Esta pesquisa foi possível em parte pelo generoso financiamento do programa Knight Campus Undergraduate Scholars e da Phil and Penny Knight Foundation.

Todos os métodos aqui detalhados foram realizados em conformidade com o protocolo IRB e aprovação (University of Oregon IRB protocol number 10182017.017). O consentimento informado foi obtido de todos os sujeitos.
1. Aparelhos de alcance
<ol><li>Coloque um tablet gráfico grande em uma área de trabalho.</li>
	<li>Use uma estrutura de alumínio ajustável de 80 a 20 para posicionar o monitor de tarefas de 6 a 8 acima do tablet em paralelo, com a tela voltada para cima (para obter uma planta, confira aqui: https://github.com/greenhouselab/Reach_TMS e Figura 1 Suplementar). NOTA: Esta configuração permite que os participantes alcancem o tablet e adquiram alvos apresentados no monitor de tarefas enquanto ocluem a visão do braço que está a alcançar.</li>
	<li>Use a configuração descrita em Kim et al.3 como referência.</li>
</ol>2. Interfaces da máquina
<ol><li>Ligue o tablet ao computador através de uma porta USB. Conecte o monitor de tarefas ao computador através da porta HDMI. Conecte a porta TMS traseira ao computador através de um cabo DB-9.</li>
	<li>Conecte o sistema EMG ao computador por meio de um DAQ da placa PCI-6220. Conecte o fotodiodo ao sistema EMG através de um cabo BNC.</li>
</ol>3. Sensor de fotodiodo
<ol><li>Conecte um sensor de fotodiodo ao cabo BNC. Prenda o sensor de fotodiodo com fita adesiva no canto superior direito do monitor de tarefas, com o sensor voltado para a tela, a ≤ 1 cm de distância. NOTA: Isso registrará o tempo dos estímulos apresentados no monitor de tarefas como dados analógicos em um canal de entrada independente.</li>
</ol>4. Software
<ol><li>Baixe o VETA Toolbox26 (https://github.com/greenhouselab/Veta) para o MATLAB 2018 para interagir com o hardware para coleta de dados.</li>
	<li>Baixe o código de tarefa de alcance (https://github.com/greenhouselab/Reach_TMS) desenvolvido para o controle de parâmetros experimentais e interface com o tablet.</li>
</ol>5. Triagem dos participantes e consentimento informado
<ol><li>Rastreie o assunto em busca de contraindicações para TMS. Os critérios de exclusão incluem uma história pessoal ou familiar de convulsão, cefaleia, trauma cerebral, desmaios, estresse crônico ou ansiedade, problemas com o sono e qualquer medicação neuroativa. Critérios de exclusão adicionais incluem quaisquer implantes de metal no cérebro ou crânio e qualquer uso recreativo de drogas ou álcool nas 24 horas anteriores ao teste. Os critérios de inclusão incluíram destro e idade entre 18 e 35 anos.</li>
	<li>Fornecer uma explicação por escrito do procedimento e dos riscos associados, esclarecendo quaisquer outras questões que o participante possa ter.</li>
	<li>Obter o consentimento informado dos participantes.</li>
</ol>6. Configuração do assunto
<ol><li>Posicione o sujeito em uma cadeira confortável de frente para o tablet. Certifique-se de que os joelhos estão flexionados a 90° com as pernas sob a mesa.</li>
	<li>Prepare a pele e coloque eletrodos EMG.<ol><li>Use lixa de grão fino para abrasar suavemente a pele no local do primeiro interósseo dorsal direito (IED), extensor radial do carpo e músculos deltoideos anteriores, bem como a proeminência C4 na base do pescoço, para detectar artefatos elétricos produzidos pelo pulso TMS. NOTA: Os locais de gravação muscular podem ser adaptados com base nas necessidades do usuário.</li>
		<li>Esfregue cada área abrasada com uma almofada de preparação de álcool uma vez por local do eletrodo para limpar.</li>
		<li>Coloque um eletrodo EMG em cada local. Certifique-se de que os eletrodos funcionem perpendicularmente às fibras musculares. Coloque o eletrodo terra na proeminência óssea do cotovelo direito.</li>
		<li>Prenda cada eletrodo com fita adesiva.</li>
	</ol></li>
	<li>Verifique a qualidade da gravação EMG. Use a caixa de ferramentas VETA para visualizar todos os traços EMG e garantir que eles estejam livres de artefatos. Se os vestígios de EMG forem barulhentos, certifique-se de que o solo esteja devidamente colocado e que todos os eletrodos façam contato adequado com a pele.</li>
