Esta pesquisa foi apoiada por doações da Fundação de Pesquisa - Flandres (FWO, projeto Nr G.0420.02 e G.0443.11N), a Fundação Hercules (concessão Nr AUHA0012), concertadas Acções de Investigação (GOA financiamento) da Universidade de Antuérpia, e parcialmente patrocinado pela EC - FP6 projeto Dimi, LSHB-CT-2005-512146 e EC - FP6 projeto EMIL LSHC-CT-2004-503569 para A.VdL. G.DG e CP são bolsistas de pós-doutorado da Fundação de Pesquisa - Flandres (FWO).

1. Preparação dos estímulos auditivos <ol><li> Primeiro gravar o som-estímulos ao ser jogado dentro do furo do sistema MR 7T. O furo é de um espaço confinado, que pode distorcer os estímulos auditivos, resultando na melhoria de determinadas frequências auditivas. Figura 1 mostra as frequências aumentadas e suprimida, como mostrado pelas nossas gravações de ruído branco feito no local da cabeça da ave no magneto usando um microfone de fibra óptica (Optimic 1160, Optoacoustics). Para compensar este aumento artificial, uma função de equalizador é aplicada a cada estímulo usando o software WaveLab. Para nossa configuração particular, a função consiste em um kernel gaussiano com os seguintes parâmetros: amplitude máxima:-20dB, centrado em 3750 Hz, largura: 0,05 oitavas (correspondente à faixa 2.500-5.000 Hz para o nosso sistema). </li><li> Os estímulos músicas são compostas por vários motivos músicas individuais de cada pássaro intercaladas com períodos de silêncio. O dguração destes períodos silenciosos é ajustado para manter a quantidade total de som e silêncio idênticas para todos os estímulos. Esta construção conserva a variabilidade intra-individual e inter-individual natural da duração da música. O comprimento total de cada estímulo é de 16 seg. A intensidade de cada canção é normalizada em termos de correspondência raiz quadrada média e high-pass filtrado a 400 Hz, antes de ser integrado ao estímulo completo (canção e períodos de silêncio). Essas manipulações são feitas utilizando o software Praat. </li><li> O experimento consiste de um botão ON / OFF projeto alternando períodos de estimulação auditiva bloco (em blocos) com períodos de descanso (OFF blocos) (Figura 2). Cada bloco (ON e OFF) dura 16 segundos, o que corresponde ao tempo de aquisição de duas imagens (veja abaixo para aquisição). Cada tipo de estímulo é apresentado 25 vezes, resultando na aquisição de 50 imagens por estímulo e por assunto. A ordem de apresentação das condições deve ser ao acaso dentro e entreassuntos. Esta ordem aleatória dos estímulos podem ser codificadas em software de apresentação. </li></ol> 2. Assunto Preparação 2.1 Sujeito eo tamanho do grupo Aqui é apresentado um protocolo adaptado especificamente para a utilização de (adulto) mandarins. A escolha da espécie depende da pergunta científica. No entanto, outras considerações como ave robustez para anestesia pode também ser tida em conta. Zebra tentilhões (Taeniopygia guttata) devem ser alojados em viveiros sob 12 horas de luz: 12 horas de fotoperíodo escuro e ter acesso a comida e água ad libitum durante todo o estudo. O número mínimo de indivíduos por ensaio é 15. Esse número leva em conta a sensibilidade de fMRI spin-echo ea variabilidade inter-individual natural de fenômenos biológicos medidos no experimento. 2.2 Instalação de configuração e preparação do animal (Para especificaçãodo equipamento utilizado, referimo-nos a lista de reagentes e equipamentos específicos no final do artigo) <ol><li> Instalar a máscara bico na cama MRI de um sistema de MR T7 e conectá-lo ao dispositivo controlador de gás com tubos de plástico. Abra as duas garrafas de gás oxigênio e nitrogênio e ligar o dispositivo controlador de gás (oxigênio vazão: 200 cc / min; nitrogênio: 400 cc / min). </li></ol> Como mencionado acima, um sistema de RM T7 é usado na configuração apresentada. Outros sistemas de RM com diferentes intensidades de campo também são possíveis, mas