Este trabalho foi financiado pelo Centro de Tecnologia de Comunicação Neural (CNCT), um Centro de Recursos P41 financiado pelo Instituto Nacional de Biomedical Imaging and Bioengineering (NIBIB, P41 EB002030) e apoiado pelo National Institutes of Health (NIH). Os autores agradecem a Vetter Rio de NeuroNexus Tecnologias para o desenvolvimento de técnicas cirúrgicas, e Paras Patel, da Universidade de Michigan para a elaboração da lista de equipamento utilizado durante as cirurgias.

1. Pré-implante Procedimentos (Comum) <ol><li> Raspar o topo da cabeça do animal a partir de entre os olhos para bem atrás das orelhas. Use cortadores elétricos barbeiro para raspar a cabeça. Esfregue a cabeça pela primeira vez com álcool isopropílico, então betadine (3x). Aplique lubrificante ocular. </li><li> Monte o animal em barras de ouvido estereotáxicas. Direcione a ponta da barra fixa orelha direita estereotáxica no conduto auditivo, da orelha direita do animal, movendo os lados da cabeça contra o canal. Extremo cuidado deve ser tomado para assegurar que cada ponta da orelha-bar está devidamente posicionado no conduto auditivo. Em seguida, pressione a barra de orelha esquerda solta dentro do canal auditivo e aplicar pressão interna leve. Segure o nariz do animal e wiggle frente e para trás com firmeza. Se o animal está montado corretamente a cabeça vai se sentir rigidamente montado. </li></ol> 2. Pré-implantação Cirurgia (Comum) <ol><li> Com uma tesoura fina, cortar dois circ meiales de dentro para fora da linha média, eliminação parcial do couro cabeludo </li><li> Raspar e remover o tecido conjuntivo periósteo que adere ao osso. Raspagem com uma borda romba, tais como a parte de trás de uma lâmina de bisturi ou a ponta de uma mecha de algodão estéril irá minimizar o sangramento porque os capilares será esmagado em vez de cortar suavemente. Sangramento ósseo controle usando cera de osso ou um ferro de cauterização. </li><li> Desinfetar e limpar a superfície óssea usando peróxido de hidrogênio. Seca-se o osso para fazer as suturas cranianas mais claramente visível. O bregma e pontos lambda deve notar-se e usado para nivelar a cabeça. O local da craniotomia e implante de eletrodo deve ser medida com relação ao bregma e pode ser temporariamente marcado com uma caneta ou por perfuração rasa na superfície. A localização craniotomia dependerá dos objectivos experimentais do estudo (isto é, do motor, as experiências sensoriais) 1. </li><li> Perfurar screwholes dentro do osso e colocar o chão e estabilizar stripulações. Sempre utilize aço inoxidável ou parafusos de titânio. Parafusos joalheiro pequeno (por exemplo, # 2-56, 00-80 ou #) com quantos threads por polegada possível é desejável. </li></ol> 3. Procedimentos de implante de silicone dos eletrodos <ol><li> Fure a craniotomia, após a implantação parafusos. Perfurar quatro marcas superficiais piloto para os cantos da craniotomia. Utilizar as marcas piloto como uma guia de perfuração para fora do perímetro da craniotomia. Remover o centro de massa de osso que não foi perfurado utilizando um par de pinças resistentes. A aresta da craniotomia aberta pode precisar de ser limpo com a continuação da perfuração. Finos pedaços de osso pode ser cortada com um par de microrongeurs. Planeje sua cirurgia com cuidado para evitar grandes vasos sanguíneos, como o seio sagital, que pode aparecer dentro de 0,5 mm da sutura mediana longitudinal 1. Punção do seio sagital podem causar hemorragia extensa. Exposed dura deve ser mantido hidratado com aCSF ou solução salina. </li><li> Para perfurar a dura-mátervocê vai precisar de moda um pequeno gancho utilizando uma agulha hipodérmica estéril de calibre pequeno (por exemplo, &lt;calibre 28). Tomar o bisel da agulha e pressioná-lo contra uma superfície plana firme (tal como a parte plana de um bisturi) de inclinação ligeiramente para formar uma curva de 90 graus no ponto. Use este gancho para apanhar a superfície da dura-máter, e levantá-lo a partir da superfície do cérebro. A dura pode ser cortado com tesoura micro ou pode ser rasgada por meio de movimentos laterais do gancho dura-máter. Tomar cuidado para evitar vasos sanguíneos na superfície do cérebro quando se utiliza o gancho dura-máter. Deve notar CSF vazando quando dura é ressecado e uma diferença de cor a partir da superfície da dura-máter. </li><li> Cuidadosamente anexar o fio terra do eléctrodo de silício em torno da base do parafuso chão, e tato no lugar com cimento dental. Os eletrodos de silicone deve ser colocado com cuidado para que os cabos eletrodos de cabo são arqueadas sobre a craniotomia. </li><li> Os implantes serão colocados utilizando um motor linear atuador placed num aparelho estereotáxico. Para fixar o eléctrodo para o dispositivo de inserção, polietileno glicol (PEG) é aquecida com um ferro de soldar e aplicado a inserção da haste e do eléctrodo de gravação. </li><li> Com o eléctrodo protegido, manualmente diminuir a ponta do eléctrodo para o local desejado estereotáxico sobre a superfície do cérebro. </li><li> Usando o interface de software para o actuador linear, mover o eléctrodo na profundidade desejada dentro do tecido cerebral. </li><li> Fixar o eléctrodo de registo no cérebro, anexando PEG a partir de um parafuso adjacente ao cabo do eléctrodo. Agora é possível remover o eléctrodo a partir do dispositivo de inserção através da adição de solução salina para dissolver o PEG ligado. Elevar o dispositivo de inserção de distância da craniotomia e de repetição para cada eléctrodo. </li><li> Cubra a craniotomia exposta com Gelfoam embebida de solução salina. Um polímero de silicone é, em seguida, utilizada para cobrir o cabo do eléctrodo e protegê-lo a partir do acrílico dental. Posicione o conector na finallocalização, em seguida, aplicar acrílico dental para fazer um headcap robusto. </li></ol> 4. MicroECoG procedimentos de implante de eléctrodos <ol><li> Implantação do eletrodo microECoG envolverá uma craniotomia um pouco maior. Para um dispositivo de 5 mm x 5, um 6 x 6 mm craniotomia deve ser feita. Antes de perfurar a craniotomia, curável por UV acrílico dental é aplicada à periferia do local craniotomia enquanto ela ainda está seco e não em risco de tocar a dura-máter ou pia. </li><li> Uma broca cirúrgica estéril é usado com uma rebarba # 107 para perfurar fora da superfície de osso na forma geral do craniotomia. Quanto menor # 106 da rebarba pode então ser usada para perfurar o resto do osso para baixo para uma camada fina e transparente. Fórceps, então, ser capaz de levantar a parte restante do osso. O microECoG pode ser implantado por via epidural ou subdurally. Novamente, mantenha a dura bem hidratado com CSF artificial ou solução salina. </li><li> A fim de implantar o microECoG, coloque um braço estereotáxico sobre a open crânio, e proteger o eletrodo para o braço com fita estéril. O eléctrodo pode agora ser abaixado para dentro do craniotomia. Certifique-se que os sites de eletrodos são voltados para baixo e vai fazer contato com a dura ou superfície pial. Se mantida úmida, o eletrodo deve deslizar sobre o tecido e vai ficar no lugar. </li><li> O fio terra está ligado ao parafuso de massa enrolando em torno de pelo menos três vezes sobre e sob si. O parafuso de chão pode ser qualquer parafuso que tenha entrado em contacto com a dura-máter. O fio de referência pode também ser ligado ao parafuso de referência da mesma maneira. </li><li> Pequenos pedaços de Gelfoam embebido salina deve ser colocado em torno do eléctrodo, onde há dura ou pia exposta. Uma pequena quantidade de Gelfoam embebido salina também deve cobrir o topo do eléctrodo de película fina. Curável por UV acrílico dental podem ser aplicados para o início da Gelfoam e pode ser usado para criar uma tampa da cabeça estável. O acrílico é aplicada diretamente para o filme fino cabo covering até o conector é atingido. Ter cuidado para não cobrir além da parte inferior da tampa de ligação. </li><li> Alternativamente, a implantação do microECoG em 4,3 pode ser imediatamente seguido pela implantação de uma matriz microeléctrodo de silício (passos 3,2-3,6) através de pequenos orifícios que são fabricados no substrato microECoG. Isto permite a gravação simultânea de ambas as unidades individuais em várias profundidades juntamente com gravações de alta resolução de campo a partir da superfície do cérebro circundante. </li></ol> 5. Recuperação Pós-Operatória <ol><li> Depois que o cimento esteja completamente endurecido, suturar a pele firmemente em torno do cabeça-tampão e retire o animal do quadro estereotáxico. </li><li> Aplique o pó anti-séptico ou pomada antibiótica copiosamente em torno da ferida. Se houver qualquer sangramento das orelhas, coloque algum bem antibiótico no canal do ouvido. </li><li> Mantenha o animal aquecido como barbitúricos impedir o animal de manter a sua temperatura corporal. Casa each cronicamente implantado animal numa gaiola separada. Geralmente, leva quatro a sete dias para que o animal recuperar completamente da cirurgia. </li></ol> 6. Os resultados representativos A bem sucedida cirurgia de implante de eletrodo de silício terá gravar sites com impedâncias de medição entre 500kOhm 2MOhm, e eletrodos de filme fino entre 10kOhm-50kOhm (a 1kHz). O sinal neural pode ser verificado a cirurgia imediatamente pós também. Deverá ser capaz de ver picos sobre os eléctrodos implantados e ver oscilações de ondas lentas sobre o eléctrodo de película fina de superfície (Figura 1). <img src="/files/ftp_upload/3565/3565fig1.jpg" alt="A Figura 1" /> Figura 1. Os resultados representativos da actividade única unidade e oscilações ECOG. A) dados em banda larga a partir de 6 canais simultaneamente gravados de um eletrodo de silício crônica implantado no neocórtex. Observe que os picos pode ser visto em sites de gravação. b) EOscilações CG dos 6 canais de uma 16-canal matriz eléctrodo de película fina uECoG sobre a superfície do cérebro. A média de todos os 16 sinais foram removidos de cada traço (referência média comum), e um filtro digital 500 Hz passa baixo foi aplicado.

