Biomedical subjects

S Pitzalis

Publications and source records attributed to S Pitzalis.

12 recordsLinked to original sources

PubMed2005

Cortical plasticity following surgical extension of lower limbs.

Human cortical plasticity has been studied after peripheral sensory alterations due to amputations or grafts, while sudden 'quasi-physiological' changes in the dimension of body parts have not been investigated yet. We examined the cortical reorganization in achondroplastic dwarfs submitted to progressive elongation (PE) of lower limbs through the Ilizarov technique. This paradigm is ideal for studying cortical plasticity because it avoids the perturbation connected with deafferentation and re-afferentation. Somatosensory evoked-potentials (SEP) and fMRI studies were performed before and after PE during foot and knee stimulation, above and below the surgical fracture. A body schema test was also performed. Following PE, cortical modifications were observed in the primary somatosensory cortex for foot stimulation and in higher order somatosensory cortices for foot and knee. The former modifications tended to decrease 6 months after the elongation ending, whereas the latter tended to persist. Results are interpreted in terms of cortical adaptation mediated by temporary disorganization.

Achondroplasia↗

PubMed2004

Separate neural systems for processing action- or non-action-related sounds.

The finding of a multisensory representation of actions in a premotor area of the monkey brain suggests that similar multimodal action-matching mechanisms may also be present in humans. Based on the existence of an audiovisual mirror system, we investigated whether sounds referring to actions that can be performed by the perceiver underlie different processing in the human brain. We recorded multichannel ERPs in a visuoauditory version of the repetition suppression paradigm to study the time course and the locus of the semantic processing of action-related sounds. Results show that the left posterior superior temporal and premotor areas are selectively modulated by action-related sounds; in contrast, the temporal pole is bilaterally modulated by non-action-related sounds. The present data, which support the hypothesis of distinctive action sound processing, may contribute to recent theories about the evolution of human language from a mirror system precursor.

Acoustic Stimulation↗

PubMed2001

Mapping of contralateral space in retinotopic coordinates by a parietal cortical area in humans.

The internal organization of a higher level visual area in the human parietal cortex was mapped. Functional magnetic resonance images were acquired while the polar angle of a peripheral target for a delayed saccade was gradually changed. A region in the superior parietal cortex showed robust retinotopic mapping of the remembered target angle. The map reversed when the direction of rotation of the remembered targets was reversed and persisted unchanged when study participants detected rare target reappearances while maintaining fixation, or when the eccentricity of successive remembered targets was unpredictable. This region may correspond to the lateral intraparietal area in macaque monkeys.

Brain Mapping↗

PubMed2001

Influence of the radial and vertical dimensions on lateral neglect.

The influence of radial (near-far) and vertical (upper-lower) dimensions on lateral visuo-spatial neglect was studied using two horizontal line-bisection tasks (one motor and one perceptual). A group of 15 patients with neglect and a group of 14 right-brain damaged patients without neglect were examined. This latter group was used to define the range of variability in line-bisection performance that was independent of neglect. For the radial dimension, some neglect patients showed greater errors in far space than in near space (for both stimuli presented in the upper and lower space). Fewer patients showed the opposite pattern (i.e., greater errors for near-space stimuli). These near-far asymmetries were present for both the motor and perceptual conditions and showed a good degree of intra-individual consistency. This finding contradicts the hypothesis that the motor component is critical for yielding such asymmetry. For the vertical dimension, the results indicated that neglect patients make more bisection errors for lower-space stimuli than for upper-space stimuli. This vertical asymmetry was nearly always confined to stimuli in near space. Asymmetries along the vertical dimension were present for both perceptual and motor conditions, although intra-individual consistency was low. When perceptual and motor conditions were directly compared, several neglect patients showed greater errors in the perceptual than in the motor task.

Aged↗

PubMed2001

Spatial anisotropy of saccadic latency in normal subjects and brain-damaged patients.

In the present study, reaction time of oblique and orthogonal saccades was investigated in normal subjects and in two groups of patients with right (RBD) and left (LBD) vascular cerebral lesions and no signs of spatial neglect. Clear altitudinal effects were present in each group of subjects: saccadic latencies were longer in the lower than in the upper part of the visual field for both orthogonal and oblique saccades. Asymmetry along the horizontal meridian was present only in case of right hemisphere damage. This supports the view that a lesion in the right hemisphere causes a greater deficit of visual-spatial processing than a left hemisphere lesion. A cerebral lesion in the right and/or left hemisphere produces a general slowing in the saccadic latency and a general reduction in the accuracy of saccades with respect to normal subjects performance. Further, it seems that making saccades in oblique direction reduces the general saccade efficiency.

Adult↗

PubMed2000

Autosomal dominant partial epilepsy with auditory features: description of a new family.

