1,721,130 research outputs found
Linguaggio: correlati anatomici, funzionali e plasticità cerebrale
No full textIl linguaggio è probabilmente la principale caratteristica che rende unica la specie umana rispetto a tutte le altre specie viventi. Da questo punto di vista si comprende perché non appena furono disponibili le primissime strumentazioni di indagine non invasiva del cervello umano in vivo (PET), nella prima metà degli anni 80, queste vennero immediatamente utilizzate per studiare le aree cerebrali umane coinvolte nel linguaggio. Si comprende pure come, rispetto ad altri processi cognitivi quali l’apprendimento, l’attenzione, le emozioni, ecc., il linguaggio è uno dei pochi che non può usufruire dell’indubbio vantaggio di avere un modello animale confrontabile o di riferimento, e questo limite è particolarmente evidente nel caso delle patologie del linguaggio quali la dislessia e l’afasia
PSAAL: a LabVIEW 3 program for data acquisition and analysis in psychophysiological experiments
Full text linkPSAAL (Physiological Signals Acquisition and Analysis in LabVIEW language) is a group of seven programs, written in LabVIEW 3.0 language and specialized for acquisition, analysis, reduction, and display of peripheral and central physiological data. The main characteristics of the programs are the wide range of use for most short-duration psychophysiological paradigms and the easy-to-use graphic interface. In addition, two noteworthy features of LabVIEW are included: the portability of the programs on Macintosh, PowerMac, IBM, HP-UX, and SUN computers, and the capability of handling acquisition on many National Instruments A/D boards, including the low-cost ones. PSAAL performs acquisition and simple reduction of peripheral physiological responses with 12- or 16-bit resolution according to the A/D board used. Analysis includes conversion of electrocardiogram into heart rate, the elaboration of the main parameters of skin conductance responses, electromyogram, startle reflex, and averaging of evoked potentials or other event-related physiological responses, under different experimental conditions. The programs allow the user to perform the organization of the data in a spreadsheet ready for most statistical packages and without the use of other spreadsheet applications
Brain plasticity in aphasic patients: Intra- and inter-hemispheric reorganisation of the whole linguistic network probed by N150 and N350 components
Full text linkThe present study examined linguistic plastic reorganization of language through Evoked Potentials
in a group of 17 non-fluent aphasic patients who had suffered left perisylvian focal lesions, and
showed a good linguistic recovery. Language reorganisation was probed with three linguistic
tasks (Phonological, Semantic, Orthographic), the early word recognition potential (N150) and the
later phonological-related component (N350). Results showed the typical left-lateralised posterior
N150 in healthy controls (source: left Fusiform Gyrus), that was bilateral (Semantic) or right sided
(Phonological task) in patients (sources: right Inferior/Middle Temporal and Fusiform Gyri). As regards
N350, controls revealed different intra- and inter-hemispheric linguistic activation across linguistic
tasks, whereas patients exhibited greater activity in left intact sites, anterior and posterior to the
damaged area, in all tasks (sources: Superior Frontal Gyri). A comprehensive neurofunctional model
is presented, describing how complete intra- and inter-hemispheric reorganisation of the linguistic
networks occurs after aphasic damage in the strategically dominant left perisylvian linguistic centres
Influence of Phonological, Semantic and Orthographic tasks on the early linguistic components N150 and N350
No full textWith the present investigation, which comprised two ERP experiments, we aimed to compare the earliest linguistic waves, namely the N 150 and the N350, evoked by single words during three explicit tasks, Phonological, Semantic and Orthographic. With respect to past studies using different samples of stimuli for different tasks, in the present research we used the same sample of words and varied only the tasks. Results were consistent across experiments and showed in the Phonological and Semantic tasks a comparable NI 50 peaking over left posterior regions, but for the N350 a maximum at left frontal sites in the Phonological, and a bilateral frontal component in the Semantic task. Furthermore, compared with these tasks, the Orthographic task involved a cortical network confined to left posterior sites both in the early and late latencies, a network which was probably relevant for the discrimination of the visual features requested by the task rather than for the irrelevant linguistic features of the stimuli
Language lateralization in Phonological, Semantic and Orthographic tasks: A slow evoked potential study
No full textMost of literature on language has shown how different word-classes activate distinct neural networks within linguistic cortical areas. The present investigation aimed to demonstrate that, by means of slow evoked potentials and using the same set of words in different tasks, it is possible to activate cortical networks that are spatially and temporally distinguished. Twenty healthy subjects had to evaluate, in a word pair matching session, whether two words rhymed (phonological task), were semantically related (semantic task) or were written in the same letter case (orthographic task). Slow wave amplitude was computed in three relevant time windows: the last 0.5 s of first word presentation (W1), the initial contingent negative variation (iCNV) and the terminal CNV (tCNV). During W1 and iCNN7 intervals, both the orthographic and the phonological tasks were left lateralized. Furthermore, the phonological task was more lateralized than the orthographic because of a greater inhibition of the right hemisphere, whereas the orthographic task was characterized by a greater bilateral posterior activation. During the tCNV, only the phonological task remained left lateralized while orthographic and semantic were bilaterally distributed. Although the use of the same set of words tends to activate widely overlapped networks, in the present research task manipulation was effective in demonstrating task dependent differences in brain lateralization. Thus, the present paradigm and the adopted tasks are especially suited for studying deficit and recovery of language in patients affected by linguistic disorders such as developmental dyslexia and aphasia
Language-related gamma EEG frontal reduction is associated with positive symptoms in schizophrenia patients
No full textOBJECTIVES: Frontal hypoactivation has been consistently found in schizophrenia. We hypothesized that patients' deficit is asymmetrical, i.e., centred over the left frontal locations, associated with loss of language-related asymmetry, and correlated with positive symptoms.