<ol>
	<li>Paxinos, G. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> The Rat Brain in Stereotaxic Coordinates. , (2007).</li><li>Fujisawa, S. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Behavior-dependent+short-term+assembly+dynamics+in+the+medial+prefrontal+cortex.">Behavior-dependent short-term assembly dynamics in the medial prefrontal cortex.</a> Nat. Neurosci. 11 (7), 823-833 (2008).</li><li>Merrill, D. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electrical+stimulation+of+excitable+tissue:+design+of+efficacious+and+safe+protocols.">Electrical stimulation of excitable tissue: design of efficacious and safe protocols.</a> J. Neurosci. Methods. 141, 171-171 (2005).</li><li>Gage, G. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Naive+coadaptive+cortical+control.">Naive coadaptive cortical control.</a> J. Neural Eng. 2, 52-52 (2005).</li><li>Marzullo, T. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Development+of+Closed-Loop+Neural+Interface+Technology+in+a+Rat+Model:+Combining+Motor+Cortex+Operant+Conditioning+With+Visual+Cortex+Microstimulation.">Development of Closed-Loop Neural Interface Technology in a Rat Model: Combining Motor Cortex Operant Conditioning With Visual Cortex Microstimulation.</a> IEEE Trans. Neur. Sys. and Rehab. Eng. 18 (2), 117-126 (2010).</li><li>Maynard, E. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Utah+intracortical+electrode+array:+a+recording+structure+for+potential+brain-computer+interfaces.">The Utah intracortical electrode array: a recording structure for potential brain-computer interfaces.</a> Electroencephalogr. Clin. Neurophysiol. 102, 228-239 (1997).</li><li>Kipke, D. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Silicon-substrate+intracortical+microelectrode+arrays+for+long-term+recording+of+neuronal+spike+activity+in+cerebral+cortex.">Silicon-substrate intracortical microelectrode arrays for long-term recording of neuronal spike activity in cerebral cortex.</a> IEEE Trans. Neural Syst. Rehab. Eng. 11 (2), 151-155 (2003).</li><li>Vetter, R. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chronic+neural+recording+using+silicon-substrate+microelectrode+arrays+implanted+in+cerebral+cortex.">Chronic neural recording using silicon-substrate microelectrode arrays implanted in cerebral cortex.</a> IEEE Trans. Biomed. Eng. 51 (6), 896-904 (2004).</li></ol>