a T7 é alcançado um bom compromisso entre a relação sinal-ruído e grau de artefatos de suscetibilidade (ver discussão). Em mais elevadas intensidades de campo a relação sinal-para-ruído irá aumentar juntamente com o grau de artefactos de susceptibilidade. <ol start="2"><li> Ligue o sistema de controle de feedback e um dispositivo de fluxo de ar quente. </li><li> Anestesiar o tentilhão com 3% de isoflurano em uma mistura de oxigênio e nitrogênio através da introdução de seu bicona máscara e segurando a cabeça para baixo até que a ave está totalmente anestesiado. Isto pode ser verificada por meio de puxar o pé suavemente: quando a ave está completamente sedado o pé não vai ser retraído pela ave. Além disso, os olhos da ave irá ser parcialmente fechada. </li><li> Introduzir a sonda de temperatura cloacal para a tela a temperatura do corpo e monitorar a taxa de respiração, colocando um sensor pneumático debaixo da barriga do passarinho zebra. Feche o revestimento para conter o corpo do animal (Figura 3). </li><li> Manter a taxa de respiração dentro do intervalo de 40-100 ciclos por minuto e manter a temperatura corporal constante dentro de uma faixa estreita de 40 ± 0,5 ° C. Quando o intervalo para respirar é muito baixa / alta, ajustar o nível de anestesia (% isoflurano) em conformidade. Quando o problema persistir, o ensaio deve ser parado e o animal retirado da instalação, a fim de recuperar. </li><li> Posicione os alto-falantes dinâmicos não-magnéticos de cada lado da cabeça do passarinho zebra e congar-los para o amplificador. Certifique-se de que os fios dos alto-falantes são levados para longe da sonda de temperatura, pois pode influenciar a leitura da temperatura quando muito perto. </li><li> Coloque a bobina de superfície no topo da cabeça Finch zebra e a posição de zebra no centro do íman (e automaticamente o centro da bobina de transmissão, que está situado no meio do íman). </li><li> Reduzir o nível de anestesia para 1,5% de isoflurano misturado com o oxigênio e nitrogênio. </li></ol> 3. Aquisição de Dados <ol><li> Adquirir um conjunto de 1 sagital, uma horizontal e uma imagem olheiro coronal gradiente-eco (GE) (sequence-piloto tri) e conjuntos de imagens multi-slice horizontal, coronal e sagital (T 2 ponderada aquisição rápida de relaxamento avançada (pilotagem RARE) sequência SE) para determinar a posição do cérebro no íman (Figura 4). </li><li> Diminuir o ruído dos gradientes, aumentando os tempos de rampa para 1000 mS. </li> &lt;li&gt; Prepare a sequência de fMRI: RARE T seqüência 2 ponderada, eficaz TE: 60 ms, TR: 2000 ms, fato raro: 8, FOV: 16 mm, tamanho da matriz: 64 x 32, a orientação: sagital, espessura de corte: 0,75 mm, Inter-slice espessura de espaço: 0,05 milímetros, 15 fatias cobrindo quase todo o cérebro (Figura 4). </li><li> Selecione o protocolo auditiva (estímulos auditivos e tempo de entrega estímulo) no software de apresentação. Este protocolo consiste de uma seqüência de comandos - para o início de estímulos auditivos específicos - que são executadas em um número específico de digitalização. Em cada repetição na sequência fMRI, o software do scanner irá enviar um gatilho para o software de apresentação auditiva que por sua vez registra o número de varredura e executa o comando correspondente. </li><li> Para garantir que o software de apresentação auditiva não perder qualquer gatilho do leitor, o protocolo auditivo é iniciada em primeiro lugar. Uma vez que o protocolo é completamente carregado, a sequência de ressonância magnética é iniciado. </li><li> Cada experimento RMf é precedida pela aquisição de 12 imagens falsas para permitir que o sinal atribuído ao ruído scanner para alcançar um estado estável antes de iniciar a estimulação auditiva. </li><li> Após a aquisição de zero preencher os dados a 64 x 64. </li><li> Dê uma primeira olhada (preliminar) com os resultados utilizando a ferramenta