Biomedical subjects

Daniela Perani

Publications and source records attributed to Daniela Perani.

29 records · Page 2Linked to original sources

PubMed2005

The neural basis of first and second language processing.

Fundamental breakthroughs in the neurosciences, combined with technical innovations for measuring brain activity, are shedding new light on the neural basis of second language (L2) processing, and on its relationship to native language processing (L1). The long-held assumption that L1 and L2 are necessarily represented in different brain regions in bilinguals has not been confirmed. On the contrary, the available evidence indicates that L1 and L2 are processed by the same neural devices. The neural differences in L1 and L2 representations are only related to the specific computational demands, which vary according to the age of acquisition, the degree of mastery and the level of exposure to each language. Finally, the acquisition of L2 could be considered as a dynamic process, requiring additional neural resources in specific circumstances.

Humans↗

PubMed2005

The neural basis of language talent in bilinguals.

In a recent paper, Chee et al. report differences in the patterns of brain activation and deactivation in bilinguals with different levels of proficiency in their second language. Most intriguingly, this research addressed the issue of the neural basis of phonological working memory (PWM), which is crucial in language acquisition, in subjects who were under comparable social pressure to be bilinguals. The results led the authors to suggest that a more readily available working memory system might correlate with the attainment of superior proficiency in a second language.

Brain↗

PubMed2005

Two aspects of impaired consciousness in Alzheimer's disease.

Alzheimer's disease (AD) is a degenerative dementia characterized by different aspects of impaired consciousness. For example, there is a deficit of controlled processes that require conscious processing of information. Such an impairment is indexed by decreased performances at controlled cognitive tasks, and it is related to reduced brain metabolic activity in a network of frontal, posterior associative, and limbic regions. Another aspect of impaired consciousness is that AD patients show variable levels of anosognosia concerning their cognitive deficits. A discrepancy score between patient's and caregiver's assessment of cognitive functions is one of the most frequently used measures of anosognosia. A high discrepancy score has been related to impaired activity in the superior frontal sulcus and the parietal cortex in AD. Anosognosia for cognitive deficits in AD could be partly explained by impaired metabolism in parts of networks subserving self-referential processes (e.g., the superior frontal sulcus) and perspective-taking (e.g., the temporoparietal junction). We hypothesize that these patients are impaired in the ability to see themselves with a third-person perspective (i.e., being able to see themselves as other people see them).

Agnosia↗

PubMed2005

Listening to action-related sentences activates fronto-parietal motor circuits.

Observing actions made by others activates the cortical circuits responsible for the planning and execution of those same actions. This observation-execution matching system (mirror-neuron system) is thought to play an important role in the understanding of actions made by others. In an fMRI experiment, we tested whether this system also becomes active during the processing of action-related sentences. Participants listened to sentences describing actions performed with the mouth, the hand, or the leg. Abstract sentences of comparable syntactic structure were used as control stimuli. The results showed that listening to action-related sentences activates a left fronto-parieto-temporal network that includes the pars opercularis of the inferior frontal gyrus (Broca's area), those sectors of the premotor cortex where the actions described are motorically coded, as well as the inferior parietal lobule, the intraparietal sulcus, and the posterior middle temporal gyrus. These data provide the first direct evidence that listening to sentences that describe actions engages the visuomotor circuits which subserve action execution and observation.

Acoustic Stimulation↗

PubMed2004

Early use of artificial sensibility in hand transplantation.

Hands were transplanted from brain-dead donors for the treatment of two male unilateral amputees, aged 35 years and 32 years, involved in the Italian Hand Transplantation Programme. Each had lost his right dominant hand, in a farming accident and an explosion, respectively. In one case artificial sensibility was applied postoperatively using a Sensor Glove that transformed vibrotactile stimuli induced by touch, to stereophonic vibroacoustic stimuli perceived through earphones. The principle is based on the brain's capacity for multimodal plasticity, implying that deprivation of one sense (somatosensory) can be compensated for by another sense (auditory). Functional magnetic resonance images (fMRI) taken at regular intervals showed that cortical remodelling of the transplanted hand within the sensory-motor maps occurred early in the patient who used the artificial sensibility regimen compared with the one who did not. We conclude that postoperative use of a device using hearing as a substitution for sensation in hand transplantation may have considerable potential value for speeding up cortical integration of a transplanted hand.