DRK é co-proprietário de NeuroNexus Technologies.

Há um interesse crescente no uso de interfaces de gravação intracortical e superfície multicanal para pesquisar o funcionamento do cérebro 2, fornecendo microstimulation 3, ou sinais de controle para sistemas de neuropróteses 4,5. Os métodos descritos neste vídeo demonstram como implantar sistemas de eléctrodos de crônicas penetrantes e de superfície. Enquanto outros sistemas de eléctrodos de silício crônicas existem 6, temos focado na implantação de eletrodos planos desenvolvidos por NeuroNexus Technologies 7,8. Técnicas para a implantação de sistemas de eléctrodos de outros irá variar consideravelmente. Dos passos cirúrgicos descritos, a montagem do animal nas barras de orelha estereotáxicas pode ser o mais difícil e, o passo mais importante na determinação da precisão da colocação dos eléctrodos implantados. Cuidado extremo deve ser tomado, por conseguinte, para assumir que cada ponta da orelha-bar está correctamente posicionada no conduto auditivo. Depois Assurance que a ponta da orelha-bar está no conduto auditivo do ouvido direito do animal, soltar o pescoço do animal com sua mão direita enquanto o polegar esquerdo eo indicador continuar a apoiar a cabeça e aplicar pressão da cabeça contra a ponta da orelha-bar. Com a mão direita, pressione a barra de orelha esquerda solta dentro do canal auditivo e aplicar pressão interna leve. Mova o lado esquerdo da cabeça do animal para baixo e para frente e ao redor até que você possa sentir o deslizamento da ponta da orelha esquerda-bar no conduto auditivo. Com a mão direita, continuar a aplicar pressão sobre a barra de orelha esquerda. Solte a cabeça do animal e, com a mão agora livre da esquerda, aperte o parafuso de fixação da barra de orelha esquerda.

