Apoiada por KIST Grant (2E21510), o programa Cientista Nacional de Honra do Ministério da Educação e do Programa de Pesquisa para a Ciência Tecnologia Original cérebro através da Fundação Nacional de Pesquisa da Coréia financiado pelo Ministério da Educação, Ciência e Tecnologia (2010-0018944).

1. Sumário C57BL/6J - ratos 129S4/SvJae híbrido (12 ~ 15 semanas de idade) são anestesiados com cetamina (120 mg / kg ip) e xilazina (6 mg / kg, ip) cocktail. Beliscar a cauda ou dedo do pé precede a cirurgia para inspecionar a profundidade da anestesia. O mouse é fixada pelo aparelho estereotáxico (David Kopf Instruments, modelo 902, Califórnia, EUA). O couro cabeludo é incisada na linha média cerca de 25 mm para expor o crânio sob o tratamento de lidocaína para diminuição da dor. Quaisquer detritos sobre o crânio é varrido por dicas de solução salina, algodão embebido para melhorar a aderência do eletrodo para o crânio. Os pontos bregma e lambda são marcadas e definidas no mesmo plano horizontal. O conjunto de microeletrodos poliimida base (PBM-array) é posicionado de modo que a sua linha média vertical encontra a linha média do crânio. O ponto bregma deve estar localizado no meio da camada de 5 ª a anterior de PBM-array. Dois ou três microparafusos são usados ​​no espaço nulo na borda do crânio para ajudar a proteger a posição do eletrodo com cimento dental. Para sustentar o conector PBM-matriz, que a posição de uma strut no meio da cabeça, e cobri-lo com cimento dental. Após a cura, a pele é suturada incisão, e pelo menos cinco dias são dadas para a recuperação. Durante a recuperação, os ratos estão alojados em gaiolas individuais com livre acesso a comida e água. Após a recuperação, gravação de EEG é realizado. Procedimentos de cuidados com os animais, cirúrgicos e de gravação estavam de acordo com as diretrizes para a Animal Care Institucional e Comitê Use, seguindo lei de 1992 do Laboratório Coréia Regulamentos Animal Care e diretrizes associados. As matrizes PBM-neste manuscrito foram fabricados, como descrito por Choi. et. al. 1 Entre em contato com os autores a usar a mesma matriz de PBM no vídeo. 2. Procedimento <ol><li> Preparar os instrumentos e aparelhos cirúrgicos esterilizados estereotáxica. </li><li> Anestesiar o rato com anestesia (por exemplo, ketamina / xilazina com uma dose de 120 e 60 mg / kg ip, respectivamente). Beliscar a cauda ou dedo do pé precede a cirurgia para inspecionar a profundidade da anestesia. </li><li> Monte o mouse sobre o aparelho estereotáxico, colocando barras de ouvido no canal do rato orelha e apertando-o no lugar. Os olhos podem ser cobertos com geléia biocompatível (por exemplo, vaselina) para manter os olhos sequem a luz por cirurgia. Após hidratação a cabeça do rato com etanol 70%, raspar os pêlos fora de sua cabeça. </li><li> Inciso da cabeça cerca de 25 mm com um couro cabeludo. É recomendável aplicar uma pequena quantidade de cloridrato de lidocaína a 2% sob o couro cabeludo. Beliscar a pele com pinças micro (Ferramentas Ciência Fine (EUA), Inc., 18052-03, Califórnia, EUA) para manter a incisão aberta. </li><li> Limpe os restos de tecido remanescente no crânio com compressas de algodão embebido com solução salina melhorar a aderência do PBM-array para o crânio. Utilizando peróxido para remover o resíduo da membrana também é eficaz. </li><li> Encontre o bregma e lambda pontos no crânio, e marcá-los com uma caneta à base de óleo. Coloque o PBM-matriz de modo que sua linha média vertical encontra a linha média do crânio, como mostrado na Figura 1. Posição do bregma no meio da camada de 5 ª a anterior de PBM-array com uma gota de água da torneira. Swab eletrodo o filme do medial para lateral com cuidado para melhor aderência. A fim de ajudar o filme mais apertado vara eletrodo para o crânio, o eletrodo de filme deve estar completamente seca no crânio. O eletrodo de filme continua a ser fixado no crânio por força de van der Waals. Quando re-posicionamento do eletrodo, mais uma gota de água da torneira é necessário para evitar que o eletrodo de ser rasgado. <img src="/files/ftp_upload/2562/2562fig1.jpg" alt="Figura 1" /> Figura 1. (Esquerda) A PBM-array no crânio do rato. O eixo ântero-posterior do PBM-array corresponde a linha entre o bregma (BP) e pontos de lambda (LP). (Direito) O suposto posições de eletrodos na superfície do cérebro do rato. A anatomia do rato são segmentados da 3-D digital de banco de dados de ressonância magnética atlas de um cérebro adulto do rato C57BL/6J produzido em laboratório nacional Brookhaven e os locais de eletrodos são marcadas de acordo com a medição estereotáxica. Solo (G) e de referência (Ref) eletrodos estão marcados na figura à direita. </li><li> Marcar pelo menos três posições na área aberta do crânio, e depois fazer buracos nesses locais usando uma broca de dentista para o posicionamento dos microparafusos de apoio. Estes microparafusos têm um papel de balaústres e mecanicamente apoio do cimento dental no crânio. Cuidado extra é necessária durante a perfuração. Uma vez que o crânio do rato consiste em camadas finas, a hemorragia pode ocorrer facilmente durante a perfuração. Quando o sangramento acontece, pare de perfuração e aplicar pequena quantidade de pó hemostático no buraco. </li><li> Aplique o cimento acrílico dental (Vertex-Dental, Vertex auto-cura, Holanda) para cobrir o PBM-array, parafusos âncora, eo resto do crânio. Prepare o cimento odontológico em um c gluey e viscososondition. </li><li> Posição uma vara rígida como um suporte no meio da cabeça com cola forte (por exemplo, Loctite, Henkel Loctite Corp, Dublin, Irlanda). Coloque fita dupla face adesiva na parte traseira do avião conector. Manipular a posição do conector PBM-array para conectar-se com a ponta do suporte. A distância vertical entre o crânio eo conector deve ser superior a 5 mm. Ater ao plano conector ea ponta da vara com cola forte para melhor adesão. </li><li> Certifique-se que o cimento dental é completamente curado. Em seguida, aplique o cimento dental de acrílico, sobre o crânio e parte traseira do avião conector para proteger o conector para o crânio. </li><li> Remova os grampos micro. Sutura incisão da pele com fibra de costura esterilizada. Remova o mouse do aparelho. Você pode aplicar cimento acrílico dental extras para proteger o crânio exposto. Aplicar um (pomada fucidin, Dong Farmácia Wha, Coréia do Sul) antibiótico ao redor do cimento e da pele suturada. </li><li> Posicione o mouse em uma gaiola esterilizados até que recupera seu peso original (aproximadamente 5 a 7 dias). Recomenda-se não introduzir quaisquer companheiros de gaiola. </li><li> Após a recuperação, conecte o mouse por um circuito impresso leve conector da placa (PCB) para a caixa de entrada de um sistema amplificador multicanal EEG (Synamps 2, North Carolina, EUA), em sua própria gaiola. As linhas de conexão deverão ser tratados com cuidado para não se emaranhar. </li><li> Após uma hora de habituação, executar a gravação de EEG. Scan 4.4. (Carolina do Norte, EUA), software de aquisição foi utilizado neste experimento. Um conjunto traço típico tempo de rato EEG é mostrado na Figura 2. Recomenda-se a log o vídeo para relacionar o comportamento do mouse. </li><li> Sinal obtido pode ser analisado pelo MATLAB (MathWorks, Natick, MA, EUA) para produzir o mapa topográfico do cérebro. Topografias amostra de mapa de energia EEG do cérebro do rato são mostrados na Figura 3. </li></ol> 3. Resultados representante Se acima procedimentos cirúrgicos são realizados corretamente, 40 canais de gravação do mouse EEG será realizada com sucesso sem canais ruim. Figuras a seguir mostram o representante primas traços EEG e mapas topográficos. <img src="/files/ftp_upload/2562/2562fig2.jpg" alt="Figura 2" /> Figura 2. Um traço amostra de crise de ausência EEG experimentando induzida pela injeção γ-butirolactona (GBL, 50mg/kg, ip). Red barra indica espícula-onda e descargas (SWDS) durante a crise de ausência. Os eixos horizontais e verticais indicam tempo e tensão, respectivamente. O número segue a montagem de canais definidos na figura. 1 (direita). <img src="/files/ftp_upload/2562/2562fig3.jpg" alt="Figura 3" /> Figura 3. Os mapas topográficos indicam a distribuição de energia 06/02 Hz. O valor no colorbar representa a escala de cores do mapa de energia. Durante espícula-onda e descargas (SWDS) induzida por γ-butirolactona (GBL, 50mg/kg, ip), o poder nas regiões cortical frontoparietal grandes aumentar significativamente em comparação com a alimentação antes de GBL injeção (Baseline).

