FD foi apoiado por um Young Investigator Award da Aliança Nacional dos EUA para a Pesquisa sobre Esquizofrenia e Depressão e um Prêmio CPRF da Fundação de Pesquisa Psiquiátrica Canadense.

I. Projeto de tarefas, estímulos, e protocolo experimental <ol><li> A tarefa básica deste protocolo é um atraso de resposta tarefa WM, onde novas tarefas irrelevantes distratores emocionais e neutros são apresentados durante o intervalo de atraso entre os memorandos e sondas (ver Figura 1 para o diagrama que ilustra a tarefa original). Relacionados a eventos de dados fMRI são registrados enquanto os participantes executar esta tarefa. Scrambled versões do distratores real também pode ser usado como controle perceptual, que têm idênticas propriedades básicas (freqüência, por exemplo espacial e luminosidade). </li></ol><img src="/files/ftp_upload/2434/2434fig1.jpg" alt="Figura 1" /> Figura 1. Diagrama geral da tarefa de memória Delayed-Response Trabalhando com Distração (de 6, com permissão). Três faces são utilizadas na exposição, a fim de envolver fortemente o sistema executivo dorsal, e pares de distratores romance são utilizados a fim de aumentar a Impact de distração emocional sobre WM desempenho e atividade cerebral. O impacto de distratores emocionais também pode ser aumentada, apresentando as imagens em cores (não mostrado), e por sorteio distratores com conteúdo emocional e semântica similar. Neste contexto, especial atenção deve ser dada a partida também imagens emocionais e neutros em propriedades básicas, como brilho e freqüência espacial 15, para evitar a introdução confunde possível. Os participantes são orientados a manter seu foco na tarefa WM enquanto ainda está processando a distratores, e para dar respostas rápidas e precisas para as sondagens, pressionando um botão de resposta (1 = Velha, 2 = Novo). Para a apresentação do estímulo, usamos CIGAL ( <a href="http://www.nitrc.org/projects/cigal/">http://www.nitrc.org/projects/cigal/</a> ). Os memorandos e sondas podem ser apresentados a cores ou a preto e branco. <ol start="2"><li> É aconselhável que o sexo dos rostos na exposição tem proporções equilibradas do sexo masculino (50%) e females (50%). Proporção equilibrada semelhante também é recomendado para o Velho (50%) e (50%) New sondas. A dificuldade da tarefa WM pode ser variado alterando as proporções e / ou pela variação de outros fatores - por exemplo, a semelhança das características faciais entre os rostos de memorando mesma e sua semelhança com as sondas, e / ou através da manipulação da presença / ausência de extra-facial apresenta na exposição (ver também o filme). Além de rostos, outros estímulos também pode ser usado como memorandos e sondas 9. </li><li> Recomenda-se que os ensaios 30-40 por condição 6, 11 ser usado com este projeto, embora dada a sua estabilidade como um sinal de design &quot;slow-paced&quot; fMRI robusta também pode ser obtida com ensaios menos (veja Materiais suplementares de 6). Isto permite a recolha de dados fMRI em ~ 1,5-2 horas., Que é viável para uso em participantes saudáveis ​​e clínicos. Apesar de sua pequena desvantagem devido ao número relativamente menor de ensaiosque podem estar envolvidos em relação ao &quot;fast-paced&quot; designs, este projeto tem a vantagem de obter sinal de fMRI mais estável de um único ensaio e melhor separação do sinal associada com estudos individuais e dentro de estímulos julgamento / fases, que também são vantajosos para funcionais análises de conectividade. </li><li> Variação do tipo de distratores também contribui para a versatilidade deste projeto, adaptando-o de acordo com os objetivos das investigações e as populações-alvo. Distratores emocionais e neutros no projeto original 6 foram selecionados a partir do International Affective Picture System 16, mas efeitos similares podem ser obtidos com estímulos outros novos que são eficazes como distratores 12, e / ou com manipulações que