<table border="1"><tbody><tr><td> Equipamento </td><td> Companhia </td><td> Número de catálogo </td><td> Comentários </td></tr><tr><td> Parafuso de osso - # 2-56 x 3/16, Phillips pan, 18-8 S / S </td><td> BoltDepot </td><td> 7650 </td><td></td></tr><tr><td> Parafuso de osso - # 2-56 x 1/8, phillips cabeça pan, 18-8 S / S </td><td> BoltDepot </td><td> 9617 </td><td></td></tr><tr><td> Tanque de oxigênio Grande - K Tamanho </td><td> Gases criogénicos </td><td> OXKME </td><td></td></tr><tr><td> Pequeno tanque de oxigênio - E Tamanho </td><td> Gases criogénicos </td><td> OXYE-AL </td><td></td></tr><tr><td> Vannas-Tubingen Primavera Tesoura - 2,5 milímetros Blade, Angled </td><td> Belas Ferramentas Ciência </td><td> 15002-08 </td><td></td></tr><tr><td> Dumont # 5 Fórceps, Teflon </td><td> Belas Ferramentas Ciência </td><td> 11626-11 </td><td></td></tr><tr><td> Dumont # 5 Fórceps, Dumostar </td><td> Belas Ferramentas Ciência </td><td> 11295-10 </td><td></td></tr><tr><td> Estudante Vannas Primavera Tesoura </td><td> Belas Ferramentas Ciência </td><td> 91500-09 </td><td></td></tr><tr><td> Adson Pinça </td><td> Belas Ferramentas Ciência </td><td> 11006-12 </td><td></td></tr><tr><td> Friendman-Pearson Ronqeur, Curvo </td><td> Belas Ferramentas Ciência </td><td> 16221-14 </td><td></td></tr><tr><td> Iris Tesoura - ToughCut </td><td> Belas Ferramentas Ciência </td><td> 14058-11 </td><td></td></tr><tr><td> Vannas-Tubingen Primavera Tesoura - Lâmina de 5mm, em linha reta </td><td> Fine Ciência Ferramentas </td><td> 15003-08 </td><td></td></tr><tr><td> Handle bisturi </td><td> Belas Ferramentas Ciência </td><td> 10003-12 </td><td></td></tr><tr><td> Caixa de Esterilização de plástico </td><td> Belas Ferramentas Ciência </td><td> 20810-02 </td><td></td></tr><tr><td> Régua de aço inoxidável </td><td> Belas Ferramentas Ciência </td><td> 30086-15 </td><td></td></tr><tr><td> Probe &amp; Espátula - 14 centímetros Straight </td><td> Belas Ferramentas Ciência </td><td> 10090-13 </td><td></td></tr><tr><td> Pinça hemostática reta </td><td> Belas Ferramentas Ciência </td><td> 13002-10 </td><td></td></tr><tr><td> Hemostat Curvo </td><td> Belas Ferramentas Ciência </td><td> 13003-10 </td><td></td></tr><tr valign="bottom"><td> Micro Broca Stainless rebarbas de aço - 0,7 mm </td><td> Belas Ferramentas Ciência </td><td> 19008-07 </td><td> 10/Pack </td></tr><tr valign="bottom"><td> Broca Micro inoxidável rebarbas de aço - 0,5 mm </td><td> Belas Ferramentas Ciência </td><td> 19007-05 </td><td> 10/Pack </td></tr><tr valign="bottom"><td> Parafusos auto-atarrachantes óssea - 1.17mm (diam) - 4,7 mm (comprimento) </td><td> Belas Ferramentas Ciência </td><td> 19010-00 </td><td> 100/Pack </td></tr><tr valign="bottom"><td> Lágrimas artificiais </td><td> Pescador </td><td> NC9860842 </td><td> Cada </td></tr><tr valign="bottom"><td> Betadine </td><td> Pescador </td><td> 19-066452 </td><td> Garrafa </td></tr><tr valign="bottom"><td> F-AIR Filtros de Carbono </td><td> Pescador </td><td> NC9112250 </td><td> Vasilha </td></tr><tr valign="bottom"><td> Algodão aplicador Derrubado, não estéril </td> &lt;td&gt; Serviços de Material </td><td> 1104 </td><td> 10Pack/Case </td></tr><tr valign="bottom"><td> Gaze 2 &quot;x 2&quot; </td><td> Serviços material </td><td> 1630 </td><td> 25Pack/Case </td></tr><tr valign="bottom"><td> Ponta da agulha, 23 GA x 1 &quot; </td><td> Serviços material </td><td> 39412 </td><td> Vendido por Processo </td></tr><tr valign="bottom"><td> Ponta da agulha, 27 GA x 1,25 &quot; </td><td> Serviços material </td><td> 25251 </td><td></td></tr><tr valign="bottom"><td> Ponta da agulha, 30 GA x 0,5 &quot; </td><td> Serviços material </td><td> 22023 </td><td> 10Box/Case </td></tr><tr valign="bottom"><td> Pomada, 0,6 g antibiótico triplo </td><td> Serviços material </td><td> 2528 </td><td></td></tr><tr valign="bottom"><td> Bolsa, Self Seal Esterilização Pouche<html> s, 3,5 &quot;x 8&quot; </td><td> Serviços material </td><td> 1023 </td><td> 10Box/Case </td></tr><tr valign="bottom"><td> Solução de Ringer 1000ml </td><td> Serviços material </td><td> 5263 </td><td> 12Bag/Case </td></tr><tr valign="bottom"><td> Lâmina de bisturi descartável estéril # 15 </td><td> Serviços material </td><td> 1975 </td><td> 3Box/Case </td></tr><tr valign="bottom"><td> Sutura, Nylon Agulha w/P-3, 5-0, 18in. </td><td> Serviços material </td><td> 4618 </td><td> 12/Box </td></tr><tr valign="bottom"><td> Resguardo, descartável 23 &quot;x 36&quot; </td><td> Serviços material </td><td> 2545 </td><td> 15Pack/Case </td></tr><tr valign="bottom"><td> Lubrificante, estéril Jelly Cirúrgica </td><td> Serviços material </td><td> 2538 </td><td> 12Box/Case </td></tr>&quot;&gt; <td> Absorvível espuma de gel 2cmx6cmx7mm </td><td> Serviços material </td><td> 3107 </td><td></td></tr><tr valign="bottom"><td> Seis peças Set Screwdriver Set Screw- </td><td> Nacional Jewelers Suprimentos </td><td> ETSCR98001 </td><td></td></tr><tr valign="bottom"><td> Kwik Sil adesiva </td><td> WPI </td><td> KWIK-SIL </td><td></td></tr><tr valign="bottom"><td> Kwik Sil Tubos </td><td> WPI </td><td> 600009 </td><td></td></tr><tr valign="top"><td> Crônicas de eletrodos de silicone 16 a 64 locais </td><td> NeuroNexus Technologies </td><td> Varia em Design Probe </td><td></td></tr><tr valign="top"><td> Crônicas de eletrodos de filme fino de superfície (microECoG) 16 a 32 locais </td><td> NeuroNexus Technologies </td><td> Varia em Design Probe </td><td>&nbsp;
 </td>
 </tr>
 </tbody>
</table>

surgical implantation of chronic neural electrodes for recording single unit activity and electrocorticographic signals

O sucesso de gravações a longo prazo electrofisiológicos depende muitas vezes da qualidade da cirurgia de implante. Aqui nós fornecemos informações úteis para os cirurgiões que estão aprendendo o processo de implantação de sistemas de eléctrodos. Nós demonstramos o procedimento de implantação de ambos um penetrante e um eléctrodo de superfície. O processo cirúrgico é descrita do início ao fim, incluindo as descrições detalhadas de cada passo ao longo do procedimento. Deve também ser notado que este guia de vídeo é focado para procedimentos realizados em modelos de roedores e outros modelos animais de pequeno porte. Modificações dos procedimentos descritos são viáveis ​​para outros modelos animais.

Watch this Scientific Journal Video about Surgical Implantation of Chronic Neural Electrodes for Recording Single Unit Activity and Electrocorticographic Signals at JoVE.com

Surgical Implantation of Chronic Neural Electrodes for Recording Single Unit Activity and Electrocorticographic Signals

Nós fornecemos informações úteis para os cirurgiões que estão aprendendo o processo de implantação de eletrodos de registro crônicas neurais. Técnicas para sistemas de eléctrodos de ambos penetrantes e de superfície são descritos em um modelo animal de roedores.

Implante cirúrgico de crônicas Eletrodos Neurais para registrar a atividade única Unidade e Sinais eletrocorticográfica

The success of long-term electrophysiological recordings often depends on the quality of the implantation surgery.  Here we provide useful information for ...

surgical-implantation-chronic-neural-electrodes-for-recording-single

Research

JoVE Journal

Neuroscience

47.2K visualizações.  University of Michigan. Nós fornecemos informações úteis para os cirurgiões que estão aprendendo o processo de implantação de eletrodos de registro crônicas neurais. Técnicas para sistemas de eléctrodos de ambos penetrantes e de superfície são descritos em um modelo animal de roedores.