<ol>
	<li>Choi, J. H., Koch, K. P., Poppendieck, W., Lee, M., Shin, H. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=High+resolution+Electroencephalography+in+Freely+Moving+Mice.">High resolution Electroencephalography in Freely Moving Mice.</a> J Neurophysiol. , .</li><li>Lee, M., Shin, H. S., Choi, J. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Simultaneous+recording+of+brain+activity+and+functional+connectivity+in+the+mouse+brain.">Simultaneous recording of brain activity and functional connectivity in the mouse brain.</a> Conf Proc IEEE Eng Med Biol Soc. , 2934-2936 (2009).</li></ol>

Não há conflitos de interesse declarados.

Aqui relatamos os procedimentos cirúrgicos e de gravação para a aquisição de alta densidade EEG em ratos movimentando-se livremente. Este método permite-nos obter mapas funcional do cérebro a partir do modelo do rato para estudar os mecanismos moleculares de 1,2 rítmica espontânea ou atividades do evento relacionado cérebro. Aquisição de todos os canais no PBM-matriz é uma condição necessária para obter o mapeamento do cérebro inteiro, porém, fazer um contato seguro para cada canal é muito desafiador. Para manter contato constante do canal para o crânio, os seguintes procedimentos são encontrados para ser importante. Primeiro de tudo, todos os restos de tecido no crânio pode separar o eletrodo do crânio. Por isso, é muito importante para remover todos os restos de tecido com cotonetes esterilizados e secar a superfície do crânio. Em segundo lugar, a capacidade de PBM-array que pode aderir à superfície do crânio é van der Waals força. Sugere-se aplicar uma gota de água da torneira no crânio para construir uma camada de água antes de aplicar PBM-array para o crânio. Em terceiro lugar, a viscosidade direito de cimento dental é muito importante. Se ele for muito corrimento, pode construir uma camada isolante sob o PBM-array. Se for muito densa, o cimento dental vai cair facilmente separados do crânio devido ao seu próprio peso. Por fim, pelo menos três microparafusos de apoio devem ser implantados no crânio para fazer o cimento dental fortemente ligada ao crânio. Os microparafusos apoio segurar o cimento dental e seguro o headstage, que é essencial para o estudo de longo prazo. A aplicação de PBM-array será limitado para o estudo crônico com ratos adultos, devido ao seu tamanho e peso. Baseado em nossa experiência, os camundongos mais pesado do que 25 g são adequados para uso. Como outras aplicações, através do espaço nulo entre os ramos em nosso PBM-array, pode-se introduzir eletrodos secundário para a gravação ou a finalidade de estimulação.

