This work was supported by CAS Key Laboratory of Mental Health, Institute of Psychology,&#160;the National Natural Science Foundation of China (31671141 and 31822025), the 13th Five-year Informatization Plan of the Chinese Academy of Sciences (XXH13506), and the Scientific Foundation project of the Institute of Psychology, Chinese Academy of Sciences (Y6CX021008).

Adult male Sprague-Dawley rats (weighing 400 - 450 g) were used in the experiment. All surgical and experimental procedures followed the Guide for Care and Use of Laboratory Animals of the National Institutes of Health. The procedures were approved by the Research Ethics Committee at the Institute of Psychology, Chinese Academy of Sciences.
1. Electrode Implantation
<ol>
	<li>Anesthetize the rat in a chamber with 5% isoflurane and an air flow rate of 1 L/min before the surgery.</li>
	<li>Using a stereotaxic apparatus, fix the head of the rat with its nose placed into the anesthetic mask. Administrate isoflurane via the anesthetic mask at a concentration of 2% with an air flow rate of 0.5 L/min to maintain the anesthetic depth during the surgery. Note that the surgical tolerance is achieved when the rat fails to respond to toe-pinching.</li>
	<li>Apply ophthalmic ointment to the eyes to avoid corneal drying.</li>
	<li>Shave the top of the rat scalp using a standard shaver.</li>
	<li>Sterilize the scalp using the medical iodophor disinfectant solution and 75% alcohol to remove the iodine.</li>
	<li>Inject lidocaine (2%) into the scalp for local analgesia. Administer atropine (0.2 mL i.p.) to inhibit respiratory hypersecretion.</li>
	<li>Make a midline incision of approximately 2 - 3 cm on the scalp using a scalpel. Cut and remove part of the scalp along the midline and expose the cranium. Use the electrocoagulator to stop the bleeding, when necessary.</li>
	<li>Mark the locations of ECoG electrodes based on the predefined stereotaxic coordinates (placed according to the position of Bregma) and the locations of the reference and ground electrodes on the midline (placed 2 and 4 mm caudally to the Lambda, respectively).</li>
	<li>Drill holes (diameter: 0.5 mm) for the ECoG screws, using an electric cranial drill on the skull at the marked sites, without destroying the dura.</li>
	<li>Drive a stainless-steel screw (outside diameter: 0.6 mm), which connects to the insulation-coated copper wire, into the hole for approximately 1 mm depth without penetrating the underlying dura. These screws act as ECoG, reference, and ground electrodes during the experiment.</li>
	<li>Place a protective shell base on the cranium. Fix the base with its adjacent screws on the cranium using dental acrylic. Use medical cotton that could be removed afterward to protect the area that is intended to be used for depth wire implantation from being covered. 
	NOTE: The protective shell is a custom-designed 3D-printed polylactic product, which consists of three parts: a base, a wall, and a cap. The wall is covered by copper tapers to construct as a Faraday cage.</li>
	<li>Mark the locations of the depth wire electrodes based on the predefined stereotaxic coordinates.</li>
	<li>Drill small holes (diameter: 0.2 mm) on the skull around the marked sites for wire implantation, and carefully remove the bone flap to expose the dura. Wash the craniotomy frequently, using normal saline. Figure 1 describes the set-up before the implantation of the depth wire electrodes.</li>
	<li>Using a needle, lift and cut the dura without damaging the pia mater, vessels, and the surface of the neocortex.</li>
	<li>Lower the depth wire electrodes to the surface of the neocortex and, then, slowly penetrate the brain to the target depth. Frequently stop moving down the electrodes for cortical resilience. In the present study, the depth of the wire tip is 0.5 mm under the cortical surface.</li>
	<li>Seal the craniotomy with a mixture of wax and paraffin oil to ensure that the depth wire electrodes can be moved for subsequent experimental manipulations.</li>
	<li>Fix the electrode apparatus using dental acrylic on the skull.</li>
	<li>Weld each copper wire that connects to the ECoG screw to the corresponding channel on the connector module. Cover the welding spots using clay to avoid potential contact between different channels.</li>
	<li>Assemble the protective shell wall to the base and weld the reference and ground electrodes to the corresponding channels.</li>
	<li>Fix the cap to the protective shell using tapes to avoid contamination.</li>
	<li>Inject the rat with penicillin (60,000 U, i.p.) immediately after surgery to prevent postsurgical infections.</li>
	<li>Single-house the rat in a temperature- and humidity-controlled cage and keep it in a 12-h day/night cycle after the surgery, with food and water ad libitum for at least one week prior to the LEP experiment. 
	NOTE: To simultaneously record ECoG and cortical LFP activities, an apparatus was used here that was assembled with two types of electrodes linked to a connector module, which contained several microdrives attached to the tungsten wire arrays. The gold pins were used to connect the tungsten wires to the electrode interface board (EIB) of the connector module by pressing the wires into small metal holes on the EIB. Two metal holes on the EIB were soldered with coated copper wires, and the open end of each copper wire was soldered with the corresponding copper wire connected to ECoG screw. The details of fabrication have been described elsewhere21.</li>
