Name: recording eeg in freely moving neonatal rats using a novel method
Uploaded: 2017-05-29T12:30:00
Description: Watch this Scientific Journal Video about Recording EEG in Freely Moving Neonatal Rats Using a Novel Method at JoVE.com

This work was supported by the Natural Science Foundation of China (31171355) and the Natural Science Foundation of Guangdong (S2011010003403, 2014A030313440).

Animal care, surgical procedure, and recording procedures were in accordance with the guidelines for the South China Normal University Animal Care and Use Committee.
1. Electrode Preparation (Figure 1A-C)
NOTE: Computer pin loci is simply a pronged contact as a part of signal interface in communication devices. It consists of a male connector that plugs into the female connector.
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	<li>Carefully separate the male and female pins from the computer pin loci (<st...

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	<li>Pereda, A. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electrical+synapses+and+their+functional+interactions+with+chemical+synapses.">Electrical synapses and their functional interactions with chemical synapses.</a> Nat Rev Neurosci. 15 (4), 250-263 (2014).</li><li>Chorev, E., Epsztein, J., Houweling, A. R., Lee, A. K., Brecht, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electrophysiological+recordings+from+behaving+animals--going+beyond+spikes.">Electrophysiological recordings from behaving animals--going beyond spikes.</a> Curr Opin Neurobiol. 19 (5), 513-519 (2009).</li><li>Freeborn, D. L., McDaniel, K. L., Moser, V. C., Herr, D. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Use+of+electroencephalography+(EEG)+to+assess+CNS+changes+produced+by+pesticides+with+different+modes+of+action:+effects+of+permethrin,+deltamethrin,+fipronil,+imidacloprid,+carbaryl,+and+triadimefon.">Use of electroencephalography (EEG) to assess CNS changes produced by pesticides with different modes of action: effects of permethrin, deltamethrin, fipronil, imidacloprid, carbaryl, and triadimefon.</a> Toxicol Appl Pharmacol. 282 (2), 184-194 (2015).</li><li>Werhahn, K. J., Hartl, E., Hamann, K., Breimhorst, M., Noachtar, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Latency+of+interictal+epileptiform+discharges+in+long-term+EEG+recordings+in+epilepsy+patients.">Latency of interictal epileptiform discharges in long-term EEG recordings in epilepsy patients.</a> Seizure. 29, 20-25 (2015).</li><li>Staba, R. J., Stead, M., Worrell, 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=Electrophysiological+biomarkers+of+epilepsy.">Electrophysiological biomarkers of epilepsy.</a> Neurotherapeutics. 11 (2), 334-346 (2014).</li><li>Nimmrich, V., Draguhn, A., Axmacher, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neuronal+Network+Oscillations+in+Neurodegenerative+Diseases.">Neuronal Network Oscillations in Neurodegenerative Diseases.</a> Neuromolecular Med. 17 (3), 270-284 (2015).</li><li>Zayachkivsky, A., Lehmkuhle, M. J., Dudek, F. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Long-term+Continuous+EEG+Monitoring+in+Small+Rodent+Models+of+Human+Disease+Using+the+Epoch+Wireless+Transmitter+System.">Long-term Continuous EEG Monitoring in Small Rodent Models of Human Disease Using the Epoch Wireless Transmitter System.</a> J Vis Exp. (101), e52554 (2015).</li><li>Zayachkivsky, A., Lehmkuhle, M. J., Fisher, J. H., Ekstrand, J. J., Dudek, F. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Recording+EEG+in+immature+rats+with+a+novel+miniature+telemetry+system.">Recording EEG in immature rats with a novel miniature telemetry system.</a> J Neurophysiol. 109 (3), 900-911 (2013).</li><li>Dzhala, V. I., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=NKCC1+transporter+facilitates+seizures+in+the+developing+brain.">NKCC1 transporter facilitates seizures in the developing brain.</a> Nat Med. 11 (11), 1205-1213 (2005).</li><li>Tucker, A. M., Aquilina, K., Chakkarapani, E., Hobbs, C. E., Thoresen, M. <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+amplitude-integrated+electroencephalography+and+interburst+interval+in+the+rat.">Development of amplitude-integrated electroencephalography and interburst interval in the rat.</a> Pediatr Res. 65 (1), 62-66 (2009).</li><li>Savard, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Involvement+of+neuronal+IL-1beta+in+acquired+brain+lesions+in+a+rat+model+of+neonatal+encephalopathy.">Involvement of neuronal IL-1beta in acquired brain lesions in a rat model of neonatal encephalopathy.</a> J Neuroinflammation. 10, 110 (2013).</li><li>Cuaycong, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+novel+approach+to+the+study+of+hypoxia-ischemia-induced+clinical+and+subclinical+seizures+in+the+neonatal+rat.">A novel approach to the study of hypoxia-ischemia-induced clinical and subclinical seizures in the neonatal rat.</a> Dev Neurosci. 33 (3-4), 241-250 (2011).</li></ol>