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high-density eeg recordings of the freely moving mice using polyimide-based microelectrode

Eletroencefalograma (EEG) indica a média de atividade elétrica das populações neuronal em um nível de grande escala. É amplamente utilizado como uma ferramenta não-invasivo de monitorização cerebral em neurociência cognitiva, bem como uma ferramenta de diagnóstico para a epilepsia e distúrbios do sono em neurologia. No entanto, o mecanismo subjacente de geração de ritmo EEG ainda está sob o véu. Introduziu recentemente microeletrodo poliimida-based (PBM-array) para mouse de alta resolução EEG 1 é um dos ensaios para responder às questões neurofisiológicas em sinais EEG com base em um rico recurso genético que contém o modelo do rato para a análise do processo de geração de complexos EEG. Esta aplicação de nanofabricated PBM-array ao crânio do mouse é uma ferramenta eficiente para a coleta em larga escala a atividade cerebral de camundongos transgênicos e acomoda a identificar os correlatos neurais a certos ritmos EEG em conjunto com o comportamento. No entanto a sua espessura ultra-fina e estrutura bifurcada causar problemas no manuseio e implantação de PBM-array. No vídeo apresentado, as etapas de preparação e cirurgia para a implantação de PBM-array em um crânio do rato são descritas passo a passo. Manuseio e cirurgia dicas para ajudar os pesquisadores a ter sucesso na implantação também são fornecidos.

Watch this Scientific Journal Video about High-density EEG Recordings of the Freely Moving Mice using Polyimide-based Microelectrode at JoVE.com

High-density EEG Recordings of the Freely Moving Mice using Polyimide-based Microelectrode

Neste artigo, descrevemos o procedimento de cirurgia e tratamento de dicas para implantação de ultra-fina matriz de microeletrodos poliimida-based (PBM-array) no crânio do rato para a aquisição de alta densidade encefalografia (EEG) em um modelo de mouse.

Gravações de alta densidade EEG dos Ratos movimentando-se livremente usando Polyimide baseado microeletrodos

Electroencephalogram (EEG) indicates the averaged electrical activity of the neuronal populations on a large-scale level. It is widely utilized as a ...

high-density-eeg-recordings-freely-moving-mice-using-polyimide-based

Research

JoVE Journal

Neuroscience

36.9K visualizações.  Korea Institute of Science and Technology (KIST). Neste artigo, descrevemos o procedimento de cirurgia e tratamento de dicas para implantação de ultra-fina matriz de microeletrodos poliimida-based (PBM-array) no crânio do rato para a aquisição de alta densidade encefalografia (EEG) em um modelo de mouse.

Vídeo: High-density EEG Recordings of the Freely Moving Mice using Polyimide-based Microelectrode

Combining Computer Game-Based Behavioural Experiments With High-Density EEG and Infrared Gaze Tracking

Experimental paradigms are valuable insofar as the timing and other parameters of their stimuli are well specified and controlled, and insofar as they yield data relevant to the cognitive processing that occurs under ecologically valid conditions. These two goals often are at odds, since well controlled stimuli often are too repetitive to sustain subjects' motivation. Studies employing electroencephalography (EEG) are often especially sensitive to this dilemma between ecological validity and experimental control: attaining sufficient signal-to-noise in physiological averages demands large numbers of repeated trials within lengthy recording sessions, limiting the subject pool to individuals with the ability and patience to perform a set task over and over again. This constraint severely limits researchers' ability to investigate younger populations as well as clinical populations associated with heightened anxiety or attentional abnormalities. Even adult, non-clinical subjects may not be able to achieve their typical levels of performance or cognitive engagement: an unmotivated subject for whom an experimental task is little more than a chore is not the same, behaviourally, cognitively, or neurally, as a subject who is intrinsically motivated and engaged with the task. A growing body of literature demonstrates that embedding experiments within video games may provide a way between the horns of this dilemma between experimental control and ecological validity. The narrative of a game provides a more realistic context in which tasks occur, enhancing their ecological validity (Chaytor &amp; Schmitter-Edgecombe, 2003). Moreover, this context provides motivation to complete tasks. In our game, subjects perform various missions to collect resources, fend off pirates, intercept communications or facilitate diplomatic relations. In so doing, they also perform an array of cognitive tasks, including a Posner attention-shifting paradigm (Posner, 1980), a go/no-go test of motor inhibition, a psychophysical motion coherence threshold task, the Embedded Figures Test (Witkin, 1950, 1954) and a theory-of-mind (Wimmer &amp; Perner, 1983) task. The game software automatically registers game stimuli and subjects' actions and responses in a log file, and sends event codes to synchronise with physiological data recorders. Thus the game can be combined with physiological measures such as EEG or fMRI, and with moment-to-moment tracking of gaze. Gaze tracking can verify subjects' compliance with behavioural tasks (e.g. fixation) and overt attention to experimental stimuli, and also physiological arousal as reflected in pupil dilation (Bradley et al., 2008). At great enough sampling frequencies, gaze tracking may also help assess covert attention as reflected in microsaccades - eye movements that are too small to foveate a new object, but are as rapid in onset and have the same relationship between angular distance and peak velocity as do saccades that traverse greater distances. The distribution of directions of microsaccades correlates with the (otherwise) covert direction of attention (Hafed &amp; Clark, 2002).