</ol>
2. Data Collection
<ol>
	<li>Tickle the rat at least 1x a day for three or more consecutive days before the experiment to ensure that the rat gets familiar with the experimenter22.</li>
	<li>Place the rat in the behavior chamber for at least 1 h before the experiment to ensure the rat acclimatizes to the recording environment. 
	NOTE: The chamber is a plastic cube with a side length of 30 cm. The bottom of the chamber is made of an iron grating with ~8 mm gaps.</li>
	<li>Connect the recording headstage with the electrode module gently, to avoid scaring the rat and damaging the electrode module.</li>
	<li>Set up the laser generator, connect the optic fiber, and adjust the spot size of the laser according to the equipment operator&#8217;s manual. Connect the digital output from the trigger generator to the digital input port of the recording board. 
	NOTE: Take care not to curl the optic fiber excessively to avoid breaking off the fiber. Before recording, make sure the trigger signals are displayed and recorded by the recording software. In this protocol, radiant-heat stimuli are generated by an infrared neodymium yttrium aluminum perovskite (Nd: YAP) laser with a wavelength of 1.34 &#956;m. The diameter of the laser spot size is set at approximately 5 mm by focusing lenses. A He-Ne laser pointed to the stimulated area, which is defined depending on the objective of the experiment. Also, the stimulus energy of the laser pulses is determined according to the experimental design. The laser pulse duration is 4 ms.</li>
	<li>Set the video camera beneath the corner of the experimental chamber to continuously record the nociceptive behaviors of the rat when its paw receives nociceptive laser stimuli. Adjust the position and direction of the camera to make sure the nociceptive behaviors are completely recorded throughout the experiment. 
	NOTE: A high-speed charge-coupled device (CCD) camera is highly recommended, as it can deliver the operating signals to the main board of the recording system to record the onset time and duration of the nociceptive behavior precisely. Nociceptive behaviors are assessed by the experimenter after each laser stimulus, according to previously defined criteria based on the animal movement23,24, as follows: no movement (score = 0), head-turning (including shaking or elevating the head; score = 1), flinching (i.e., a small abrupt body jerking movement; score = 2), withdrawal (i.e., paw retraction from the laser stimulus; score = 3), licking and whole-body movement (score = 4).</li>
	<li>Deliver ongoing white noise (50 dB SPL) via a loudspeaker at the top of the chamber. 
	NOTE: As shown in previous studies10,25, laser stimulation delivered on the skin generates ultrasounds that can be detected by the rat auditory system. For this reason, ongoing white noise is played throughout the experiment to avoid the activation of the auditory system in response to laser-generated ultrasounds. This procedure allows the selective recording of brain responses related to the activation of the nociceptive system.</li>
	<li>Collect the electrophysiological data from both the ECoG and the depth wire electrodes, using the recording system according to the equipment operator&#8217;s manual. 
	NOTE: The operating signals of the camera and the trigger signals of the laser pulses are sampled simultaneously with the electrophysiological data at the same sampling rate (all data are amplified and digitized using a sampling rate of 20,000 Hz), which ensures that all data are time-synchronized.</li>
	<li>Deliver the laser pulses to the plantar of the rat&#8217;s forepaw through the gaps in the bottom of the chamber. 
	NOTE: The laser stimulus is only delivered when the rat is spontaneous stillness for more than 2 s based on the experimenter&#8217;s observation, to minimize the signal contamination of the movement-related artifacts. To avoid nociceptor fatigue or sensitization, the target of the laser beam is displaced manually after each stimulus, and the interstimulus interval is never shorter than 40 s. ECoG and LFP signals can be recorded several times from each rat. The rat needs to be put in the experimental chamber 1 h before each recording session. After all recording sessions, the rat was deeply anesthetized and perfused transcardially with ice-cold phosphate-buffered saline followed by 4% paraformaldehyde. The brain was removed from the skull and sectioned to identify the electrode positions.</li>
</ol>
3. Data Analysis
<ol>
	<li>Filter the continuous data with a band-pass filter between 1 and 30 Hz.</li>
	<li>Epoch the data using an analysis window of 3 s, extended from 1 s before to 2 s after the onset of laser stimuli. Baseline correction is performed by subtracting the mean amplitude within the prestimulus interval.</li>
	<li>Manually reject the epochs that are contaminated by gross artifacts.</li>
	<li>Compute the averaged LEP waveforms that are time-locked to the onset of laser stimuli for each experimental condition.</li>
	<li>Compute the wavelet transform coherence (WTC) of LEP waveforms recorded from ECoGs and depth wire electrodes. 
	NOTE: WTC is a technique to perform the coherence between pairs of electrodes as a function of time and frequency. The WTC between two signals can be calculated for any time-frequency point, which has the advantage of generating coherence values for the entire time-frequency spectrum. The details of the methodology have been described elsewhere26.</li>
</ol>