Vídeo: Surgical Implantation of Chronic Neural Electrodes for Recording Single Unit Activity and Electrocorticographic Signals

Recording Human Electrocorticographic (ECoG) Signals for Neuroscientific Research and Real-time Functional Cortical Mapping

Neuroimaging studies of human cognitive, sensory, and motor processes are usually based on noninvasive techniques such as electroencephalography (EEG), magnetoencephalography or functional magnetic-resonance imaging. These techniques have either inherently low temporal or low spatial resolution, and suffer from low signal-to-noise ratio and/or poor high-frequency sensitivity. Thus, they are suboptimal for exploring the short-lived spatio-temporal dynamics of many of the underlying brain processes. In contrast, the invasive technique of electrocorticography (ECoG) provides brain signals that have an exceptionally high signal-to-noise ratio, less susceptibility to artifacts than EEG, and a high spatial and temporal resolution (i.e., &lt;1 cm/&lt;1 millisecond, respectively). ECoG involves measurement of electrical brain signals using electrodes that are implanted subdurally on the surface of the brain. Recent studies have shown that ECoG amplitudes in certain frequency bands carry substantial information about task-related activity, such as motor execution and planning1, auditory processing2 and visual-spatial attention3. Most of this information is captured in the high gamma range (around 70-110 Hz). Thus, gamma activity has been proposed as a robust and general indicator of local cortical function1-5. ECoG can also reveal functional connectivity and resolve finer task-related spatial-temporal dynamics, thereby advancing our understanding of large-scale cortical processes. It has especially proven useful for advancing brain-computer interfacing (BCI) technology for decoding a user's intentions to enhance or improve communication6 and control7. Nevertheless, human ECoG data are often hard to obtain because of the risks and limitations of the invasive procedures involved, and the need to record within the constraints of clinical settings. Still, clinical monitoring to localize epileptic foci offers a unique and valuable opportunity to collect human ECoG data. We describe our methods for collecting recording ECoG, and demonstrate how to use these signals for important real-time applications such as clinical mapping and brain-computer interfacing. Our example uses the BCI2000 software platform8,9 and the SIGFRIED10 method, an application for real-time mapping of brain functions. This procedure yields information that clinicians can subsequently use to guide the complex and laborious process of functional mapping by electrical stimulation.
Prerequisites and Planning:
Patients with drug-resistant partial epilepsy may be candidates for resective surgery of an epileptic focus to minimize the frequency of seizures. Prior to resection, the patients undergo monitoring using subdural electrodes for two purposes: first, to localize the epileptic focus, and second, to identify nearby critical brain areas (i.e., eloquent cortex) where resection could result in long-term functional deficits. To implant electrodes, a craniotomy is performed to open the skull. Then, electrode grids and/or strips are placed on the cortex, usually beneath the dura. A typical grid has a set of 8 x 8 platinum-iridium electrodes of 4 mm diameter (2.3 mm exposed surface) embedded in silicon with an inter-electrode distance of 1cm. A strip typically contains 4 or 6 such electrodes in a single line. The locations for these grids/strips are planned by a team of neurologists and neurosurgeons, and are based on previous EEG monitoring, on a structural MRI of the patient's brain, and on relevant factors of the patient's history. Continuous recording over a period of 5-12 days serves to localize epileptic foci, and electrical stimulation via the implanted electrodes allows clinicians to map eloquent cortex. At the end of the monitoring period, explantation of the electrodes and therapeutic resection are performed together in one procedure.
In addition to its primary clinical purpose, invasive monitoring also provides a unique opportunity to acquire human ECoG data for neuroscientific research. The decision to include a prospective patient in the research is based on the planned location of their electrodes, on the patient's performance scores on neuropsychological assessments, and on their informed consent, which is predicated on their understanding that participation in research is optional and is not related to their treatment. As with all research involving human subjects, the research protocol must be approved by the hospital's institutional review board. The decision to perform individual experimental tasks is made day-by-day, and is contingent on the patient's endurance and willingness to participate. Some or all of the experiments may be prevented by problems with the clinical state of the patient, such as post-operative facial swelling, temporary aphasia, frequent seizures, post-ictal fatigue and confusion, and more general pain or discomfort.
At the Epilepsy Monitoring Unit at Albany Medical Center in Albany, New York, clinical monitoring is implemented around the clock using a 192-channel Nihon-Kohden Neurofax monitoring system. Research recordings are made in collaboration with the Wadsworth Center of the New York State Department of Health in Albany. Signals from the ECoG electrodes are fed simultaneously to the research and the clinical systems via splitter connectors. To ensure that the clinical and research systems do not interfere with each other, the two systems typically use separate grounds. In fact, an epidural strip of electrodes is sometimes implanted to provide a ground for the clinical system. Whether research or clinical recording system, the grounding electrode is chosen to be distant from the predicted epileptic focus and from cortical areas of interest for the research. Our research system consists of eight synchronized 16-channel g.USBamp amplifier/digitizer units (g.tec, Graz, Austria). These were chosen because they are safety-rated and FDA-approved for invasive recordings, they have a very low noise-floor in the high-frequency range in which the signals of interest are found, and they come with an SDK that allows them to be integrated with custom-written research software. In order to capture the high-gamma signal accurately, we acquire signals at 1200Hz sampling rate-considerably higher than that of the typical EEG experiment or that of many clinical monitoring systems. A built-in low-pass filter automatically prevents aliasing of signals higher than the digitizer can capture. The patient's eye gaze is tracked using a monitor with a built-in Tobii T-60 eye-tracking system (Tobii Tech., Stockholm, Sweden). Additional accessories such as joystick, bluetooth Wiimote (Nintendo Co.), data-glove (5th Dimension Technologies), keyboard, microphone, headphones, or video camera are connected depending on the requirements of the particular experiment.
Data collection, stimulus presentation, synchronization with the different input/output accessories, and real-time analysis and visualization are accomplished using our BCI2000 software8,9. BCI2000 is a freely available general-purpose software system for real-time biosignal data acquisition, processing and feedback. It includes an array of pre-built modules that can be flexibly configured for many different purposes, and that can be extended by researchers' own code in C++, MATLAB or Python. BCI2000 consists of four modules that communicate with each other via a network-capable protocol: a Source module that handles the acquisition of brain signals from one of 19 different hardware systems from different manufacturers; a Signal Processing module that extracts relevant ECoG features and translates them into output signals; an Application module that delivers stimuli and feedback to the subject; and the Operator module that provides a graphical interface to the investigator.
A number of different experiments may be conducted with any given patient. The priority of experiments will be determined by the location of the particular patient's electrodes. However, we usually begin our experimentation using the SIGFRIED (SIGnal modeling For Realtime Identification and Event Detection) mapping method, which detects and displays significant task-related activity in real time. The resulting functional map allows us to further tailor subsequent experimental protocols and may also prove as a useful starting point for traditional mapping by electrocortical stimulation (ECS).
Although ECS mapping remains the gold standard for predicting the clinical outcome of resection, the process of ECS mapping is time consuming and also has other problems, such as after-discharges or seizures. Thus, a passive functional mapping technique may prove valuable in providing an initial estimate of the locus of eloquent cortex, which may then be confirmed and refined by ECS. The results from our passive SIGFRIED mapping technique have been shown to exhibit substantial concurrence with the results derived using ECS mapping10.
The protocol described in this paper establishes a general methodology for gathering human ECoG data, before proceeding to illustrate how experiments can be initiated using the BCI2000 software platform. Finally, as a specific example, we describe how to perform passive functional mapping using the BCI2000-based SIGFRIED system.