Procedures for recording high-density EEG and gaze data during computer game-based cognitive tasks are described. Using a video game to present cognitive tasks enhances ecological validity without sacrificing experimental control.

Jogo computador baseado combinando experimentos comportamentais com alta densidade de rastreamento Gaze EEG e Infravermelho

Experimental paradigms are valuable insofar as the timing and other parameters of their stimuli are well specified and controlled, and insofar as they ...

Neurociência

Recording Single Neurons' Action Potentials from Freely Moving Pigeons Across Three Stages of Learning

While the subject of learning has attracted immense interest from both behavioral and neural scientists, only relatively few investigators have observed single-neuron activity while animals are acquiring an operantly conditioned response, or when that response is extinguished. But even in these cases, observation periods usually encompass only a single stage of learning, i.e. acquisition or extinction, but not both (exceptions include protocols employing reversal learning; see Bingman&#160;et al.1 for an example). However, acquisition and extinction entail different learning mechanisms and are therefore expected to be accompanied by different types and/or loci of neural plasticity.
Accordingly, we developed a behavioral paradigm which institutes three stages of learning in a single behavioral session and which is well suited for the simultaneous recording of single neurons&#39; action potentials. Animals are trained on a single-interval forced choice task which requires mapping each of two possible choice responses to the presentation of different novel visual stimuli (acquisition). After having reached a predefined performance criterion, one of the two choice responses is no longer reinforced (extinction). Following a certain decrement in performance level, correct responses are reinforced again (reacquisition). By using a new set of stimuli in every session, animals can undergo the acquisition-extinction-reacquisition process repeatedly. Because all three stages of learning occur in a single behavioral session, the paradigm is ideal for the simultaneous observation of the spiking output of multiple single neurons. We use pigeons as model systems, but the task can easily be adapted to any other species capable of conditioned discrimination learning.

Learning new stimulus-response associations engages a wide range of neural processes which are ultimately reflected in changing spike output of individual neurons. Here we describe a behavioral protocol allowing for the continuous registration of single-neuron activity while animals acquire, extinguish, and reacquire a conditioned response within a single experimental session.

Registro do potencial de ação simples Neurônios &#39;de livremente mover Pombos em três estágios da aprendizagem

While the subject of learning has attracted immense interest from both behavioral and neural scientists, only relatively few investigators have observed ...