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</ol>

&#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160; &#160; The authors have nothing to declare.

In the present study, we described a technique to concurrently record ECoGs and cortical LFP responses elicited by nociceptive laser stimuli from freely moving rats. The results showed that LEP responses could be clearly detected after the onset of laser stimuli in both ECoG and LFP signals. The simultaneous recording of ECoG and cortical LFP signals will enable scientists to investigate their relationship for better understanding the contribution of neuronal activities to the LEP components.
...

EEG is a technique to record electrical potentials and oscillatory brain activities generated by the synchronized activities of thousands of neurons in the brain. It is popularly used in many basic studies and clinical applications1,2. For instance, EEG responses to intense laser heat pulses (i.e., LEPs) are widely adopted to investigate the peripheral and central processing of nociceptive sensory input3,4,5. In humans, LEPs mainly consist of three distinct deflections: the early component (N1) that is somatotopically organized and likely to reflect the activity of the primary somatosensory cortex (S1)6, and the late components (N2 and P2) that are centrally distributed and more likely to reflect the activity&#160;of the secondary somatosensory cortex, insula, and anterior cingulate cortex7,8. In previous studies9,10, we demonstrated that rat LEPs, sampled using ECoG (a type of intracranial EEG) from electrodes placed directly on the exposed surface of the brain, also consist of three distinct deflections (i.e., somatotopically organized N1 and the centrally distributed N2 and P2). The polarity, order, and topography of the rat LEP components are similar to human LEPs11. However, due to the limited spatial resolution of the scalp EEG and subdural ECoG recordings12, as well as the inaccurate nature of EEG source analysis techniques13, the detailed contribution of the neural activities to the LEP components is much debated. For example, it is unclear if and the extent to which S1 contributes to the early part of the cortical response (N1) elicited by laser stimuli6.
Different from the recording technique at the macroscopic level, direct intracranial recordings using microwire arrays aided by a stereotaxic apparatus and microdrives14,15 could measure neural activities (e.g., LFPs) of specific regions. LFPs mainly reflect the summation of inhibitory or excitatory postsynaptic potentials of local neuronal populations16. Since LFP-sampled neural activities reflect neuronal processes occurring within hundreds of micrometers around the recording electrode, this recording technique is widely used to investigate the information processing in the brain at the mesoscopic level. However, it only focuses on precise local changes of brain activities and cannot answer the question of how signals from multiple regions are integrated (e.g., how LEP components are integrated at multiple brain regions).
It is worth noting that the simultaneous recording of an ECoG and cortical LFPs from freely moving rats could facilitate the investigation of cortical information processing at both macroscopic and mesoscopic levels. In addition, this methodology provides an excellent opportunity to investigate the extent to which the neural activities of the predefined brain regions contribute to the LEPs. Indeed, several previous studies have assessed the coherence between spikes, cortical LFP, and ECoG signals17,18 and demonstrated that the LFP19,20 adjacent to the EEG electrode contributes to the formation of stimulus-related brain responses. However, the existing technique is usually used to record brain responses from anesthetized animals due to the lacking of a protective shell to prevent the electrodes from being damaged by the collision. In other words, the technique that could build the bridge of electrocortical signals at the mesoscopic (cortical LFP) and macroscopic (EEG and ECoG) levels in freely moving rats is still lacking.
To address this issue, we developed a technique that could record an ECoG and cortical LFPs in multiple brain regions simultaneously from freely moving rats. This technique helps establish the direct relationship of electrocortical signals at the mesoscopic and macroscopic levels, thus facilitating the investigation of nociceptive information processing in the brain.