Here, we report surgical and recording procedures to acquire EEG in freely moving neonatal rat pups by wired method (Figure 3). It has been suggested that the P7-P12 rat pup is at the developmental age that corresponds to a full-term human neonate 10,11. It is technically difficult to obtain high-quality EEG recording data when working with rat pups in this age group. In addition, it requires specialized handling and great care ...

It is well established that continuous communication between neurons is required to obtain normal brain function. The interneuronal communication primarily takes place at synapses, where information from one neuron is conveyed to a second neuron. This synaptic transmission is mediated by two types of dedicated structural arrangements: electrical or chemical synapses 1. Electrophysiology is the field that captures the electrical potential produced during interneuronal communication that control overall body functions and behavior 2. EEG is the most commonly used method among many electrophysiological techniques.
EEG is a technique used to detect changes in electrical signals produced by internal or external stimuli. Moreover, it is an essential test for clinical diagnosis and outcome prediction of various neurological conditions such as epilepsy, Parkinson&#39;s and Alzheimer&#39;s disease, as well as effects of pharmacological and toxicological agents 3. Generally, an epileptic patient shows hyperexcitability and impaired functional connectivity within the brain; these are summarized as interictal epileptiform discharges (IEDs) and can be recorded by EEG in the form of sharp, transient spikes; sharp waves; spike-wave complexes; or polyspikes 4. The main feature of the epileptic brain is the spontaneous occurrence of epileptic seizures, which can be recorded either from the scalp or from the brain parenchyma in order to locate the brain area responsible for the seizures 5. Furthermore, EEG also has very important implications in neurodegenerative disorders like Alzheimer&#39;s disease (AD). Research suggests that altered EEG recordings and impaired oscillatory networks in AD patients are common. However, our knowledge about the pathophysiology of network oscillations in neurodegenerative diseases is surprisingly incomplete and needs to be further explored 6.
In this protocol, we have designed a simple electrode with which one can record EEG to understand the electrical communication in both the normal and the pathological brain. The surgical implantation in this method is cheaper than other available procedures 7. Moreover, this method can be used to record high-quality and stable EEG signals for longer timeframes (i.e., 2-4 h every day for 1 week). In addition, we used lighter electrodes (weighing approximately 26 mg) that enable the animals to behave more naturally 8. This method is widely applicable to the study of EEG in neonatal rat pups that requires the amplifier and digitizer, commonly used in electrophysiology lab and does not require any additional devices.

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			<td>Computer pin</td>
			<td></td>
			<td></td>
			<td></td>
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		<tr>
			<td>Pincer</td>
			<td>DELI Group Co., Ltd.</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>502 super glue</td>
			<td>DELI Group Co., Ltd.</td>
			<td>7144</td>
			<td></td>
		</tr>
		<tr>
			<td>Drying oven</td>
			<td>Boxun</td>
			<td>GZX-9140MBE</td>
			<td></td>
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		<tr>
			<td>Isofluorane</td>
			<td>RWD Life Science</td>
			<td>902-0000-522</td>
			<td></td>
		</tr>
		<tr>
			<td>Stereotaxic apparatus</td>
			<td>RWD Life Science</td>
			<td>900-0068-507</td>
			<td></td>
		</tr>
		<tr>
			<td>Anesthesia apparatus</td>
			<td>RWD Life Science</td>
			<td>902-0000-510</td>
			<td></td>
		</tr>
		<tr>
			<td>Homeothermic Heating Device</td>
			<td>Harvard Apparatus</td>
			<td>K 024509</td>
			<td></td>
		</tr>
		<tr>
			<td>Amplifier Model 3000&#160;</td>
			<td>A-M Systems</td>
			<td>61558</td>
			<td></td>
		</tr>
		<tr>
			<td>Micro1401 Analog Digital converter</td>
			<td>Cambridge Electronic Design Ltd.</td>
			<td>4383</td>
			<td>Data acquisition unit</td>
		</tr>
		<tr>
			<td>Spike2</td>
			<td>Cambridge Electronic Design Ltd.</td>
			<td></td>
			<td></td>
		</tr>
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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.