funcional de paravisão (opção de processamento / Imagem Funcional). Calcule a resposta BOLD diferencial entre todos em blocos ea linha de base (OFF blocos). Esta análise dá uma primeira indicação da qualidade da experiência. Se nenhuma ativação é visto nas áreas auditivas primárias nesta fase, o pássaro provavelmente não ouviu / processados ​​os estímulos auditivos, devido a problemas técnicos com a apresentação do estímulo, o nível de anestesia, etc A instalação deverá ser verificada e medida repetida. </li><li> Executar uma seqüência T2 RARE 3D anatômica com a mesma orientação quanto aos exames de ressonância magnética anteriores e com TE eficaz: 60 ms, TR: 2000 ms, fato raro: 8, FOV: 16 mm, o tamanho da matriz: 256 x 128 x 64. </li><li> Zero-preencher os dados a 256 x 256 x 256. </li><li> Leve o tentilhão da cama MRI e deixá-lo recuperar da anestesia em uma gaiola sob uma lâmpada vermelha. Normalmente, a recuperação de uma Finch zebra após anestesia com isoflurano vai relativamente rápido (máximo 5 minutos). Depois de apenas alguns minutos, os pássaros vão tentar levantar-se e uma vez que a ave está totalmente recuperado, ele vai pousar em um ramo em vez de sentar no fundo da gaiola. A duração da anestesia é de cerca de 2 horas para o presente experimento. O tempo máximo de isoflurano anestesia aplicada a tentilhões-zebra em nosso laboratório é de 6 horas, após o que as aves também se recuperou dentro de 5 min. </li></ol> 4. Informática <ol><li> Converta o MR-dados para analisar ou formato Nifti. </li><li> Porque SPM foi desenvolvido para processar os dados de ressonância magnética adquiridos nos seres humanos, isto é, para os voxels de cerca de 2 mm. Inúmeras definições SPM são adaptados a este tamanho aproximado voxel. Se a pessoa não faz wformiga para mudar todas as configurações, a maneira mais simples de proceder é aumentar artificialmente o tamanho do voxel dos dados de fMRI de aves. Ajuste o tamanho do voxel no cabeçalho multiplicando o tamanho real, voxel por 10 usando MRIcro. Deve notar-se, que este ajustamento não influencia os dados em si, não reamostragem ou quaisquer outras modificações que os dados são aplicados. </li></ol> Uma alternativa para isso é o uso da &#39;SPMMouse &quot;, que é um conjunto de ferramentas que permite SPM para abrir e analisar arquivos de qualquer dimensão do voxel. A ferramenta permite que os &#39;cérebros&#39; SPM vidro a ser criado a partir de qualquer imagem, e ajusta automaticamente os padrões de escalas de comprimento com base nos cabeçalhos de arquivos de imagem ou dados introduzidos pelo utilizador. Assim, este toolbox funciona da maneira oposta do que aquilo que nos propomos. Em vez de mudar o tamanho do voxel das imagens para caber no SPM, as configurações padrão do SPM são alteradas para usar imagens com diferentes tamanhos de voxel. <ol start="3"><li> Realinhar os dados de fMRI. Co-registrar o conjunto de dados 3D anatômico de tele séries temporais fMRI. Normalizar os dados em 3D (e da série co-registrada tempo fMRI) para o tentilhão cérebro MRI atlas. Aplicar a matriz de transformação para o conjunto de dados de fMRI. Isso tudo pode ser feito utilizando o Statistical Parametric Mapping (SPM) software 8. </li><li> Suavizar os dados com uma largura do kernel Gaussian 0,5 mm usando SPM8. </li><li> Realizar análises baseadas em voxel estatísticos utilizando SPM8. Modelo os dados como um carro de caixa (sem função resposta hemodinâmica). Estimar os parâmetros do modelo com o algoritmo da máxima verossimilhança restrita clássico. Calcular o efeito médio de cada estímulo auditivo em cada disciplina (análise de efeito fixo) e, em seguida, calcular estatísticas como desejava para análises de grupo (análise de efeito misto). </li><li> Projetar o mapa estatístico paramétrico para o tentilhão atlas (Figura 5) 9 em SPM8 para localizar as ativações funcionais (Figura 6). </li></ol>