<table><tbody><tr><td>Male Sprague-Drawley rats</td><td>Vital River</td><td></td><td></td></tr><tr><td>Isoflurane</td><td>RWD Life Science</td><td></td><td></td></tr><tr><td>Small animal isoflurane anaesthetic system</td><td>RWD Life Science</td><td></td><td>Including the anesthesia gas mask for rats</td></tr><tr><td>Stereotaxic apparatus</td><td>RWD Life Science</td><td></td><td></td></tr><tr><td>The apparatus with combined ECoG and LFP electrodes</td><td></td><td></td><td>The apparatus is home-made, which assembles the ECoG and depth wire electrodes to a connector module</td></tr><tr><td>3D-printed protective shell</td><td></td><td></td><td>The texture of shell is polylactic, and the shell is home-made and contains three parts: a base, a wall and a cap. The wall is covered by copper tapers to construct as a Faraday cage</td></tr><tr><td>Tungsten wires (diameter: 50 mm)</td><td>California Fine Wires Company</td><td></td><td>The electrodes for cortical LFP recording</td></tr><tr><td>&amp;nbsp;Stainless steel screws&lt;br/&gt; (diameter: 0.6 mm)</td><td></td><td></td><td>The electrodes for ECoG recording</td></tr><tr><td>Electric cranial drill</td><td>RWD Life Science</td><td></td><td></td></tr><tr><td>&amp;nbsp;Drill bit (diameter: 0.5 mm)</td><td>RWD Life Science</td><td></td><td>The drill is used for drilling the holes of ECoG screws</td></tr><tr><td>&amp;nbsp;Drill bit (diameter: 0.2 mm)</td><td>RWD Life Science</td><td></td><td>The drill is used for drilling the holes of depth wires&amp;nbsp;</td></tr><tr><td>Dental arylic powder</td><td>SNC dental</td><td></td><td></td></tr><tr><td>Dental arylic liquid</td><td>SNC dental</td><td></td><td></td></tr><tr><td>Paraffin</td><td>Fisher Scientific</td><td></td><td>The mixture is used for seal the craniotomy to ensure the following movement of micro-wire arrays</td></tr><tr><td>Mineral Oil</td><td>Fisher Scientific</td><td></td><td></td></tr><tr><td>Electrocoagulator&amp;nbsp;</td><td>Bovie medical Corporation</td><td></td><td></td></tr><tr><td>RHD2132 Amplifier Boards&amp;nbsp;</td><td>Intan Technologies</td><td></td><td>A 32-channel headstage</td></tr><tr><td>RHD2000 systerm</td><td>Intan Technologies</td><td></td><td>The data acquisition systerm</td></tr><tr><td>Infrared neodymium yttrium aluminum perovskite (Nd:YAP) laser generator</td><td>Electronical Engineering</td><td></td><td></td></tr><tr><td>Matlab R2016b</td><td>The MathWorks&amp;nbsp;</td><td></td><td></td></tr></tbody></table>

simultaneous recordings of cortical local field potentials and electrocorticograms in response to nociceptive laser stimuli from freely moving rats