Recording Human Electrocorticographic ECoG Signals for Neuroscientific Research and Real-time Functional Cortical Mapping

We present a method for collecting electrocorticographic signals for research purposes from humans who are undergoing invasive epilepsy monitoring. We show how to use the BCI2000 software platform for data collection, signal processing and stimulus presentation. Specifically, we demonstrate SIGFRIED, a BCI2000-based tool for real-time functional brain mapping.

Gravação Humanos eletrocorticográfica (ECOG) Sinais para pesquisa neurocientífica e mapeamento em tempo real Funcional Cortical

Neuroimaging studies of human cognitive, sensory, and motor processes are usually based on noninvasive techniques such as electroencephalography (EEG), ...

Neurociência

Optical Recording of Suprathreshold Neural Activity with Single-cell and Single-spike Resolution

Signaling of information in the vertebrate central nervous system is often carried by populations of neurons rather than individual neurons. Also propagation of suprathreshold spiking activity involves populations of neurons. Empirical studies addressing cortical function directly thus require recordings from populations of neurons with high resolution. Here we describe an optical method and a deconvolution algorithm to record neural activity from up to 100 neurons with single-cell and single-spike resolution. This method relies on detection of the transient increases in intracellular somatic calcium concentration associated with suprathreshold electrical spikes (action potentials) in cortical neurons. High temporal resolution of the optical recordings is achieved by a fast random-access scanning technique using acousto-optical deflectors (AODs)1. Two-photon excitation of the calcium-sensitive dye results in high spatial resolution in opaque brain tissue2. Reconstruction of spikes from the fluorescence calcium recordings is achieved by a maximum-likelihood method. Simultaneous electrophysiological and optical recordings indicate that our method reliably detects spikes (&gt;97% spike detection efficiency), has a low rate of false positive spike detection (&lt; 0.003 spikes/sec), and a high temporal precision (about 3 msec) 3. This optical method of spike detection can be used to record neural activity in vitro and in anesthetized animals in vivo3,4.

Understanding the function of the vertebrate central nervous system requires recordings from many neurons because cortical function arises on the level of populations of neurons. Here we describe an optical method to record suprathreshold neural activity with single-cell and single-spike resolution, dithered random-access scanning. This method records somatic fluorescence calcium signals from up to 100 neurons with high temporal resolution. A maximum-likelihood algorithm deconvolves the underlying suprathreshold neural activity from the somatic fluorescence calcium signals. This method reliably detects spikes with high detection efficiency and a low rate of false positives and can be used to study neural populations in vitro and in vivo.

A gravação ótica da atividade neural supraliminares com resolução de uma única célula e um único pico

Signaling of information in the vertebrate central nervous system is often carried by populations of neurons rather than individual neurons. Also ...

Multi-unit Recording Methods to Characterize Neural Activity in the Locust (Schistocerca Americana) Olfactory Circuits

Detection and interpretation of olfactory cues are critical for the survival of many organisms. Remarkably, species across phyla have strikingly similar olfactory systems suggesting that the biological approach to chemical sensing has been optimized over evolutionary time1. In the insect olfactory system, odorants are transduced by olfactory receptor neurons (ORN) in the antenna, which convert chemical stimuli into trains of action potentials. Sensory input from the ORNs is then relayed to the antennal lobe (AL; a structure analogous to the vertebrate olfactory bulb). In the AL, neural representations for odors take the form of spatiotemporal firing patterns distributed across ensembles of principal neurons (PNs; also referred to as projection neurons)2,3. The AL output is subsequently processed by Kenyon cells (KCs) in the downstream mushroom body (MB), a structure associated with olfactory memory and learning4,5. Here, we present electrophysiological recording techniques to monitor odor-evoked neural responses in these olfactory circuits.
First, we present a single sensillum recording method to study odor-evoked responses at the level of populations of ORNs6,7. We discuss the use of saline filled sharpened glass pipettes as electrodes to extracellularly monitor ORN responses. Next, we present a method to extracellularly monitor PN responses using a commercial 16-channel electrode3. A similar approach using a custom-made 8-channel twisted wire tetrode is demonstrated for Kenyon cell recordings8. We provide details of our experimental setup and present representative recording traces for each of these techniques.