<ol>
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Neste relatório, nós descrevemos um protocolo otimizado para o detalhado na caracterização vivo de substratos neurais da estimulação auditiva em tentilhões-zebra anestesiados. Em consonância com o protocolo apresentado, a maioria dos estudos de ativação cerebral funcionais em animais utilizando fMRI BOLD, anestesiar os animais durante a aquisição. Treinar animais para acostumá-los ao ambiente ímã eo ruído do scanner durante os períodos de estudo também é ...

<table border="1">
 <tbody>
 <tr>
 <td>Name of the reagent/equipment</td>
 <td>Company</td>
 <td>Catalogue number</td>
 <td>Comments </td>
 </tr>
 <tr>
 <td>Isoflurane anaesthetic</td>
 <td>Isoflo</td>
 <td>05260-05</td>
 <td></td>
 </tr>
 <tr>
 <td>PC-Sam hardware/software</td>
 <td>SA-Instruments</td>
 <td></td>
 <td><a href="http://www.i4sa.com" target="_blank">http://www.i4sa.com</a></td>
 </tr>
 <tr>
 <td>Monitoring and gating system</td>
 <td></td>
 <td>1025</td>
 <td></td>
 </tr>
 <tr>
 <td>MR-compatible small rodent heater system</td>
 <td></td>
 <td></td>
 <td>Model 1025 compatible</td>
 </tr>
 <tr>
 <td>Rectal temperature probe</td>
 <td></td>
 <td>RTP-102B</td>
 <td>7'', 0.044'' </td>
 </tr>
 <tr>
 <td>7T MR scanner</td>
 <td>Bruker Biospin</td>
 <td>PHS 70/16 </td>
 <td></td>
 </tr>
 <tr>
 <td>Paravision software</td>
 <td></td>
 <td>5.1</td>
 <td></td>
 </tr>
 <tr>
 <td>Gradient Insert</td>
 <td></td>
 <td>BGA9S</td>
 <td>400 mT/m, 300A, 500V</td>
 </tr>
 <tr>
 <td>Gradient Amplifiers</td>
 <td>Copley Co., USA</td>
 <td>C256</td>
 <td></td>
 </tr>
 <tr>
 <td>Transmit resonators</td>
 <td></td>
 <td></td>
 <td>Inner diameter: 72 mm, transmit only, active decoupled</td>
 </tr>
 <tr>
 <td>Receiver antenna - 20 mm quadrature Mouse Head</td>
 <td></td>
 <td></td>
 <td>Receive only, active decoupled</td>
 </tr>
 <tr>
 <td>WaveLab software</td>
 <td>Steinberg</td>
 <td></td>
 <td></td>
 </tr>
 <tr>
 <td>Praat software</td>
 <td>Paul Boersma, University of Amsterdam</td>
 <td></td>
 <td><a href="http://www.praat.org" target="_blank">http://www.praat.org</a></td>
 </tr>
 <tr>
 <td>Non-magnetic dynamic speakers</td>
 <td>Visation, Germany</td>
 <td>HK 150</td>
 <td></td>
 </tr>
 <tr>
 <td>Fiber optic microphone</td>
 <td>Optoacoustics, </td>
 <td>Optimic 1160</td>
 <td></td>
 </tr>
 <tr>
 <td>Sound amplifier</td>
 <td>Phonic corporation</td>
 <td>MM 1002a</td>
 <td></td>
 </tr>
 <tr>
 <td>Presentation software</td>
 <td>Neurobehavioral Systems Inc.</td>
 <td></td>
 <td></td>
 </tr>
 <tr>
 <td>MRIcro</td>
 <td>Chris Rorden</td>
 <td></td>
 <td><a href="http://www.cabiatl.com/mricro/mricro/" target="_blank">http://www.cabiatl.com/mricro/mricro/</a></td>
 </tr>
 <tr>
 <td>Statistical Parametric Mapping (SPM)</td>
 <td>Welcome Trust Centre for Neuroimaging</td>
 <td>8</td>
 <td><a href="http://www.fil.ion.ucl.ac.uk/spm/" target="_blank">http://www.fil.ion.ucl.ac.uk/spm/</a></td>
 </tr>
 </tbody>
</table>

functional magnetic resonance imaging (fmri) with auditory stimulation in songbirds

A neurobiologia do canto dos pássaros, como um modelo para a fala humana, é uma área pronunciado de pesquisa em neurociência comportamental. Considerando eletrofisiologia e molecular abordagens permitem a investigação de qualquer diferentes estímulos em alguns neurônios, ou um estímulo em grandes partes do cérebro, o nível de oxigenação do sangue dependente (BOLD) Ressonância Magnética funcional (fMRI) permite combinar as vantagens, ou seja, comparar a ativação neural induzida por diferentes estímulos em todo o cérebro de uma só vez. fMRI em pássaros é um desafio por causa do pequeno tamanho de seus cérebros e porque os seus ossos e, especialmente, seu crânio compreendem inúmeras cavidades de ar, induzindo importantes artefatos de suscetibilidade. Gradiente-eco (GE) fMRI BOLD tem sido aplicado com sucesso para pássaros 1-5 (para uma revisão, ver 6). Estes estudos se concentraram nas áreas primárias e secundárias auditivas cerebrais, que são regiões livres de artefatos de suscetibilidade. No entanto, devido proccessos de interesse pode ocorrer para além dessas regiões, todo o cérebro fMRI BOLD é necessário utilizar uma seqüência de ressonância magnética menos suscetíveis a esses artefatos. Isto pode ser conseguido através da utilização de spin-eco (SE) NEGRITO RMf 7,8. Neste artigo, descrevemos como usar esta técnica em tentilhões-zebra (Taeniopygia guttata), que são pequenos pássaros com um peso corporal de 15-25 g extensivamente estudado em neurociência comportamental do canto dos pássaros. O principal tema de estudos de fMRI sobre pássaros é a percepção da música e aprendizagem da música. A natureza auditiva dos estímulos combinados com os fracos sensibilidade BOLD de SE (em comparação com GE) seqüências de fMRI baseados faz com que a implementação desta técnica muito desafiador.

<html> Nós aqui apresentada visualmente uma sequência otimizada de procedimentos para a imagem de sucesso de substratos neurais dos estímulos auditivos na finch cérebro zebra. Em primeiro lugar, o procedimento descrito para a preparação dos estímulos auditivos em resultados de estímulos que podem ser incorporados num ON / OFF paradigma bloco (Figura 2) e que são normalizados para eliminar possíveis diferenças no nível de pressão de som que pode evocar uma resposta diferencial no cérebro . D...