</ol>7. Estimulação magnética transcraniana
<ol><li>Ligue a máquina TMS.</li>
	<li>Encontre o ponto quente TMS do músculo IDE direito através da estimulação do M1 esquerdo.<ol><li>Coloque a bobina ~5 cm lateral e 2 cm anterior ao vértice da cabeça, orientada ~45° para fora da linha média.</li>
		<li>Administrar pulsos de EMT uma vez a cada 4 s enquanto reposiciona a bobina em incrementos de aproximadamente 5 mm no plano anteroposterior e médio-lateral.</li>
		<li>Começando com 30% de saída máxima do estimulador, aumente gradualmente a intensidade da EMT em incrementos de 2% até que as PEmáx sejam observadas.</li>
		<li>Uma vez identificada a localização ótima, na qual os MEPs podem ser provocados de forma confiável na maioria (~75%) dos pulsos na menor intensidade possível do estimulador, determine o limiar motor de repouso (RMT) encontrando o nível de intensidade que produz MEPs com uma amplitude pico-a-pico de >50 μV em cinco de 10 pulsos.</li>
		<li>Marque a posição colocando suavemente tiras finas de fita refletiva na cabeça do participante ao longo do perímetro da bobina. Mantenha o posicionamento da bobina segurando manualmente a bobina ou usando um suporte para apoiá-la.</li>
	</ol></li>
</ol>8. Alcançando a configuração da tarefa
<ol><li>Coloque uma luva Velcro na mão direita do participante para facilitar uma postura de aperto de poder relaxada.</li>
	<li>Prenda a caneta à luva e aconselhe o sujeito a manter a mão relaxada entre os movimentos de alcance.</li>
	<li>Comunique as instruções da tarefa, que são as seguintes: Guie o cursor para a posição inicial na parte inferior da tela. Você verá uma sugestão em um dos dois locais de destino. Quando o alvo preencher com cor, alcance o alvo o mais rápido e com a maior precisão possível. Em seguida, retorne à posição inicial. Indique os locais das posições residenciais, pistas e alvos (Figura 1A).</li>
	<li>Treine o participante para cortar alvos com a caneta o mais rápido e com a maior precisão possível. Desligue as luzes da sala de tarefas para obscurecer a visão do participante dos movimentos dos braços e melhorar a visibilidade do monitor de tarefas.</li>
</ol>9. Design de tarefas
<ol><li>Controle a apresentação de estímulos visuais com o Psychtoolbox 3.0 no Matlab 2018 (Arquivo de Codificação Suplementar 1).</li>
	<li>Use os seguintes parâmetros para corresponder aos dados atuais: 20 ensaios práticos; 270 ensaios de teste; TMS em 4/5 dos ensaios de teste; A EMT coincide com o início da sugestão preparatória (EMT basal) ou 100 ms antes da sugestão imperativa (EMT atrasada) com igual frequência; 1/10 do total de ensaios são ensaios de captura, nos quais a sugestão imperativa não aparece; a posição inicial é um círculo com um raio de 2 cm posicionado no centro inferior do espaço de trabalho; dois alvos circulares com 1 cm de raio são posicionados a 15 cm da posição inicial a +45° e -45° de distância da linha média.</li>
	<li>Defina a ordem e a duração do evento da seguinte forma: sugestão preparatória a 900 ms e sugestão imperativa a 900 ms.</li>
</ol>10. Administração do TMS
<ol><li>A caixa de ferramentas VETA administra simultaneamente o TMS e registra o EMG https://github.com/greenhouselab/Veta.</li>
	<li>Controle o tempo dos pulsos TMS com a caixa de ferramentas VETA para coincidir com os eventos comportamentais escolhidos (ou seja, o início da pista preparatória ou 100 ms antes do início do alvo).</li>
	<li>Fornecer TMS com frequência suficiente para garantir um número suficiente de eurodeputados para análise. NOTA: Tal como escrito, o código de tarefa fornecerá um pulso TMS em 4/5 do total de ensaios, quer no início da sugestão preparatória - para provocar eurodeputados de linha de base - ou 100 ms antes da sugestão imperativa - para provocar eurodeputados atrasados. Os parâmetros podem ser ajustados no código de acordo com as necessidades do usuário. Ensaios sem EMT podem ser usados para avaliar o desempenho comportamental na ausência de EMT. Isso é útil para determinar qualquer possível influência do TMS no desempenho.</li>
</ol>

