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1.
Sci Rep ; 11(1): 18572, 2021 09 17.
Artigo em Inglês | MEDLINE | ID: mdl-34535718

RESUMO

Stroke is a leading cause of disability, and language impairments (aphasia) after stroke are both common and particularly feared. Most stroke survivors with aphasia exhibit anomia (difficulties with naming common objects), but while many therapeutic interventions for anomia have been proposed, treatment effects are typically much larger in some patients than others. Here, we asked whether that variation might be more systematic, and even predictable, than previously thought. 18 patients, each at least 6 months after left hemisphere stroke, engaged in a computerised treatment for their anomia over a 6-week period. Using only: (a) the patients' initial accuracy when naming (to-be) trained items; (b) the hours of therapy that they devoted to the therapy; and (c) whole-brain lesion location data, derived from structural MRI; we developed Partial Least Squares regression models to predict the patients' improvements on treated items, and tested them in cross-validation. Somewhat surprisingly, the best model included only lesion location data and the hours of therapy undertaken. In cross-validation, this model significantly out-performed the null model, in which the prediction for each patient was simply the mean treatment effect of the group. This model also made promisingly accurate predictions in absolute terms: the correlation between empirical and predicted treatment response was 0.62 (95% CI 0.27, 0.95). Our results indicate that individuals' variation in response to anomia treatment are, at least somewhat, systematic and predictable, from the interaction between where and how much lesion damage they have suffered, and the time they devoted to the therapy.


Assuntos
Anomia/etiologia , Anomia/terapia , Acidente Vascular Cerebral/complicações , Anomia/diagnóstico , Encéfalo/patologia , Gerenciamento Clínico , Feminino , Humanos , Masculino , Prognóstico
2.
Brain Imaging Behav ; 2021 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-34328618

RESUMO

A typical consequence of stroke in the right hemisphere is unilateral spatial neglect. Distinct forms of neglect have been described, such as space-based (egocentric) and object-based (allocentric) neglect. However, the relationship between these two forms of neglect is still far from being understood, as well as their neural substrates. Here, we further explore this issue by using voxel lesion symptoms mapping (VLSM) analyses on a large sample of early subacute right-stroke patients assessed with the Apples Cancellation Test. This is a sensitive test that simultaneously measures both egocentric and allocentric neglect. Behaviourally, we found no correlation between egocentric and allocentric performance, indicating independent mechanisms supporting the two forms of neglect. This was confirmed by the VLSM analysis that pointed out a link between a damage in the superior longitudinal fasciculus and left egocentric neglect. By contrast, no association was found between brain damage and left allocentric neglect. These results indicate a higher probability to observe egocentric neglect as a consequence of white matter damages in the superior longitudinal fasciculus, while allocentric neglect appears more "globally" related to the whole lesion map. Overall, these findings on early subacute right-stroke patients highlight the role played by white matter integrity in sustaining attention-related operations within an egocentric frame of reference.

3.
Eur J Nucl Med Mol Imaging ; 48(4): 1124-1133, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33029654

RESUMO

PURPOSE: To assess the brain metabolic correlates of the different regional extent of ALS, evaluated with the King's staging system, using brain 18F-2-fluoro-2-deoxy-D-glucose-PET (18F-FDG-PET). METHODS: Three hundred ninety ALS cases with King's stages 1, 2, and 3 (n = 390), i.e., involvement of 1, 2, and 3 body regions respectively, underwent brain 18F-FDG-PET at diagnosis. King's stage at PET was derived from ALSFRS-R and was regressed out against whole-brain metabolism in the whole sample. The full factorial design confirmed the hypothesis that differences among groups (King's 1, King's 2, King's 3, and 40 healthy controls (HC)) existed overall. Comparisons among stages and between each group and HC were performed. We included age at PET and sex as covariates. RESULTS: Brain metabolism was inversely correlated with stage in medial frontal gyrus bilaterally, and right precentral and postcentral gyri. The full factorial design resulted in a significant main effect of groups. There was no significant difference between stages 1 and 2. Comparing stage 3 to stage 1+2, a significant relative hypometabolism was highlighted in the former in the left precentral and medial frontal gyri, and in the right medial frontal, postcentral, precentral, and middle frontal gyri. The comparisons between each group and HC showed the extension of frontal metabolic changes from stage 1 to stage 3, with the larger metabolic gap between stages 2 and 3. CONCLUSIONS: Our findings support the hypothesis that in ALS, the propagation of neurodegeneration follows a corticofugal, regional ordered pattern, extending from the motor cortex to posterior and anterior regions.


