Biomedical subjects

Fabio Marconato

Publications and source records attributed to Fabio Marconato.

5 recordsLinked to original sources

PubMed2006

Periventricular leukomalacia specifically affects cortical MEG response to biological motion.

OBJECTIVE: Periventricular leukomalacia (PVL) underlies most of the neurological morbidity including visual-perceptual deficits in survivors of premature birth. However, it is unknown whether and, if so, how PVL affects functional cortical activity. METHODS: Here, we assessed changes in the magnetoencephalographic (MEG) response to visual displays depicting human locomotion in adolescents who were born premature with magnetic resonance imaging signs of PVL. RESULTS: Dynamics of MEG activity parallel behavioral deficits. Early (140-170 milliseconds) brain activation over the right parietal cortex was weaker in patients compared with term-born controls. INTERPRETATION: This is the first evidence for stimulus-specific modulation of cortical activity by periventricular lesions providing new insights into the functional pathology of PVL.

Adolescent↗

PubMed2005

Visually inexperienced chicks exhibit spontaneous preference for biological motion patterns.

When only a small number of points of light attached to the torso and limbs of a moving organism are visible, the animation correctly conveys the animal's activity. Here we report that newly hatched chicks, reared and hatched in darkness, at their first exposure to point-light animation sequences, exhibit a spontaneous preference to approach biological motion patterns. Intriguingly, this predisposition is not specific for the motion of a hen, but extends to the pattern of motion of other vertebrates, even to that of a potential predator such as a cat. The predisposition seems to reflect the existence of a mechanism in the brain aimed at orienting the young animal towards objects that move semi-rigidly (as vertebrate animals do), thus facilitating learning, i.e., through imprinting, about their more specific features of motion.

Animals↗

PubMed2004

Recruitment of periventricular parietal regions in processing cluttered point-light biological motion.

Recent findings point to the existence of a cortical-subcortical parietal network that drives attention-related integration of features and elements. Here we ask whether the functioning of this network might be modulated by early periventricular lesions. To this end, a cohort of adolescents who were born premature with different severity of bilateral periventricular leukomalacia (PVL) and two groups of matched peers (term-born adolescents and former preterms with normal MRI scan) were shown a set of impoverished point-light stimuli. Observers had to detect a point-light walker embedded in an array of distracters mimicking the motion of the target's dots. Patients exhibited higher susceptibility to distortions caused by distracters. In patients only, sensitivity to the point-light figure highly correlates not just with performance on additionally administered feature integration tasks but also on visual attention-demanding IQ tasks. Moreover, the sensitivity index, as well as the values of both IQ factors, decreases with an increase in the volumetric PVL extent in the parieto-occipital region. No relationship was found between these variables and the lesion extent in the frontal or temporal periventricular regions. The data suggest that visual integration and attention in processing cluttered point-light displays are intimately connected. Most importantly, periventricular parieto-occipital regions might be part of a distributed network recruited in deployment of the posterior attentional system. The functioning of this system seems to be vulnerable to bilateral periventricular damage even if it occurs very early in brain development.

Adolescent↗

PubMed2004

Hemispheric differences in the recognition of partly occluded objects by newly hatched domestic chicks (Gallus gallus).

Domestic chicks are capable of perceiving as a whole objects partly concealed by occluders ("amodal completion"). In previous studies chicks were imprinted on a certain configuration and at test they were required to choose between two alternative versions of it. Using the same paradigm we now investigated the presence of hemispheric differences in amodal completion by testing newborn chicks with one eye temporarily patched. Separate groups of newly hatched chicks were imprinted binocularly: (1) on a square partly occluded by a superimposed bar, (2) on a whole or (3) on an amputated version of the square. At test, in monocular conditions, each chick was presented with a free choice between a complete and an amputated square. In the crucial condition 1, chicks tested with only their left eye in use chose the complete square (like binocular chicks would do); right-eyed chicks, in contrast, tended to choose the amputated square. Similar results were obtained in another group of chicks imprinted binocularly onto a cross (either occluded or amputated in its central part) and required to choose between a complete or an amputated cross. Left-eyed and binocular chicks chose the complete cross, whereas right-eyed chicks did not choose the amputated cross significantly more often. These findings suggest that neural structures fed by the left eye (mainly located in the right hemisphere) are, in the chick, more inclined to a "global" analysis of visual scenes, whereas those fed by the right eye seem to be more inclined to a "featural" analysis of visual scenes.

Animals↗

PubMedDate not supplied

A rapid screening measure for the identification of visuospatial learning disability in schools.

Verbal and nonverbal forms of developmental learning disabilities have been reported. Whereas there are several instruments for evaluating children for the presence of verbal learning disabilities at school, no screening tool is available to identify children who have nonverbal learning disabilities. This study aimed at devising and validating a short screening questionnaire that can be used by teachers in primary schools to identify those children who need to be referred for clinical services because they have a visuospatial learning disability (VSLD). An 18-item Shortened Visuospatial Questionnaire (SVS) was derived from an earlier, longer version. Its validation procedure was twofold and was achieved by (a) verifying that children who had been identified with the SVS questionnaire as having a VSLD actually showed visuospatial deficits on psychometric evaluation and by (b) rating with the SVS a clinically identified population of children with VSLD. The results of the validation procedure showed that the SVS is a quick, reliable, and valid instrument that may be helpful in identifying children with VSLD in primary school.

Adolescent↗