Watch this Scientific Journal Video about Functional Magnetic Resonance Imaging fMRI with Auditory Stimulation in Songbirds at JoVE.com

Functional Magnetic Resonance Imaging fMRI with Auditory Stimulation in Songbirds

Este artigo mostra um procedimento otimizado para imagens dos substratos neurais da estimulação auditiva no cérebro songbird usando ressonância magnética funcional (fMRI). Ele descreve a preparação dos estímulos sonoros, o posicionamento do sujeito e da aquisição e posterior análise dos dados de fMRI.

Ressonância Magnética Funcional (fMRI), com estimulação auditiva em aves canoras

The neurobiology of birdsong, as a model for human speech, is a pronounced area of research in behavioral neuroscience. Whereas electrophysiology and ...

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Behavior

Functional Magnetic Resonance Imaging (fMRI) with Auditory Stimulation in Songbirds

18.0K visualizações.  University of Antwerp. Este artigo mostra um procedimento otimizado para imagens dos substratos neurais da estimulação auditiva no cérebro songbird usando ressonância magnética funcional (fMRI). Ele descreve a preparação dos estímulos sonoros, o posicionamento do sujeito e da aquisição e posterior análise dos dados de fMRI.

Vídeo: Functional Magnetic Resonance Imaging fMRI with Auditory Stimulation in Songbirds

Best Current Practice for Obtaining High Quality EEG Data During Simultaneous fMRI

Simultaneous EEG-fMRI allows the excellent temporal resolution of EEG to be combined with the high spatial accuracy of fMRI. The data from these two modalities can be combined in a number of ways, but all rely on the acquisition of high quality EEG and fMRI data. EEG data acquired during simultaneous fMRI are affected by several artifacts, including the gradient artefact (due to the changing magnetic field gradients required for fMRI), the pulse artefact (linked to the cardiac cycle) and movement artifacts (resulting from movements in the strong magnetic field of the scanner, and muscle activity). Post-processing methods for successfully correcting the gradient and pulse artifacts require a number of criteria to be satisfied during data acquisition. Minimizing head motion during EEG-fMRI is also imperative for limiting the generation of artifacts.
Interactions between the radio frequency (RF) pulses required for MRI and the EEG hardware may occur and can cause heating. This is only a significant risk if safety guidelines are not satisfied. Hardware design and set-up, as well as careful selection of which MR sequences are run with the EEG hardware present must therefore be considered.
The above issues highlight the importance of the choice of the experimental protocol employed when performing a simultaneous EEG-fMRI experiment. Based on previous research we describe an optimal experimental set-up. This provides high quality EEG data during simultaneous fMRI when using commercial EEG and fMRI systems, with safety risks to the subject minimized. We demonstrate this set-up in an EEG-fMRI experiment using a simple visual stimulus. However, much more complex stimuli can be used. Here we show the EEG-fMRI set-up using a Brain Products GmbH (Gilching, Germany) MRplus, 32 channel EEG system in conjunction with a Philips Achieva (Best, Netherlands) 3T MR scanner, although many of the techniques are transferable to other systems.

Simultaneous electroencephalography (EEG) and functional Magnetic Resonance imaging (fMRI) is a powerful neuroimaging tool. However, the inside of an MRI scanner forms a difficult environment for EEG data recording and safety must be considered whenever operating EEG equipment inside a scanner. Here, we present an optimised EEG-fMRI data acquisition protocol.

Melhores práticas correntes para obtenção de dados de alta qualidade durante o EEG fMRI simultâneo

Simultaneous  EEG-fMRI allows the excellent temporal resolution of EEG to be combined with the  high spatial accuracy of fMRI. The data  from these two ...

Comportamento

Quantitative Assessment of Cortical Auditory-tactile Processing in Children with Disabilities

Objective and easy measurement of sensory processing is extremely difficult in nonverbal or vulnerable pediatric patients. We developed a new methodology to quantitatively assess children&#39;s cortical processing of light touch, speech sounds and the multisensory processing of the 2 stimuli, without requiring active subject participation or causing children discomfort. To accomplish this we developed a dual channel, time and strength calibrated air puff stimulator that allows both tactile stimulation and sham control. We combined this with the use of event-related potential methodology to allow for high temporal resolution of signals from the primary and secondary somatosensory cortices as well as higher order processing. This methodology also allowed us to measure a multisensory response to auditory-tactile stimulation.

Objective and easy measurement of sensory processing is extremely difficult in nonverbal or vulnerable pediatric patients. We developed a new methodology to quantitatively assess infants and children&#39;s cortical processing of light touch, speech sounds, and the multisensory processing of the 2 stimuli, without requiring active subject participation or causing discomfort in vulnerable patients.