aumentam a sensibilidade da tarefa na WM detecção de diferenças comportamentais (por exemplo, avaliando também a confiança dos participantes em suas respostas) 11. </li><li> Por exemplo, em um estudo recente no pós-guerra veterans com ou sem pós-traumático (PTSD) 12, as imagens emocionais IAPS induzindo geral emoções negativas foram substituídas por imagens combate relacionados. Estas imagens eram esperados para induzir emoções que são mais especificamente ligados ao combate, traumas, e, portanto, ser distratores mais eficaz no combate expostas coortes, particularmente no grupo de PTSD. Além disso, estímulos que induzem emoções negativas específicas (por exemplo, ansiedade) ou estímulos emocionalmente positivos podem também ser usados ​​como distratores. Por exemplo, rostos exibindo expressões medo poderia induzir a ansiedade social, e, portanto, ser eficaz em investigar o impacto de distração indutores de ansiedade transitória na WM 11. Além disso, efeitos semelhantes podem ser encontrados com distratores positiva 17. </li><li> Finalmente, em conjunto com outras medidas (por exemplo, comportamentais e de personalidade relacionados), este paradigma também pode ser usado para investigar relações entre a atividade cerebral e individuais diferem<html> diferenças em vários aspectos que afetam o desempenho cognitivo nesta tarefa 8, 10, 11. </li></ol> II. Preparando o assunto para a digitalização Todos os participantes devem fornecer consentimento informado por escrito antes da execução do protocolo experimental, que deve ser aprovado por um Conselho de Ética. Antes de entrar no quarto de digitalização <ol><li> No dia da varredura, o estado atual do participante é avaliado afetiva, para controlar o efeito de humor na tarefa WM com distração. Em conjunto com avaliações pós-digitalização, essas avaliações inicial pode ser também usado para triagem de alterações no humor, como resultado da participação no estudo 11. </li><li> Antes da digitalização, o participante é informado com detalhes dos procedimentos de verificação, e é dado instruções específicas para a tarefa comportamental. O participante também completa uma curta sessão de treinos para se familiarizar com a tarefa. </li></ol>e_step &quot;&gt; Ao entrar no quarto de digitalização <ol start="3"><li> O participante encontra-se em decúbito dorsal sobre a mesa de digitalização, com amortecimento adicional para a cabeça, para assegurar o conforto durante a verificação e minimizar o movimento. Para minimizar ainda mais o movimento da cabeça, o lado não-adesiva de um comprimento de fita pode ser enrolado em torno de leve na testa do sujeito. Assuntos são dadas a proteção de ouvido, bem como fones de ouvido de isolamento para se comunicar com o pesquisador durante o exame de ressonância magnética. </li><li> Mão direita do sujeito é posicionado confortavelmente na caixa de resposta. Antes de iniciar a coleta de dados, é fundamental para se certificar de que os botões de resposta funciona corretamente e que o sujeito pode ver a tela de projeção claramente para apresentação do estímulo. Um botão de parada de emergência também é colocado nas proximidades, de modo que o assunto pode indicar qualquer necessidade urgente de parar o scanner. </li></ol> Após a sessão de digitalização <ol start="5"><li> Tarefas adicionais podem ser usadas para outros AVALIAÇÃO comportamentaists - por exemplo, para determinar a sensibilidade dos participantes para os distratores, por ranking da valência emocional / intensidade de distratores e / ou a distração subjetivamente percebido dos distratores. Estas avaliações podem ser usados ​​para garantir que a percepção subjetiva de estímulos emocionais usado durante a verificação replica efeitos anteriores mostrado na literatura, e as diferenças individuais nas avaliações podem ser usados ​​para investigar a sua influência sobre os mecanismos neurais mediando o efeito prejudicial das emoções