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Todos os autores declaram que não há conflitos de interesse

Os métodos descritos acima oferecem uma nova abordagem para estudar a preparação motora no contexto de alcançar comportamentos. Embora o alcance represente uma tarefa de modelo popular no estudo do controle motor e da aprendizagem, há uma necessidade de avaliar com precisão a dinâmica da SC associada ao comportamento de alcance. O TMS oferece um método não invasivo e temporalmente preciso de capturar a atividade de CS em pontos de tempo discretos durante o alcance. A abordagem aqui descrita comb...

O alcance direcionado a metas é um comportamento motor fundamental que permite que os seres humanos interajam e manipulem o ambiente externo. O estudo do alcance nos campos da fisiologia motora, psicologia e neurociência produziu uma literatura rica e extensa que inclui uma variedade de metodologias. Os primeiros estudos de alcance utilizaram registros neurais diretos em primatas não humanos para investigar a atividade neural no nível de neurônios individuais 1,2. Estudos mais recentes têm investigado o alcance utilizando paradigmas comportamentais que empregam a adaptação sensório-motora para explorar a natureza da aprendizagem motora e do controle 3,4,5. Tais tarefas comportamentais combinadas com ressonância magnética funcional e eletroencefalografia podem medir toda a atividade cerebral durante o alcance em humanos 6,7. Outros estudos aplicaram a EMT on-line para investigar várias características da preparação e execução do alcance 8,9,10,11,12,13,14. No entanto, continua a haver uma necessidade de uma abordagem flexível e de código aberto que combine a avaliação comportamental do alcance com o TMS. Embora a utilidade de combinar TMS com protocolos comportamentais esteja muito bem estabelecida15, aqui, examinamos especificamente a aplicação da TMS dentro do contexto de alcançar usando uma abordagem de código aberto. Isso é novo na medida em que outros grupos que publicaram usando essa combinação de métodos não disponibilizaram suas ferramentas prontamente, proibindo a replicação direta. Essa abordagem de código aberto facilita a replicação, o compartilhamento de dados e a possibilidade de estudos em vários locais. Além disso, se outros desejarem buscar novas questões de pesquisa com ferramentas semelhantes, o código-fonte aberto pode atuar como uma plataforma de lançamento para a inovação, pois é prontamente adaptável.
A EMT oferece um meio não invasivo de sondar o sistema motor em pontos de tempo precisamente controlados16. Quando aplicada sobre o córtex motor primário (M1), a EMT pode provocar uma deflexão mensurável no eletromiograma de um músculo alvo. A amplitude dessa onda de voltagem, conhecida como potencial evocado motor (PEmáx), fornece um índice do estado de excitabilidade momentânea da via corticoespinhal (SC) - um análogo resultante de todas as influências excitatórias e inibitórias na via CS17. Além de fornecer uma medição confiável dentro do sujeito da excitabilidade intrínseca da CS, a EMT pode ser combinada com outras métricas comportamentais ou cinemáticas para investigar as relações entre a atividade e o comportamento da CS de maneira temporalmente precisa. Muitos estudos têm utilizado uma combinação de EMT e eletromiografia (EMG) para abordar uma variedade de questões sobre o sistema motor, particularmente porque essa combinação de métodos torna possível investigar PEmáx sob uma vasta gama de condições comportamentais15. Uma área em que isso tem se mostrado particularmente útil é no estudo da preparação da ação, na maioria das vezes através do estudo de movimentos uniarticulares18. No entanto, há comparativamente menos estudos de EMT de movimentos naturalistas multi-articulares, como o alcance.
O objetivo atual era projetar uma tarefa de resposta atrasada que incluísse cinemática comportamental, administração on-line de EMS de pulso único e gravação EMG simultânea de vários músculos. A tarefa inclui um paradigma bidimensional de alcance ponto-a-ponto com feedback visual on-line usando um monitor orientado horizontalmente de modo que o feedback visual corresponda às trajetórias de alcance (ou seja, uma relação 1: 1 durante o feedback verídico e nenhuma transformação entre feedback visual e movimento). O projeto atual também inclui um conjunto de ensaios com uma perturbação visuomotora. No exemplo fornecido, este é um deslocamento rotacional de 20° no feedback do cursor. Estudos anteriores utilizaram um paradigma de alcance semelhante para abordar questões sobre os mecanismos e cálculos associados à adaptação sensório-motora 19,20,21,22,23,24,25. Além disso, essa abordagem permite avaliar a dinâmica da excitabilidade do sistema motor em pontos de tempo precisos durante o aprendizado motor on-line.
Como o alcance provou ser um comportamento frutífero para investigar a aprendizagem/adaptação, avaliar a excitabilidade da SC no contexto desse comportamento tem um enorme potencial para lançar luz sobre os substratos neurais envolvidos nesses comportamentos. Estes podem incluir influências inibitórias locais, mudanças nas propriedades de ajuste, o momento dos eventos neurais, etc., como foi estabelecido em pesquisas com primatas não humanos. No entanto, essas características têm sido mais difíceis de quantificar em humanos e populações clínicas. A dinâmica neural também pode ser investigada na ausência de movimento evidente em humanos usando a abordagem combinada de EMT e EMG (ou seja, durante a preparação do movimento ou em repouso).
As ferramentas apresentadas são de código aberto e o código é facilmente adaptável. Este novo paradigma produzirá insights importantes sobre os mecanismos envolvidos na preparação, execução, término e adaptação dos movimentos de alcance. Além disso, essa combinação de métodos tem o potencial de descobrir relações entre a eletrofisiologia e o comportamento de alcance em humanos.