Assuntos
Esclerose Amiotrófica Lateral , Fluordesoxiglucose F18 , Esclerose Amiotrófica Lateral/diagnóstico por imagem , Encéfalo/diagnóstico por imagem , Glucose , Humanos , Tomografia por Emissão de Pósitrons
4.
Artigo em Inglês | MEDLINE | ID: mdl-33154182

RESUMO

OBJECTIVE: The efficacy of spoken language comprehension therapies for persons with aphasia remains equivocal. We investigated the efficacy of a self-led therapy app, 'Listen-In', and examined the relation between brain structure and therapy response. METHODS: A cross-over randomised repeated measures trial with five testing time points (12-week intervals), conducted at the university or participants' homes, captured baseline (T1), therapy (T2-T4) and maintenance (T5) effects. Participants with chronic poststroke aphasia and spoken language comprehension impairments completed consecutive Listen-In and standard care blocks (both 12 weeks with order randomised). Repeated measures analyses of variance compared change in spoken language comprehension on two co-primary outcomes over therapy versus standard care. Three structural MRI scans (T2-T4) for each participant (subgroup, n=25) were analysed using cross-sectional and longitudinal voxel-based morphometry. RESULTS: Thirty-five participants completed, on average, 85 hours (IQR=70-100) of Listen-In (therapy first, n=18). The first study-specific co-primary outcome (Auditory Comprehension Test (ACT)) showed large and significant improvements for trained spoken words over therapy versus standard care (11%, Cohen's d=1.12). Gains were largely maintained at 12 and 24 weeks. There were no therapy effects on the second standardised co-primary outcome (Comprehensive Aphasia Test: Spoken Words and Sentences). Change on ACT trained words was associated with volume of pretherapy right hemisphere white matter and post-therapy grey matter tissue density changes in bilateral temporal lobes. CONCLUSIONS: Individuals with chronic aphasia can improve their spoken word comprehension many years after stroke. Results contribute to hemispheric debates implicating the right hemisphere in therapy-driven language recovery. Listen-In will soon be available on GooglePlay. TRIAL REGISTRATION NUMBER: NCT02540889.

5.
Cortex ; 113: 329-346, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30735844

RESUMO

Deficits of visuospatial orienting in brain-damaged patients affected by hemispatial neglect have been extensively investigated. Nonetheless, spontaneous spatial orienting in naturalistic conditions is still poorly understood. Here, we investigated the role played by top-down and stimulus-driven signals in overt spatial orienting of neglect patients during free-viewing of short videos portraying everyday life situations. In Experiment 1, we assessed orienting when meaningful visual events competed on the left and right side of space, and tested whether sensory salience on the two sides biased orienting. In Experiment 2, we examined whether the spatial alignment of visual and auditory signals modulates orienting. The results of Experiment 1 showed that in neglect patients severe deficits in contralesional orienting were restricted to viewing conditions with bilateral visual events competing for attentional capture. In contrast, orienting towards the contralesional side was largely spared when the videos contained a single event on the left side. In neglect patients the processing of stimulus-driven salience was relatively spared and helped orienting towards the left side when multiple events were present. Experiment 2 showed that sounds spatially aligned with visual events on the left side improved orienting towards the otherwise neglected hemispace. Anatomical scans indicated that neglect patients suffered grey and white matter damages primarily in the ventral frontoparietal cortex. This suggests that the improvement of contralesional orienting associated with visual salience and audiovisual spatial alignment may be due to processing in the relatively intact dorsal frontoparietal areas. Our data show that in naturalistic environments, the presence of multiple meaningful events is a major determinant of spatial orienting deficits in neglect patients, whereas the salience of visual signals and the spatial alignment between auditory and visual signals can counteract spatial orienting deficits. These results open new perspectives to develop novel rehabilitation strategies based on the use of naturalistic stimuli.