Electrocortical responses, elicited by laser heat pulses that selectively activate nociceptive free nerve endings, are widely used in many animal and human studies to investigate the cortical processing of nociceptive information. These laser-evoked brain potentials (LEPs) consist of several transient responses that are time-locked to the onset of laser stimuli. However, the functional properties of the LEP responses are still largely unknown, due to the lack of a sampling technique that can simultaneously record neural activities at the surface of the cortex (i.e., electrocorticogram [ECoG] and scalp electroencephalogram [scalp EEG]) and inside the brain (i.e., local field potential [LFP]). To address this issue, we present here an animal protocol using freely moving rats. This protocol is composed of three main procedures: (1) animal preparation and surgical procedures, (2) a simultaneous recording of ECoG and LFP in response to nociceptive laser stimuli, and (3) data analysis and feature extraction. Specifically, with the help of a 3D-printed protective shell, both ECoG and LFP electrodes implanted on the rat&#39;s skull were securely held together. During data collection, laser pulses were delivered on the rat&#39;s forepaws through gaps in the bottom of the chamber when the animal was in spontaneous stillness. Ongoing white noise was played to avoid the activation of the auditory system by the laser-generated ultrasounds. As a consequence, only nociceptive responses were selectively recorded. Using the standard analytical procedures (e.g., band-pass filtering, epoch extraction, and baseline correction) to extract stimulus-related brain responses, we obtained results showing that LEPs with a high signal-to-noise ratio were simultaneously recorded from ECoG and LFP electrodes. This methodology makes the simultaneous recording of ECoG and LFP activities possible, which provides a bridge of electrocortical signals at the mesoscopic and macroscopic levels, thereby facilitating the investigation of nociceptive information processing in the brain.

In the representative experiment, the electrophysiological data from five rats were recorded. The laser stimuli were delivered to the right forepaw of each rat for 20 times with &#62;40 s interstimulus intervals. The laser-evoked brain responses were recorded using both ECoG screws and depth wires, and the depth wires were implanted in bilateral primary somatosensory cortices (S1) and primary motor cortices (M1).
As summarized i...

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Simultaneous Recordings of Cortical Local Field Potentials and Electrocorticograms in Response to Nociceptive Laser Stimuli from Freely Moving Rats

We developed a technique that simultaneously records both electrocorticography and local field potentials in response to nociceptive laser stimuli from freely moving rats. This technique helps establish a direct relationship of electrocortical signals at the mesoscopic and macroscopic levels, which facilitates the investigation of nociceptive information processing in the brain.

Electrocortical responses, elicited by laser heat pulses that selectively activate nociceptive free nerve endings, are widely used in many animal and ...

simultaneous-recordings-cortical-local-field-potentials

Research

JoVE Journal

Behavior

8.6K Views.  Institute of Psychology. Deze methode helpt bij het vaststellen van de directe relatie van elektrocorticale signalen opgenomen van zowel ECoG en de diepten van draden om belangrijke vragen over de neuronale bijdragen van laser-evoke potentials te beantwoorden. Het belangrijkste voordeel van deze techniek is dat elektrodeimplantatie kan worden beschermd door polymelkige schil, dus de opname kan worden toegepast op onze vrij bewegende ratten. Deze methode kan worden toegepast bij het registreren van hersenreacties opge...