sobre a cognição 6 , 8. </li><li> Avaliações de traços de personalidade (por exemplo, traço de ansiedade, reatividade emocional) também pode ser feita após a ressonância magnética, se não for realizada antes da digitalização 11. </li></ol> III. A gravação de dados e análise Digitalização Parâmetros No estudo original 6, coletamos dados de MRI usando um scanner 4 Tesla Geral Elétrica para gravações de ressonância magnética, mas para os mais recrentes versões da tarefa que também foram sucesso na coleta de dados de ressonância magnética com um scanner de 1,5 T 11. No 4T scanner série, de 30 fatias funcional (voxel size = 4 x 4 x 4 mm) foram adquiridas axialmente com uma seqüência de pulsos espiral inversa (TR = 2.000 ms; TE = 31 ms; campo de visão = 256 x 256 milímetros) , permitindo assim full-cérebro cobertura. Da mesma forma, nos 1,5 scanner série, de 28 fatias funcional (voxel size = 4 x 4 x 4 mm), foram adquiridas axialmente com uma seqüência echoplanar (TR = 2000 ms; TE = 40 ms; campo de visão = 256 mm x 256 ). Imagens de alta resolução estruturais também foram adquiridos na orientação axial (in-plane resolution = 1 mm 2; anátomo-funcionais ratio = 4:1). Análise de Dados Usamos Statistical Parametric Mapping (SPM: <a href="http://www.fil.ion.ucl.ac.uk/spm/">http://www.fil.ion.ucl.ac.uk/spm/</a> ) em combinação com as ferramentas Matlab baseado em casa. Pré-processamento envolve etapas típicas: Garantia de qualidade *, um TRlignment correção de movimento, co-registro, normalização e suavização (usando um 8 x 8 x 8 mm Kernel) * garantia de qualidade básicos envolvidos inspeção visual dos dados, para detectar movimentos brutos dos participantes e do movimento relacionados com artefatos no dados, bem como a identificação de volumes com picos incomuns no sinal MR. Individuais e de grupo em nível de análises estatísticas envolvem comparações de atividade cerebral de acordo com o tipo distracter (distração emocional versus neutra). Além disso, correlações de dados de imagem cerebral com medidas subjetivas ou objetivas de distração (eg ratings, emocional e distração e desempenho da memória de trabalho) 6,8,11 e / ou as pontuações medidas de personalidade indexação (por exemplo, ansiedade-traço) 11 também pode ser realizada, para investigar como a atividade do cérebro co-varia de acordo com as diferenças individuais nessas medidas. Análises em todos os nossos estudos usando este protocolo tem normalmente se concentram na atividade observada durante o intervalo de atraso, when os distratores são apresentados, mas a atividade em tempo bloqueado para outros eventos (por exemplo, sondas) também pode ser investigado. IV. Resultados representante <img src="/files/ftp_upload/2434/2434fig2.jpg" alt="Figura 2" /> Figura 2. Padrão oposto da Atividade nos Sistemas Cérebro Ventral vs Dorsal na Presença de Distração Emocional (de 6, com permissão). Distratores emocionais produzidos aumento da actividade em regiões do cérebro ventral afetiva (bolhas vermelhas), como o córtex pré-frontal ventrolateral (vlPFC) e amígdala (não mostrado), ao produzir diminuição da atividade em regiões do cérebro dorsal executivo (bolhas azuis), como o córtex pré-frontal dorsolateral (CPFDL) e lateral do córtex parietal (LPC). A imagem central mostra mapas de ativação do contraste direto entre a maioria dos contra as condições menos distrair (ie, emocional versus mexidos), sobreposta a uma alta resolução de imagem cerebral exibido em um lateralvista do hemisfério direito. As barras de cores horizontal na parte inferior da imagem do cérebro indicam o gradiente de valores t dos mapas de ativação. Os gráficos de linha mostram a evolução no tempo da atividade em regiões do cérebro representante dorsal e ventral (indicado por setas codificadas por cores). As caixas de cinza retangular acima do x-eixos indicam o início e duração dos memorandos, distratores, e sondas, respectivamente. FFG = giro fusiforme.

