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Biomedical subjects

Giuseppe Sartori

Publications and source records attributed to Giuseppe Sartori.

13 recordsLinked to original sources
PubMed2006

Semantic relevance, domain specificity and the sensory/functional theory of category-specificity.

According to the sensory/functional theory of semantic memory, Living items rely more on Sensory knowledge than Non-living ones. The sensory/functional explanation of category-specificity assumes that semantic features are organised on the basis of their content. We report here a study on DAT patients with impaired performance on Living items and tests of Sensory knowledge, and show that this impairment not only disappears after parcelling out semantic relevance, but is also reversed if this parameter is appropriately manipulated. Although semantic relevance model predicts these results [Sartori, G., & Lombardi, L. (2004). Semantic relevance and semantic disorders. Journal of Cognitive Neuroscience, 16, 439-452], they run counter to both the sensory/functional theory and the domain-specific theory of category-specific impairment.

Aged↗
PubMed2006

Analysis of implantable cardioverter defibrillator signals for non conventional cardiac electrical activity characterization.

Implantable cardioverter defibrillators (ICDs) can store intracardiac electrograms (EGMs) in sinus rhythm (SR), at the onset of spontaneous ventricular tachyarrhythmias (VT) or during their course. This allows the investigation of unknown features of the heart electrical activity associated with different cardiac rhythms. In this study we propose a non conventional cardiac electrical activity characterization (CEAC) that extracts quantitative information about the power spectrum wideness and variability of the beat-by-beat morphology. We analyze 293 EGMs from 40 patients who underwent implantation of St Jude Medical-Ventritex ICDs that allow the storage of EGMs with two different modes of recording: bipolar (BIP) and unipolar or far-field (FF). The EGMs are studied with this CEAC by (1) exploring differences between the CEAC measured from FF and BIP EGMs during similar cardiac rhythms, and (2) investigating the mode of recording that allows a better separation between SR and VT rhythms. Results show that, with similar cardiac rhythm, the CEACs from FF or BIP recordings are different (for SR rhythm: sensitivity 81.5%, specificity 93.6%; for VT rhythm: sensitivity and specificity 100%); thus FF and BIP EGMs analyze different aspects of cardiac activity. The CEAC applied to FF EGMs distinguishes better EGMs obtained during SR from VT rhythms (VT vs SR with sensitivity 92.7% and specificity 79.7%) than when it is applied to BIP signals (VT vs SR with sensitivity 60% and specificity 73.3%).

Defibrillators, Implantable↗
PubMed2005

An ERP study of low and high relevance semantic features.

It is believed that the N400 elicited by concepts belonging to living is larger than N400 to non-living. This is considered as evidence that concepts are organized, in the brain, on the basis of categories. We conducted a feature-verification experiment where living and non-living concepts were matched for relevance of semantic features. Relevance is a measure of the contribution of semantic features to the "core" meaning of a concept. We found that when relevance is low the N400 is large. In addition, we found that when the two categories of living and non-living are equated for relevance the seemingly category effect at behavioral and neural level disappeared. In sum, N400 is sensitive, rather than to categories, to semantic features, thus showing that previously reported effects of semantic categories may arise as a consequence of the differing relevance of concepts belonging to living and non-living categories.

Adult↗
PubMed2005

Semantic relevance explains category effects in medial fusiform gyri.

We used functional Magnetic Resonance Imaging to explore the neural correlates of semantic relevance in 12 healthy participants performing a picture-naming task. In addition, we tested the hypothesis that category effects typically found in functional imaging can be partly explained in terms of different semantic relevance for animals and artefacts. We report that semantic relevance modulates neuronal responses in the medial fusiform gyrus bilaterally. As predicted, category effects in this region are strongly modulated by the semantic relevance of the items. Specifically, the effect of artefacts > animals is greatly reduced when the two categories are matched for semantic relevance. Thus, the present study demonstrates that neuronal responses during concept retrieval are modulated by the semantic relevance of the features. It also suggests that increased activation in the medial fusiform gyrus typically found for artefacts > animals can be explained by different semantic relevance for animal and artefact items.