Video: Simultaneous Recordings of Cortical Local Field Potentials and Electrocorticograms in Response to Nociceptive Laser Stimuli from Freely Moving Rats

Simultaneous Electroencephalography, Real-time Measurement of Lactate Concentration and Optogenetic Manipulation of Neuronal Activity in the Rodent Cerebral Cortex

Although the brain represents less than 5% of the body by mass, it utilizes approximately one quarter of the glucose used by the body at rest1. The function of non rapid eye movement sleep (NREMS), the largest portion of sleep by time, is uncertain. However, one salient feature of NREMS is a significant reduction in the rate of cerebral glucose utilization relative to wakefulness2-4. This and other findings have led to the widely held belief that sleep serves a function related to cerebral metabolism. Yet, the mechanisms underlying the reduction in cerebral glucose metabolism during NREMS remain to be elucidated.
	One phenomenon associated with NREMS that might impact cerebral metabolic rate is the occurrence of slow waves, oscillations at frequencies less than 4 Hz, in the electroencephalogram5,6. These slow waves detected at the level of the skull or cerebral cortical surface reflect the oscillations of underlying neurons between a depolarized/up state and a hyperpolarized/down state7. During the down state, cells do not undergo action potentials for intervals of up to several hundred milliseconds. Restoration of ionic concentration gradients subsequent to action potentials represents a significant metabolic load on the cell8; absence of action potentials during down states associated with NREMS may contribute to reduced metabolism relative to wake.
	Two technical challenges had to be addressed in order for this hypothetical relationship to be tested. First, it was necessary to measure cerebral glycolytic metabolism with a temporal resolution reflective of the dynamics of the cerebral EEG (that is, over seconds rather than minutes). To do so, we measured the concentration of lactate, the product of aerobic glycolysis, and therefore a readout of the rate of glucose metabolism in the brains of mice. Lactate was measured using a lactate oxidase based real time sensor embedded in the frontal cortex. The sensing mechanism consists of a platinum-iridium electrode surrounded by a layer of lactate oxidase molecules. Metabolism of lactate by lactate oxidase produces hydrogen peroxide, which produces a current in the platinum-iridium electrode. So a ramping up of cerebral glycolysis provides an increase in the concentration of substrate for lactate oxidase, which then is reflected in increased current at the sensing electrode. It was additionally necessary to measure these variables while manipulating the excitability of the cerebral cortex, in order to isolate this variable from other facets of NREMS.
	We devised an experimental system for simultaneous measurement of neuronal activity via the elecetroencephalogram, measurement of glycolytic flux via a lactate biosensor, and manipulation of cerebral cortical neuronal activity via optogenetic activation of pyramidal neurons. We have utilized this system to document the relationship between sleep-related electroencephalographic waveforms and the moment-to-moment dynamics of lactate concentration in the cerebral cortex. The protocol may be useful for any individual interested in studying, in freely behaving rodents, the relationship between neuronal activity measured at the electroencephalographic level and cellular energetics within the brain.

A procedure is described for manipulating the activity of cerebral cortical pyramidal neurons optogenetically while the electroencephalogram, electromyogram, and cerebral lactate concentration are monitored. Experimental recordings are performed on cable-tethered mice while they undergo spontaneous sleep/wake cycles. Optogenetic equipment is assembled in our laboratory; recording equipment is commercially available.

Although the brain represents less than 5% of the body  by mass, it utilizes approximately one quarter of the glucose used by the body  at rest1. The ...

Neuroscience

Simultaneous Recording of Electroretinography and Visual Evoked Potentials in Anesthetized Rats

The electroretinogram (ERG) and visual evoked potential (VEP) are commonly used to assess the integrity of the visual pathway. The ERG measures the electrical responses of the retina to light stimulation, while the VEP measures the corresponding functional integrity of the visual pathways from the retina to the primary visual cortex following the same light event. The ERG waveform can be broken down into components that reflect responses from different retinal neuronal and glial cell classes. The early components of the VEP waveform represent the integrity of the optic nerve and higher cortical centers. These recordings can be conducted in isolation or together, depending on the application. The methodology described in this paper allows simultaneous assessment of retinal and cortical visual evoked electrophysiology from both eyes and both hemispheres. This is a useful way to more comprehensively assess retinal function and the upstream effects that changes in retinal function can have on visual evoked cortical function.

This protocol describes simultaneous measurement of electroretinogram and visual evoked potentials in anesthetized rats.

The electroretinogram (ERG) and visual evoked potential (VEP) are commonly used to assess the integrity of the visual pathway. The ERG measures the ...