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Não há conflitos de interesse declarados.

Este projeto experimental forneceu evidências iniciais de imagens do cérebro que o efeito prejudicial de distração emocional sobre os processos em curso cognitiva implica modulações recíprocas entre o sistema neural HotEmo ventral e dorsal do sistema ColdEx. Essa dissociação dorso-ventral foi ligada ao desempenho WM prejudicada na presença de distração emocional 6, tem sido sistematicamente replicados em condições normais de 11/08, 14/12 clínica, e outras condiçõe...

brain imaging investigation of the impairing effect of emotion on cognition

Emoções podem afetar a cognição, exercendo tanto o aumento (por exemplo, uma melhor memória para eventos emocionais) e prejudicar (por exemplo, o aumento da distração emocional) efeitos (revisto em 1). Complementando nosso protocolo últimos dois descrevem um método que permite investigação dos correlatos neurais do efeito memória de aumento de emoção (ver também 1, 3-5), aqui apresentamos um protocolo que permite investigação dos correlatos neurais do impacto negativo da emoção na cognição. A principal característica deste método é que ele permite a identificação das modulações recíprocas entre a atividade em um sistema neural ventral, envolvida na &quot;quente&quot; a emoção de processamento (HotEmo sistema), e um sistema dorsal, envolvido em &quot;frio&quot; de nível superior cognitivo / executiva processamento (ColdEx sistema), que estão ligadas ao desempenho cognitivo e às variações individuais no comportamento (revisto em 1). Desde sua introdu inicialction 6, este projeto tem-se revelado particularmente versáteis e influentes na elucidação de vários aspectos sobre os correlatos neurais do impacto negativo de distração emocional sobre a cognição, com foco na memória de trabalho (WM), e de lidar com a distração, tais 7,11 , em ambos os saudáveis ​​11/08 e clínicas participantes 12-14.

Watch this Scientific Journal Video about Brain Imaging Investigation of the Impairing Effect of Emotion on Cognition at JoVE.com

Brain Imaging Investigation of the Impairing Effect of Emotion on Cognition

Apresentamos um protocolo que permite a investigação dos mecanismos neurais mediando o impacto negativo da emoção na cognição, utilizando ressonância magnética funcional. Este protocolo pode ser usado com participantes saudáveis ​​e clínicos.

Investigação por imagem do cérebro o efeito prejudicial da emoção sobre a Cognição

Emotions can impact cognition by exerting both enhancing (e.g., better memory for emotional events) and impairing (e.g., increased emotional ...

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Neuroscience

16.0K visualizações.  University of Alberta. Apresentamos um protocolo que permite a investigação dos mecanismos neurais mediando o impacto negativo da emoção na cognição, utilizando ressonância magnética funcional. Este protocolo pode ser usado com participantes saudáveis ​​e clínicos.

Vídeo: Brain Imaging Investigation of the Impairing Effect of Emotion on Cognition

State-Dependency Effects on TMS:  A Look at Motive Phosphene Behavior

Transcranial magnetic stimulation (TMS) is a non-invasive neurostimulatory and neuromodulatory technique that can transiently or lastingly modulate cortical excitability (either increasing or decreasing it) via the application of localized magnetic field pulses.1,2 Within the field of TMS, the term state dependency refers to the initial, baseline condition of the particular neural region targeted for stimulation. As can be inferred, the effects of TMS can (and do) vary according to this primary susceptibility and responsiveness of the targeted cortical area.3,4,5

In this experiment, we will examine this concept of state dependency through the elicitation and subjective experience of motive phosphenes. Phosphenes are visually perceived flashes of small lights triggered by electromagnetic pulses to the visual cortex. These small lights can assume varied characteristics depending upon which type of visual cortex is being stimulated. In this particular study, we will be targeting motive phosphenes as elicited through the stimulation of V1/V2 and the V5/MT+ complex visual regions.6

In this article, we examine the effects of visually relevant state dependency on TMS induced motive phosphenic presentations.

Estado de dependência-Efeitos sobre a TMS: Um olhar sobre Comportamento fosfeno Motive

Transcranial magnetic stimulation (TMS) is a non-invasive neurostimulatory and neuromodulatory technique that can transiently or lastingly modulate ...

Neurociência

Brain Imaging Investigation of the Neural Correlates of Observing Virtual Social Interactions

The ability to gauge social interactions is crucial in the assessment of others&#x2019; intentions. Factors such as facial expressions and body language affect our decisions in personal and professional life alike 1. These "friend or foe" judgements are often based on first impressions, which in turn may affect our decisions to "approach or avoid". Previous studies investigating the neural correlates of social cognition tended to use static facial stimuli 2. Here, we illustrate an experimental design in which whole-body animated characters were used in conjunction with functional magnetic resonance imaging (fMRI) recordings. Fifteen participants were presented with short movie-clips of guest-host interactions in a business setting, while fMRI data were recorded; at the end of each movie, participants also provided ratings of the host behaviour. This design mimics more closely real-life situations, and hence may contribute to better understanding of the neural mechanisms of social interactions in healthy behaviour, and to gaining insight into possible causes of deficits in social behaviour in such clinical conditions as social anxiety and autism 3.

