RESUMO
Psychopathy is characterized by glibness and superficial charm, as well as a lack of empathy, guilt and remorse, and is often accompanied by antisocial behaviour. The cerebral bases of this syndrome have been mostly studied in violent subjects or those with a criminal history. However, the antisocial component of psychopathy is not central to its conceptualization, and in fact, psychopathic traits are present in well-adjusted, non-criminal individuals within the general population. Interestingly, certain psychopathy characteristics appear to be particularly pronounced in some groups or professions. Importantly, as these so-called adaptive or successful psychopaths do not show antisocial tendencies or have significant psychiatric comorbidities, they may represent an ideal population to study this trait. Here, we investigated such a group, specifically elite female judo athletes, and compared them with matched non-athletes. Participants completed psychopathy, anger, perspective-taking and empathic concern questionnaires and underwent structural magnetic resonance imaging (MRI). Grey matter volume (GMV) was computed using voxel-based morphometry from the T1-weighted images. Athletes scored significantly higher in primary psychopathy and anger and lower in empathy and perspective taking. They also exhibited smaller GMV in the right temporal pole, left occipital cortex and left amygdala/hippocampus. GMV values for the latter cluster significantly correlated with primary psychopathy scores across both groups. These results confirm and extend previous findings to a little-studied population and provide support for the conceptualization of psychopathy as a dimensional personality trait which not only is not necessarily associated with antisocial behaviour but may potentially have adaptive value.
Assuntos
Encéfalo , Substância Cinzenta , Humanos , Feminino , Encéfalo/diagnóstico por imagem , Encéfalo/patologia , Substância Cinzenta/patologia , Córtex Cerebral/patologia , Transtorno da Personalidade Antissocial/diagnóstico por imagem , Transtorno da Personalidade Antissocial/epidemiologia , Transtorno da Personalidade Antissocial/patologia , Atletas , Imageamento por Ressonância MagnéticaRESUMO
In the last decade, the exclusive role of the hippocampus in human declarative learning has been challenged. Recently, we have shown that gains in performance observed in motor sequence learning (MSL) during the quiet rest periods interleaved with practice are associated with increased hippocampal activity, suggesting a role of this structure in motor memory reactivation. Yet, skill also develops offline as memory stabilizes after training and overnight. To examine whether the hippocampus contributes to motor sequence memory consolidation, here we used a network neuroscience strategy to track its functional connectivity offline 30 min and 24 h post learning using resting-state functional magnetic resonance imaging. Using a graph-analytical approach we found that MSL transiently increased network modularity, reflected in an increment in local information processing at 30 min that returned to baseline at 24 h. Within the same time window, MSL decreased the connectivity of a hippocampal-sensorimotor network, and increased the connectivity of a striatal-premotor network in an antagonistic manner. Finally, a supervised classification identified a low-dimensional pattern of hippocampal connectivity that discriminated between control and MSL data with high accuracy. The fact that changes in hippocampal connectivity were detected shortly after training supports a relevant role of the hippocampus in early stages of motor memory consolidation.
Assuntos
Conectoma , Hipocampo , Consolidação da Memória , Consolidação da Memória/fisiologia , Hipocampo/fisiologia , Hipocampo/ultraestrutura , Humanos , Masculino , Feminino , Adulto Jovem , Adulto , Imageamento por Ressonância Magnética , Rede Nervosa/fisiologia , Rede Nervosa/ultraestruturaRESUMO
Social emotions are critical to successfully navigate in a complex social world because they promote self-regulation of behaviour. Difficulties in social behaviour are at the core of autism spectrum disorder (ASD). However, social emotions and their neural correlates have been scarcely investigated in this population. In particular, the experience of envy has not been addressed in ASD despite involving neurocognitive processes crucially compromised in this condition. Here, we used an fMRI adapted version of a well-validated task to investigate the subjective experience of envy and its neural correlates in adults with ASD (n = 30) in comparison with neurotypical controls (n = 28). Results revealed that both groups reported similarly intense experience of envy in association with canonical activation in the anterior cingulate cortex and the anterior insula, among other regions. However, in participants with ASD, the experience of envy was accompanied by overactivation of the posterior insula, the postcentral gyrus and the posterior superior temporal gyrus, regions subserving the processing of painful experiences and mentalizing. This pattern of results suggests that individuals with ASD may use compensatory strategies based on the embodied amplification of pain and additional mentalizing efforts to shape their subjective experience of envy. Results have relevant implications to better understand the heterogeneity of this condition and to develop new intervention targets.