Recording EEG in Freely Moving Neonatal Rats Using a Novel Method

EEG is a useful method to detect electrical activity in the brain. Moreover, it is a widely used diagnostic tool for various neurological conditions, such as epilepsy and neurodegenerative disorders. However, it is technically difficult to obtain EEG recordings in neonates as it requires specialized handling and great care. Here, we present a novel method to record EEG in neonatal rat pups (P8-P15). We designed a simple and reliable electrode using computer pin loci; it can be easily implanted into the skull of a rat pup to record high-quality EEG signals in the normal and epileptic brain. Pups were given an intraperitoneal (i.p.) injection of the neurotoxin kainic acid (KA) to induce epileptic seizures. The surgical implantation performed in this procedure is less expensive than other EEG procedures for neonates. This method allows one to record high-quality and stable EEG signals for more than 1 week. Furthermore, this procedure can also be applied to adult rats and mice to study epilepsy or other neurological disorders.

Here, we introduce a novel technique designed to record electroencephalography (EEG) in freely moving neonatal epileptic pups and describe its procedures, features, and applications. This method allows one to record EEG for more than 1 week.

Gravação de EEG em Ratos Neonatais de Movimentação Livre Usando um Novo Método

EEG is a useful method to detect electrical activity in the brain. Moreover, it is a widely used diagnostic tool for various neurological conditions, such ...

Visual Evoked Potential Recordings in Mice Using a Dry Non-invasive Multi-channel Scalp EEG Sensor

For scalp EEG research environments with laboratory mice, we designed a dry-type 16 channel EEG sensor which is non-invasive, deformable, and re-usable because of the plunger-spring-barrel structural facet and mechanical strengths resulting from metal materials. The whole process for acquiring the VEP responses in vivo from a mouse consists of four steps: (1) sensor assembly, (2) animal preparation, (3) VEP measurement, and (4) signal processing. This paper presents representative measurements of VEP responses from multiple mice with a submicro-voltage signal resolution and sub-hundred millisecond temporal resolution. Although the proposed method is safer and more convenient compared to other previously reported animal EEG acquiring methods, there are remaining issues including how to enhance the signal-to-noise ratio and how to apply this technique with freely moving animals. The proposed method utilizes easily available resources and shows a repetitive VEP response with a satisfactory signal quality. Therefore, this method could be utilized for longitudinal experimental studies and reliable translational research exploiting non-invasive paradigms.

We designed a dry-type 16 channel EEG sensor which is non-invasive, deformable, and re-usable. This paper describes the whole process from manufacturing the proposed EEG electrode to signal processing of visual evoked potential (VEP) signals measured on a mouse scalp using a dry non-invasive multi-channel EEG sensor.

Gravações de potenciais evocadas visuais em ratos usando um não-invasivo seco multi-canal do couro cabeludo Sensor de EEG

For scalp EEG research environments with laboratory mice, we designed a dry-type 16 channel EEG sensor which is non-invasive, deformable, and re-usable ...

Simultaneous Recordings of Cortical Local Field Potentials, Electrocardiogram, Electromyogram, and Breathing Rhythm from a Freely Moving Rat

Monitoring the physiological dynamics of the brain and peripheral tissues is necessary for addressing a number of questions about how the brain controls body functions and internal organ rhythms when animals are exposed to emotional challenges and changes in their living environments. In general experiments, signals from different organs, such as the brain and the heart, are recorded by independent recording systems that require multiple recording devices and different procedures for processing the data files. This study describes a new method that can simultaneously monitor electrical biosignals, including tens of local field potentials in multiple brain regions, electrocardiograms that represent the cardiac rhythm, electromyograms that represent awake/sleep-related muscle contraction, and breathing signals, in a freely moving rat. The recording configuration of this method is based on a conventional micro-drive array for cortical local field potential recordings in which tens of electrodes are accommodated, and the signals obtained from these electrodes are integrated into a single electrical board mounted on the animal's head. Here, this recording system was improved so that signals from the peripheral organs are also transferred to an electrical interface board. In a single surgery, electrodes are first separately implanted into the appropriate body parts and the target brain areas. The open ends of all of these electrodes are then soldered to individual channels of the electrical board above the animal's head so that all of the signals can be integrated into the single electrical board. Connecting this board to a recording device allows for the collection of all of the signals into a single device, which reduces experimental costs and simplifies data processing, because all data can be handled in the same data file. This technique will aid the understanding of the neurophysiological correlates of the associations between central and peripheral organs.

