PubMed Health⌕ Search

Biomedical subjects

Gaspare Galati

Publications and source records attributed to Gaspare Galati.

18 recordsLinked to original sources
PubMed2006

Neural bases of personal and extrapersonal neglect in humans.

Human awareness of left space may be disrupted by cerebral lesions to the right hemisphere (hemispatial neglect). Current knowledge on the anatomical bases of this complex syndrome is based on the results of group studies that investigated primarily the best known aspect of the syndrome, which is visual neglect for near extrapersonal (or peripersonal) space. However, another component-neglect for personal space-is more often associated with, than double-dissociated from, extrapersonal neglect, especially, in chronic patients. The present investigation aimed at exploring the anatomical substrate of both extrapersonal and personal neglect by using different advanced methodological approaches to lesion-function correlation. Fifty-two right ischaemic patients were submitted to neuropsychological assessment and in-depth MRI evaluation. The borders of each patient's lesion were delimited onto its own high-resolution anatomical image and then submitted to an automated spatial normalization algorithm. Besides conventional lesion density plots and subtraction analysis, region-based statistical analyses were performed on percentage values of the lesioned tissue also using a new parcellation of the white matter (WM). Data were finally submitted to voxelwise statistical analysis using a recently proposed method (voxel-based lesion-symptom mapping). Results converged in showing that awareness of extrapersonal space is based on the integrity of a circuit of right frontal (ventral premotor cortex and middle frontal gyrus) and superior temporal regions, whereas awareness of personal space is rooted in right inferior parietal regions (supramarginal gyrus, post-central gyrus and especially the WM medial to them). Common but less crucial regions for both neglect sub-types were located in the temporo-peri-Sylvian cortex. We suggest that extrapersonal space awareness critically involves a ventral circuit recently described for the exogenous allocation and reorienting of attention in space. Disruption of personal space awareness, instead, seems to be due to a functional disconnection between regions important for coding proprioceptive and somatosensory inputs, and regions coding more abstract egocentric representations of the body in space. In conclusion, present data strongly support a segregation of personal and extrapersonal spatial awareness in humans, both from a functional and an anatomical point of view.

Adult↗
PubMed2006

Wide-field retinotopy defines human cortical visual area v6.

The retinotopic organization of a newly identified visual area near the midline in the dorsalmost part of the human parieto-occipital sulcus was mapped using high-field functional magnetic resonance imaging, cortical surface-based analysis, and wide-field retinotopic stimulation. This area was found in all 34 subjects that were mapped. It represents the contralateral visual hemifield in both hemispheres of all subjects, with upper fields located anterior and medial to areas V2/V3, and lower fields medial and slightly anterior to areas V3/V3A. It contains a representation of the center of gaze distinct from V3A, a large representation of the visual periphery, and a mirror-image representation of the visual field. Based on similarity in position, visuotopic organization, and relationship with the neighboring extrastriate visual areas, we suggest it might be the human homolog of macaque area V6, and perhaps of area M (medial) or DM (dorsomedial) of New World primates.

Animals↗
PubMed2006

Endoscopic retrograde cholangiography for intrabiliary rupture of hydatid cyst.

BACKGROUND: Hydatid disease affects most commonly the liver, and rupture into the bile ducts is a frequent complication, occurring in 5% to 25% of cases. These complications can cause major clinical problems either preoperatively or postoperatively with post-resectional abscess or prolonged biliary fistula. We reviewed our experience with preoperative endoscopic retrograde cholangiography (ERC) and the diagnosis of major cyst-biliary fistula. METHODS: During a 7-year period, 78 patients underwent surgery for hepatic hydatid disease. Ten patients, in whom a major intrabiliary rupture of the cyst was suspected on the basis of clinical and radiological criteria, underwent preoperative ERC, with clearing of the biliary tree. Endoscopic sphincterotomy was performed in 7 cases when the fluid contained daughter cysts or pus. Three patients, in whom the biliary content was fluid only, did not undergo sphincterotomy. One patient in whom a preoperative ERC was not feasible underwent operative transduodenal sphincterotomy. In all 11 patients the cyst was resected. Two patients underwent preoperative ERC, but no fistula was detected . They were compared with the remaining group of 67 patients who underwent resectional surgery during the same period, for apparently uncomplicated echinococcal cysts, and with an historical group of 569 patients operated on from January 1966 to January 1995. RESULTS: According to the clinical and radiological preoperative criteria, there were 2 false positives. Preoperative ERC allowed visualization of the fistula, clearing of the biliary tree, and sphincterotomy in selected cases. The incidence of postoperative fistula was significantly decreased after the introduction of selective preoperative ERC, on the basis of preoperative clinical and radiological criteria. CONCLUSIONS: Preoperative ERC is very helpful in patients with cyst-biliary fistula, allowing visualization of the fistula and drainage of the biliary tree, and reducing the incidence of postoperative complications from 11.1% to 7.6%. In selected cases it can solve the problem, without further surgical therapy.