This article demonstrates an experimental design in which whole-body animated characters are used in conjunction with functional magnetic resonance imaging (fMRI) to investigate the neural correlates of observing virtual social interactions.

Investigação por imagem do cérebro os correlatos neurais da Observando Virtual Interações Sociais

The ability to gauge social interactions is crucial in the assessment of others&#x2019; intentions. Factors such as facial expressions and body language ...

Brain Imaging Investigation of the Neural Correlates of Emotional Autobiographical Recollection

Recollection of emotional autobiographical memories (AMs) is important to healthy cognitive and affective functioning 1 - remembering positive AMs is associated with increased personal well-being and self-esteem 2, whereas remembering and ruminating on negative AMs may lead to affective disorders 3. Although significant progress has been made in understanding the brain mechanisms underlying AM retrieval in general (reviewed in 4, 5), less is known about the effect of emotion on the subjective re-experience of AMs and the associated neural correlates. This is in part due to the fact that, unlike the investigations of the emotion effect on memory for laboratory-based microevents (reviewed in 6, 7-9), often times AM studies do not have a clear focus on the emotional aspects of remembering personal events (but see 10). Here, we present a protocol that allows investigation of the neural correlates of recollecting emotional AMs using functional magnetic resonance imaging (fMRI). Cues for these memories are collected prior to scanning by means of an autobiographical memory questionnaire (AMQ), therefore allowing for proper selection of emotional AMs based on their phenomenological properties (i.e., intensity, vividness, personal significance). This protocol can be used in healthy and clinical populations alike.

We present a protocol that allows investigation of the neural correlates of recollecting emotional autobiographical memories, using functional magnetic resonance imaging. This protocol can be used with both healthy and clinical participants.

Investigação por imagem do cérebro os correlatos neurais da Recordação Autobiographical Emocional

Recollection of emotional autobiographical memories (AMs) is important to healthy cognitive and affective functioning 1 - remembering positive AMs is ...

Brain Imaging Investigation of the Neural Correlates of Emotion Regulation

The ability to control/regulate emotions is an important coping mechanism in the face of emotionally stressful situations. Although significant progress has been made in understanding conscious/deliberate emotion regulation (ER), less is known about non-conscious/automatic ER and the associated neural correlates. This is in part due to the problems inherent in the unitary concepts of automatic and conscious processing1. Here, we present a protocol that allows investigation of the neural correlates of both deliberate and automatic ER using functional magnetic resonance imaging (fMRI). This protocol allows new avenues of inquiry into various aspects of ER. For instance, the experimental design allows manipulation of the goal to regulate emotion (conscious vs. non-conscious), as well as the intensity of the emotional challenge (high vs. low). Moreover, it allows investigation of both immediate (emotion perception) and long-term effects (emotional memory) of ER strategies on emotion processing. Therefore, this protocol may contribute to better understanding of the neural mechanisms of emotion regulation in healthy behaviour, and to gaining insight into possible causes of deficits in depression and anxiety disorders in which emotion dysregulation is often among the core debilitating features.

We present a protocol that allows investigation of the neural correlates of deliberate and automatic emotion regulation, using functional magnetic resonance imaging. This protocol can be used in healthy participants, both young and older, as well as in clinical patients.

Investigação por imagem do cérebro os correlatos neurais da regulação emocional

The ability to control/regulate emotions is an important coping mechanism in the face of emotionally stressful situations. Although significant progress ...

