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Stefano F Cappa

Publications and source records attributed to Stefano F Cappa.

28 records · Page 2Linked to original sources
PubMed2003

Early setting of grammatical processing in the bilingual brain.

The existence of a "critical period" for language acquisition is controversial. Bilingual subjects with variable age of acquisition (AOA) and proficiency level (PL) constitute a suitable model to study this issue. We used functional magnetic resonance imaging to investigate the effects of AOA and PL on neural correlates of grammatical and semantic judgments in Italian-German bilinguals who learned the second language at different ages and had different proficiency levels. While the pattern of brain activity for semantic judgment was largely dependent on PL, AOA mainly affected the cortical representation of grammatical processes. These findings support the view that both AOA and PL affect the neural substrates of second language processing, with a differential effect on grammar and semantics.

Adult↗
PubMed2003

The role of age of acquisition and language usage in early, high-proficient bilinguals: an fMRI study during verbal fluency.

We assessed the effects of age of acquisition and language exposure on the cerebral correlates of lexical retrieval in high-proficient, early-acquisition bilinguals. Functional MRI was used to study Spanish-Catalan bilinguals who acquired either Spanish or Catalan as a first language in the first years of life. Subjects were exposed to the second language at 3 years of age, and have used both languages in daily life since then. Subjects had a comparable level of proficiency in the comprehension of both languages. Lexical retrieval with the verbal fluency task resulted in the well-established pattern of left hemispheric activation centered on the inferior frontal region. The effect of age of acquisition was assessed by dividing the subjects into two groups, on the basis of the language acquired first (Catalan-born or Spanish-born bilinguals). Functional comparisons indicated that less extensive brain activation was associated with lexical retrieval in the language acquired earlier in life. The two groups were also different in language usage/exposure, as assessed with a specific questionnaire; in particular, the exposure to the second language (Spanish) was less intensive in the case of Catalans. This was reflected in a significant interaction, indicating a more extensive activation in Catalans during production in Spanish. Overall, these results indicate that, during a production task, both age of acquisition and language exposure affect the pattern of brain activation in bilinguals, even if both languages are acquired early and with a comparable level of proficiency.

Adult↗
PubMed2003

The residual calculation abilities of a patient with severe aphasia: evidence for a selective deficit of subtraction procedures.

We report the case study of a severe fluent aphasic patient, who showed relatively preserved numerical abilities. A detailed investigation of number processing indicated good numerical comprehension and a relative sparing of addition and subtraction abilities; on the other hand, multiplication and division were severely impaired. A further study of multi-digit operations showed that the patient's performance was characterized by a selective impairment of the borrowing procedure, in which she applied the so-called Smaller-from-Larger bug, typically observed in children learning to calculate. The present case provides further evidence for the dissociation between operations based on verbal sequences and on quantity manipulation, respectively impaired and preserved in patients with severe aphasia. Moreover, it provides evidence indicating that procedures may be dissociated from conceptual knowledge within a single arithmetical operation.

Aphasia↗
PubMed2003

Role of the anterior temporal lobe in repetition and semantic priming: evidence from a patient with a category-specific deficit.

Neuroimaging studies in healthy participants have implicated anterior temporal lobe regions and the fusiform gyrus in repetition priming and semantic priming. Only the investigation of patients with selective lesions, however, can establish the necessity of these particular regions. To this end, we administered three tests of repetition priming (pseudoword identification; masked-form priming; category-exemplar generation) and a test of semantic priming to a patient (J.P.) with a category-specific deficit stemming from bilateral damage to the anterior fusiform gyrus and anterior temporal regions. On all of the repetition priming tasks, J.P. showed priming effects within 1 S.D. of 10 age- and education-matched CON; ANOVAs indicated no interaction between group and prime condition. These findings suggest that the anterior fusiform and anterior temporal lobe are not required for these priming effects. J.P. also showed normal repetition priming even for items that he had never been able to name or to provide semantic information about. On the semantic priming task, J.P. showed normal levels of priming across categories. When we separately analyzed his priming for items he could never name or access information about versus items that he had been able to name on at least two testing sessions, we found priming for the latter items, but not for the former. This result suggests that category-specific deficits resulting from damage to the anterior temporal lobes may disrupt the automatic, rapid access of semantic information of some items.

Adult↗
PubMed2003

Questioning the living/nonliving dichotomy: evidence from a patient with an unusual semantic dissociation.

In this article the authors describe a patient (J.P.) whose category-specific naming deficit eluded the classical dichotomies between living versus nonliving items or visual versus functional attributes. At age 22, he had herpes simplex encephalitis followed by a left temporal lobectomy. J.P. was tested on measures of visual perception, category naming, fluency, and name-picture matching. He showed a severe impairment naming and identifying fruits, vegetables, and musical instruments. His performance with animals and birds was spared inconsistently, meaning that even the preserved categories were, at some point, affected. J.P.'s unusual deficit supports the hypothesis that semantic knowledge is organized in the brain on the basis of object properties, which can cut across the living-nonliving categorical distinction.