Adult↗

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

Atypical dementia associated with a novel presenilin-2 mutation.

We describe an Italian pedigree with hereditary dementia associated with a novel T122R mutation in the presenilin-2 gene (PSEN2). The clinical history, symptom presentation, and structural neuroimaging were consistent with an atypical form of dementia. Disease expression varied within family members. One in a pair of mutated monozygotic twins had evident signs of disease, whereas the other did not, even if her functional neuroimaging investigations, cerebrospinal fluid levels of Abeta1-42, and Tau protein were able to provide markers for future disease development. These observations suggest the importance of still unknown biological and perhaps environmental factors in the disease determination.

Aged↗

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

Brain activation patterns during video sexual stimulation following the administration of apomorphine: results of a placebo-controlled study.

OBJECTIVES: To evaluate the in vivo effect of apomorphine sublingual versus placebo on cortical and subcortical brain activation during video sexual stimulation. METHODS: Ten patients with psychogenic erectile dysfunction and six potent controls underwent functional magnetic resonance of the brain during video sexual stimulation after the administration of either apomorphine sublingual 4mg or placebo following a randomized, double blind design. Functional magnetic resonance sessions were performed with a 7-day interval. RESULTS: In potent controls, viewing erotic versus neutral films induced bilateral activations in a network of occipito-parietal and temporal inferior regions, in dorsolateral and premotor frontal cortex, in anterior temporal limbic areas and the thalamus, which were comparable to the patient activations during erotic stimulation in the placebo condition. However, a striking difference was found in patients, who demonstrated a significant and extended activation in the cingulate gyrus, frontal mesial and frontal basal cortex, bilaterally, in comparison with potent controls. These activated neural systems were modulated by apomorphine administration which produced a picture that was similar to the one seen in potent controls. In patients with spychogenic erectile dysfunction apomorphine sublingual caused an increase in the extension of the activated networks, plus additional activation foci in subcortical and deep structures, namely in the nucleus accumbens, hypothalamus and mesencephalon: this activation was greater than that seen with placebo. Interestingly, a down-regulation in the frontal basal and temporal limbic cortex was present as shown by a decrease of functional magnetic resonance imaging signal reflecting a deactivation of these regions. CONCLUSIONS: Apomorphine significantly enhances the activation of cortical and subcortical brain function during video sexual stimulation. Patients with psychogenic erectile dysfunction may have an underlying functional abnormality of the brain acting as a previously unrecognised aetiological factor.

Administration, Sublingual↗

PubMed2003

Predominant ventromedial frontopolar metabolic impairment in frontotemporal dementia.

In a multicenter study, FDG-PET images in a population of 29 patients with frontotemporal dementia (FTD) were compared to controls with similar age from each center. A conjunction analysis led to identification of the ventromedial frontopolar cortex as the single region affected in each and every FTD patients. This precise regional metabolic impairment should be integrated with recent neuropsychological researches, such as those showing that the ventromedial frontal cortex is critically involved in decision-making processes based on personal experience, feelings of rightness or social knowledge, processes that are characteristically impaired in FTD.

Aged↗

PubMed2002

Neural correlates for the acquisition of natural language syntax.

Some types of simple and logically possible syntactic rule never occur in human language grammars, leading to a distinction between grammatical and nongrammatical syntactic rules. Comparison of the neuroanatomical correlates underlying the acquisition of grammatical and nongrammatical rules can provide relevant evidence on the neural processes dedicated to language acquisition in a given developmental stage. Until present no direct evidence on the neural mechanisms subserving language acquisition at any developmental stage has been supplied. We used fMRI in investigating the acquisition of grammatical and nongrammatical rules in the specified sense in 14 healthy adults. Grammatical rules compared with nongrammatical rules specifically activated a left hemispheric network including Broca's area, as shown by direct comparisons between the two rule types. The selective role of Broca's area was further confirmed by time x condition interactions and by proficiency effects, in that higher proficiency in grammatical rule usage, but not in usage of nongrammatical rules, led to higher levels of activation in this area. These findings provide evidence for the neural mechanisms underlying language acquisition in adults.

Adult↗