Brain Imaging Investigation of the Memory-Enhancing Effect of Emotion

Emotional events tend to be better remembered than non-emotional events1,2. One goal of cognitive and affective neuroscientists is 
to understand the neural mechanisms underlying this enhancing effect of emotion on memory. A method that has proven particularly influential in the 
investigation of the memory-enhancing effect of emotion is the so-called subsequent memory paradigm (SMP). This method was originally used to investigate the 
neural correlates of non-emotional memories3, and more recently we and others also applied it successfully to studies of emotional memory (reviewed in4, 5-7). 
Here, we describe a protocol that allows investigation of the neural correlates of the memory-enhancing effect of emotion using the SMP in conjunction with 
event-related functional magnetic resonance imaging (fMRI). An important feature of the SMP is that it allows separation of brain activity specifically 
associated with memory from more general activity associated with perception. Moreover, in the context of investigating the impact of emotional stimuli, 
SMP allows identification of brain regions whose activity is susceptible to emotional modulation of both general/perceptual and memory-specific processing. 
This protocol can be used in healthy subjects8-15, as well as in clinical patients where there are alterations in the neural correlates of emotion perception 
and biases in remembering emotional events, such as those suffering from depression and post-traumatic stress disorder (PTSD)16, 17.

We present a protocol that uses functional magnetic resonance imaging to investigate the neural correlates of the memory-enhancing effect of emotion. This protocol allows identification of brain activity specifically linked to memory-related processing, contrary to more general perceptual processing, and can be used with healthy and clinical populations.

Investigação de imagens do cérebro do Efeito Memória de aumento da Emoção

Emotional events tend to be better remembered than non-emotional events1,2. One goal of cognitive and affective neuroscientists is 
to understand the ...

Enabling High Grayscale Resolution Displays and Accurate Response Time Measurements on Conventional Computers

Display systems based on conventional computer graphics cards are capable of generating images with 8-bit gray level resolution. However, most experiments in vision research require displays with more than 12 bits of luminance resolution. Several solutions are available. Bit++ 1 and DataPixx 2 use the Digital Visual Interface (DVI) output from graphics cards and high resolution (14 or 16-bit) digital-to-analog converters to drive analog display devices. The VideoSwitcher 3 described here combines analog video signals from the red and blue channels of graphics cards with different weights using a passive resister network 4 and an active circuit to deliver identical video signals to the three channels of color monitors. The method provides an inexpensive way to enable high-resolution monochromatic displays using conventional graphics cards and analog monitors. It can also provide trigger signals that can be used to mark stimulus onsets, making it easy to synchronize visual displays with physiological recordings or response time measurements.
Although computer keyboards and mice are frequently used in measuring response times (RT), the accuracy of these measurements is quite low. The RTbox is a specialized hardware and software solution for accurate RT measurements. Connected to the host computer through a USB connection, the driver of the RTbox is compatible with all conventional operating systems. It uses a microprocessor and high-resolution clock to record the identities and timing of button events, which are buffered until the host computer retrieves them. The recorded button events are not affected by potential timing uncertainties or biases associated with data transmission and processing in the host computer. The asynchronous storage greatly simplifies the design of user programs. Several methods are available to synchronize the clocks of the RTbox and the host computer. The RTbox can also receive external triggers and be used to measure RT with respect to external events. 
Both VideoSwitcher and RTbox are available for users to purchase. The relevant information and many demonstration programs can be found at <a href="http://lobes.usc.edu/">http://lobes.usc.edu/</a>.

Conventional computer hardware can not generate visual stimuli with sufficiently high grayscale resolution and measure response times with sufficient accuracy. We describe how to use the VideoSwitcher to produce high-resolution monochromatic displays, and the RTbox to measure response times with high accuracy on conventional computer hardware.

Ativando alta escala de cinza monitores de resolução e Medidas resposta precisa de tempo em computadores convencionais

Display systems based on conventional computer graphics cards are capable of generating images with 8-bit gray level resolution. However, most experiments ...