<table><tbody><tr><td>2-Port Native PCI Express&amp;nbsp;</td><td>StarTech.com</td><td>RS232 Card with 16950 UART&amp;nbsp;</td><td>Must be compatible with desktop computer</td></tr><tr><td>Adjustable 80-20 aluminum frame</td><td>any</td><td></td><td></td></tr><tr><td>Alcohol prep pads</td><td>any</td><td></td><td>EMG preparation</td></tr><tr><td>Bagnoli Bipolar Electrodes</td><td>Delsys</td><td>DE 2.1</td><td></td></tr><tr><td>Bagnoli Reference Electrode</td><td>Delsys</td><td>USX2000</td><td>2&amp;rdquo; (5cm) Round</td></tr><tr><td>Bagnoli-8 EMG System</td><td>Delsys</td><td></td><td></td></tr><tr><td>Chair</td><td>any</td><td></td><td></td></tr><tr><td>Computer monitor for EMG/TMS</td><td>n/a</td><td></td><td></td></tr><tr><td>Desk</td><td>any</td><td></td><td></td></tr><tr><td>Desktop Computer</td><td>Dell</td><td>xps 8930</td><td>RAM: 16 GB, Storage: 1TB, Graphics: 1060 6GB&amp;nbsp;</td></tr><tr><td>EMG electrodes</td><td>Delsys</td><td>Sensor Adhesive Interface</td><td></td></tr><tr><td>Fine grain sandpaper</td><td>any</td><td></td><td>EMG preparation</td></tr><tr><td>Graphics tablet</td><td>Wacom</td><td>Intuos-4 XL</td><td></td></tr><tr><td>Handle of paint roller</td><td>any</td><td></td><td>to be used as stylus handle, hollowed out center must be large enough for stylus to sit securely inside&amp;nbsp;</td></tr><tr><td>Medical tape</td><td>any</td><td></td><td>To secure EMG electrodes</td></tr><tr><td>PCI-6220 card DAQ</td><td>National Instruments</td><td></td><td>To interface EMG system</td></tr><tr><td>Photodiode Sensor</td><td>Vishay</td><td>BPW21R</td><td>To record timing of task events into EMG trace.</td></tr><tr><td>Rear TMS port</td><td>Magstim</td><td></td><td>Included with TMS machine</td></tr><tr><td>Right-handed polyethylene glove</td><td>any</td><td></td><td>Cut out thumb and index finger of glove to expose FDI muscle</td></tr><tr><td>Sensory Adhesive Interface, 2-slot</td><td>Delsys</td><td>SC-F01</td><td></td></tr><tr><td>Stylus</td><td>Wacom</td><td>Intuos-4 grip pen</td><td></td></tr><tr><td>Tablet-to-Computer USB cable&amp;nbsp;</td><td>any</td><td></td><td>Included in Tablet purchase</td></tr><tr><td>Task Monitor</td><td>Asus</td><td>VG248</td><td></td></tr><tr><td>TMS coil</td><td>Magstim</td><td>D70 Remote Coil</td><td>7cm diameter, figure-of-eight coil</td></tr><tr><td>TMS machine</td><td>Magstim</td><td>200-2</td><td></td></tr><tr><td>TMS-to-Computer DB9 cable</td><td>any</td><td></td><td>Connects to PCIe Serial Card</td></tr><tr><td>Velcro</td><td>any</td><td></td><td>To be placed on glove and stylus handle</td></tr></tbody></table>

assessing corticospinal excitability during goal-directed reaching behavior

Alcançar é um comportamento amplamente estudado em fisiologia motora e pesquisa em neurociências. Embora o alcance tenha sido examinado usando uma variedade de manipulações comportamentais, ainda existem lacunas significativas na compreensão dos processos neurais envolvidos no planejamento, execução e controle do alcance. A nova abordagem descrita aqui combina uma tarefa de alcance bidimensional com estimulação magnética transcraniana (EMT) e eletromiografia simultânea (EMG) gravação de múltiplos músculos. Este método permite a detecção não invasiva da atividade corticoespinhal em pontos de tempo precisos durante o desdobramento dos movimentos de alcance. O código de tarefa de exemplo inclui uma tarefa de resposta atrasada com dois possíveis destinos exibidos ± 45° fora da linha média. A EMT de pulso único é entregue na maioria dos ensaios de tarefa, seja no início da sugestão preparatória (linha de base) ou 100 ms antes da sugestão imperativa (atraso). Este desenho amostral é adequado para investigar alterações na excitabilidade corticoespinhal durante a preparação do alcance. O código de amostra também inclui uma perturbação visuomotora (ou seja, rotação do cursor de ± 20°) para investigar os efeitos da adaptação na excitabilidade corticoespinhal durante a preparação do alcance. Os parâmetros da tarefa e a entrega da EMT podem ser ajustados para abordar hipóteses específicas sobre o estado do sistema motor durante o comportamento de alcance. Na implementação inicial, os potenciais evocados motores (PEmáx) foram obtidos com sucesso em 83% dos ensaios de EMT, e as trajetórias de alcance foram registradas em todos os ensaios.