Assuntos
Movimentos Oculares/fisiologia , Orientação Espacial/fisiologia , Transtornos da Percepção/fisiopatologia , Acidente Vascular Cerebral/fisiopatologia , Idoso , Atenção/fisiologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Transtornos da Percepção/etiologia , Estimulação Luminosa , Acidente Vascular Cerebral/complicações , Percepção Visual/fisiologia
6.
J Sleep Res ; 27(6): e12680, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-29527742

RESUMO

Continuous positive airway pressure (CPAP) is the first-choice treatment for obstructive sleep-disordered breathing. Automatic bilevel ventilation can be used to treat obstructive sleep-disordered breathing when CPAP is ineffective, but clinical experience is still limited. To assess the outcome of titration with CPAP and automatic bilevel ventilation, the charts of 356 outpatients (obstructive sleep apnea, n = 242; chronic obstructive pulmonary disease + obstructive sleep apnea overlap, n = 80; obesity hypoventilation syndrome [OHS], n = 34; 103 females) treated for obstructive sleep-disordered breathing from January 2014 to April 2017 were reviewed. Positive airway pressure titration was considered successful in the case of sleep-disordered breathing resolution (apnea-hypopnea index <10/hr) with cumulative time at SaO2  < 90% (CT90%) <10% and/or improved daytime arterial blood gases at the end of titration. CPAP was effective in 268 patients (75.0%). CPAP treatment failure (n = 88) occurred in 13.6% of obstructive sleep apnea, 32.5% of overlap, and 85.3% of OHS patients. Compared with successful CPAP cases, patients undergoing the automatic bilevel ventilation trial showed higher body mass index (39.3 ± 10.5 kg/m2 versus 34.8 ± 6.9 kg/m2 , p < 0.0001), worse mean nocturnal SaO2 (89.2 ± 4.0% versus 91.3 ± 4.0%, p < 0.003) and CT90% (40.6 ± 28.6% versus 24.0 ± 23.3%), but similar age (62.8 ± 11.9 years versus 60.5 ± 12.0 years, p = 0.11), apnea-hypopnea index (39.4 ± 23.2/hr versus 41.0 ± 21.2/hr, p = 0.55) and oxygen desaturation index (37.8 ± 23.5/hr versus 39.2 ± 21.1/hr, p = 0.61) at diagnosis. Automatic bilevel ventilation was successful in 79.5% of CPAP treatment failures (n = 70). Automatic bilevel ventilation failure was independently associated with baseline body mass index >40 kg/m2 (odds ratio 6.16, confidence interval 1.50-25.17, p = 0.011) and CT90% >42% (odds ratio 5.87, confidence interval 1.39-24.83, p = 0.016). During follow-up, automatic bilevel ventilation treatment failed in seven patients (10%), and compliance was similar in CPAP (4.5 ± 2.2 hr) and automatic bilevel ventilation (5.2 ± 2.3 hr, p = 0.09) groups. Automatic bilevel ventilation was useful to treat sleep-disordered breathing, but failed in patients with severe OHS.


Assuntos
Índice de Massa Corporal , Pressão Positiva Contínua nas Vias Aéreas/métodos , Cooperação do Paciente , Apneia Obstrutiva do Sono/diagnóstico , Apneia Obstrutiva do Sono/terapia , Adulto , Idoso , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Respiração Artificial/métodos , Estudos Retrospectivos , Apneia Obstrutiva do Sono/fisiopatologia
7.
Brain ; 140(11): 3039-3054, 2017 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-29053773

RESUMO

See Thompson and Woollams (doi:10.1093/brain/awx264) for a scientific commentary on this article. Previous research with aphasic patients has shown that picture naming can be facilitated by concurrent phonemic cueing [e.g. initial phoneme(s) of the word that the patient is trying to retrieve], both as an immediate word retrieval technique, and when practiced repeatedly over time as a long-term anomia treatment. Here, to investigate the neural mechanisms supporting word retrieval, we adopted­for the first time­a functional magnetic resonance imaging task using the same naming procedure as it occurs during the anomia treatment process. Before and directly after a 6-week anomia treatment programme, 18 chronic aphasic stroke patients completed our functional magnetic resonance imaging protocol­a picture naming task aided by three different types of phonemic cues (whole words, initial phonemes, final phonemes) and a noise-control condition. Patients completed a naming task based on the training materials, and a more general comprehensive battery of language tests both before and after the anomia treatment, to determine the effectiveness and specificity of the therapy. Our results demonstrate that the anomia treatment was effective and specific to speech production, significantly improving both patients' naming accuracy and reaction time immediately post-treatment (unstandardized effect size: 29% and 17%, respectively; Cohen's d: 3.45 and 1.83). Longer term gains in naming were maintained 3 months later. Functional imaging results showed that both immediate and long-term facilitation of naming involved a largely overlapping bilateral frontal network including the right anterior insula, inferior frontal and dorsal anterior cingulate cortices, and the left premotor cortex. These areas were associated with a neural priming effect (i.e. reduced blood oxygen level-dependent signal) during both immediate (phonemically-cued versus control-cue conditions), and long-term facilitation of naming (i.e. treated versus untreated items). Of note is that different brain regions were sensitive to different phonemic cue types. Processing of whole word cues was associated with increased activity in the right angular gyrus; whereas partial word cues (initial and final phonemes) recruited the left supplementary motor area, and right anterior insula, inferior frontal cortex, and basal ganglia. The recruitment of multiple and bilateral areas may help explain why phonemic cueing is such a successful behavioural facilitation tool for anomia treatment. Our results have important implications for optimizing current anomia treatment approaches, developing new treatments, and improving speech outcome for aphasic patients.