This study introduces a method for the simultaneous recording of local field potentials in the brain, electrocardiograms, electromyograms, and breathing signals of a freely moving rat. This technique, which reduces experimental costs and simplifies data analysis, will contribute to the understanding of the interactions between the brain and peripheral organs.

Gravações simultâneas de potenciais de campo corticais Local, eletrocardiograma, eletromiograma e respirar o ritmo de um rato andando livremente

Monitoring the physiological dynamics of the brain and peripheral tissues is necessary for addressing a number of questions about how the brain controls ...

Noninvasive EEG Recordings from Freely Moving Piglets

The method allows the recording of high-quality electroencephalograms (EEGs) from freely moving piglets directly in the pigpen. We use a one-channel telemetric electroencephalography system in combination with standard self-adhesive hydrogel electrodes. The piglets are calmed down without the use of sedatives. After their release into the pigpen, the piglets behave normally&#8212;they drink and sleep in the same cycle as their siblings. Their sleep phases are used for the EEG recordings.

Here, we present a protocol to record telemetric electroencephalograms (EEGs) from freely moving piglets directly in the pigpen without the use of a sedative, making it possible to record typical EEG patterns during non-REM sleep, like spindle bursts.

Gravações de EEG não invasiva de leitões movimentando-se livremente

The method allows the recording of high-quality electroencephalograms (EEGs) from freely moving piglets directly in the pigpen. We use a one-channel ...

Microdialysis of Excitatory Amino Acids During EEG Recordings in Freely Moving Rats

Microdialysis is a well-established neuroscience technique that correlates the changes of neurologically active substances diffusing into the brain interstitial space with the behavior and/or with the specific outcome of a pathology (e.g., seizures for epilepsy). When studying epilepsy, the microdialysis technique is often combined with short-term or even long-term video-electroencephalography (EEG) monitoring to assess spontaneous seizure frequency, severity, progression and clustering. The combined microdialysis-EEG is based on the use of several methods and instruments. Here, we performed in vivo microdialysis and continuous video-EEG recording to monitor glutamate and aspartate outflow over time, in different phases of the natural history of epilepsy in a rat model. This combined approach allows the pairing of changes in the neurotransmitter release with specific stages of the disease development and progression. The amino acid concentration in the dialysate was determined by liquid chromatography. Here, we describe the methods and outline the principal precautionary measures one should take during in vivo microdialysis-EEG, with particular attention to the stereotaxic surgery, basal and high potassium stimulation during microdialysis, depth electrode EEG recording and high-performance liquid chromatography analysis of aspartate and glutamate in the dialysate. This approach may be adapted to test a variety of drug or disease induced changes of the physiological concentrations of aspartate and glutamate in the brain. Depending on the availability of an appropriate analytical assay, it may be further used to test different soluble molecules when employing EEG recording at the same time.

Here, we describe a method for in vivo microdialysis to analyze aspartate and glutamate release in the ventral hippocampus of epileptic and non-epileptic rats, in combination with EEG recordings. Extracellular concentrations of aspartate and glutamate may be correlated with the different phases of the disease.

Microdialysis de aminoácidos excitatórios durante as gravações de EEG em ratos movimentando-se livremente

Microdialysis is a well-established neuroscience technique that correlates the changes of neurologically active substances diffusing into the brain ...

Long-term Sensory Conflict in Freely Behaving Mice

Long-term sensory conflict protocols are a valuable means of studying motor learning. The presented protocol produces a persistent sensory conflict for experiments aimed at studying long-term learning in mice. By permanently wearing a device fixed on their heads, mice are continuously exposed to a sensory mismatch between visual and vestibular inputs while freely moving in home cages. Therefore, this protocol readily enables the study of the visual system and multisensory interactions over an extended timeframe that would not be accessible otherwise. In addition to lowering the experimental costs of long-term sensory learning in naturally behaving mice, this approach accommodates the combination of in vivo and in vitro experiments. In the reported example, video-oculography is performed to quantify the vestibulo-ocular reflex (VOR) and optokinetic reflex (OKR) before and after learning. Mice exposed to this long-term sensory conflict between visual and vestibular inputs presented a strong VOR gain decrease but exhibited few OKR changes. Detailed steps of device assembly, animal care, and reflex measurements are hereby reported.