A execução bem-sucedida dos métodos descritos inclui o registro de dados do tablet, traços EMG e elicitação confiável de eurodeputados. Um experimento foi concluído que incluiu 270 ensaios de teste com TMS entregues em 4/5 dos ensaios (216 ensaios).
Os dados foram coletados de 16 participantes (oito mulheres; oito homens) com idades entre 25 ± 10 anos, todos autodeclarados destros. Avaliamos a eficácia da perturbação visual no desempenho comportamental derivando uma função de apr...

Watch this Scientific Journal Video about Assessing Corticospinal Excitability During Goal-Directed Reaching Behavior at JoVE.com

Assessing Corticospinal Excitability During Goal-Directed Reaching Behavior

Alcançar é uma habilidade fundamental que permite que os seres humanos interajam com o ambiente. Diversos estudos têm como objetivo caracterizar o comportamento de alcance utilizando uma variedade de metodologias. Este artigo oferece uma aplicação de código aberto de estimulação magnética transcraniana para avaliar o estado de excitabilidade corticoespinhal em humanos durante o desempenho da tarefa.

Avaliando a excitabilidade corticoespinhal durante o comportamento de alcance direcionado a objetivos

Reaching is a widely studied behavior in motor physiology and neuroscience research. While reaching has been examined using a variety of behavioral ...

assessing-corticospinal-excitability-during-goal-directed-reaching

Research

JoVE Journal

Neuroscience

1.6K visualizações.  University of Oregon. Alcançar é uma habilidade fundamental que permite que os seres humanos interajam com o ambiente. Diversos estudos têm como objetivo caracterizar o comportamento de alcance utilizando uma variedade de metodologias. Este artigo oferece uma aplicação de código aberto de estimulação magnética transcraniana para avaliar o estado de excitabilidade corticoespinhal em humanos durante o desempenho da tarefa.

Vídeo: Assessing Corticospinal Excitability During Goal-Directed Reaching Behavior

Corticospinal Excitability Modulation During Action Observation

This study used the transcranial magnetic stimulation/motor evoked potential (TMS/MEP) technique to pinpoint when the automatic tendency to mirror someone else's action becomes anticipatory simulation of a complementary act. TMS was delivered to the left primary motor cortex corresponding to the hand to induce the highest level of MEP activity from the abductor digiti minimi (ADM; the muscle serving little finger abduction) as well as the first dorsal interosseus (FDI; the muscle serving index finger flexion/extension) muscles. A neuronavigation system was used to maintain the position of the TMS coil, and electromyographic (EMG) activity was recorded from the right ADM and FDI muscles. Producing original data with regard to motor resonance, the combined TMS/MEP technique has taken research on the perception-action coupling mechanism a step further. Specifically, it has answered the questions of how and when observing another person's actions produces motor facilitation in an onlooker's corresponding muscles and in what way corticospinal excitability is modulated in social contexts.

Single-pulse transcranial magnetic stimulation over the primary motor cortex, neuronavigation, and registration of electromyographic activity of hand muscles were used in this study to explore corticospinal excitability while participants were observing action sequences.

Modulação de excitabilidade corticospinal durante a observação de ação

This study used the transcranial magnetic stimulation/motor evoked potential (TMS/MEP) technique to pinpoint when the automatic tendency to mirror someone ...

Comportamento

Methods to Explore the Influence of Top-down Visual Processes on Motor Behavior

Kinesthetic awareness is important to successfully navigate the environment. When we interact with our daily surroundings, some aspects of movement are deliberately planned, while others spontaneously occur below conscious awareness. The deliberate component of this dichotomy has been studied extensively in several contexts, while the spontaneous component remains largely under-explored. Moreover, how perceptual processes modulate these movement classes is still unclear. In particular, a currently debated issue is whether the visuomotor system is governed by the spatial percept produced by a visual illusion or whether it is not affected by the illusion and is governed instead by the veridical percept. Bistable percepts such as 3D depth inversion illusions (DIIs) provide an excellent context to study such interactions and balance, particularly when used in combination with reach-to-grasp movements. In this study, a methodology is developed that uses a DII to clarify the role of top-down processes on motor action, particularly exploring how reaches toward a target on a DII are affected in both deliberate and spontaneous movement domains.

It is unclear how top-down signals from the ventral visual stream affect movement. We developed a paradigm to test motor behavior towards a target on a 3D depth inversion illusion. Significant differences are reported in both deliberate, goal-directed movements and automatic actions under illusory and veridical viewing conditions.

