Sergio Chieffi - Academia.edu (original) (raw)

Papers by Sergio Chieffi

Journal of Psychiatry, 2016

Asymmetries of visuospatial attention has long been described in hemispatial neglect, a neurologi... more Asymmetries of visuospatial attention has long been described in hemispatial neglect, a neurological syndrome in which brain damaged patients fail to acknowledge or explore stimuli presented to the contralesional side of space. Asymmetries for spatial attention were also investigated in schizophrenia. In this review, we report the researches that, using tasks selectively employed to study visuospatial processing in neglect patients, demonstrated hemineglect-like behaviour in schizophrenia. Intriguingly, these studies produced mixed evidence. Some researches found biases towards the left hemispace suggesting a right hemineglect, others towards the right hemispace suggesting a left hemineglect. We examine the possible factors that may have contributed in producing these conflicting findings.

Neuropsychologia, 1992

In this investigation we studied the influence of object velocity on the transport and on the gra... more In this investigation we studied the influence of object velocity on the transport and on the grasp components of prehension movements directed to approaching objects. Three experiments were carried out. In the first experiment six subjects were required to reach and grasp a sphere that approached them with a constant velocity. The effects of four velocities were studied. The results showed that the end point of the arm movement changed with object velocity: nearer the body with higher than with lower object velocities. Transport velocity increased with movement amplitude and the deceleration phase decreased in duration with higher object velocities. On the contrary the grasp component was not affected by object velocity. The second experiment was a control experiment carried out in order to verify whether a possible influence of object velocity on the grasp could be revealed in an experimental condition in which grasp planning relies without doubt on visual computation of all object features. In this experiment object velocity and object size were randomly varied. The results showed that the grasp was not influenced by object velocity, whereas it was sensitive to changes of object size. The third experiment had the twofold aim of establishing (1) whether transport velocity was influenced by object velocity once the location in space at which the object had to be grasped was fixed and (2) whether the grasp kinematics differed for prehension movements directed respectively to stationary or to moving objects. Results showed that the first part of the transport is affected only by distance, whereas the deceleration phase decreased with increasing object velocity. This last result suggests that subjects minimized object displacements in order to grasp the sphere correctly. The grasp component differed between the conditions of stationary and moving stimuli only in the relative timing between finger aperture and closure phases. The closure phase decreased in the condition of moving stimuli. The results of the three experiments indicate the dependence of transport parameters on object velocity, whereas grasp parameters appear to be unaffected.

Histology and histopathology, 2014

Although testicular germ cell tumors (TGCTs) are relatively uncommon, they are particularly impor... more Although testicular germ cell tumors (TGCTs) are relatively uncommon, they are particularly important, as they tend to affect children and young men, the most common tumor being in males aged from 20 to 40 years, and the incidence has been increasing in the last years. TGCTs comprise two major histologic groups: seminomas and non-seminomas germ cell tumors (NSGCTs). NSGCTs can be further divided into embryonal, carcinoma, Teratoma, yolk sac tumor, and choriocarcinoma. Seminomas and NSGCTs present significant differences in clinical features, therapy, and prognosis, and both show characteristics of the Primordial Germ Cells (PGCs). For proper diagnosis of the different histological subgroups, immunohistochemistry is required using different molecular markers, such as Aurora B, GPR30, Nek2, HMGA1, HMGA2, and others, and they could represent useful novel molecular targets for antineoplastic strategies. More insight into the pathogenesis of TGCTs is likely to contribute not only to bett...