Co-analysis of Brain Structure and Function using fMRI and Diffusion-weighted Imaging

The study of complex computational systems is facilitated by network maps, such as circuit diagrams. Such mapping is particularly informative when studying the brain, as the functional role that a brain area fulfills may be largely defined by its connections to other brain areas. In this report, we describe a novel, non-invasive approach for relating brain structure and function using magnetic resonance imaging (MRI). This approach, a combination of structural imaging of long-range fiber connections and functional imaging data, is illustrated in two distinct cognitive domains, visual attention and face perception. Structural imaging is performed with diffusion-weighted imaging (DWI) and fiber tractography, which track the diffusion of water molecules along white-matter fiber tracts in the brain (Figure 1). By visualizing these fiber tracts, we are able to investigate the long-range connective architecture of the brain. The results compare favorably with one of the most widely-used techniques in DWI, diffusion tensor imaging (DTI). DTI is unable to resolve complex configurations of fiber tracts, limiting its utility for constructing detailed, anatomically-informed models of brain function. In contrast, our analyses reproduce known neuroanatomy with precision and accuracy. This advantage is partly due to data acquisition procedures: while many DTI protocols measure diffusion in a small number of directions (e.g., 6 or 12), we employ a diffusion spectrum imaging (DSI)1, 2 protocol which assesses diffusion in 257 directions and at a range of magnetic gradient strengths. Moreover, DSI data allow us to use more sophisticated methods for reconstructing acquired data. In two experiments (visual attention and face perception), tractography reveals that co-active areas of the human brain are anatomically connected, supporting extant hypotheses that they form functional networks. DWI allows us to create a "circuit diagram" and reproduce it on an individual-subject basis, for the purpose of monitoring task-relevant brain activity in networks of interest.

We describe a novel approach for simultaneous analysis of brain function and structure using magnetic resonance imaging (MRI). We assess brain structure with high-resolution diffusion-weighted imaging and white-matter fiber tractography. Unlike standard structural MRI, these techniques allow us to directly relate anatomical connectivity to functional properties of brain networks.

Co-análise de estrutura e função cerebral usando ressonância magnética funcional e imagem ponderada em difusão

The study of complex computational systems is facilitated by network maps, such as circuit diagrams. Such mapping is particularly informative when ...

In Vivo Two-photon Imaging Of Experience-dependent Molecular Changes In Cortical Neurons

The brain's ability to change in response to experience is essential for healthy brain function, and abnormalities in this process contribute to a variety of brain disorders1,2. To better understand the mechanisms by which brain circuits react to an animal's experience requires the ability to monitor the experience-dependent molecular changes in a given set of neurons, over a prolonged period of time, in the live animal. While experience and associated neural activity is known to trigger gene expression changes in neurons1,2, most of the methods to detect such changes do not allow repeated observation of the same neurons over multiple days or do not have sufficient resolution to observe individual neurons3,4. Here, we describe a method that combines in vivo two-photon microscopy with a genetically encoded fluorescent reporter to track experience-dependent gene expression changes in individual cortical neurons over the course of day-to-day experience. 
One of the well-established experience-dependent genes is Activity-regulated cytoskeletal associated protein (Arc)5,6. The transcription of Arc is rapidly and highly induced by intensified neuronal activity3, and its protein product regulates the endocytosis of glutamate receptors and long-term synaptic plasticity7. The expression of Arc has been widely used as a molecular marker to map neuronal circuits involved in specific behaviors3. In most of those studies, Arc expression was detected by in situ hybridization or immunohistochemistry in fixed brain sections. Although those methods revealed that the expression of Arc was localized to a subset of excitatory neurons after behavioral experience, how the cellular patterns of Arc expression might change with multiple episodes of repeated or distinctive experiences over days was not investigated. 
In vivo two-photon microscopy offers a powerful way to examine experience-dependent cellular changes in the living brain8,9. To enable the examination of Arc expression in live neurons by two-photon microscopy, we previously generated a knock-in mouse line in which a GFP reporter is placed under the control of the endogenous Arc promoter10. This protocol describes the surgical preparations and imaging procedures for tracking experience-dependent Arc-GFP expression patterns in neuronal ensembles in the live animal. In this method, chronic cranial windows were first implanted in Arc-GFP mice over the cortical regions of interest. Those animals were then repeatedly imaged by two-photon microscopy after desired behavioral paradigms over the course of several days. This method may be generally applicable to animals carrying other fluorescent reporters of experience-dependent molecular changes4.