Assuntos
Anomia/diagnóstico por imagem , Anomia/terapia , Afasia/diagnóstico por imagem , Afasia/terapia , Sinais (Psicologia) , Imageamento por Ressonância Magnética/métodos , Adulto , Idoso , Anomia/etiologia , Afasia/etiologia , Doença Crônica , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estimulação Luminosa/métodos , Tempo de Reação/fisiologia , Acidente Vascular Cerebral/complicações , Acidente Vascular Cerebral/diagnóstico por imagem , Acidente Vascular Cerebral/terapia , Resultado do Tratamento , Adulto Jovem
8.
Front Hum Neurosci ; 10: 320, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27445760

RESUMO

In daily life the brain is exposed to a large amount of external signals that compete for processing resources. The attentional system can select relevant information based on many possible combinations of goal-directed and stimulus-driven control signals. Here, we investigate the behavioral and physiological effects of competition between distinctive visual events during free-viewing of naturalistic videos. Nineteen healthy subjects underwent functional magnetic resonance imaging (fMRI) while viewing short video-clips of everyday life situations, without any explicit goal-directed task. Each video contained either a single semantically-relevant event on the left or right side (Lat-trials), or multiple distinctive events in both hemifields (Multi-trials). For each video, we computed a salience index to quantify the lateralization bias due to stimulus-driven signals, and a gaze index (based on eye-tracking data) to quantify the efficacy of the stimuli in capturing attention to either side. Behaviorally, our results showed that stimulus-driven salience influenced spatial orienting only in presence of multiple competing events (Multi-trials). fMRI results showed that the processing of competing events engaged the ventral attention network, including the right temporoparietal junction (R TPJ) and the right inferior frontal cortex. Salience was found to modulate activity in the visual cortex, but only in the presence of competing events; while the orienting efficacy of Multi-trials affected activity in both the visual cortex and posterior parietal cortex (PPC). We conclude that in presence of multiple competing events, the ventral attention system detects semantically-relevant events, while regions of the dorsal system make use of saliency signals to select relevant locations and guide spatial orienting.

9.
Front Psychiatry ; 6: 134, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26441695

RESUMO

OBJECTIVE: Sleep disturbances such as insomnia and nightmares are core components of post-traumatic stress disorder (PTSD), yet their neurobiological relationship is still largely unknown. We investigated brain alterations related to sleep disturbances in PTSD patients and controls by using both structural and functional neuroimaging techniques. METHOD: Thirty-nine subjects either developing (n = 21) or not developing (n = 18) PTSD underwent magnetic resonance imaging and a symptom-provocation protocol followed by the injection of 99mTc-hexamethylpropyleneamineoxime. Subjects were also tested with diagnostic and self-rating scales on the basis of which a Sleep Disturbances Score (SDS; i.e., amount of insomnia/nightmares) was computed. RESULTS: Correlations between SDS and gray matter volume (GMV)/regional cerebral blood flow (rCBF) were computed in the whole sample and separately in the PTSD and control groups. In the whole sample, higher sleep disturbances were associated with significantly reduced GMV in amygdala, hippocampus, anterior cingulate, and insula; increased rCBF in midbrain, precuneus, and insula; and decreased rCBF in anterior cingulate. This pattern was substantially confirmed in the PTSD group, but not in controls. CONCLUSION: Sleep disturbances are associated with GMV loss in anterior limbic/paralimbic, PTSD-sensitive structures and with functional alterations in regions implicated in rapid eye movement-sleep control, supporting the existence of a link between PTSD and sleep disturbance.