Multi-unit Recording Methods to Characterize Neural Activity in the Locust Schistocerca Americana Olfactory Circuits

We demonstrate variations of the extracellular multi-unit recording technique to characterize odor-evoked responses in the first three stages of the invertebrate olfactory pathway. These techniques can easily be adapted to examine ensemble activity in other neural systems as well.

Multi-unidade Métodos de gravação para caracterizar a atividade neural no Locust (<em&gt; Schistocerca Americana</em&gt;) Circuitos olfatórias

Detection and interpretation of olfactory cues are critical for the survival  of many organisms. Remarkably, species across phyla have strikingly similar ...

A Method for Systematic Electrochemical and Electrophysiological Evaluation of Neural Recording Electrodes

New materials and designs for neural implants are typically tested separately, with a demonstration of performance but without reference to other implant characteristics.&#160;This precludes a rational selection of a particular implant as optimal for a particular application and the development of new materials based on the most critical performance parameters.&#160;This article develops a protocol for in vitro and in vivo testing of neural recording electrodes.&#160;Recommended parameters for electrochemical and electrophysiological testing are documented with the key steps and potential issues discussed.&#160;This method eliminates or reduces the impact of many systematic errors present in simpler in vivo testing paradigms, especially variations in electrode/neuron distance and between animal models.&#160;The result is a strong correlation between the critical in vitro and in vivo responses, such as impedance and signal-to-noise ratio.&#160;This protocol can easily be adapted to test other electrode materials and designs.&#160;The in vitro techniques can be expanded to any other nondestructive method to determine further important performance indicators.&#160;The principles used for the surgical approach in the auditory pathway can also be modified to other neural regions or tissue.

Different electrode coatings affect neural recording performance through changes to electrochemical, chemical and mechanical properties. Comparison of electrodes in vitro is relatively simple, however comparison of in vivo response is typically complicated by variations in electrode/neuron distance and between animals. This article provides a robust method to compare neural recording electrodes.

Um Método para Sistemática de Eletroquímica e eletrofisiológica Avaliação do Neurais gravação Eletrodos

New materials and designs for neural implants are typically tested separately, with a demonstration of performance but without reference to other implant ...

Fabrication of High Contact-Density, Flat-Interface Nerve Electrodes for Recording and Stimulation Applications

Many attempts have been made to manufacture multi-contact nerve cuff electrodes that are safe, robust and reliable for long term neuroprosthetic applications. This protocol describes a fabrication technique of a modified cylindrical nerve cuff electrode to meet these criteria. Minimum computer-aided design and manufacturing (CAD and CAM) skills are necessary to consistently produce cuffs with high precision (contact placement 0.51 &#177; 0.04 mm) and various cuff sizes. The precision in spatially distributing the contacts and the ability to retain a predefined geometry accomplished with this design are two criteria essential to optimize the cuff&#39;s interface for selective recording and stimulation. The presented design also maximizes the flexibility in the longitudinal direction while maintaining sufficient rigidity in the transverse direction to reshape the nerve by using materials with different elasticities. The expansion of the cuff&#39;s cross sectional area as a result of increasing the pressure inside the cuff was observed to be 25% at 67 mm Hg. This test demonstrates the flexibility of the cuff and its response to nerve swelling post-implant. The stability of the contacts&#39; interface and recording quality were also examined with contacts&#39; impedance and signal-to-noise ratio metrics from a chronically implanted cuff (7.5 months), and observed to be 2.55 &#177; 0.25 k&#8486; and 5.10 &#177; 0.81 dB respectively.

This article provides a detailed description on the fabrication process of a high contact-density flat interface nerve electrode (FINE). This electrode is optimized for recording and stimulating neural activity selectively within peripheral nerves.

Fabricação de alta Contact densidade, eletrodos nervosas Plano de Interface para gravação e estimulação Applications

Many attempts have been made to manufacture multi-contact nerve cuff electrodes that are safe, robust and reliable for long term neuroprosthetic ...

Implantation of Chronic Silicon Probes and Recording of Hippocampal Place Cells in an Enriched Treadmill Apparatus

An important requisite for understanding brain function is the identification of behavior and cell activity correlates. Silicon probes are advanced electrodes for large-scale electrophysiological recording of neuronal activity, but the procedures for their chronic implantation are still underdeveloped. The activity of hippocampal place cells is known to correlate with an animal&#39;s position in the environment, but the underlying mechanisms are still unclear. To investigate place cells, here we describe a set of techniques which range from the fabrication of devices for chronic silicon probe implants to the monitoring of place field activity in a cue-enriched treadmill apparatus. A micro-drive and a hat are built by fitting and fastening together 3D-printed plastic parts. A silicon probe is mounted on the micro-drive, cleaned, and coated with dye. A first surgery is performed to fix the hat on the skull of a mouse. Small landmarks are fabricated and attached to the belt of a treadmill. The mouse is trained to run head-fixed on the treadmill. A second surgery is performed to implant the silicon probe in the hippocampus, following which broadband electrophysiological signals are recorded. Finally, the silicon probe is recovered and cleaned for reuse. The analysis of place cell activity in the treadmill reveals a diversity of place field mechanisms, outlining the benefit of the approach.

We describe the diverse steps to implant chronic silicon probes and to record place cells in mice that are running head-fixed on a cue-enriched treadmill apparatus.

Implantação de sondas de silicone crônica e gravação de lugar Hippocampal células em um aparelho de esteira enriquecido

An important requisite for understanding brain function is the identification of behavior and cell activity correlates. Silicon probes are advanced ...