Adult↗
PubMed2005

Feature type effects in semantic memory: an event related potentials study.

It is believed that the N400 elicited by concepts belonging to Living things is larger than the N400 to Non-living things. This is considered as evidence that concepts are organized, in the brain, on the basis of categories. Similarly, differential N400 to Sensory and Non-sensory semantic features is taken as evidence for a neural organisation of conceptual memory based on semantic features. We conducted a feature-verification experiment where Living and Non-living concepts are described by Sensory and Non-sensory features and were matched for Age-of-Acquisition, typicality and familiarity and finally for relevance of semantic features. Relevance is a measure of the contribution of semantic features to the "core" meaning of a concept. We found that when Relevance is low then the N400 is large. In addition, we found that when the two categories of Living and Non-living concepts are matched for relevance the seemingly category effect at the neural level disappeared. Also no difference between Sensory and Non-sensory descriptions was detected when relevance was matched. In sum, N400 does not differ between categories or feature types. Previously reported effects of semantic categories and feature type may have arisen as a consequence of the differing Relevance of concepts belonging to Living and Non-living categories.

Adult↗
PubMed2005

Category deficits and paradoxical dissociations in Alzheimer's disease and Herpes Simplex Encephalitis.

Most studies examining category specificity are single-case studies of patients with living or nonliving deficits. Nevertheless, no explicit or agreed criteria exist for establishing category-specific deficits in single cases regarding the type of analyses, whether to compare with healthy controls, the number of tasks, or the type of tasks. We examined two groups of patients with neurological pathology frequently accompanied by impaired semantic memory (19 patients with Alzheimer's disease and 15 with Herpes Simplex Encephalitis). Category knowledge was examined using three tasks (picture naming, naming-to-description, and feature verification). Both patient groups were compared with age- and education-matched healthy controls. The profile in each patient was examined for consistency across tasks and across different analyses; however, both proved to be inconsistent. One striking finding was the presence of paradoxical dissociations (i.e., patients who were impaired for living things on one task and nonliving things on another task). The findings have significant implications for how we determine category effects and, more generally, for the methods used to document double dissociations across individual cases in this literature.

Aged↗
PubMed2004

Remote memory in advanced Alzheimer's disease.

The present study investigated remote memory functioning in advanced dementia of Alzheimer type (DAT). Remote memory measures included the Autobiographical Memory Enquiry (AME) and autobiographical fluency (AF), as well as recognition of remote public events and famous faces. Ten DAT patients were selected with Mini-Mental State Exam (MMSE) scores less than 15. Compared to healthy controls, DAT patients were impaired on all measures of remote memory, although autobiographical fluency for names was only borderline impaired. There was no clear evidence of a monotonic temporal gradient with the AME; however, both subjects groups showed better preserved early compared to more recent public-event memory. A measure of semantic fluency was correlated with autobiographical and remote public-event memory among the patients only. Overall, results indicate a minimal outline of preserved remote memory in advanced DAT, with evidence of an association between remote memory performance and executive functioning.

Aged↗
PubMed2004

Malingering and retrograde amnesia: the historic case of the Collegno amnesic.

Assessment of feigned cognitive disorders is an important field of neuropsychology because of its applications to forensic settings. Strategies for detecting malingering in amnesia are available for anterograde amnesia. Less attention has been given to malingering in retrograde amnesia. The case of the 'Smemorato di Collegno' (The Collegno Amnesic) is probably the most famous case of malingered retrograde amnesia ever known in Italy. In 1926, a man who appeared to have lost all his autobiographical memories and identity spent nearly a year in the Collegno asylum of Turin without a name. He was later initially identified as Giulio Canella, Director of the 'Scuola Normale di Verona' who had disappeared during the war in 1916. He was suspected of later identified as being Mario Bruneri, a petty crook from Turin who played the part of an amnesic whose retrograde memory gradually returned. A lengthy investigation was required before this conclusion was reached. Several clinicians and renowned academics evaluated the case, but only Alfredo Coppola, diagnosed "malingered retrograde amnesia" using a method that was extremely innovative for the times. The aim of the present paper is to review the original cognitive evaluation and the strategies used for malingering detection in the "Collegno case". The outcome of the case is then discussed in the light of present-day forensic neuropsychology and the level of advancement of mental examination achieved in the 1920s in Europe is highlighted.