10.
Hum Brain Mapp ; 35(4): 1597-614, 2014 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-23616340

RESUMO

Previous studies on crossmodal spatial orienting typically used simple and stereotyped stimuli in the absence of any meaningful context. This study combined computational models, behavioural measures and functional magnetic resonance imaging to investigate audiovisual spatial interactions in naturalistic settings. We created short videos portraying everyday life situations that included a lateralised visual event and a co-occurring sound, either on the same or on the opposite side of space. Subjects viewed the videos with or without eye-movements allowed (overt or covert orienting). For each video, visual and auditory saliency maps were used to index the strength of stimulus-driven signals, and eye-movements were used as a measure of the efficacy of the audiovisual events for spatial orienting. Results showed that visual salience modulated activity in higher-order visual areas, whereas auditory salience modulated activity in the superior temporal cortex. Auditory salience modulated activity also in the posterior parietal cortex, but only when audiovisual stimuli occurred on the same side of space (multisensory spatial congruence). Orienting efficacy affected activity in the visual cortex, within the same regions modulated by visual salience. These patterns of activation were comparable in overt and covert orienting conditions. Our results demonstrate that, during viewing of complex multisensory stimuli, activity in sensory areas reflects both stimulus-driven signals and their efficacy for spatial orienting; and that the posterior parietal cortex combines spatial information about the visual and the auditory modality.


Assuntos
Percepção Auditiva/fisiologia , Encéfalo/fisiologia , Orientação/fisiologia , Percepção Espacial/fisiologia , Percepção Visual/fisiologia , Estimulação Acústica , Adulto , Mapeamento Encefálico , Simulação por Computador , Potenciais Evocados , Medições dos Movimentos Oculares , Movimentos Oculares/fisiologia , Feminino , Humanos , Imageamento por Ressonância Magnética , Masculino , Modelos Neurológicos , Testes Neuropsicológicos , Estimulação Luminosa , Gravação em Vídeo , Adulto Jovem
11.
Clin Neurophysiol ; 123(1): 129-36, 2012 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-21741302

RESUMO

OBJECTIVE: The aim of this study was to investigate the effects induced by an exposure to a GSM signal (Global System for Mobile Communication) on brain BOLD (blood-oxygen-level dependent) response, as well as its time course while performing a Go-NoGo task. METHODS: Participants were tested twice, once in presence of a "real" exposure to GSM radiofrequency signal and once under a "sham" exposure (placebo condition). BOLD response of active brain areas and reaction times (RTs) while performing the task were measured both before and after the exposure. RESULTS: RTs to the somatosensory task did not change as a function of exposure (real vs sham) to GSM signal. BOLD results revealed significant activations in inferior parietal lobule, insula, precentral and postcentral gyri associated with Go responses after both ''real'' and ''sham'' exposure, whereas no significant effects were observed in the ROI analysis. CONCLUSIONS: The present fMRI study did not detect any brain activity changes by mobile phones. Also RTs in a somatosensory task resulted unaffected. SIGNIFICANCE: No changes in BOLD response have been observed as a consequence of RF-EMFs exposure.


Assuntos
Telefone Celular , Cognição/fisiologia , Desempenho Psicomotor/fisiologia , Adulto , Encéfalo/irrigação sanguínea , Encéfalo/fisiologia , Mapeamento Encefálico/instrumentação , Mapeamento Encefálico/métodos , Humanos , Imageamento por Ressonância Magnética , Masculino , Oxigênio/sangue , Ondas de Rádio , Tempo de Reação/fisiologia , Adulto Jovem
12.
Psychol Res Behav Manag ; 4: 87-96, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-22114539

RESUMO

This paper reviews the affective neuroscience dealing with the effects of traumatic events. We give an overview of the normal fear reactions, the pathological fear reaction, and the character of emotional episodic memories. We find that both emotions and emotional memories are a tripartite unit of sensory information, autonomic reaction, and motor impulse (the PRM complex). We propose that emotions and movements are part and parcel of the same complex. This is our main finding from the review of affective neuroscience, and from here we focus on psychotherapy with post-trauma reactions. The finding of the process of memory reconsolidation opens up a new treatment approach: affective psychotherapy focused on reconsolidation. The meaning of reconsolidation is that an emotional memory, when retrieved and being active, will rest in a labile form, amenable to change, for a brief period of time, until it reconsolidates in the memory. This leads us to the conclusion that emotions, affects, must be evoked during the treatment session and that positive emotion must come first, because safety must be part of the new memories. In the proposed protocol of affective psychotherapy based on reconsolidation the emotional episodic memory is relived in a safe and positive setting, focused in turn on the sensory experience, the autonomic reaction, and the motor impulse. Then it is followed by a fantasy of a different positive version of the same event. All in all treatment should provide a series of new memories without fear related to the original event. With the focus on the motor program, and the actions, there is a natural link to art therapy and to the mode of play, which can rehearse and fantasize new positive actions.