Métodos para pesquisar a influência de cima para baixo processos visuais em Comportamento Motor

Kinesthetic awareness is important to successfully navigate the environment. When we interact with our daily surroundings, some aspects of movement are ...

Force and Position Control in Humans - The Role of Augmented Feedback

During motor behaviour, humans interact with the environment by for example manipulating objects and this is only possible because sensory feedback is constantly integrated into the central nervous system and these sensory inputs need to be weighted in order meet the task specific goals. Additional feedback presented as augmented feedback was shown to have an impact on motor control and motor learning. A number of studies investigated whether force or position feedback has an influence on motor control and neural activation. However, as in the previous studies the presentation of the force and position feedback was always identical, a recent study assessed whether not only the content but also the interpretation of the feedback has an influence on the time to fatigue of a sustained submaximal contraction and the (inhibitory) activity of the primary motor cortex using subthreshold transcranial magnetic stimulation. This paper describes one possible way to investigate the influence of the interpretation of feedback on motor behaviour by investigating the time to fatigue of submaximal sustained contractions together with the neuromuscular adaptations that can be investigated using surface EMG. Furthermore, the current protocol also describes how motor cortical (inhibitory) activity can be investigated using subthreshold TMS, a method known to act solely on the cortical level. The results show that when participants interpret the feedback as position feedback, they display a significantly shorter time to fatigue of a submaximal sustained contraction. Furthermore, subjects also displayed an increased inhibitory activity of the primary cortex when they believed to receive position feedback compared when they believed to receive force feedback. Accordingly, the results show that interpretation of feedback results in differences on a behavioural level (time to fatigue) that is also reflected in interpretation-specific differences in the amount of inhibitory M1 activity.

Controlling an identical movement with position or force feedback results in different neural activation and motor behavior. This protocol describes how to investigate behavioral changes by looking at neuromuscular fatigue and how to evaluate motor cortical (inhibitory) activity using subthreshold TMS with respect to the interpretation of augmented feedback.

Controle força e posição em Seres Humanos - O papel do feedback Augmented

During motor behaviour, humans interact with the environment by for example manipulating objects and this is only possible because sensory feedback is ...

Investigating Motor Skill Learning Processes with a Robotic Manipulandum

Skilled reaching tasks are commonly used in studies of motor skill learning and motor function under healthy and pathological conditions, but can be time-intensive and ambiguous to quantify beyond simple success rates. Here, we describe the training procedure for reach-and-pull tasks with ETH Pattus, a robotic platform for automated forelimb reaching training that records pulling and hand rotation movements in rats. Kinematic quantification of the performed pulling attempts reveals the presence of distinct temporal profiles of movement parameters such as pulling velocity, spatial variability of the pulling trajectory, deviation from midline, as well as pulling success. We show how minor adjustments in the training paradigm result in alterations in these parameters, revealing their relation to task difficulty, general motor function or skilled task execution. Combined with electrophysiological, pharmacological and optogenetic techniques, this paradigm can be used to explore the mechanisms underlying motor learning and memory formation, as well as loss and recovery of function (e.g. after stroke).

A paradigm is presented for training and analysis of an automated skilled reaching task in rats. Analysis of pulling attempts reveals distinct subprocesses of motor learning.

Investigação dos processos de aprendizagem motora habilidade com uma Robotic Manipulandum

Skilled reaching tasks are commonly used in studies of motor skill learning and motor function under healthy and pathological conditions, but can be ...

Intracortical Inhibition Within the Primary Motor Cortex Can Be Modulated by Changing the Focus of Attention

It is well recognized that an external focus (EF) compared with an internal focus (IF) of attention improves motor learning and performance. Studies have indicated benefits in accuracy, balance, force production, jumping performance, movement speed, oxygen consumption, and fatiguing task. Although behavioral outcomes of using an EF strategy are well explored, the underlying neural mechanisms remain unknown. A recent TMS study compared the activity of the primary motor cortex (M1) between an EF and an IF. More precisely, this study showed that, when adopting an EF, the activity of intracortical inhibitory circuits is enhanced.
On the behavioral level, the present protocol tests the influence of attentional foci on the time to task failure (TTF) when performing submaximal contractions of the first dorsal interosseous (FDI). Additionally, the current paper describes two TMS protocols to assess the influence of attentional conditions on the activity of cortical inhibitory circuits within the M1. Thus, the present article describes how to use single-pulse TMS at intensities below the motor threshold (subTMS) and paired-pulse TMS, inducing short-interval intracortical inhibition (SICI) when applied to the M1. As these methods are assumed to reflect the responsiveness of GABAergic inhibitory neurons, without being affected by spinal reflex circuitries, they are well suited to measuring the activity of intracortical inhibitory circuits within the M1.
The results show that directing attention externally improves motor performance, as participants were able to prolong the time to task failure. Moreover, the results were accompanied by a larger subTMS-induced electromyography suppression and SICI when adopting an EF compared to an IF. As the level of cortical inhibition within the M1 was previously demonstrated to influence motor performance, the enhanced inhibition with an EF might contribute to the better movement efficiency observed in the behavioral task, indicated by a prolonged TTF with an EF.