The presented protocol produces a persistent sensory conflict for experiments aimed at studying long-term learning. By permanently wearing a fixed device on their heads, mice are continuously exposed to a sensory mismatch between visual and vestibular inputs while freely moving in home cages.

A longo prazo conflito sensorial em livremente, comportando-se ratos

Long-term sensory conflict protocols are a valuable means of studying motor learning. The presented protocol produces a persistent sensory conflict for ...

Hybrid Microdrive System with Recoverable Opto-Silicon Probe and Tetrode for Dual-Site High Density Recording in Freely Moving Mice

Multi-regional neural recordings can provide crucial information to understanding fine-timescale interactions between multiple brain regions. However, conventional microdrive designs often only allow use of one type of electrode to record from single or multiple regions, limiting the yield of single-unit or depth profile recordings. It also often limits the ability to combine electrode recordings with optogenetic tools to target pathway and/or cell type specific activity. Presented here is a hybrid microdrive array for freely moving mice to optimize yield and a description of its fabrication and reuse of the microdrive array. The current design employs nine tetrodes and one opto-silicon probe implanted in two different brain areas simultaneously in freely moving mice. The tetrodes and the opto-silicon probe are independently adjustable along the dorsoventral axis in the brain to maximize the yield of unit and oscillatory activities. This microdrive array also incorporates a set-up for light, mediating optogenetic manipulation to investigate the regional- or cell type-specific responses and functions of long-range neural circuits. In addition, the opto-silicon probe can be safely recovered and reused after each experiment. Because the microdrive array consists of 3D-printed parts, the design of microdrives can be easily modified to accommodate various settings. First described is the design of the microdrive array and how to attach the optical fiber to a silicon probe for optogenetics experiments, followed by fabrication of the tetrode bundle and implantation of the array into a mouse brain. The recording of local field potentials and unit spiking combined with optogenetic stimulation also demonstrate feasibility of the microdrive array system in freely moving mice.

This protocol describes the construction of a hybrid microdrive array that allows implantation of nine independently adjustable tetrodes and one adjustable opto-silicon probe in two brain regions in freely moving mice. Also demonstrated is a method for safely recovering and reusing the opto-silicon probe for multiple purposes.

Sistema híbrido do Microdrive com a ponta de prova recuperável do opto-silicone e tetrode para a gravação high-density do duplo-local em ratos livremente moventes

Multi-regional neural recordings can provide crucial information to understanding fine-timescale interactions between multiple brain regions. However, ...

Multi-Fiber Photometry to Record Neural Activity in Freely-Moving Animals

Recording the activity of a group of neurons in a freely-moving animal is a challenging undertaking. Moreover, as the brain is dissected into smaller and smaller functional subgroups, it becomes paramount to record from projections and/or genetically-defined subpopulations of neurons. Fiber photometry is an accessible and powerful approach that can overcome these challenges. By combining optical and genetic methodologies, neural activity can be measured in deep brain structures by expressing genetically-encoded calcium indicators, which translate neural activity into an optical signal that can be easily measured. The current protocol details the components of a multi-fiber photometry system, how to access deep brain structures to deliver and collect light, a method to account for motion artifacts, and how to process and analyze fluorescent signals. The protocol details experimental considerations when performing single and dual color imaging, from either single or multiple implanted optic fibers.

This protocol details how to implement and perform multi-fiber photometry recordings, how to correct for calcium-independent artifacts, and important considerations for dual-color photometry imaging.

Fotometria de múltiplas fibras para gravar atividade neural em animais em movimento livre

Recording the activity of a group of neurons in a freely-moving animal is a challenging undertaking. Moreover, as the brain is dissected into smaller and ...