13.
Front Psychol ; 2: 271, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-22059077

RESUMO

An unanswered question in adult language learning or late bi and multilingualism is why individuals show marked differences in their ability to imitate foreign accents. While recent research acknowledges that more adults than previously assumed can still acquire a "native" foreign accent, very little is known about the neuro-cognitive correlates of this special ability. We investigated 140 German-speaking individuals displaying varying degrees of "mimicking" capacity, based on natural language text, sentence, and word imitations either in their second language English or in Hindi and Tamil, languages they had never been exposed to. The large subject pool was strictly controlled for previous language experience prior to magnetic resonance imaging. The late-onset (around 10 years) bilinguals showed significant individual differences as to how they employed their left-hemisphere speech areas: higher hemodynamic activation in a distinct fronto-parietal network accompanied low ability, while high ability paralleled enhanced gray matter volume in these areas concomitant with decreased hemodynamic responses. Finally and unexpectedly, males were found to be more talented foreign speech mimics.

14.
Neuron ; 69(5): 1015-28, 2011 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-21382559

RESUMO

In everyday life attention operates within complex and dynamic environments, while laboratory paradigms typically employ simple and stereotyped stimuli. This fMRI study investigated stimulus-driven spatial attention using a virtual-environment video. We explored the influence of bottom-up signals by computing saliency maps of the environment and by introducing attention-grabbing events in the video. We parameterized the efficacy of these signals for the orienting of spatial attention by measuring eye movements and used these parameters to analyze the imaging data. The efficacy of bottom-up signals modulated ongoing activity in dorsal fronto-parietal regions and transient activation of the ventral attention system. Our results demonstrate that the combination of computational, behavioral, and imaging techniques enables studying cognitive functions in ecologically valid contexts. We highlight the central role of the efficacy of stimulus-driven signals in both dorsal and ventral attention systems, with a dissociation of the efficacy of background salience versus distinctive events in the two systems.


Assuntos
Atenção/fisiologia , Encéfalo/fisiologia , Orientação/fisiologia , Percepção Espacial/fisiologia , Percepção Visual/fisiologia , Adulto , Mapeamento Encefálico , Meio Ambiente , Movimentos Oculares/fisiologia , Humanos , Processamento de Imagem Assistida por Computador , Imageamento por Ressonância Magnética , Estimulação Luminosa , Tempo de Reação/fisiologia
15.
Brain Res Bull ; 82(1-2): 46-56, 2010 Apr 29.
Artigo em Inglês | MEDLINE | ID: mdl-20223285

RESUMO

Meditation refers to a family of complex emotional and attentional regulatory practices, which can be classified into two main styles - focused attention (FA) and open monitoring (OM) - involving different attentional, cognitive monitoring and awareness processes. In a functional magnetic resonance study we originally characterized and contrasted FA and OM meditation forms within the same experiment, by an integrated FA-OM design. Theravada Buddhist monks, expert in both FA and OM meditation forms, and lay novices with 10 days of meditation practice, participated in the experiment. Our evidence suggests that expert meditators control cognitive engagement in conscious processing of sensory-related, thought and emotion contents, by massive self-regulation of fronto-parietal and insular areas in the left hemisphere, in a meditation state-dependent fashion. We also found that anterior cingulate and dorsolateral prefrontal cortices play antagonist roles in the executive control of the attention setting in meditation tasks. Our findings resolve the controversy between the hypothesis that meditative states are associated to transient hypofrontality or deactivation of executive brain areas, and evidence about the activation of executive brain areas in meditation. Finally, our study suggests that a functional reorganization of brain activity patterns for focused attention and cognitive monitoring takes place with mental practice, and that meditation-related neuroplasticity is crucially associated to a functional reorganization of activity patterns in prefrontal cortex and in the insula.