If the above surgical procedures are conducted properly, one channel rat neonatal pup EEG recording will be successfully performed. 10 min after the KA injection, a regular pattern of behavioral signs emerged in the form of irregular movements and scratching, tremors, and loss of balance. Figure 2 shows the representative raw EEG traces and interictal, ictal-tonic, and ictal-clonic expanded traces. Recurrent interictal and ictal EEG discharge patterns started 15-60 min (30 &#177;5.2 min; ...

Watch this Scientific Journal Video about Recording EEG in Freely Moving Neonatal Rats Using a Novel Method at JoVE.com

Recording EEG in Freely Moving Neonatal Rats Using a Novel Method

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.

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 ...

The overall goal of this method is to record EEGs from freely moving neonatal rat pups, using a novel electrode set up that is stable for a week or longer. This method will have answered key questions in the field of neuroscience and will be beneficial in the study of a neonatal epilepsy. By using this technique, one can record high quality and stable EEG signals for longer timeframes.Which will help in the diagnosis of various neuro-pathological disorders. Generally, individuals new to this method will struggle because neonatal rat at p8 to p15 are very difficult to handle and require great care. The electrode requires a pronged contact to function as the signal interface with the communication devices.A computer pin lo sai fills this role. Carefully separate the male and female pins from a computer pin lo sai using pliers. Then, connect the male and female pins together to form an electrode, and secure the connection with cyanoacrylate.Make several such electrodes. Once the bonds have hardened, put the electrodes into a beaker filled with distilled water for ten minutes. Then, place them into an ultrasonic cleaner to clean the electrodes.Then, transfer the beaker to an oven set to 45 degrees Celsius, and heat them for half an hour. Lastly, sterilize the electrodes with a 30-minute UV exposure. In a bio-safety hood, first set up the sterilized surgical tools, and a sterilized stereotaxic apparatus for the surgery.Then, anesthetize the neonatal rat pup using two point five percent isoflurane. When the pup is deeply anesthetized, reduce the isoflurane to one percent. Prior to proceeding, use a toe pinch to ensure that the mouse is sufficiently anesthetized.Next, fix the head of the pup in the stereotaxic apparatus. Position the ear bars in the ear canals and gently tighten the bars. Be careful:the neonatal skull is very soft.Now, make a fifteen-millimeter midline incision into the skull. Then, with forceps, gently pull apart the scalp to widen the incision. To keep the incision open, use a piece of saline-soaked cotton.Now, locate the bregma and lambda, and mark them with a pencil. The following electrode implantation steps are critical and must be executed precisely. First, using a 26-gauge needle, make a burr hole into the prefrontal cortex, two millimeters anterior to the bregma and within zero point five millimeters of the midline.Next, make a burr hole into the hippocampus at one point eight millimeters posterior to the bregma and zero point five millimeters lateral of the midline. The needle should not penetrate more than two millimeters below the cortical surface to minimize brain damage. Now, using forceps, insert the reference electrode in the cortex hole, and insert the recording electrodes into the hippocampus hole.Then, apply erythromycin ointment around the electrodes, and fix the electrodes in place with cyanoacrylate. While the glue bonds, prepare dental cement at a gluey and viscous consistency. The viscosity of the dental cement is critical.If the dental cement is too thin, it may result in building up an undesired insulating layer under the electrode. If the cement is too dense, the electrodes will be more easily detached because of the excess mass. Before applying the cement, thoroughly dry the skull and the electrodes.Then, secure the electrodes to the skull with dental cement. Following this, apply some picric acid onto the electrodes to add another layer of protection to them. Now, remove the animal from the stereotaxic frame, and inject 300 microliters of ten percent glucose solution subcutaneously.Then, transfer the animal to a heated blanket to keep it at 37 degrees Celsius until it is ambulatory. Once ambulatory, administer buprenorphine to mediate post-surgical pain, and transfer the pup to its home cage with its dam. Before using the implant, wait at least two days for the pup to recover.After the recovery period, house the pup alone to make recordings for about ten minutes so that the pup may become familiar with the environment. Connect the electrodes to an amplifier, and connect the amplifier to an AD converter attached to a computer. Be careful not to tangle these connections.Next, on the data acquisition unit, select a sampling rate of at least 10, 000 hertz for recording, and check for proper data transmission. Collect a baseline recording. After taking a baseline recording, inject the pup intraperitoneally with kainic acid to induce epileptic seizures.Fifteen minutes after the injection, observe and record the epileptic discharges. Save the digitized data, and analyze it using signal-processing software. Reveal the power level of different frequency components in the neonatal EEGs using power spectrum analysis.Calculate the power from one-minute timeframes by finding root mean square amplitude from one to one hundred hertz, which is the EEG band. Ten minutes after the kainic acid injection, recurrent interictal and ictal EEG discharge patterns were recorded. The most common seizures recorded were the tonic clonic type.The ictal tonic duration lasted about fifteen seconds. It was also observed that tonic discharges were followed by clonic bursts. After watching this video, you should have a good understanding of how to implant electrodes and obtain high-quality EEG recordings from p8 to p15 neonatal rat pups.Once mustered, the cervical implantation can be done in less than ten minutes depending on the complexity of the surgery.