Biliary Fistula↗
PubMed2006

Functional anatomy of derivational morphology.

Lexical morphology involves two types of suffixes: inflectional suffixes, which have a grammatical function, and derivational suffixes with a word formation function. In this study, functional magnetic resonance imaging (fMRI) was used during processing of Italian derived and inflected words. In the derivational task, subjects were asked to produce nouns derived from verbs and from adjectives (e.g., to observe--observation; kind--kindness). After the presentation of the derived noun, they had to generate the corresponding verb (e.g., failure--to fail: generation task). In the inflectional task, subjects had to produce the past participle of the verb or the plural form of the adjective or the derived noun. Behavioural data were collected in separate sessions in two different conditions. In the first experiment, as in the fMRI study, vocal reaction times (RTs) were measured from the offset of the auditory stimulus to the onset of the participant's response. In the second experiment, run with a different group of participants, RTs were recorded starting from the onset of the auditory stimulus to the onset of the response. The fMRI results showed that, relative to the inflectional task and to a repetition task, the derivational task, but not the verb generation task, brought about an activation of left fronto-parietal regions, documenting a specific involvement of these areas in the processing of derived words. Although less extended, similar activation was found for verb inflection but was absent for noun and adjective plural forms. Analysis of behavioral data indicated that an explanation in terms of task difficulty was unlikely related to the imaging results.

Adult↗
PubMed2005

The appreciation of wine by sommeliers: a functional magnetic resonance study of sensory integration.

We set out to investigate how the expertise of a sommelier is embodied in neural circuitry by comparing brain activity elicited by wine tasting with that found in naive drinkers of wine. We used fMRI to study 7 sommeliers and 7 age- and sex-matched control subjects to test the hypothesis that any difference in brain activity would reflect a learned ability to integrate information from gustatory and olfactory senses with past experience. A group analysis showed activation of a cerebral network involving the left insula and adjoining orbito-frontal cortex in sommeliers. Both these areas have been implicated in gustatory/olfactory integration in primates. In addition, activation was found bilaterally in the dorsolateral prefrontal cortex, which is implicated in high-level cognitive processes such as working memory and selection of behavioral strategies. Naive individuals activated the primary gustatory cortex and brain areas, including the amygdala, implicated in emotional processing.

Adult↗
PubMed2005

Neural systems underlying observation of humanly impossible movements: an FMRI study.

Previous studies have indicated that largely overlapping parts of a complex, mainly fronto-parietal, neural network are activated during both observation and execution of an action. If these two processes are inextricably linked, increases of neural activity contingent upon action observation should be found only for movements that can actually be performed. Using functional magnetic resonance imaging, we investigated whether observation of possible and biomechanically impossible movements of fingers activated the same neural systems. Thirteen healthy subjects were scanned during observation of video-clips showing abduction/adduction movements of the right index or the little finger, which were defined as biomechanically possible or impossible according to the range of their angular displacement at the metacarpo-phalangeal joint. The mere observation of possible and impossible hand movements induced a selective activation of left precentral and left inferior frontal regions, thus indicating that motor-related areas map body actions even when they violate the constraints of human anatomy. An increase of the blood oxygen level-dependent signal selectively linked to observation of impossible hand movements was found in sensorimotor parietal regions. Our results suggest that while premotor areas code human actions regardless of whether they are biologically possible or impossible, sensorimotor parietal regions may be important for coding the plausibility of actions.

Adult↗
PubMed2005

Transcranial magnetic stimulation highlights the sensorimotor side of empathy for pain.