Using two different transcranial magnetic stimulation (TMS) protocols, this manuscript describes how to measure and compare cortical inhibition within the primary motor cortex when adopting different attentional foci.

Inibição intracortical dentro o córtex Motor primário pode ser modulada, alterando o foco de atenção

It is well recognized that an external focus (EF) compared with an internal focus (IF) of attention improves motor learning and performance. Studies have ...

A Modified Lean and Release Technique to Emphasize Response Inhibition and Action Selection in Reactive Balance

Assessment of reactive balance traditionally imposes some type of perturbation to upright stance or gait followed by measurement of the resultant corrective behavior. These measures include muscle responses, limb movements, ground reaction forces, and even direct neurophysiological measures such as electroencephalography. Using this approach, researchers and clinicians can infer some basic principles regarding how the nervous system controls balance to avoid a fall. One limitation with the way in which these assessments are currently used is that they heavily emphasize reflexive actions without any need to revise automatic postural reactions. Such an exclusive focus on these highly stereotypical reactions would fail to adequately address how we can modify these reactions should the need arise (e.g., avoiding an obstacle with a recovery step). This would appear to be a glaring omission when one considers the enormous complexity of the environments we face daily. Overall, the status quo when evaluating the neural control of balance fails to truly expose how higher brain resources contribute to preventing falls in complex settings. The present protocol offers a way to require suppression of automatic, but inappropriate corrective balance reactions, and force a selection among alternative action choices to successfully recover balance following postural perturbation.

Here we offer a protocol that allows the user to selectively change affordances and/or constraints on movements that are relevant for recovering balance after postural perturbation.

Uma técnica de lean e liberação modificada para enfatizar a inibição de resposta e a seleção de ação no equilíbrio reativo

Assessment of reactive balance traditionally imposes some type of perturbation to upright stance or gait followed by measurement of the resultant ...

Measuring and Manipulating Functionally Specific Neural Pathways in the Human Motor System with Transcranial Magnetic Stimulation

Understanding interactions between brain areas is important for the study of goal-directed behavior. Functional neuroimaging of brain connectivity has provided important insights into fundamental processes of the brain like cognition, learning, and motor control. However, this approach cannot provide causal evidence for the involvement of brain areas of interest. Transcranial magnetic stimulation (TMS) is a powerful, noninvasive tool for studying the human brain that can overcome this limitation by transiently modifying brain activity. Here, we highlight recent advances using a paired-pulse, dual-site TMS method with two coils that causally probes cortico-cortical interactions in the human motor system during different task contexts. Additionally, we describe a dual-site TMS protocol based on cortical paired associative stimulation (cPAS) that transiently enhances synaptic efficiency in two interconnected brain areas by applying repeated pairs of cortical stimuli with two coils. These methods can provide a better understanding of the mechanisms underlying cognitive-motor function as well as a new perspective on manipulating specific neural pathways in a targeted fashion to modulate brain circuits and improve behavior. This approach may prove to be an effective tool to develop more sophisticated models of brain-behavior relations and improve diagnosis and treatment of many neurological and psychiatric disorders.

This article describes new approaches to measure and strengthen functionally specific neural pathways with transcranial magnetic stimulation. These advanced noninvasive brain stimulation methodologies can provide new opportunities for the understanding of brain-behavior relations and development of new therapies to treat brain disorders.

Medir e manipular vias neurais funcionalmente específicas no sistema motor humano com estimulação magnética transcraniana

Understanding interactions between brain areas is important for the study of goal-directed behavior. Functional neuroimaging of brain connectivity has ...

Neurociência

An Emerging Target Paradigm to Evoke Fast Visuomotor Responses on Human Upper Limb Muscles

To reach towards a seen object, visual information has to be transformed into motor commands. Visual information such as the object&#8217;s color, shape, and size are processed and integrated within numerous brain areas, then ultimately relayed to the motor periphery. In some instances, a reaction is needed as fast as possible. These fast visuomotor transformations, and their underlying neurological substrates, are poorly understood in humans as they have lacked a reliable biomarker. Stimulus-locked responses (SLRs) are short latency (&#60;100 ms) bursts of electromyographic (EMG) activity representing the first wave of muscle recruitment influenced by visual stimulus presentation. SLRs provide a quantifiable output of rapid visuomotor transformations, but SLRs have not been consistently observed in all subjects in past studies. Here we describe a new, behavioral paradigm featuring the sudden emergence of a moving target below an obstacle that consistently evokes robust SLRs. Human participants generated visually guided reaches toward or away from the emerging target using a robotic manipulandum while surface electrodes recorded EMG activity from the pectoralis major muscle. In comparison to previous studies that investigated SLRs using static stimuli, the SLRs evoked with this emerging target paradigm were larger, evolved earlier, and were present in all participants. Reach reaction times (RTs) were also expedited in the emerging target paradigm. This paradigm affords numerous opportunities for modification that could permit systematic study of the impact of various sensory, cognitive, and motor manipulations on fast visuomotor responses. Overall, our results demonstrate that an emerging target paradigm is capable of consistently and robustly evoking activity within a fast visuomotor system.