Acute In Vivo Electrophysiological Recordings of Local Field Potentials and Multi-unit Activity from the Hyperdirect Pathway in Anesthetized Rats

Converging evidence shows that many neuropsychiatric diseases should be understood as disorders of large-scale neuronal networks. To better understand the pathophysiological basis of these diseases, it is necessary to precisely characterize in which way the processing of information is disturbed between the different neuronal parts of the circuit. Using extracellular in vivo electrophysiological recordings, it is possible to accurately delineate neuronal activity within a neuronal network. The application of this method has several advantages over alternative techniques, e.g., functional magnetic resonance imaging and calcium imaging, as it allows a unique temporal and spatial resolution and does not rely on genetically engineered organisms. However, the use of extracellular in vivo recordings is limited since it is an invasive technique that cannot be universally applied. In this article, a simple and easy to use method is presented with which it is possible to simultaneously record extracellular potentials such as local field potentials and multiunit activity at multiple sites of a network. It is detailed how a precise targeting of subcortical nuclei can be achieved using a combination of stereotactic surgery and online analysis of multi-unit recordings. Thus, it is demonstrated, how a complete network such as the hyperdirect cortico-basal ganglia loop can be studied in anesthetized animals in vivo.

Acute In Vivo Electrophysiological Recordings of Local Field Potentials and Multi-unit Activity from the Hyperdirect Pathway in Anesthetized Rats

In this study, the methodology is presented on how to perform multi-site in vivo electrophysiological recordings from the hyperdirect pathway under urethane anesthesia.

Converging evidence shows that many neuropsychiatric diseases should be understood as disorders of large-scale neuronal networks. To better understand the ...

Concurrent Recording of Co-localized Electroencephalography and Local Field Potential in Rodent

Although electroencephalography (EEG) is widely used as a non-invasive technique for recording neural activities of the brain, our understanding of the neurogenesis of EEG is still very limited. Local field potentials (LFPs) recorded via a multi-laminar microelectrode can provide a more detailed account of simultaneous neural activity across different cortical layers in the neocortex, but the technique is invasive. Combining EEG and LFP measurements in a pre-clinical model can greatly enhance understanding of the neural mechanisms involved in the generation of EEG signals, and facilitate the derivation of a more realistic and biologically accurate mathematical model of EEG. A simple procedure for acquiring concurrent and co-localized EEG and multi-laminar LFP signals in the anesthetized rodent is presented here. We also investigated whether EEG signals were significantly affected by a burr hole drilled in the skull for the insertion of a microelectrode. Our results suggest that the burr hole has a negligible impact on EEG recordings.

This protocol describes a simple method for concurrent recording of co-localized electroencephalography (EEG) and multi-laminar local field potential in an anesthetized rat. A burr hole drilled in the skull for the insertion of a microelectrode is shown to produce negligible distortion of the EEG signal.

Although electroencephalography (EEG) is widely used as a non-invasive technique for recording neural activities of the brain, our understanding of the ...

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.

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

Integrated Protocol for FUN and Fiber Photometry in Free-Moving Mice

Simultaneous Focused Ultrasound Neuromodulation and Fiber Photometry Recording in Free-Moving Mouse

Focused ultrasound neuromodulation (FUN) represents a promising approach for non-invasive perturbation of neuronal circuits at deep brain regions. It is compatible with most of the existing modalities for monitoring brain functions in vivo. Integration with brain function recording modalities not only enables us to address orders and disorders of specific brain functions with closed-loop feedback but also provides us with mechanistic insights about FUN itself. Here, we provide a modified, simple, dependable, and robust protocol for the simultaneous application of FUN and fiber photometry GCaMP6s fluorescence recording in free-moving mice. This involves the fabrication of a well-sized single transducer and its temporary placement on the mice, along with the secure fixation of a fiber optical implant to facilitate the smooth passage of the transducer. The combination of FUN and fiber photometry provides for the optical recording of neural circuitry responses upon FUN in real-time in deep brain regions. To demonstrate the efficiency of this protocol, Thy1-GCaMP6s mice were used as an example to record the neuroactivity in the anterior thalamic nucleus during FUN while the mice are freely moving. We believe that this protocol can promote the widespread use of FUN in both the neuroscience field and the biomedical ultrasound field.