Pain is intimately linked with action systems that are involved in observational learning and imitation. Motor responses to one's own pain allow freezing or escape reactions and ultimately survival. Here we show that similar motor responses occur as a result of observation of painful events in others. We used transcranial magnetic stimulation to record changes in corticospinal motor representations of hand muscles of individuals observing needles penetrating hands or feet of a human model or noncorporeal objects. We found a reduction in amplitude of motor-evoked potentials that was specific to the muscle that subjects observed being pricked. This inhibition correlated with the observer's subjective rating of the sensory qualities of the pain attributed to the model and with sensory, but not emotional, state or trait empathy measures. The empathic inference about the sensory qualities of others' pain and their automatic embodiment in the observer's motor system may be crucial for the social learning of reactions to pain.

Adult↗
PubMed2004

Intrahepatic accessory spleen: imaging features.

The authors present a case report of a 60-year-old man with a hepatic unknown mass. For diagnosis, they used ECO, CT (with and without contrast), MR (with and without contrast) and an ultrasound-assisted percutaneous lesion biopsy. Thus the mass-lesion in the liver appeared to be an intrahepatic accessory spleen in a patient afflicted with chronic hepatitis.

Chronic Disease↗
PubMed2004

Reference frames for spatial cognition: different brain areas are involved in viewer-, object-, and landmark-centered judgments about object location.

Functional magnetic resonance imaging was used to compare the neural correlates of three different types of spatial coding, which are implicated in crucial cognitive functions of our everyday life, such as visuomotor coordination and orientation in topographical space. By manipulating the requested spatial reference during a task of relative distance estimation, we directly compared viewer-centered, object-centered, and landmark-centered spatial coding of the same realistic 3-D information. Common activation was found in bilateral parietal, occipital, and right frontal premotor regions. The retrosplenial and ventromedial occipital-temporal cortex (and parts of the parietal and occipital cortex) were significantly more activated during the landmark-centered condition. The ventrolateral occipital-temporal cortex was particularly involved in object-centered coding. Results strongly demonstrate that viewer-centered (egocentric) coding is restricted to the dorsal stream and connected frontal regions, whereas a coding centered on external references requires both dorsal and ventral regions, depending on the reference being a movable object or a landmark.

Adult↗
PubMed2003

Cortical modulation of whole body movements in brain-damaged patients.

The aim of the present study was to assess whether the consistent bias in reproducing distances and lengths on visual tasks that characterizes hemispatial neglect is also present when whole body displacements have to be calculated and reproduced. Two different experiments were proposed to participants with right brain lesions and neglect syndrome (RN+), right (RN-) and left brain lesions (LN-) without neglect and to participants without brain damage (C). In Experiment 1, participants actively reproduced passive linear displacements in the same or in a different direction. This task could be performed using only vestibular and somatosensory input, since no relevant visual input was available. In Experiment 2, relevant visual information had to be integrated with vestibular and somatosensory information in order to make the active reproduction. In Experiment 1, all brain-damaged groups reproduced the horizontal displacements similarly to the control group and without any spatial asymmetry. In Experiment 2, when vestibular, somatosensory and visually remembered information was required to produce an integrated mental representation, RN+ processed contralesional displacements differently from ipsilesional ones. Rectilinear displacements of the whole body in space were not affected by focal left and right brain lesions, suggesting that the computation of nonvisual information can be accomplished by brain structures different from those involved in spatial visual processes. However, when body displacements in space required a mental representation based on visual and nonvisual sensory information, a significant asymmetry appeared only in patients with hemispatial neglect. Some attempts are made to identify the neural substrates involved in this integration.

Aged↗
PubMed2002

Horizontal space misrepresentation in unilateral brain damage. I. Visual and proprioceptive-motor influences in left unilateral neglect.