Assuntos
Atenção/fisiologia , Encéfalo , Cognição/fisiologia , Meditação , Adulto , Encéfalo/anatomia & histologia , Encéfalo/fisiologia , Budismo/psicologia , Humanos , Imageamento por Ressonância Magnética/métodos , Masculino , Meditação/psicologia , Pessoa de Meia-Idade , Desempenho Psicomotor/fisiologia
16.
J Psychiatr Res ; 44(7): 477-85, 2010 May.
Artigo em Inglês | MEDLINE | ID: mdl-19942229

RESUMO

There is converging evidence of gray matter (GM) structural alterations in different limbic structures in Post-Traumatic Stress Disorder (PTSD) patients. The aim of this study was to evaluate GM density in PTSD in relation to trauma load, and to assess the GM differences between responders (R) and non-responders (NR) to EMDR therapy. Magnetic Resonance Imaging (MRI) scans of 21 subjects exposed to occupational trauma, who developed PTSD (S), and of 22 who did not (NS), were compared by means of an optimized Voxel-Based Morphometry (VBM) analysis as implemented in SPM. Within S, further comparisons were made between 10 R and 5 NR. A regression analysis between GM density and the Traumatic Antecedents Questionnaire (TAQ) was also performed on all 43 subjects. Results showed a significantly lower GM density in S as compared to NS in the left posterior cingulate and the left posterior parahippocampal gyrus. Moreover, NR showed a significantly lower GM density as compared to R in bilateral posterior cingulate, as well as anterior insula, anterior parahippocampal gyrus and amygdala in the right hemisphere. Regression analysis showed that GM density negatively correlated with trauma load in bilateral posterior cingulate, left anterior insula, and right anterior parahippocampal gyrus. In conclusion, a GM lower density in limbic and paralimbic cortices were found to be associated with PTSD diagnosis, trauma load, and EMDR treatment outcome, suggesting a view of PTSD characterized by memory and dissociative disturbances.


Assuntos
Mapeamento Encefálico , Córtex Cerebral/patologia , Sistema Límbico/patologia , Transtornos de Estresse Pós-Traumáticos/patologia , Adulto , Feminino , Lateralidade Funcional , Humanos , Imageamento Tridimensional/métodos , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Vias Neurais/patologia , Inquéritos e Questionários
18.
Psychiatry Res ; 173(1): 8-14, 2009 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-19443186

RESUMO

Principal component analysis (PCA) provides a method to explore functional brain connectivity. The aim of this study was to identify regional cerebral blood flow (rCBF) distribution differences between Alzheimer's disease (AD) patients and controls (CTR) by means of volume of interest (VOI) analysis and PCA. Thirty-seven CTR, 30 mild AD (mildAD) and 27 moderate AD (modAD) subjects were investigated using single photon emission computed tomography with (99m)Tc-hexamethylpropylene amine oxime. Analysis of covariance (ANCOVA), PCA, and discriminant analysis (DA) were performed on 54 VOIs. VOI analysis identified in both mildAD and modAD subjects a decreased rCBF in six regions. PCA in mildAD subjects identified four principal components (PCs) in which the correlated VOIs showed a decreased level of rCBF, including regions that are typically affected early in the disease. In five PCs, including parietal-temporal-limbic cortex, and hippocampus, a significantly lower rCBF in correlated VOIs was found in modAD subjects. DA significantly discriminated the groups. The percentage of subjects correctly classified was 95, 70, and 81 for CTR, mildAD and modAD groups, respectively. PCA highlighted, in mildAD and modAD, relationships not evident when brain regions are considered as independent of each other, and it was effective in discriminating groups. These findings may allow neurophysiological inferences to be drawn regarding brain functional connectivity in AD that might not be possible with univariate analysis.


Assuntos
Doença de Alzheimer/diagnóstico por imagem , Encéfalo/irrigação sanguínea , Encéfalo/diagnóstico por imagem , Circulação Cerebrovascular , Análise de Componente Principal , Tomografia Computadorizada de Emissão de Fóton Único , Idoso , Doença de Alzheimer/diagnóstico , Doença de Alzheimer/psicologia , Análise de Variância , Mapeamento Encefálico/métodos , Análise Discriminante , Feminino , Hipocampo/irrigação sanguínea , Hipocampo/diagnóstico por imagem , Humanos , Masculino , Pessoa de Meia-Idade , Lobo Parietal/irrigação sanguínea , Lobo Parietal/diagnóstico por imagem , Análise de Componente Principal/métodos , Compostos Radiofarmacêuticos , Índice de Gravidade de Doença , Tecnécio Tc 99m Exametazima , Lobo Temporal/irrigação sanguínea , Lobo Temporal/diagnóstico por imagem , Tomografia Computadorizada de Emissão de Fóton Único/métodos
19.
CNS Spectr ; 13(9): 805-14, 2008 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-18849900

