred and egocentric neglect, as observed in patients' copies of multi-item drawings. Based on these results and available neurophysiological, clinical and brain imaging data, it is proposed that disruption of a cerebral network including dorsal occipital and parietal areas and the supplementary eye fields could be the main cause of object-centred neglect. (c) 2007 Elsevier Ltd. All rights reserved
Determining priority between attentional and referential-coding sources of the Simon effect through optokinetic stimulation
No full textThe “Simon effect” is the performance advantage for spatially corresponding target–response ensemblesthat is observed when coding of target position is irrelevant for the selection of motor responses. The“attentional-shift” account of the Simon effect holds that it arises from the congruency between responselocation and the direction of the last shift of attention toward the target. The “referential-coding” accounttraces the origin of the Simon effect back to the congruency between the response location and theposition of the target with respect to a spatial reference frame. We were able to contrast these twohypotheses using full-field horizontal optokinetic stimulation (OKS). It was shown that OKS moving inone horizontal direction drives covert orienting of attention toward the side of arrival of OKS, i.e. the “Incoming”side, which is opposed to the direction of OKS motion toward the “Out-going” side (Teramoto etal., 2004; Watanabe, 2001). We therefore asked healthy participants to discriminate between slow andfast velocities of leftward or rightward OKS. “Fast” and “slow” responses were associated to responsebuttons positioned in the left or right side of space. The “attentional-shift” account of the Simon effectpredicts that response compatibility should be related to the direction of the attentional shift induced byOKS, i.e. in the direction opposite to OKS motion. By contrast, the “referential-coding” hypothesis predictsthat response compatibility should be related to the direction of OKS displacement with respect to itsstarting position.Weobserved faster RTs when the response button was on the “In-coming” side of space,opposite to the direction ofOKSmotion. This result supports priority of attentional over referential-codingfactors in the genesis of the Simon effect
Simulating object-centred neglect with head centred coding of space based on non linear gaze-dependent units
No full textCollana: Advances in Consciousness Researc
Neural Correlates of the Spatial and Expectancy Components of Endogenous and Stimulus-Driven Orienting of Attention in the Posner Task
No full textVoluntary orienting of visual attention is conventionally measured in tasks with predictive central cues followed by frequent valid targets at the cued location and by infrequent invalid targets at the uncued location. This implies that invalid targets entail both spatial reorienting of attention and breaching of the expected spatial congruency between cues and targets. Here, we used event-related functional magnetic resonance imaging (fMRI) to separate the neural correlates of the spatial and expectancy components of both endogenous orienting and stimulus-driven reorienting of attention. We found that during endogenous orienting with predictive cues, there was a significant deactivation of the right Temporal-Parietal Junction (TPJ). We also discovered that the lack of an equivalent deactivation with nonpredictive cues was matched to drop in attentional costs and preservation of attentional benefits. The right TPJ showed equivalent responses to invalid targets following predictive and nonpredictive cues. On the contrary, infrequent-unexpected invalid targets following predictive cues specifically activated the right Middle and Inferior Frontal Gyrus (MFG-IFG). Additional comparisons with spatially neutral trials demonstrated that, independently of cue predictiveness, valid targets activate the left TPJ, whereas invalid targets activate both the left and right TPJs. These findings show that the selective right TPJ activation that is found in the comparison between invalid and valid trials results from the reciprocal cancelling of the different activations that in the left TPJ are related to the processing of valid and invalid targets. We propose that left and right TPJs provide "matching and mismatching to attentional template" signals. These signals enable reorienting of attention and play a crucial role in the updating of the statistical contingency between cues and targets
Deficient reinforcement learning in medial frontal cortex as a model of dopamine-related motivational deficits in ADHD
No full textAttention Deficit/Hyperactivity Disorder (ADHD) is a pathophysiologically complex and heterogeneous condition with both cognitive and motivational components. We propose a novel computational hypothesis of motivational deficits in ADHD, drawing together recent evidence on the role of anterior cingulate cortex (ACC) and associated mesolimbic dopamine circuits in both reinforcement learning and ADHD. Based on findings of dopamine dysregulation and ACC involvement in ADHD we simulated a lesion in a previously validated computational model of ACC (Reward Value and Prediction Model, RVPM). We explored the effects of the lesion on the processing of reinforcement signals. We tested specific behavioral predictions about the profile of reinforcement-related deficits in ADHD in three experimental contexts; probability tracking task, partial and continuous reward schedules, and immediate versus delayed rewards. In addition, predictions were made at the neurophysiological level. Behavioral and neurophysiological predictions from the RVPM-based lesion-model of motivational dysfunction in ADHD were confirmed by data from previously published studies. RVPM represents a promising model of ADHD reinforcement learning suggesting that ACC dysregulation might play a role in the pathogenesis of motivational deficits in ADHD. However, more behavioral and neurophysiological studies are required to test core predictions of the model. In addition, the interaction with different brain networks underpinning other aspects of ADHD neuropathology (i.e., executive function) needs to be better understood.<br/