In Vivo Two-photon Imaging Of Experience-dependent Molecular Changes In Cortical Neurons

Experience-dependent molecular changes in neurons are essential for the brain's ability to adapt in response to behavioral challenges. An in vivo two-photon imaging method is described here that allows the tracking of such molecular changes in individual cortical neurons through genetically encoded reporters.

Vivo em dois fótons de imagem de experiência dependentes de alterações moleculares em neurônios corticais

The brain's ability to change in response to experience is essential for healthy brain function, and abnormalities in this process contribute to a variety ...

A Dual Tracer PET-MRI Protocol for the Quantitative Measure of Regional Brain Energy Substrates Uptake in the Rat

We present a method for comparing the uptake of the brain&#39;s two key energy substrates: glucose and ketones (acetoacetate [AcAc] in this case) in the rat. The developed method is a small-animal positron emission tomography (PET) protocol, in which&#160;11C-AcAc and 18F-fluorodeoxyglucose (18F-FDG) are injected sequentially in each animal. This dual tracer PET acquisition is possible because of the short half-life of 11C (20.4 min). The rats also undergo a magnetic resonance imaging (MRI) acquisition seven days before the PET protocol. Prior to image analysis, PET and MRI images are coregistered to allow the measurement of regional cerebral uptake (cortex, hippocampus, striatum, and cerebellum). A quantitative measure of 11C-AcAc and 18F-FDG brain uptake (cerebral metabolic rate; &#956;mol/100 g/min) is determined by kinetic modeling using the image-derived input function (IDIF) method. Our new dual tracer PET protocol is robust and flexible; the two tracers used can be replaced by different radiotracers to evaluate other processes in the brain. Moreover, our protocol is applicable to the study of brain fuel supply in multiple conditions such as normal aging and neurodegenerative pathologies such as Alzheimer&#39;s and Parkinson&#39;s diseases.

Small-animal positron emission tomography enables the assessment of the brain&#39;s two main energy substrates:&#160;glucose and ketones. In the present method, 11C-acetoacetate and 18F-fluorodeoxyglucose are injected sequentially in each animal, and their uptake is measured quantitatively in specific brain regions determined from the magnetic resonance images.

A dupla Tracer PET-MRI Protocolo para a medida quantitativa da Regional cérebro substratos energéticos Captação no Rato

We present a method for comparing the uptake of the brain&#39;s two key energy substrates: glucose and ketones (acetoacetate [AcAc] in this case) in the ...

Effects of Transcranial Alternating Current Stimulation on the Primary Motor Cortex by Online Combined Approach with Transcranial Magnetic Stimulation

Transcranial Alternating Current Stimulation (tACS) is a neuromodulatory technique able to act through sinusoidal electrical waveforms in a specific frequency and in turn modulate ongoing cortical oscillatory activity. This neurotool allows the establishment of a causal link between endogenous oscillatory activity and behavior. Most of the tACS studies have shown online effects of tACS. However, little is known about the underlying action mechanisms of this technique because of the AC-induced artifacts on Electroencephalography (EEG) signals. Here we show a unique approach to investigate online physiological frequency-specific effects of tACS of the primary motor cortex (M1) by using single pulse Transcranial Magnetic Stimulation (TMS) to probe cortical excitability changes. In our setup, the TMS coil is placed over the tACS electrode while Motor Evoked Potentials (MEPs) are collected to test the effects of the ongoing M1-tACS. So far, this approach has mainly been used to study the visual and motor systems. However, the current tACS-TMS setup can pave the way for future investigations of cognitive functions. Therefore, we provide a step-by-step manual and video guidelines for the procedure.

Transcranial Alternating Current Stimulation (tACS) allows the modulation of cortical excitability in a frequency-specific fashion. Here we show a unique approach which combines online tACS with single pulse Transcranial Magnetic Stimulation (TMS) in order to "probe" cortical excitability by means of Motor Evoked Potentials.

Efeitos da estimulação da corrente alternada transcraniana no córtex Motor primário por on-line abordagem combinada com estimulação magnética transcraniana

Transcranial Alternating Current Stimulation (tACS) is a neuromodulatory technique able to act through sinusoidal electrical waveforms in a specific ...