Presented here is a behavioral paradigm that elicits robust fast visuomotor responses on human upper limb muscles during visually guided reaches.

Um paradigma de alvo emergente para evocar respostas rápidas do visuomotor sobre músculos dos membros superiores humanos

To reach towards a seen object, visual information has to be transformed into motor commands. Visual information such as the object&#8217;s color, shape, ...

In Vivo Wireless Optogenetic Control of Skilled Motor Behavior

Fine motor skills are essential in everyday life and can be compromised in several nervous system disorders. The acquisition and performance of these tasks require sensory-motor integration and involve precise control of bilateral brain circuits. Implementing unimanual behavioral paradigms in animal models will improve the understanding of the contribution of brain structures, like the striatum, to complex motor behavior as it allows manipulation and recording of neural activity of specific nuclei in control conditions and disease during the performance of the task. 
Since its creation, optogenetics has been a dominant tool for interrogating the brain by enabling selective and targeted activation or inhibition of neuronal populations. The combination of optogenetics with behavioral assays sheds light on the underlying mechanisms of specific brain functions. Wireless head-mounted systems with miniaturized light-emitting diodes (LEDs) allow remote optogenetic control in an entirely free-moving animal. This avoids the limitations of a wired system being less restrictive for animals' behavior without compromising light emission efficiency. The current protocol combines a wireless optogenetics approach with high-speed videography in a unimanual dexterity task to dissect the contribution of specific neuronal populations to fine motor behavior.

In Vivo Wireless Optogenetic Control of Skilled Motor Behavior

The present protocol describes how to use wireless optogenetics combined with high-speed videography in a single pellet reach-to-grasp task to characterize the neural circuits involved in the performance of skilled motor behavior in freely moving mice.

In vivo Controle Optogenético Sem Fio do Comportamento Motor Qualificado

Fine motor skills are essential in everyday life and can be compromised in several nervous system disorders. The acquisition and performance of these ...

<meta charset="utf8"></head><body>Avaliação quantitativa do uso da mão na lesão unilateral do nervo

Block Building Task Identifies Distinct Groups of Left/Right-hand Choice Patterns After Unilateral Peripheral Nerve Injury

Numerous methods exist to assess hand and arm function after upper extremity peripheral nerve injury, but peripheral injuries are often unilateral, and few existing methods are designed to capture the unique consequences of unilateral injury. Unilateral impairment of an upper extremity can lead to increased or decreased use of the dominant hand, and either change may be adaptive or maladaptive depending on the individual patient&#8217;s needs. To identify atypical hand usage (left/right choices), researchers and clinicians need to measure it. However, hand usage is traditionally assessed with self-report surveys, which do not necessarily reflect actual left/right-hand choices. Here, this gap in knowledge is addressed with the Block Building Task (BBT), which provides a rapid, quantitative, inexpensive assessment of left/right-hand choices in an unconstrained environment. In the BBT, participants build abstract shapes with interlocking plastic bricks, with no instructions about hand usage. The primary outcome is the fraction of reaches (i.e., for the initial pickup of each brick) made with each hand. After unilateral peripheral nerve injury, patients fell into three clusters: approximately typical hand use (44%), always use the dominant hand (44%), or never use the dominant hand (13%). Even among patients with an injured dominant hand, atypically elevated use of the dominant hand occurred regularly (36%). Notably, hand usage was not predicted by clinical characteristics, so the BBT provides an objective measurement of left/right-hand choices that are not otherwise predictable from the clinical characteristics of patients with peripheral nerve injury. The BBT protocol will be of interest to researchers or clinicians interested in the assessment of conditions with asymmetric effects on the upper limb.

<meta charset="utf8"></head><body>A tarefa de construção de blocos identifica grupos distintos de padrões de escolha da mão esquerda/direita após lesão unilateral do nervo periférico

The block-building task provides a rapid, objective, quantitative measurement of how often individuals choose to use their left versus right hand for reach-to-grasp action. After unilateral peripheral nerve injury, patients often shift to near-total usage of one hand, the direction of which is not predictable from other clinical factors.

A tarefa de construção de blocos identifica grupos distintos de padrões de escolha da mão esquerda/direita após lesão unilateral do nervo periférico

Numerous methods exist to assess hand and arm function after upper extremity peripheral nerve injury, but peripheral injuries are often unilateral, and ...