PURPOSE: To report the clinical and genetic study of a new family with autosomal dominant partial epilepsy with auditory features (ADPEAF). METHODS: All the living affected members underwent a full clinical, neurophysiological, and magnetic resonance imaging (MRI) study. Genetic analysis was performed by typing their DNA with seven microsatellite markers previously found to cosegregate with ADPEAF on chromosome 10q24. RESULTS: The three living affected members had a childhood onset of rare and drug-responsive tonic-clonic seizures constantly preceded by a humming sensation. Routine and sleep electroencephalograms revealed rare and inconstant focal abnormalities over both temporal regions. MRI detected atrophy with increased T2 signal in the subcortical lateral portion of the right temporal lobe in one case. Analysis of 10q24 polymorphic alleles showed the same haplotype in all three affected members but different alleles in unaffected individuals. CONCLUSIONS: ADPEAF is a distinct condition with homogeneous clinical features. Genetic findings are consistent with linkage of ADPEAF to chromosome 10q24.

Adolescent↗

PubMed1999

Expression analysis of 21 transcripts physically anchored within the chromosomal region 10q24.

Chromosome band 10q24 harbors the critical regions for inherited neurological disorders such as partial epilepsy (EPT), urofacial syndrome, and a distinct form of spastic paraparesis. To facilitate the selection of candidate genes for these diseases, we determined the mRNA sizes and analyzed the expression patterns of 21 brain transcripts defined by expressed sequence tags previously localized along a 7.4-Mb interval of 10q24. In addition to a number of widely expressed transcribed sequences, we identified several transcripts exclusively or predominantly expressed in the brain, which represent potential candidates for the neurological diseases associated with this genomic region.

Abnormalities, Multiple↗

PubMed1998

Molecular basis of open-angle glaucoma in Italy.

Glaucoma is a group of ocular diseases characterized by an optic neuropathy in which degeneration of retinal ganglion cells leads to a characteristic excavation of the optic nerve head. Primary open-angle glaucoma (POAG) can be subdivided into two groups according to age of onset:- 1. the more common middle- to late-age onset, chronic open-angle glaucoma (COAG) diagnosed after the age of 40 years; 2. the rarer juvenile open-angle glaucoma (JOAG), which is diagnosed between the age of 3 years and early adulthood. Recently, the gene coding for the trabecular meshwork-induced glucocorticoid response protein (TIGR), located in chromosome 1 (1q23-25), was found mutated in patients affected by POAG. In this work we describe the clinical and molecular genetic features of several Italian families affected by autosomal dominant POAG, collected in various regions of Italy.

Adult↗

PubMed1998

Identification of fragmented pictures in patients with brain damage.

Identification of fragmented pictures was investigated using line drawings (Snodgrass, Smith, Feenan, & Corwin, 1987) in 236 healthy participants and 43 patients with unilateral lesions of the right or left hemisphere. Perceptual closure (the integration of fragments into a meaningful perceptual whole) depended on the amount of physical visual information, the age of the patient, and the location of the lesion. Patients with right-side lesions showed more impairment than those with left-side lesions, confirming the importance of the right hemisphere in perceptual closure tasks. Right-hemisphere functions involved in perceptual closure, however, were not completely abolished, as performance improved with increasing visual information. The advantages of Snodgrass fragmented pictures as a neuropsychological test are discussed.

Journal Article↗

PubMed1998

Identification of a novel mutation (S13F) in the CFTR gene in a CF patient of Sardinian origin.

In this paper, we describe a novel CF mutation consisting in a C-->T substitution at nucleotide 170 in exon 1 of CFTR gene, converting a serine residue into phenylalanine at position 12 (S13F) of the CFTR protein. This mutation was detected in a single patient of Sardinian descent in compound heterozygosity with T338I, who presented at 9 years of age with hyponatremic dehydration associated with hypochloremia, hypokaliemia and metabolic alkalosis. Sweat chloride values were 120 mmol/l. Now the patient is 11 years old and has not shown so far any pancreatic or lung involvement. The serine to phenylalanine substitution is a non-conservative change, replacing a non polar for a polar amino acid residue and therefore is most likely a disease-causing mutation.

Child↗

PubMed1997

Vertical neglect: behavioral and electrophysiological data.

Both behavioral and electrophysiological methods were used to assess altitudinal neglect. In the first experiment, 100 patients with neglect completed Albert's Barrage test. Most omissions were present in the lower left quadrant. In 16 patients, visual evoked potentials to stimuli in the four quadrants were separately recorded (Exp. 2). Latencies in the lower left quadrant were longer than those in the other quadrants. A third experiment provided electrophysiological normative data from 13 young normal subjects. Overall, the results showed that both the horizontal and vertical dimensions of space are affected in neglect patients.

Adult↗

PubMed1995

A specific cystic fibrosis mutation (T3381) associated with the phenotype of isolated hypotonic dehydration.

We carried out molecular screening for mutations in the cystic fibrosis transmembrane regulator (CFTR) gene in eight children of Sardinian descent seen because of hypotonic dehydration associated with hyponatremia, hypochloremia, hypokalemia, and metabolic alkalosis; none had pulmonary or pancreatic involvement. All the patients had the T3381 mutation either in homozygosity or compound heterozygosity with another CF mutation. The T3381 mutation was not detected in patients with CF who had classic symptoms or in healthy persons of the same descent. These data suggest that the T3381 mutation is associated with a specific mild CF phenotype.

Child↗