Amnesia, Retrograde↗
PubMed2004

Semantic relevance and semantic disorders.

Semantic features are of different importance in concept representation. The concept elephant may be more easily identified from the feature than from the feature . We propose a new model of semantic memory to measure the relevance of semantic features for a concept and use this model to investigate the controversial issue of category specificity. Category-specific patients have an impairment in one domain of knowledge (e.g., living), whereas the other domain (e.g., nonliving) is relatively spared. We show that categories differ in the level of relevance and that, when concepts belonging to living and nonliving categories are equated to this parameter, the category-specific disorder disappears. Our findings suggest that category specificity, as well as other semantic-related effects, may be explained by a semantic memory model in which concepts are represented by semantic features with associated relevance values.

Adult↗
PubMed2003

He can tell which master craftsman blew a Venetian vase, but he can not name the Pope: a patient with a selective difficulty in naming faces.

A patient with damage to the left fronto-temporal region could not name faces, although his recognition and semantic knowledge of people were found to be intact. At variance with described anomics for persons' names, this patient was able to retrieve on definition names of people whose faces he could not name. When, instead, objects were to be named with a person's name, as in the case of manufacturers of Murano glass, the patient, a Murano glass master, was perfect. That is, he could tell which master craftsman in the famous Venini glass-works in Venice had blown a vase, but he could not identify the Pope from a picture. Naming faces is therefore shown to be independent of naming objects.

Humans↗
PubMed2003

A brief and unobtrusive instrument to detect simulation and exaggeration in patients with whiplash syndrome.

The objective of this study was to develop and test a brief and unobtrusive instrument to detect exaggeration and simulation in whiplash syndrome. The instrument consists of eight scenarios with ten response options that have to be ordered according to how easy a behavior is to perform. Twenty-five simulating and 25 non-simulating patients with whiplash syndrome of grades 2 and 3 according to the Quebec Task Force classification as well as 25 simulating and 25 non-simulating controls completed the instrument. In a cross-validation study 20 controls and 20 patients participated. Malingering and exaggeration scores were determined for each subject and patient. The scores were summed up and compared across malingering and exaggerating subjects and controls and cut-off values were determined to classify the patients. T-tests and a discriminant analysis were used to determine classification accuracy. The instrument correctly identified 94% of the simulators and 84% of the exaggerators in both samples. This brief and unobtrusive instrument can detect exaggeration and simulation in whiplash syndrome.

Adult↗
PubMed2002

Local electrogram assessment of unidirectional isthmus block is sufficient to predict the acute and long-term success of cavo-tricuspid isthmus ablation.

BACKGROUND: This study investigated whether a minimal approach to typical atrial flutter ablation using an 8 mm tip catheter with a 150 W generator with only the documentation of clockwise block by means of local criteria predicts a good long-term outcome. METHODS: Seventy patients underwent typical atrial flutter ablation. A multipolar catheter was inserted into the coronary sinus (CS) and an 8 mm tip ablation catheter was used to ablate and map the isthmus. The ablation line was performed in the posteroseptal region. The clockwise block was confirmed by recording a corridor of double potentials along the line and by counterclockwise activation of the portion of the isthmus just beyond the lesion line as demonstrated by measuring the conduction times during CS pacing. RESULTS: In case of block, the mean distance between the two split atrial electrograms was 129 +/- 31 ms. Acute isthmus block was achieved in all 70 patients. The median of the radiofrequency pulses was 10 (range 1-36). No immediate or late complications were noted. The long-term follow-up (19.5 +/- 4 months) revealed recurrence of typical atrial flutter in 2 cases (2.8%). CONCLUSIONS: Our results demonstrate that the acute success rate following typical atrial flutter isthmus ablation using an 8 mm tip catheter with a 150 W generator is high. No complications occurred. Moreover, the documentation of just the clockwise isthmus block using a minimal approach according to local electrogram criteria is a good predictor of the long-term success.

Atrial Flutter↗