Avaliação Quantitativa de processamento cortical auditivo-tátil em Crianças com Deficiência

Objective and easy measurement of sensory processing is extremely difficult in nonverbal or vulnerable pediatric patients. We developed a new methodology ...

Stimulating the Lip Motor Cortex with Transcranial Magnetic Stimulation

Transcranial magnetic stimulation (TMS) has proven to be a useful tool in investigating the role of the articulatory motor cortex in speech perception. Researchers have used single-pulse and repetitive TMS to stimulate the lip representation in the motor cortex. The excitability of the lip motor representation can be investigated by applying single TMS pulses over this cortical area and recording TMS-induced motor evoked potentials (MEPs) via electrodes attached to the lip muscles (electromyography; EMG). Larger MEPs reflect increased cortical excitability. Studies have shown that excitability increases during listening to speech as well as during&#160;viewing speech-related movements. TMS can be used also to disrupt the lip motor representation. A 15-min train of low-frequency sub-threshold repetitive stimulation has been shown to suppress motor excitability for a further 15-20 min. This TMS-induced disruption of the motor lip representation impairs subsequent performance in demanding speech perception tasks and modulates auditory-cortex responses to speech sounds. These findings are consistent with the suggestion that the motor cortex contributes to speech perception. This article describes how to localize the lip representation in the motor cortex and how to define the appropriate stimulation intensity for carrying out both single-pulse and repetitive TMS experiments.

Transcranial magnetic stimulation (TMS) has proven to be a useful tool in investigating the role of the articulatory motor cortex in speech perception.&#160; This article describes how to record motor evoked potentials (MEPs) from the lip muscles and how to disrupt the motor lip representation using repetitive TMS.

Estimular o Lip Motor Cortex com Estimulação Magnética Transcraniana

Transcranial magnetic stimulation (TMS) has proven to be a useful tool in investigating the role of the articulatory motor cortex in speech perception. ...

Transcranial Direct Current Stimulation and Simultaneous  Functional Magnetic Resonance Imaging

Transcranial direct current stimulation (tDCS) is a noninvasive brain stimulation technique that uses weak electrical currents administered to the scalp to manipulate cortical excitability and, consequently, behavior and brain function. In the last decade, numerous studies have addressed short-term and long-term effects of tDCS on different measures of behavioral performance during motor and cognitive tasks, both in healthy individuals and in a number of different patient populations. So far, however, little is known about the neural underpinnings of tDCS-action in humans with regard to large-scale brain networks. This issue can be addressed by combining tDCS with functional brain imaging techniques like functional magnetic resonance imaging (fMRI) or electroencephalography (EEG).
In particular, fMRI is the most widely used brain imaging technique to investigate the neural mechanisms underlying cognition and motor functions. Application of tDCS during fMRI allows analysis of the neural mechanisms underlying behavioral tDCS effects with high spatial resolution across the entire brain. Recent studies using this technique identified stimulation induced changes in task-related functional brain activity at the stimulation site&#160;and also in more distant brain regions, which were associated with behavioral improvement. In addition, tDCS administered during resting-state fMRI allowed identification of widespread changes in whole brain functional connectivity.
Future studies using this combined protocol should yield new insights into the mechanisms of tDCS action in health and disease and new options for more targeted application of tDCS in research and clinical settings. The present manuscript describes this novel technique in a step-by-step fashion, with a focus on technical aspects of tDCS administered during fMRI.

Transcranial direct current stimulation (tDCS) is a noninvasive brain stimulation technique. It has successfully been used in basic research and clinical settings to modulate brain function in humans. This article describes the implementation of tDCS and simultaneous functional magnetic resonance imaging (fMRI), to investigate the neural basis of tDCS effects.

Transcraniana direto Estimulação atual e simultânea Ressonância Magnética Funcional

Transcranial direct current stimulation (tDCS) is a noninvasive brain stimulation technique that uses weak electrical currents administered to the scalp ...

Transcranial Magnetic Stimulation for Investigating Causal Brain-behavioral Relationships and their Time Course

Transcranial magnetic stimulation (TMS) is a safe, non-invasive brain stimulation technique that uses a strong electromagnet in order to temporarily disrupt information processing in a brain region, generating a short-lived &#8220;virtual lesion.&#8221; Stimulation that interferes with task performance indicates that the affected brain region is necessary to perform the task normally. In other words, unlike neuroimaging methods such as functional magnetic resonance imaging (fMRI) that indicate correlations between brain and behavior, TMS can be used to demonstrate causal brain-behavior relations. Furthermore, by varying the duration and onset of the virtual lesion, TMS can also reveal the time course of normal processing. As a result, TMS has become an important tool in cognitive neuroscience. Advantages of the technique over lesion-deficit studies include better spatial-temporal precision of the disruption effect, the ability to use participants as their own control subjects, and the accessibility of participants. Limitations include concurrent auditory and somatosensory stimulation that may influence task performance, limited access to structures more than a few centimeters from the surface of the scalp, and the relatively large space of free parameters that need to be optimized in order for the experiment to work. Experimental designs that give careful consideration to appropriate control conditions help to address these concerns. This article illustrates these issues with TMS results that investigate the spatial and temporal contributions of the left supramarginal gyrus (SMG) to reading.