recording-eeg-in-freely-moving-neonatal-rats-using-a-novel-method

Research

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Neuroscience

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

Electroencephalogram (EEG) indicates the averaged electrical activity of the neuronal populations on a large-scale level. It is widely utilized as a noninvasive brain monitoring tool in cognitive neuroscience as well as a diagnostic tool for epilepsy and sleep disorders in neurology. However, the underlying mechanism of EEG rhythm generation is still under the veil. Recently introduced polyimide-based microelectrode (PBM-array) for high resolution mouse EEG1 is one of the trials to answer the neurophysiological questions on EEG signals based on a rich genetic resource that the mouse model contains for the analysis of complex EEG generation process. This application of nanofabricated PBM-array to mouse skull is an efficient tool for collecting large-scale brain activity of transgenic mice and accommodates to identify the neural correlates to certain EEG rhythms in conjunction with behavior. However its ultra-thin thickness and bifurcated structure cause a trouble in handling and implantation of PBM-array. In the presented video, the preparation and surgery steps for the implantation of PBM-array on a mouse skull are described step by step. Handling and surgery tips to help researchers succeed in implantation are also provided.

In this article, we described the surgery procedure and handling tips for implantation of ultra-thin polyimide-based microelectrode array (PBM-array) on the mouse skull for acquisition of high-density encephalography (EEG) in a mouse model.

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

A General Method for Evaluating Incubation of Sucrose Craving in Rats

For someone on a food-restricted diet, food craving in response to food-paired cues may serve as a key behavioral transition point between abstinence and relapse to food taking 1. Food craving conceptualized in this way is akin to drug craving in response to drug-paired cues. A rich literature has been developed around understanding the behavioral and neurobiological determinants of drug craving; we and others have been focusing recently on translating techniques from basic addiction research to better understand addiction-like behaviors related to food 2-4.
As done in previous studies of drug craving, we examine sucrose craving behavior by utilizing a rat model of relapse. In this model, rats self-administer either drug or food in sessions over several days. In a session, lever responding delivers the reward along with a tone+light stimulus. Craving behavior is then operationally defined as responding in a subsequent session where the reward is not available. Rats will reliably respond for the tone+light stimulus, likely due to its acquired conditioned reinforcing properties 5. This behavior is sometimes referred to as sucrose seeking or cue reactivity. In the present discussion we will use the term "sucrose craving" to subsume both of these constructs.
In the past decade, we have focused on how the length of time following reward self-administration influences reward craving. Interestingly, rats increase responding for the reward-paired cue over the course of several weeks of a period of forced-abstinence. This "incubation of craving" is observed in rats that have self-administered either food or drugs of abuse 4,6. This time-dependent increase in craving we have identified in the animal model may have great potential relevance to human drug and food addiction behaviors.
Here we present a protocol for assessing incubation of sucrose craving in rats. Variants of the procedure will be indicated where craving is assessed as responding for a discrete sucrose-paired cue following extinction of lever pressing within the sucrose self-administration context (Extinction without cues) or as responding for sucrose-paired cues in a general extinction context (Extinction with cues).

Responding for food or drug-paired cues increases over the course of a period of abstinence and this may relate to an increased susceptibility to relapse behaviors. Here we detail a procedure for evaluating this "incubation of craving" in rats that have self-administered sucrose.

For someone on a food-restricted diet, food craving in response to food-paired cues may serve as a key behavioral transition point between abstinence and ...

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.