Patients with unilateral neglect can misperceive horizontal distances in the contralesional space as being shorter than equivalent ipsilesional ones. We evaluated the visual and motor-proprioceptive components of space misrepresentation through a distance reproduction task performed both with and without visual guidance. Four groups of right brain damaged patients (neglect with hemianopia (N+H+), neglect with inferior quandrantanopia (N+Q+), neglect without hemianopia (N+H-) and patients without neglect or hemianopia (N-H-)) and one group of healthy controls (C) performed the line bisection task and reproduced horizontal distances either by setting the endpoints or by doubling the length of a line in the contralesional or ipsilesional space. The doubling length task was administered in three different conditions: (a) visuomotor (the patient draws the line in free vision); (b) visual (by sight the patient guides the examiner drawing the line); (c) proprioceptive-motor (the patient is blindfolded and manually inspects and extends the horizontal distance subtended by the line). Compared to C and N-H- patients, only N+H+ patients exhibited a significant ipsilesional shift in line bisection. N+H+ patients showed the most severe contralesional-overextension/ipsilesional-underextension asymmetry in the endpoint, visuomotor and visual line extension task. In the proprioceptive-motor condition no asymmetry was found and N+H- showed greater overextension on both sides of space. In N+H-, brain damage was mainly centered in central-frontal cortex and basal ganglia. These findings re-emphasize the relevance of damage to visual retinotopically organized representations of space in the genesis of horizontal space misrepresentation of neglect patients and suggest the possible association of a non-lateralized defective processing of proprioceptive-motor information with unilateral neglect.

Adult↗
PubMedDate not supplied

Hürthle cell tumors of the thyroid gland. Personal experience and review of literature.

BACKGROUND: Oncocytic cell neoplasm of the thyroid is currently recognized as a histological entity, but doubts still exist about its clinical and evolutionary categorization. Controversies concern occurrence and frequency of malignant forms, natural history and therapeutic strategies. MATERIALS AND METHODS: The authors report six cases of Hürthle cell tumor. Five cases were adenoma, one was carcinoma. Morpho-functional pre-operative evaluation and inter-operative histopathological test were performed in all patients. One patient underwent lobectomy (absence of unusual characteristics of the adenoma Hürthle cell) and five underwent total thyroidectomies (1 carcinoma). All patients were treated with suppressive hormonal therapy. RESULTS: No mortality and morbidity was recorded. All patients are undergoing follow-up (adenomas: average 64.2 months; carcinoma: 132 months) and none of them show recurrent symptoms. DISCUSSION: Hürthle cell tumors can be diversified in adenoma and carcinoma. Almost all reports classify oncocytic nodules as malignant when capsular and/or vascular invasion is present or when there is peri-thyroid tissue infiltration or lymphatic or hematic metastases. A clear differentiation between adenoma and carcinoma is determined by a histological test. Also an intra-operative histopathological analysis is sometimes unable to show minimal signs of invasion. Conflicting observations about the biological behaviour of Hürthle cell neoplasm lead to different therapeutic strategies. The authors believe lobectomy is the treatment of choice when a clear histological diagnosis of adenoma has been made. When carcinoma is diagnosed or when doubts exist after intraoperative histological test, the authors recommend total thyroidectomy followed by scintigraphic test and preventive radio-active therapy. All patients should be treated with suppressive hormonal therapy and undergo periodic check-ups.

Adenoma, Oxyphilic↗
PubMedDate not supplied

Significance of T stadium and grading as prognostic factors in transitional cell carcinoma of the ureter.

BACKGROUND: Surgery is nowadays the standard treatment for carcinoma of the ureter, even if adjuvant therapies can modify the prognosis in selected patients. Because of the small number of patients in the literature series, the significance of prognostic factors that can be used in clinical practice is still controversial, as is the choice of the most suitable surgical and adjuvant treatment. PATIENTS AND METHODS: We considered 27 consecutive patients (Ta-T2 N0 M0) who underwent radical surgery (nephroureterectomy with bladder cuff excision and lymphoadenectomy) for transitional cell carcinoma of the ureter, from 1982 through 1992. Seven patients (25.9%) had Ta tumors, 7 patients (25.9%) had T1 tumors and 13 patients (48.2%) had T2 tumors. In 4 cases (14.8%) the tumor was well-differentiated (G1), in 14 cases (51.8%) it was mildly-differentiated (G2), and in 9 cases (33.4%) it was poorly-differentiated. RESULTS: Thirteen of the 14 patients affected by Ta-T1 tumors were alive 10 years after surgery (one patient lost at follow-up); in the T2 tumor group the 5-year survival rate was 84.6% and 10-year survival rate was 69.2%. According to grading, the 10-year survival rate was 100% for G1 tumors, the 3, 5 and 10-year survival rates were, respectively, 100%, 92.8% G3 tumors. CONCLUSION: Data from our study show the significance of the T stage and grading as prognostic factors.

Aged↗