Assuntos
Transtorno do Espectro Autista , Transtorno Autístico , Adulto , Humanos , Ciúme , Transtorno Autístico/diagnóstico por imagem , Transtorno do Espectro Autista/diagnóstico por imagem , Mapeamento Encefálico/métodos , Lobo Temporal/diagnóstico por imagem , Imageamento por Ressonância Magnética , DorRESUMO
Individuals with autism spectrum disorder (ASD) present difficulties in integrating mental state information in complex moral tasks. Yet, ASD research has not examined whether this process is influenced by emotions, let alone while capturing its neural bases. We investigated how language-induced emotions modulate intent-based moral judgment in ASD. In a fMRI task, 30 adults with ASD and 27 neurotypical controls read vignettes whose protagonists commit harm either accidentally or intentionally, and then decided how much punishment the protagonist deserved. Emotional content was manipulated across scenarios through the use of graphic language (designed to trigger arousing negative responses) vs. plain (just-the-facts, emotionless) language. Off-line functional connectivity correlates of task performance were also analyzed. In ASD, emotional (graphic) descriptions amplified punishment ratings of accidental harms, associated with increased activity in fronto-temporo-limbic, precentral, and postcentral/supramarginal regions (critical for emotional and empathic processes), and reduced connectivity among the orbitofrontal cortex and the angular gyrus (involved in mentalizing). Language manipulation did not influence intentional harm processing in ASD. In conclusion, in arousing and ambiguous social situations that lack intentionality clues (i.e. graphic accidental harm scenarios), individuals with ASD would misuse their emotional responses as the main source of information to guide their moral decisions. Conversely, in face of explicit harmful intentions, they would be able to compensate their socioemotional alterations and assign punishment through non-emotional pathways. Despite limitations, such as the small sample size and low ecological validity of the task, results of the present study proved reliable and have relevant theoretical and translational implications.
Assuntos
Transtorno do Espectro Autista , Transtorno Autístico , Adulto , Humanos , Julgamento , Punição , Emoções , Princípios MoraisRESUMO
Recent evidence suggests that gains in performance observed while humans learn a novel motor sequence occur during the quiet rest periods interleaved with practice (micro-offline gains, MOGs). This phenomenon is reminiscent of memory replay observed in the hippocampus during spatial learning in rodents. Whether the hippocampus is also involved in the production of MOGs remains currently unknown. Using a multimodal approach in humans, here we show that activity in the hippocampus and the precuneus increases during the quiet rest periods and predicts the level of MOGs before asymptotic performance is achieved. These functional changes were followed by rapid alterations in brain microstructure in the order of minutes, suggesting that the same network that reactivates during the quiet periods of training undergoes structural plasticity. Our work points to the involvement of the hippocampal system in the reactivation of procedural memories.
Assuntos
Hipocampo/fisiologia , Aprendizagem/fisiologia , Destreza Motora/fisiologia , Adolescente , Adulto , Feminino , Humanos , Imageamento por Ressonância Magnética , Masculino , Memória , Adulto JovemRESUMO
BACKGROUND: Fractional anisotropy (FA) and mean diffusivity (MD) are frequently used to evaluate longitudinal changes in white matter (WM) microstructure. Recently, there has been a growing interest in identifying experience-dependent plasticity in gray matter using MD. Improving registration has thus become a major goal to enhance the detection of subtle longitudinal changes in cortical microstructure. PURPOSE: To optimize normalization of diffusion tensor images (DTI) to improve registration in gray matter and reduce variability associated with multisession registrations. STUDY TYPE: Prospective longitudinal study. SUBJECTS: Twenty-one healthy subjects (18-31 years old) underwent nine MRI scanning sessions each. FIELD STRENGTH/SEQUENCE: 3.0T, diffusion-weighted multiband-accelerated sequence, MP2RAGE sequence. ASSESSMENT: Diffusion-weighted images were registered to standard space using different pipelines that varied in the features used for normalization, namely, the nonlinear registration algorithm (FSL vs. ANTs), the registration target (FA-based vs. T1 -based templates), and the use of intermediate individual (FA-based or T1 -based) targets. We compared the across-session test-retest reproducibility error of these normalization approaches for FA and MD in white and gray matter. STATISTICAL TESTS: Reproducibility errors were compared using a repeated-measures analysis of variance with pipeline as the within-subject factor. RESULTS: The registration of FA data to the FMRIB58 FA atlas using ANTs yielded lower reproducibility errors in white matter (P < 0.0001) with respect to FSL. Moreover, using the MNI152 T1 template as the target of registration resulted in lower reproducibility errors for MD (P < 0.0001), whereas the FMRIB58 FA template performed better for FA (P < 0.0001). Finally, the use of an intermediate individual template improved reproducibility when registration of the FA images to the MNI152 T1 was carried out within modality (FA-FA) (P < 0.05), but not via a T1 -based individual template. DATA CONCLUSION: A normalization approach using ANTs to register FA images to the MNI152 T1 template via an individual FA template minimized test-retest reproducibility errors both for gray and white matter. LEVEL OF EVIDENCE: 1 TECHNICAL EFFICACY STAGE: 1 J. Magn. Reson. Imaging 2020;52:766-775.