METHOD: The amplitude of EEG gamma band (36-48Hz) was measured during the processing of three linguistic (Phonological vs. Semantic vs. Visuo-perceptual) tasks and used as index of activation/connectivity in 18 schizophrenia patients and 18 healthy participants.
RESULTS: Healthy controls showed higher gamma in frontal sites, revealing a significantly greater left vs. right asymmetry in all linguistic tasks, whereas patients exhibited decreased and bilateral gamma amplitude (i.e., reduced activation/connectivity) in frontal regions. The patients' left hypofrontality during phonological processing was positively correlated with higher levels of Delusions (P1) and Hallucination (P3) PANSS subscales. A significantly greater left posterior gamma amplitude was found in patients compared with controls.
CONCLUSION: Results suggest, in schizophrenia patients, a functional deficit of left frontal regions including Broca's area, a key site playing a fundamental hierarchical role between and within hemispheres which integrates many basic processes in linguistic and conceptual organization. The significant correlation between lack of the left anterior asymmetry and increased positive symptoms is in line with Crow's hypothesis postulating the aetiological role of disrupted linguistic frontal asymmetry on the onset of the key symptoms of schizophrenia
Cortical plasticity of language measured by EEG in a case of anomic aphasia
No full textAphasia is a neurological disorder caused by a left hemisphere damage which is generally followed by some degree of spontaneous or therapy induced language recovery. Identifying the mechanisms underlying this recovery is difficult, but determining the neural substrate of recovery and its relationship with specific aspects of word processing may provide cues for language intervention. This study explores the cortical dynamics of linguistic functions during the rehabilitation-induced recovery of language in a patient, CR, affected by anomic aphasia. To this aim we mapped the language-related cortical activity of CR by means of the slow cortical potentials before and after a rehabilitative training. Thus, the first EEG measure showed the dysfunctional cortical networks related to the anomic disease and the second EEG revealed the new cortical circuits underlying the functional recovery
EEG delta band as a marker of brain damage in aphasic patients after recovery of language
No full textIn this study spectral delta percentage was used to assess both brain dysfunction/inhibition and functional linguistic impairment during different phases of word processing. To this aim, EEG delta amplitude was measured in 17 chronic non-fluent aphasic patients while engaged in three linguistic tasks: Orthographic, Phonological and Semantic. Average mapping of aphasics' structural lesion showed core damage in the left cortical-subcortical perisylvian areas. Delta amplitude was overall significantly higher in aphasics with respect to matched controls, a result in line with the view that diaschisis/cortical inhibition persists to some extent also in the chronic phase. Analysis of regions of interest revealed a peak of delta activity in left perilesional EEG sites, posterior to the core damage where residual suffering tissue probably projects its dysfunctional activity. Time course of word processing showed in patients greater delta percentage/inhibition in the first interval after word offset in correspondence of which verbal working memory is engaged. The significant interaction including group and task factors points to greater left posterior inhibition in aphasics across all tasks and left vs. right anterior relative disinhibition only during the Phonological task, whereas controls showed greater left vs. right disinhibition at anterior sites in all tasks. Delta band, in addition to its ability to reflect structural damage, was effective in the assessment of functional impairment as well as of linguistic reorganization of aphasics at hemispheric level with a spatial scalp distribution consistent with lesion map
Psychophysiological stress responses in upper limb amputees with and without phantom limb pain
No full textThe present experiment tested the hypothesis that phantom limb pain amputees show a different pattern of psychophysiological reactivity to stress compared with painfree amputees. Six phantom limb pain (PLP) and five painfree upper-extremity amputees were administered two groups of tasks: stressful and relaxing. The measured dependent variables were skin temperature recorded at both stump and intact site, heart ratel blood pressure, subjective pain and stress ratings. Phantom limb pain patients were characterized by higher stump temperature compared with phantom limb painfree patients. This effect was observed during the whole recording. Consistently with the between-subjects effect, when PLP patients exhibited higher skin temperature (during relaxation, compared with during stressful tasks), they perceived more pain. The experiment showed higher cardiovascular reactivity in PLP patients, specifically to the stressful free-speech task, which focused on recollection of the amputation event. As compared with the painfree patients, during the personal stressor, PLP patients' heart rate and systolic blood pressure increased, indicating a greater sympathetic response. Results indicate that peripheral factors. such as stump temperature reliably differentiate PLP from painfree patients. Moreover, the clear cardiovascular hyperreactivity observed in PLP patients during their report of amputation suggests that PLP is associated with a long-term emotional memory for the painful experience of that event. These results are consistent with most reports in the literature relating phantom pain development to the experience of preamputation pain
- …