Transcranial magnetic stimulation (TMS) is a technique for non-invasively disrupting neural information processing and measuring its effect on behavior. When TMS interferes with a task, it indicates that the stimulated brain region is necessary for normal task performance, allowing one to systematically relate brain regions to cognitive functions.

Estimulação Magnética Transcraniana para investigar relações causais Brain-comportamentais e seu Curso de Tempo

Transcranial magnetic stimulation (TMS) is a safe, non-invasive brain stimulation technique that uses a strong electromagnet in order to temporarily ...

Transferring Cognitive Tasks Between Brain Imaging Modalities: Implications for Task Design and Results Interpretation in fMRI Studies

As cognitive neuroscience methods develop, established experimental tasks are used with emerging brain imaging modalities. Here transferring a paradigm (the visual oddball task) with a long history of behavioral and electroencephalography (EEG) experiments to a functional magnetic resonance imaging (fMRI) experiment is considered. The aims of this paper are to briefly describe fMRI and when its use is appropriate in cognitive neuroscience; illustrate how task design can influence the results of an fMRI experiment, particularly when that task is borrowed from another imaging modality; explain the practical aspects of performing an fMRI experiment. It is demonstrated that manipulating the task demands in the visual oddball task results in different patterns of blood oxygen level dependent (BOLD) activation. The nature of the fMRI BOLD measure means that many brain regions are found to be active in a particular task. Determining the functions of these areas of activation is very much dependent on task design and analysis. The complex nature of many fMRI tasks means that the details of the task and its requirements need careful consideration when interpreting data. The data show that this is particularly important in those tasks relying on a motor response as well as cognitive elements and that covert and overt responses should be considered where possible. Furthermore, the data show that transferring an EEG paradigm to an fMRI experiment needs careful consideration and it cannot be assumed that the same paradigm will work equally well across imaging modalities. It is therefore recommended that the design of an fMRI study is pilot tested behaviorally to establish the effects of interest and then pilot tested in the fMRI environment to ensure appropriate design, implementation and analysis for the effects of interest.

Transferring a paradigm with a history of use in EEG experiments to an fMRI experiment is considered. It is demonstrated that manipulating the task demands in the visual oddball task resulted in different patterns of BOLD activation and illustrated how task design is crucial in fMRI experiments.

Transferência de tarefas cognitivas entre o cérebro métodos de imagem: Implicações para o Projeto Tarefa e interpretação dos resultados em estudos de fMRI

As cognitive neuroscience methods develop, established experimental tasks are used with emerging brain imaging modalities. Here transferring a paradigm ...

Design and Implementation of an fMRI Study Examining Thought Suppression in Young Women with, and At-risk, for Depression

Ruminative brooding is associated with increased vulnerability to major depression. Individuals who regularly ruminate will often try to reduce the frequency of their negative thoughts by actively suppressing them. We aim to identify the neural correlates underlying thought suppression in at-risk and depressed individuals. Three groups of women were studied; a major depressive disorder group, an at-risk group (having a first degree relative with depression) and controls. Participants performed a mixed block-event fMRI paradigm involving thought suppression, free thought and motor control periods. Participants identified the re-emergence of &#8220;to-be-suppressed&#8221; thoughts (&#8220;popping&#8221; back into conscious awareness) with a button press. During thought suppression the control group showed the greatest activation of the dorsolateral prefrontal cortex, followed by the at-risk, then depressed group. During the re-emergence of intrusive thoughts compared to successful re-suppression of those thoughts, the control group showed the greatest activation of the anterior cingulate cortices, followed by the at-risk, then depressed group. At-risk participants displayed anomalies in the neural regulation of thought suppression resembling the dysregulation found in depressed individuals. The predictive value of these changes in the onset of depression remains to be determined.

We aim to identify the neural correlates underlying sustained and transient thought suppression, and thought re-emergence in controls, at-risk and depressed individuals. Activation was greatest for controls compared to the at-risk and the depressed group in the dorsolateral prefrontal cortex during thought suppression and anterior cingulate cortex during thought re-emergence.

Design e Implementação de um Estudo de fMRI Examinar Pensei Suppression em mulheres jovens com, e em situação de risco, para a depressão

Ruminative brooding is associated with increased vulnerability to major depression. Individuals who regularly ruminate will often try to reduce the ...