Assuntos
Substância Branca , Encéfalo/diagnóstico por imagem , Imagem de Difusão por Ressonância Magnética , Imagem de Tensor de Difusão , Estudos Longitudinais , Imageamento por Ressonância Magnética , Estudos Prospectivos , Reprodutibilidade dos Testes , Substância Branca/diagnóstico por imagemRESUMO
A new method for detecting activations in random fields, which may be useful for addressing the issue of multiple comparisons in neuroimaging, is presented. This method is based on some constructs of mathematical morphology--specifically, morphological erosions and dilations--that enable the detection of active regions in random fields possessing moderate activation levels and relatively large spatial extension, which may not be detected by the standard methods that control the family-wise error rate. The method presented here permits an appropriate control of the false positive errors, without having to adjust any threshold values, other than the significance level. The method is easily adapted to permutation-based procedures (with the usual restrictions), and therefore does not require strong assumptions about the distribution and spatio-temporal correlation structure of the data. Some examples of applications to synthetic data, including realistic fMRI simulations, as well as to real fMRI and electroencephalographic data are presented, illustrating the power of the presented technique. Comparisons with other methods that combine voxel intensity and cluster size, as well as some extensions of the method presented here based on their basic ideas are presented as well.
RESUMO
A new method for detecting activations in random fields, which may be useful for addressing the issue of multiple comparisons in neuroimaging, is presented. This method is based on some constructs of mathematical morphology - specifically, morphological erosions and dilations - that enable the detection of active regions in random fields possessing moderate activation levels and relatively large spatial extension, which may not be detected by the standard methods that control the family-wise error rate. The method presented here permits an appropriate control of the false positive errors, without having to adjust any threshold values, other than the significance level. The method is easily adapted to permutation-based procedures (with the usual restrictions), and therefore does not require strong assumptions about the distribution and spatio-temporal correlation structure of the data. Some examples of applications to synthetic data, including realistic fMRI simulations, as well as to real fMRI and electroencephalographic data are presented, illustrating the power of the presented technique. Comparisons with other methods that combine voxel intensity and cluster size, as well as some extensions of the method presented here based on their basic ideas are presented as well.
Assuntos
Algoritmos , Encéfalo/anatomia & histologia , Encéfalo/fisiologia , Interpretação de Imagem Assistida por Computador/métodos , Processamento de Sinais Assistido por Computador , Estatísticas não Paramétricas , Eletroencefalografia , Potenciais Evocados/fisiologia , Humanos , Imageamento por Ressonância MagnéticaRESUMO
Parkinson's disease is a movement disorder whose principal symptoms are tremor, rigidity, bradykinesia and postural instability. Initially, drugs like L: -dopa or dopaminergic agonists are able to control these symptoms, but with the progress of the disease these drugs become less effective. Previous studies have reported that repetitive transcranial magnetic stimulation (rTMS) can improve these motor symptoms. The objective of this study was to investigate the neural mechanisms through which 25 Hz rTMS may improve motor symptoms in Parkinson's disease. In a double-blind placebo-controlled study, we evaluated the effects of 25 Hz. rTMS in 10 Parkinson's disease patients. Fifteen rTMS sessions were performed over the primary cortex on both hemispheres (one after the other) during a 12-week period. The patients were studied using functional magnetic resonance imaging during performance of a simple tapping and a complex tapping task, 1 week before the administration of the first rTMS session and just after the last session. rTMS improved bradykinesia, while functional magnetic resonance imaging showed different cortical patterns in prefrontal cortex when patients performed the complex tapping test. Furthermore, the improvement in bradykinesia is associated with caudate nucleus activity increases in simple tapping. Finally, we observed a relative change in functional connectivity between the prefrontal areas and the supplementary motor area after rTMS. These results show a potential beneficial effect of repetitive transcranial magnetic stimulation on bradykinesia in Parkinson's disease which is substantiated by neural changes observed in functional magnetic resonance imaging.
Assuntos
Encéfalo/irrigação sanguínea , Doença de Parkinson/patologia , Doença de Parkinson/terapia , Estimulação Magnética Transcraniana/métodos , Estimulação Acústica/métodos , Idoso , Encéfalo/fisiopatologia , Mapeamento Encefálico , Feminino , Humanos , Processamento de Imagem Assistida por Computador/métodos , Estudos Longitudinais , Imageamento por Ressonância Magnética/métodos , Masculino , Pessoa de Meia-Idade , Atividade Motora/fisiologia , Oxigênio/sangue , Desempenho Psicomotor/fisiologia , Tempo de Reação/fisiologiaRESUMO
BACKGROUND: Word reading involves several steps, from the visual perception of each of its constitutent elements to its recognition as an entity with a specific meaning. Various brain structures participate in these processes, depending of the linguistic and cognitive characteristics of the stimulus. Our objective was to characterize brain activity through the use of functional magnetic resonance imaging (FMRI) associated with the process of noun reading. METHODS: Eleven healthy right-handed volunteers participated in a lexical decision task involving 58 written nouns. An equal number of letter sequences were used as control stimuli. Reaction times were also recorded. RESULTS: There was a difference (p < 0.05) in reaction time between nouns and letter sequences in the lexical decision task. FMRI contrasted between conditions revealed significant activations in several areas involved in reading. CONCLUSIONS: The brain activation may reflect the different perceptual demands associated with the initial processing of nouns, as compared to meaningless letter sequences. We attribute the difference between our results and those previously reported to the particular characteristics of the pronunciation rules of written Spanish.