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

A Novel Behavioral Assay to Investigate Gustatory Responses of Individual, Freely-moving Bumble Bees (Bombus terrestris)

Generalist pollinators like the buff-tailed bumble bee, Bombus terrestris, encounter both nutrients and toxins in the floral nectar they collect from flowering plants. Only a few studies have described the gustatory responses of bees toward toxins in food, and these experiments have mainly used the proboscis extension response on restrained honey bees. Here, a new behavioral assay is presented for measuring the feeding responses of freely-moving, individual worker bumble bees to nutrients and toxins. This assay measures the amount of solution ingested by each bumble bee and identifies how tastants in food influence the microstructure of the feeding behavior.
The solutions are presented in a microcapillary tube to individual bumble bees that have been previously starved for 2-4 hr. The behavior is captured on digital video. The fine structure of the feeding behavior is analyzed by continuously scoring the position of the proboscis (mouthparts) from video recordings using event logging software. The position of the proboscis is defined by three different behavioral categories: (1) proboscis is extended and in contact with the solution, (2) proboscis is extended but not in contact with the solution and (3) proboscis is stowed under the head. Furthermore the speed of the proboscis retracting away from the solution is also estimated.
In the present assay the volume of solution consumed, the number of feeding bouts, the duration of the feeding bouts and the speed of the proboscis retraction after the first contact is used to evaluate the phagostimulatory or the deterrent activity of the compounds tested.
This new taste assay will allow researchers to measure how compounds found in nectar influence the feeding behavior of bees and will also be useful to pollination biologists, toxicologists and neuroethologists studying the bumble bee&#39;s taste system.

A Novel Behavioral Assay to Investigate Gustatory Responses of Individual, Freely-moving Bumble Bees Bombus terrestris

A novel behavioral assay is described for investigating the short term gustatory responses of the mouthparts of freely-moving bumble bees (Bombus terrestris) toward nutrients and toxins in solution.

Generalist pollinators like the buff-tailed bumble bee, Bombus terrestris, encounter both nutrients and toxins in the floral nectar they collect from ...

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.

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

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.

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.

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 ...

Wireless Electrophysiological Recording of Neurons by Movable Tetrodes in Freely Swimming Fish

The neural mechanisms governing fish behavior remain mostly unknown, although fish constitute the majority of all vertebrates. The ability to record brain activity from freely moving fish would advance research on the neural basis of fish behavior considerably. Moreover, precise control of the recording location in the brain is critical to studying coordinated neural activity across regions in fish brain. Here, we present a technique that records wirelessly from the brain of freely swimming fish while controlling for the depth of the recording location. The system is based on a neural logger associated with a novel water-compatible implant that can adjust the recording location by microdrive-controlled tetrodes. The capabilities of the system are illustrated through recordings from the telencephalon of goldfish.

A novel wireless technique for recording extracellular neural signals from the brain of freely swimming goldfish is presented. The recording device is composed of two tetrodes, a microdrive, a neural data logger, and a waterproof case. All parts are custom-made except for the data logger and its connector.

The neural mechanisms governing fish behavior remain mostly unknown, although fish constitute the majority of all vertebrates. The ability to record brain ...

Intracerebroventricular Delivery of Gut-Derived Microbial Metabolites in Freely Moving Mice

The impact of gut microbiota and their metabolites on host physiology and behavior has been extensively investigated in this decade. Numerous studies have revealed that gut microbiota-derived metabolites modulate brain-mediated physiological functions through intricate gut-brain pathways in the host. Short-chain fatty acids (SCFAs) are the major bacteria-derived metabolites produced during dietary fiber fermentation by the gut microbiome. Secreted SCFAs from the gut can act at multiple sites in the periphery, affecting the immune, endocrine, and neural responses due to the vast distribution of SCFAs receptors. Therefore, it is challenging to differentiate the central and peripheral effects of SCFAs through oral and intraperitoneal administration of SCFAs. This paper presents a video-based method to interrogate the functional role of SCFAs in the brain via a guide cannula in freely moving mice. The amount and type of SCFAs in the brain can be adjusted by controlling the infusion volume and rate. This method can provide scientists with a way to appreciate the role of gut-derived metabolites in the brain.

Gut-derived microbial metabolites have multifaceted effects leading to complex behavior in animals. We aim to provide a step-by-step method to delineate the effects of gut-derived microbial metabolites in the brain via intracerebroventricular delivery via a guide cannula.

The impact of gut microbiota and their metabolites on host physiology and behavior has been extensively investigated in this decade. Numerous studies have ...