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1.
Neuroimage ; 267: 119833, 2023 02 15.
Artigo em Inglês | MEDLINE | ID: mdl-36572133

RESUMO

BACKGROUND: Transcranial magnetic stimulation (TMS) is an FDA-approved therapeutic option for treatment resistant depression. However, exact mechanisms-of-action are not fully understood and individual responses are variable. Moreover, although previously suggested, the exact network effects underlying TMS' efficacy are poorly understood as of today. Although, it is supposed that DLPFC stimulation indirectly modulates the sgACC, recent evidence is sparse. METHODS: Here, we used concurrent interleaved TMS/fMRI and state-of-the-science purpose-designed MRI head coils to delineate networks and downstream regions activated by DLPFC-TMS. RESULTS: We show that regions of increased acute BOLD signal activation during TMS resemble a resting-state brain network previously shown to be modulated by offline TMS. There was a topographical overlap in wide spread cortical and sub-cortical areas within this specific RSN#17 derived from the 1000 functional connectomes project. CONCLUSION: These data imply a causal relation between DLPFC-TMS and activation of the ACC and a broader network that has been implicated in MDD. In the broader context of our recent work, these data imply a direct relation between initial changes in BOLD activity mediated by connectivity to the DLPFC target site, and later consolidation of connectivity between these regions. These insights advance our understanding of the mechanistic targets of DLPFC-TMS and may provide novel opportunities to characterize and optimize TMS therapy in other neurological and psychiatric disorders.


Assuntos
Imageamento por Ressonância Magnética , Estimulação Magnética Transcraniana , Humanos , Encéfalo/diagnóstico por imagem , Mapeamento Encefálico , Córtex Pré-Frontal Dorsolateral
2.
Neuroimage ; 169: 342-351, 2018 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-29253656

RESUMO

Population receptive field (pRF) mapping based on functional magnetic resonance imaging (fMRI) is an ideal method for obtaining detailed retinotopic information. One particularly promising application of pRF mapping is the estimation and quantification of visual field effects, for example scotomata in patients suffering from macular dysfunction or degeneration (MD) or hemianopic defects in patients with intracranial dysfunction. However, pRF mapping performance is influenced by a number of factors including spatial and temporal resolution, distribution of dural venous sinuses and patient performance. This study addresses the ability of current pRF methodology to assess the size of simulated scotomata in healthy individuals. The data demonstrate that central scotomata down to a radius of 2.35° (4.7° diameter) visual angle can be reliably estimated in single subjects using high spatial resolution protocols and multi-channel receive array coils.


Assuntos
Mapeamento Encefálico/métodos , Reconhecimento Visual de Modelos/fisiologia , Mascaramento Perceptivo/fisiologia , Córtex Visual/diagnóstico por imagem , Campos Visuais/fisiologia , Adulto , Feminino , Voluntários Saudáveis , Humanos , Imageamento por Ressonância Magnética , Masculino , Escotoma/diagnóstico por imagem , Adulto Jovem
3.
Transl Psychiatry ; 7(1): e1008, 2017 01 24.
Artigo em Inglês | MEDLINE | ID: mdl-28117844

RESUMO

Several previous functional magnetic resonance imaging (fMRI) studies have demonstrated the predictive value of brain activity during emotion processing for antidepressant response, with a focus on clinical outcome after 6-8 weeks. However, longitudinal studies emphasize the paramount importance of early symptom improvement for the course of disease in major depressive disorder (MDD). We therefore aimed to assess whether neural activity during the emotion discrimination task (EDT) predicts early antidepressant effects, and how these predictive measures relate to more sustained response. Twenty-three MDD patients were investigated once with ultrahigh-field 7T fMRI and the EDT. Following fMRI, patients received Escitalopram in a flexible dose schema and were assessed with the Hamilton Depression Rating Scale (HAMD) before, and after 2 and 4 weeks of treatment. Deactivation of the precuneus and posterior cingulate cortex (PCC) during the EDT predicted change in HAMD scores after 2 weeks of treatment. Baseline EDT activity was not predictive of HAMD change after 4 weeks of treatment. The precuneus and PCC are integral components of the default mode network (DMN). We show that patients who exhibit stronger DMN suppression during emotion processing are more likely to show antidepressant response after 2 weeks. This is, to our knowledge, the first study to show that DMN activity predicts early antidepressant effects. However, DMN deactivation did not predict response at 4 weeks, suggesting that our finding is representative of early, likely treatment-related, yet unspecific symptom improvement. Regardless, early effects may be harnessed for optimization of treatment regimens and patient care.


Assuntos
Antidepressivos/uso terapêutico , Encéfalo/fisiopatologia , Citalopram/uso terapêutico , Transtorno Depressivo Maior/tratamento farmacológico , Adolescente , Adulto , Transtorno Depressivo Maior/fisiopatologia , Emoções , Feminino , Neuroimagem Funcional , Giro do Cíngulo/fisiopatologia , Humanos , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Vias Neurais/fisiopatologia , Lobo Parietal/fisiopatologia , Resultado do Tratamento , Adulto Jovem
4.
Neuroimage ; 142: 211-224, 2016 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-27389789

RESUMO

Functional MRI enables the acquisition of a retinotopic map that relates regions of the visual field to neural populations in the visual cortex. During such a "population receptive field" (PRF) experiment, stable gaze fixation is of utmost importance in order to correctly link the presented stimulus patterns to stimulated retinal regions and the resulting Blood Oxygen Level Dependent (BOLD) response of the appropriate region within the visual cortex. A method is described that compensates for unstable gaze fixation by recording gaze position via an eyetracker and subsequently modifies the input stimulus underlying the PRF analysis according to the eyetracking measures. Here we show that PRF maps greatly improve when the method is applied to data acquired with either saccadic or smooth eye movements. We conclude that the technique presented herein is useful for studies involving subjects with unstable gaze fixation, particularly elderly patient populations.


Assuntos
Mapeamento Encefálico/métodos , Medições dos Movimentos Oculares , Movimentos Oculares/fisiologia , Imageamento por Ressonância Magnética/métodos , Percepção de Movimento/fisiologia , Reconhecimento Visual de Modelos/fisiologia , Córtex Visual/diagnóstico por imagem , Adulto , Feminino , Humanos , Masculino , Adulto Jovem
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