RESUMO

INTRODUCTION: 99mTc-d,l-hexamethylpropylene amine oxime (99mTc-HMPAO) retention in brain is proportional to cerebral blood flow and related to both the local hemodynamic state and to the cellular content of reduced glutathione. Alterations of the regional distribution of 99mTc-HMPAO retention, with discrepant results, have been reported at functional brain imaging of unipolar depression. Since mitochondrial involvement has been reported in depressed patients, the aim of the study was to explore whether the 99mTc-HMPAO retention at single-photon emission computed tomography in depressed patients may relate to different levels of mitochondrial function. METHODS: All patients had audiological and muscular symptoms, somatic symptoms that are common in depression. Citrate synthase (CS) activity assessed in muscle mitochondria correlated strongly with the activities of three mitochondrial respiratory chain enzymes and was used as a marker of mitochondrial function. K-means clustering performed on CS grouped eight patients with low and 11 patients with normal CS. Voxel-based analysis was performed on the two groups by statistical parametric mapping. RESULTS: Voxel-based analysis showed significantly higher 99mTc-HMPAO retention in the patients with low CS compared with the patients with normal CS in the posterior and inferior frontal cortex, the superior and posterior temporal cortex, the somato-sensory cortex, and the associative parietal cortex. CONCLUSION: Low muscle CS in depressed patients is related to higher regional 99mTc-HMPAO retention that may reflect cerebrovascular adaptation to impaired intracellular metabolism and/or intracellular enzymatic changes, as previously reported in mitochondrial disorder. Mitochondrial dysfunction in varying proportions of the subjects may explain some of the discrepant results for 99mTc-HMPAO retention in depression.


Assuntos
Encéfalo/diagnóstico por imagem , Citrato (si)-Sintase/metabolismo , Transtorno Depressivo/diagnóstico por imagem , Processamento de Imagem Assistida por Computador , Imageamento Tridimensional , Mitocôndrias Musculares/diagnóstico por imagem , Tomografia Computadorizada de Emissão de Fóton Único , Adulto , Mapeamento Encefálico , Córtex Cerebral/diagnóstico por imagem , Dominância Cerebral/fisiologia , Complexo I de Transporte de Elétrons/fisiologia , Feminino , Lobo Frontal/diagnóstico por imagem , Humanos , Masculino , Pessoa de Meia-Idade , Tecnécio Tc 99m Exametazima/farmacocinética
20.
Brain ; 131(Pt 7): 1783-92, 2008 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-18502782

RESUMO

Multiple sclerosis is an autoimmune disease predominantly affecting the white matter of the CNS, causing--among functional sequelae-cortico--cortical partial or total disconnection. Since functional connectivity linking cerebral regions is reliably reflected by synchronization of their neuronal firing, in this study an electrophysiological parameter measured by magnetoencephalography was used to quantify an intra-cortical connectivity (ICC) index focused on the primary somatosensory cortical areas (S1). Twenty-one patients affected by mild (Extended Disability Scale Score, median 1,5) relapsing-remitting (RR) multiple sclerosis in the remitting phase without clinically evident sensory impairment were evaluated. Three dimensional MRI was used to quantify the lesion load, discriminating black hole and non-black hole portions, normalized by individual brain volumes. When matched with a control population, multiple sclerosis patients showed a reduced ICC combined with the complete loss of the finger-dependent functional specialization in S1 cortex of the dominant hemisphere. No association was found between ICC impairment and disease duration, or prolongation of the central sensory conduction time, presence of spinal cord lesions and ongoing disease modifying therapy. The ICC index slightly correlated with the lesion load. A local index of ICC in a circumscribed brain primary area was altered in mildly disabled RR-multiple sclerosis patients, also in absence of any impairment of central sensory conduction. In conclusion, the diffuse damage influencing the multi-nodal network subtending complex cerebral functions also affects intrinsic cortical connectivity. The S1 ICC index is proposed as a highly sensitive and simple-to-test functional measure for the evaluation of intra-cortical synchronization mechanisms in RR-multiple sclerosis.


Assuntos
Córtex Cerebral/fisiopatologia , Esclerose Múltipla Recidivante-Remitente/fisiopatologia , Vias Neurais/fisiopatologia , Adulto , Mapeamento Encefálico/métodos , Avaliação da Deficiência , Feminino , Humanos , Imageamento Tridimensional/métodos , Imageamento por Ressonância Magnética/métodos , Magnetoencefalografia/métodos , Masculino , Pessoa de Meia-Idade , Esclerose Múltipla Recidivante-Remitente/patologia , Vias Neurais/patologia , Processamento de Sinais Assistido por Computador , Fatores de Tempo
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