Journal of endocrinological investigation, 2012

Testicular germ cell tumors (TGCT), are the most frequent solid malignant tumors in men 20-40 yr ... more Testicular germ cell tumors (TGCT), are the most frequent solid malignant tumors in men 20-40 yr of age, and the most frequent cause of death from solid tumors in this age group. TGCT can be subdivided into seminoma and nonseminoma germ cell tumors (NSGCT), including embryonal cell carcinoma, choriocarcinoma, yolk sac tumor, and teratoma. Seminomas and NSGCT do not only present distinctive clinical features, but they also show significant differences as far as therapy and prognosis are concerned. Many novel markers have given further advantages to discriminate between histological subgroups. In addition, therapeutic approaches for the treatment of TGCT have been proposed: humanized antibodies against receptors/surface molecules on cancer cells, inhibitors of serine-threonine, and tyrosine kinases, and others. The review will focus on the recent advances in the research of molecular alterations identified in TGCT and on novel targeted anti-neoplastic strategies that might help to tre...

Current Medicinal Chemistry, 2013

Behavioural Brain Research, 2009

We examined whether and how deictic gestures and words influence each other when the content of t... more We examined whether and how deictic gestures and words influence each other when the content of the gesture was congruent or incongruent with that of the simultaneously produced word. Two experiments were carried out. In Experiment 1, the participants read aloud the deictic word 'QUA' ('here') or 'LA" ('there'), printed on a token placed near to or far from their body. Simultaneously, they pointed towards one's own body, when the token was placed near, or at a remote position, when the token was placed far. In this way, participants read 'QUA' ('here') and pointed towards themselves (congruent condition) or a remote position (incongruent condition); or they read 'LA" ('there') and pointed towards a remote position (congruent condition) or themselves (incongruent condition). In a control condition, in which a string of 'X' letters was printed on the token, the participants were silent and only pointed towards themselves (token placed near) or a remote position (token placed far). In Experiment 2, the participants read aloud the deictic word placed in the near or far position without gesturing. The results showed that the congruence/incongruence between the content of the deictic word and that of the gesture affected gesture kinematics and voice spectra. Indeed, the movement was faster in the congruent than in the control and incongruent conditions; and it was slower in the incongruent than in the control condition. As concerns voice spectra, formant 2 (F2) decreased in the incongruent conditions. The results suggest the existence of a bidirectional interaction between speech and gesture production systems.

Behavioural Brain Research, 1992

Tile temporal coupling between the transport and grasp components of prehension movements was inv... more Tile temporal coupling between the transport and grasp components of prehension movements was investigated through two experiments. In Experiment !, six normal subjects were required to reach and grasp each of three spheres located at three different distances (Blocked trials). In Experiment 2, a visual perturbation paradigm was used in which the location of the object to be reached and grasped could change at the beginning ofarm movement (Perturbed trials). The same subjects participated in both experiments. Kinematics of wrist trajectory (transport component) and ofdistance between thumb and index finger (grasp component) were analyzed. The results of Experiment 1 showed that the two components could be temporally coupled during their time course. In Experiment 2, the visual perturbation affected both the components, but different times were required by each component to reorganize the movement towards the new target. These different times caused the decoupling of those events that appeared synchronized in Experiment 1. Finally, evidence was found to suggest that planning of grip formation takes into account not only the perceived characteristics of the object, but also the time planned by the transport component to reach the object.

Behavioral and Brain Sciences, 2004

ABSTRACT

Cortex, 1989

We investigated whether the errors made by aphasic patients and right brain-damaged (RBD) patient... more We investigated whether the errors made by aphasic patients and right brain-damaged (RBD) patients on a word-picture matching test were differently related to the semantic and perceptual difficulties of the task. To this effect, the target picture was presented in one condition along with two semantically similar distractors, in another condition with two perceptually similar distractors, and in a third condition with two distractors that were both semantically and perceptually similar. There were also two control conditions in which part of targets that had been originally shown with semantic distractors were now presented with perceptual distractors and vice versa. The findings were consistent with the hypothesis that aphasics mainly fail when the task involves semantic discrimination and RBD patients when it involves perceptual discrimination. In aphasics the semantic perceptual condition produced the highest number of errors, but this was due, it was argued, to an increase of the semantic demands of the task.