Left and right temporal-parietal junctions (TPJs) as "match/mismatch" hedonic machines: A unifying account of TPJ function
No full textExperimental and theoretical studies have tried to gain insights into the involvement of the Temporal Parietal Junction (TPJ) in a broad range of cognitive functions like memory, attention, language, self-agency and theory of mind. Recent investigations have demonstrated the partition of the TPJ in discrete subsectors. Nonetheless, whether these subsectors play different roles or implement an overarching function remains debated. Here, based on a review of available evidence, we propose that the left TPJ codes both matches and mismatches between expected and actual sensory, motor, or cognitive events while the right TPJ codes mismatches. These operations help keeping track of statistical contingencies in personal, environmental, and conceptual space. We show that this hypothesis can account for the participation of the TPJ in disparate cognitive functions, including "humour", and explain: a) the higher incidence of spatial neglect in right brain damage; b) the different emotional reactions that follow left and right brain damage; c) the hemispheric lateralisation of optimistic bias mechanisms; d) the lateralisation of mechanisms that regulate routine and novelty behaviours. We propose that match and mismatch operations are aimed at approximating "free energy", in terms of the free energy principle of decision-making. By approximating "free energy", the match/mismatch TPJ system supports both information seeking to update one's own beliefs and the pleasure of being right in one's own' current choices. This renewed view of the TPJ has relevant clinical implications because the misfunctioning of TPJ-related "match" and "mismatch" circuits in unilateral brain damage can produce low-dimensional deficits of active-inference and predictive coding that can be associated with different neuropsychological disorders.(c) 2022 Elsevier B.V. All rights reserved
Anticipatory and target related “match/mismatch” activities of the TPJ
No full textBasing on available evidence, here we consider that the left and right TPJ display increased activity both when anticipating a behaviorally relevant target event and at the moment of post-target processing. This evidence might help resolving debated issues on the function of the TPJ
Selective reorienting response of the left hemisphere to invalid visual targets in the right side of space. Relevance for the spatial neglect syndrome
No full textIn humans, damage in the right hemisphere often provokes the striking inability to attend the left side of space, i.e. left spatial neglect. For years the leading hypothesis for the higher epidemiological incidence of left over right spatial neglect has been that the right hemisphere can orient attention to both sides of space while the left hemisphere only to the right side. Because of this hemispheric specialization, patients with lesion in the left hemisphere do not usually suffer right spatial neglect. Though comprehensive and very influential, to date, this explanation only found clear support in a MEG investigation into stimulus driven shifts of auditory attention. In contrast, no evidence for the same hypothesis was ever gathered from studies of visual attention run with behavioral paradigms that have importantly influenced the interpretation and modeling of attentional deficits in left spatial neglect. Here we report the first fMRI evidence directly supporting this long-standing hypothesis on the hemispheric lateralisation of mechanisms regulating orienting of spatial attention in the human brain. By demonstrating that the left hemisphere selectively reorients attention to invalidly cued visual targets in the right side of space we provide a more comprehensive account for deficits of spatial attention suffered by right brain damaged patients with left unilateral neglect
Two different endoscopic procedures made feasible by the Janus mask in a high-risk patient
No full textThe Janus mask is a full face mask designed for providing noninvasive ventilation (NIV) during any kind of upper endoscopies (e.g., fiber-optic bronchoscopy, gastrointestinal endoscopy, and transesophageal echocardiography). Due to its unique conformation, its use can be considered for both elective and urgent endoscopic procedures in high-risk patients. In this case report, we present a patient with acute respiratory failure who underwent two consecutive different endoscopic procedures (fiber-optic bronchoscopy and gastrointestinal endoscopy) during continuous positive airway pressure support by means of this novel NIV mask, thus avoiding tracheal intubation and at the same time, improving his respiratory condition
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