Chronic Implantation of Whole-cortical Electrocorticographic Array in the Common Marmoset

Electrocorticography (ECoG) allows the monitoring of electrical field potentials from the cerebral cortex with high spatiotemporal resolution. Recent development of thin, flexible ECoG electrodes has enabled conduction of stable recordings of large-scale cortical activity. We have developed a whole-cortical ECoG array for the common marmoset. The array continuously covers almost the entire lateral surface of cortical hemisphere, from the occipital pole to the temporal and frontal poles, and it captures whole-cortical neural activity in one shot. This protocol describes a chronic implantation procedure of the array in the epidural space of the marmoset brain. Marmosets have two advantages regarding ECoG recordings, one being the homologous organization of anatomical structures in humans and macaques, including frontal, parietal, and temporal complexes. The other advantage is that the marmoset brain is lissencephalic and contains a large number of complexes, which are more difficult to access in macaques with ECoG, that are exposed to the brain surface.These features allow direct access to most cortical areas beneath the surface of the brain. This system provides an opportunity to investigate global cortical information processing with high resolutions at a sub-millisecond order in time and millimeter order in space.

We have developed a whole-cortical electrocorticographic array for the common marmoset that continuously covers almost the entire lateral surface of cortex, from the occipital pole to the temporal and frontal poles. This protocol describes a chronic implantation procedure of the array in the epidural space of the marmoset brain.

Crônica implantação de matriz Electrocorticographic todo-cortical no sagui comum

Electrocorticography (ECoG) allows the monitoring of electrical field potentials from the cerebral cortex with high spatiotemporal resolution. Recent ...

Wide-field Single-photon Optical Recording in Brain Slices Using Voltage-sensitive Dye

Wide-field single photon voltage-sensitive dye (VSD) imaging of brain slice preparations is a useful tool to assess the functional connectivity in neural circuits. Due to the fractional change in the light signal, it has been difficult to use this method as a quantitative assay. This article describes special optics and slice handling systems, which render this technique stable and reliable. The present article demonstrates the slice handling, staining, and recording of the VSD-stained hippocampal slices in detail. The system maintains physiological conditions for a long time, with good staining, and prevents mechanical movements of the slice during the recordings. Moreover, it enables staining of slices with a small amount of the dye. The optics achieve high numerical aperture at low magnification, which allows recording of the VSD signal at the maximum frame rate of 10 kHz, with 100 pixel x 100-pixel spatial resolution. Due to the high frame rate and spatial resolution, this technique allows application of the post-recording filters that provide sufficient signal-to-noise ratio to assess the changes in neural circuits.

We introduce a reproducible and stable optical recording method for brain slices using voltage-sensitive dye. The article describes voltage-sensitive dye staining and recording of optical signals using conventional hippocampal slice preparations.

Gravação ótica do único-fóton do largo-campo em fatias do cérebro usando a tintura tensão-sensível

Wide-field single photon voltage-sensitive dye (VSD) imaging of brain slice preparations is a useful tool to assess the functional connectivity in neural ...

Preparation of Peripheral Nerve Stimulation Electrodes for Chronic Implantation in Rats

Peripheral nerve cuff electrodes have long been used in the neurosciences and related fields for stimulation of, for example, vagus or sciatic nerves. Several recent studies have demonstrated the effectiveness of chronic VNS in enhancing central nervous system plasticity to improve motor rehabilitation, extinction learning, and sensory discrimination. Construction of chronically implantable devices for use in such studies is challenging due to rats&#8217; small size, and typical protocols require extensive training of personnel and time-consuming microfabrication methods. Alternatively, commercially available implantable cuff electrodes can be purchased at a significantly higher cost. In this protocol, we present a simple, low-cost method for construction of small, chronically implantable peripheral nerve cuff electrodes for use in rats. We validate the short and long-term reliability of our cuff electrodes by demonstrating that VNS in ketamine/xylazine anesthetized rats produces decreases in breathing rate consistent with activation of the Hering-Breuer reflex, both at the time of implantation and up to 10 weeks after device implantation. We further demonstrate the suitability of the cuff electrodes for use in chronic stimulation studies by pairing VNS with skilled lever press performance to induce motor cortical map plasticity.

Existing approaches for constructing chronically implantable peripheral nerve cuff electrodes for use in small rodents often require specialized equipment and/or highly trained personnel. In this protocol we demonstrate a simple, low-cost approach for fabricating chronically implantable cuff electrodes, and demonstrate their effectiveness for vagus nerve stimulation (VNS) in rats.

Preparação de Eletrodos de Estimulação Nervosa Periférica para Implantação Crônica em Ratos

Peripheral nerve cuff electrodes have long been used in the neurosciences and related fields for stimulation of, for example, vagus or sciatic nerves. ...

Gravação LFP no cérebro de camundongos para pesquisa cognitiva e análise de drogas

Dual Extracellular Recordings in the Mouse Hippocampus and Prefrontal Cortex

The technique of recording local field potentials (LFPs) is an electrophysiological method used to measure the electrical activity of localized neuronal populations. It serves as a crucial tool in cognitive research, particularly in brain regions like the hippocampus and prefrontal cortex. Dual LFP recordings between these areas are of particular interest as they allow the exploration of interregional signal communication. However, methods for performing these recordings are rarely described, and most commercial recording devices are either expensive or lack adaptability to accommodate specific experimental designs. This study presents a comprehensive protocol for performing dual-electrode LFP recordings in the mouse hippocampus and the prefrontal cortex to investigate the effects of antipsychotic drugs and potassium channel modulators on LFP properties in these areas. The technique enables the measurement of LFP properties, including power spectra within each brain region and coherence between the two. Additionally, a low-cost, custom-designed recording device has been developed for these experiments. In summary, this protocol provides a means to record signals with high signal-to-noise ratios in different brain regions, facilitating the investigation of interregional information communication within the brain.

Autor em destaque: Estudando os impactos das drogas nos sinais cerebrais usando o protocolo de gravação LFP duplo em camundongos

This protocol outlines the use of a custom-designed recording device and electrodes to record local field potentials and investigate information flow in the mouse hippocampus and prefrontal cortex.

Gravações extracelulares duplas no hipocampo de camundongos e córtex pré-frontal

The technique of recording local field potentials (LFPs) is an electrophysiological method used to measure the electrical activity of localized neuronal ...