Adult↗
PubMed2003

The heterogeneity of category-specific semantic disorders: evidence from a new case.

We report a new case of category-specific semantic impairment, affecting living entities, in a patient with traumatic brain damage. In the present investigation we attempted to replicate as closely as possible the testing procedures which have been developed by Caramazza and Shelton (1998) to evaluate EW, a patient with a selective semantic disorder for the animal category. The results in our patient indicated a different performance profile, characterised by a more extensive semantic disorder for living entities, and by a more severe loss of specific visual rather than functional knowledge. These findings concur with other evidence indicating that category-specific semantic disorders are heterogeneous, reflecting different mechanisms of impairment, most likely associated with different neurobiological underpinnings.

Adult↗
PubMed2002

Exploring the syndrome of spatial unilateral neglect through an illusion of length.

Both a neuropsychological syndrome (unilateral spatial neglect) and a visual illusion of length (the Brentano version of the Müller-Lyer illusion) bring about a misjudgement of the subjective centre of a horizontal line, with a unilateral shift. In experiment 1 we investigated, in patients with left unilateral neglect, illusory effects of horizontal length, with the aim of exploring the functional and neural basis of horizontal space perception, and the role of visual processing in shaping the patients' bisection performance. Fourteen right-brain-damaged patients with left spatial unilateral neglect, seven with and seven without left visual half-field deficits (assessed by confrontation, perimetry, and visual event-related potentials), entered this study. Two conditions of manual line bisection were assessed: setting the mid-point of a horizontal line, and of the shaft of the Brentano-Müller-Lyer illusion, with either a left- or a right-sided expansion. Both groups of patients set the subjective midpoint to the right of the objective centre of the line, consistent with the presence of left neglect. Patients with neglect and left hemianopia showed no illusory effects and a greater bisection error. The effects of the illusion, by contrast, were fully present in neglect patients without hemianopia, in both illusory conditions, adding to, or subtracting from, the rightward bisection bias. Anatomoclinical correlations revealed an association of damage to the occipital regions with the lack of illusory effects. Conversely, more anterior damage, sparing these regions, did not disrupt the illusion, revealing a dissociation between visual and spatial processing of extension. These findings suggest that processing of the Müller-Lyer illusion of length is likely to occur in the occipital cortex, at a retinotopic level of representation. In neglect patients with left homonymous hemianopia the visual deficit adds to the spatial bias, yielding a greater error in line bisection, but not in other visual exploratory tasks, such as cancellation, where the contribution of retinotopic frames is likely to be comparatively minor. Experiment 2 showed preserved illusory effects in patients with homonymous visual field defects without spatial unilateral neglect, suggesting that preserved spatial processing may compensate for unilateral visual field defects.

Adult↗
PubMed2002

Modulation of the lexical-semantic network by auditory semantic priming: an event-related functional MRI study.

The current event-related fMRI study specifies the neuroanatomical correlates of semantic priming and differences in semantic relation types using an auditory primed lexical decision task (LDT). Word pairs consisted of different relation types, associations (key-chain), pure categorical relations (cow-dog), and unrelated words (table-window), as well as word-pseudoword (way-tinne) and pseudoword-pseudoword (ahurn-döva) pairs. The factor lexical status, i.e., the processing of words compared to pseudowords, was associated with activation in the middle temporal gyri and the left striatum. The factor relatedness, i.e., the contrast between unrelated and related target words, was associated with increased activation of the left inferior frontal gyrus, the deep frontal operculum bilaterally, and the middle frontal gyri. A direct contrast between the two semantic relation types indicated that the processing of purely categorical compared to associative information recruits the right precuneus, the isthmus gyrus cinguli, and the cuneus, suggesting more effortful processing of the former information type. The present data show that the factors lexical status, semantic relatedness, and type of semantic relation in a primed LDT modulate the hemodynamic response in cerebral areas that subserve auditory word recognition and subsequent lexical-semantic processing.

Adult↗
PubMed2002

Attentional dysfunction of chronic schizophrenia: No association with long-term institutionalization.

Attentional processes play a central role in information selection, which is impaired in schizophrenic patients. In the present study, we attempted to characterize the attentional performance of chronic schizophrenics using a computerized assessment of the multiple components of attentional function. Two comparable samples, consisting, respectively, of out-patients and in-patients, were tested in order to assess the effect of chronic institutionalization. Twenty-four subjects (half in-patients and half out-patients) fulfillling DSM-IV criteria for schizophrenia were examined with a standard computerized battery for the assessment of attention, namely Testbatterie zur Aufmerksamkeitsprufung (TAP). Both groups were impaired on all measures of attentional processing (in terms of both reaction times and number of errors). There were no significant differences in attentional performance between in- and out-patients. In conclusion, the present findings confirm the presence of pervasive attentional dysfunction in chronic schizophrenia; the lack of significant differences in performance between in- and out-patients supports the hypothesis that the cognitive deficits are inherently associated with the illness and cannot be attributed to environmental/social factors.

Adult↗