Neuronavigation-guided Repetitive Transcranial Magnetic Stimulation for Aphasia

Repetitive transcranial magnetic stimulation (rTMS) is widely used for several neurological conditions, as it has gained acknowledgement for its potential therapeutic effects. Brain excitability is non-invasively modulated by rTMS, and rTMS to the language areas has proved its potential effects on treatment of aphasia. In our protocol, we aim to artificially induce virtual aphasia in healthy subjects by inhibiting Brodmann area 44 and 45 using neuronavigational TMS (nTMS), and F3 of the International 10-20 EEG system for conventional TMS (cTMS). To measure the degree of aphasia, changes in reaction time to a picture naming task pre- and post-stimulation are measured and compare the delay in reaction time between nTMS and cTMS. Accuracy of the two TMS stimulation methods is compared by averaging the Talairach coordinates of the target and the actual stimulation. Consistency of stimulation is demonstrated by the error range from the target. The purpose of this study is to demonstrate use of nTMS and to describe the benefits and limitations of the nTMS compared to those of cTMS.

This study is designed to test the hypothesis that neuronavigational system-guided transcranial magnetic stimulation has higher accuracy for targeting the intended target as demonstrated by eliciting a greater degree of virtual aphasia in healthy subjects, measured by delay in reaction time to picture naming.

Repetitiva Estimulação Magnética Transcraniana guiada por neuronavegação para a afasia

Repetitive transcranial magnetic stimulation (rTMS) is widely used for several neurological conditions, as it has gained acknowledgement for its potential ...

Treating Clinical Depression with Repetitive Deep Transcranial Magnetic Stimulation Using the Brainsway H1-coil

Repetitive transcranial magnetic stimulation (rTMS) is an emerging non-pharmacological approach to treating many brain-based disorders. rTMS uses electromagnetic coils to stimulate areas of the brain non-invasively. Deep transcranial magnetic stimulation (dTMS) with the Brainsway H1-coil system specifically is a type of rTMS indicated for treating patients with major depressive disorder (MDD) who are resistant to medication. The unique H1-coil design of this device is able to stimulate neuronal pathways that lie deeper in the targeted brain areas than those reached by conventional rTMS coils. dTMS is considered to be low-risk and well tolerated, making it a viable treatment option for people who have not responded to medication or psychotherapy trials for their depression.
Randomized, sham-control studies have demonstrated that dTMS produces significantly greater improvement in depressive symptoms than sham dTMS treatment in patients with major depression that has not responded to antidepressant medication. In this paper, we will review the methodology for treating major depression with dTMS using an H1-coil.

Here we present a protocol outlining the methodology for treatment of Major Depressive Disorder using the deep Transcranial Magnetic Stimulation (dTMS) system.

Tratar depressão clínica com Estimulação Magnética Transcraniana repetitiva profundo Usando o H1-coil Brainsway

Repetitive transcranial magnetic stimulation (rTMS) is an emerging non-pharmacological approach to treating many brain-based disorders. rTMS uses ...

Repetitive Transcranial Magnetic Stimulation to the Unilateral Hemisphere of Rat Brain

Previous rodent models of repetitive transcranial magnetic stimulation (rTMS) adopted whole-brain stimulation instead of unilateral hemispheric rTMS, which is unlike the protocols used for human subjects. We report a successful application of rTMS to the unilateral hemisphere of rat brain. The rTMS was delivered with a low-frequency (1 Hz), high-frequency (20 Hz), or sham stimulation protocol to one side of the brain by using a small 25-mm figure-8 coil. We placed the center of the coil 1 cm lateral to the vertex on the biauricular line and angulated the coil 45&#176; to the ground to minimize a potential direct effect of rTMS on the contralateral cortex. We also used an in-house water cooling system to enable repetitive magnetic stimulation for more than 20 min, even at a 20-Hz stimulation frequency. Increases in the transcriptions of immediate early genes (Arc, Junb, and Egr2) were greater after rTMS than after sham stimulation. After 5 consecutive days of 20-min 1-Hz rTMS, bdnf mRNA expression was significantly higher in stimulated cortex than in contralateral side. The model presented herein will elucidate the molecular mechanisms of rTMS by allowing analysis of the inter-hemispheric difference in its effect.

We applied repetitive transcranial magnetic stimulation (rTMS) to the unilateral hemisphere of rat brain, by placing a 25-mm figure-8 coil 1 cm lateral to the vertex on the biauricular line and angulating the coil by 45&#176;. An in-house water cooling system was used for rTMS for more than 20 min.

Estimulação Magnética Transcraniana repetitiva para o Hemisfério unilateral do cérebro de rato

Previous rodent models of repetitive transcranial magnetic stimulation (rTMS) adopted whole-brain stimulation instead of unilateral hemispheric rTMS, ...