Author Spotlight: Integration of Fiber Photometry and Focused Ultrasound Neuromodulation for Investigating Neural Modulation in Freely Moving Mice

The protocol includes transducer manufacturing, parameters reporting, surgical procedure, and signal recording for the entire operational workflow of concurrent focused ultrasound neuromodulation and fiber photometry recording in free-moving mice.

Focused ultrasound neuromodulation (FUN) represents a promising approach for non-invasive perturbation of neuronal circuits at deep brain regions. It is ...

In Vivo Electrophysiological Recordings of Brain Activities from Multiple Sites in Rats

Source: Haumesser, J. K., et al. <a href="https://app.jove.com/v/55940">Acute In Vivo Electrophysiological Recordings of Local Field Potentials and Multi-unit Activity from the Hyperdirect Pathway in Anesthetized Rats.</a> J. Vis. Exp.(2017).
This video demonstrates the detailed procedure for preparing an anesthetized rat for electrophysiological recordings of brain activity from multiple sites. The scalp is dissected to access the skull, and holes are drilled at precise locations to install and secure electrodes. Tungsten microwire electrodes are then inserted into the targeted location to record the data.

All procedures involving animal models have been reviewed by the local institutional animal care committee and the JoVE veterinary review board.
1. ...

JoVE Encyclopedia of Experiments

Neurophysiology

Electrophysiology Techniques

Optogenetic Stimulation and Electrophysiological Recording of Synaptic Events in Rat Brain Slices

Source: Kinnavane, L., et al. <a href="https://app.jove.com/v/63077">Ex Vivo Optogenetic Interrogation of Long-Range Synaptic Transmission and Plasticity from Medial Prefrontal Cortex to Lateral Entorhinal Cortex.</a> J. Vis. Exp. (2022)
This video demonstrates the procedure for studying synaptic efficiency in the lateral entorhinal cortex (LEC) by optogenetically stimulating medial prefrontal cortex (mPFC) axons and recording the responses of pyramidal neurons in the LEC. This method combines patch-clamp recordings with synaptic activation by light stimulation to study synaptic plasticity.

All procedures involving animal samples have been reviewed and approved by the appropriate animal ethical review committee.
1. Electrophysiology and ...

Stimulation and Modulation Techniques

Recording of Local Field Potential from Both Hemispheres of the Mouse Brain

Source: Chen, Y., et al. <a href="https://app.jove.com/v/59310">Evaluation of Hemisphere Lateralization with Bilateral Local Field Potential Recording in Secondary Motor Cortex of Mice.</a> J. Vis. Exp. (2019).
This video demonstrates in vivo recording of local field potential (LFP) from bilateral M2 areas of the mouse brain. An anesthetized mouse is secured and prepared for the procedure. To record LFPs, insert microelectrodes into the target coordinates of the bilateral M2 areas, which are responsible for complex motor movements.

All procedures involving animal models have been reviewed by the local institutional animal care committee and the JoVE veterinary review board.
1. Animal ...

Concurrent Electroencephalographic and Local Field Potential Recordings in an Anesthetized Rat

Source: Kang, S., et al. <a href="https://app.jove.com/v/56447">Concurrent Recording of Co-localized Electroencephalography and Local Field Potential in Rodent.</a> J. Vis. Exp. (2017).
This video demonstrates the procedure for concurrent recordings of co-localized electroencephalography (EEG) and local field potentials (LFPs) in an anesthetized rat. The process involves preparing the rat and attaching stimulating electrodes to its whisker pads. An EEG spider electrode is placed on the rat&#39;s skull for surface EEG measurements. At the same time, a multi-channel microelectrode is inserted into a specific brain region through a burr hole in the skull to record neural activity from a localized brain area.

Simultaneous Recordings of Cortical Local Field Potentials and Electrocorticograms in Response to Nociceptive Laser Stimuli from Freely Moving Rats

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