An Integrated Method for Crafting Flexible and Convenient Electrophysiological Optrodes for Multi-Region In Vivo Recording

We investigated brain networks and neural circuits using multimodal approaches which encompass technical such as multichannel electrode optical recording, fiber photometry, neuromodulation, and functional magnetic resonance imaging. We are trying to answer how different brain regions communicate and intact in vivo, both in housing and distal states. We use flexible vessels for natural fiber replication and the implantation to connect the molecular, cellular, cycles, and network layers.

This comprehensive approach allow us to study neurological disorders more effectively and provide a deep understanding of their underlying mechanisms. Our results pave the way for neuroscientific question about how flexible multiregion brain recordings can be, how different brain circuits interreact in epilepsy, and how this could apply to other neurological disorders. It offers fringe insights into your neural activities across various brain regions.

To begin, cut an appropriate length of tungsten wire and burn off the insulation layer at one end to expose the tungsten wire. Then, fold the other end of the wire into an L shape. Carefully place the L end of the tungsten wire onto the optical fiber.

Dip a drop of adhesive and apply it at the interface of the optical fiber and the tungsten wire. At the corner of the L shape, use adhesive to closely bond the base of the optical fiber and the tungsten wire together. Then, use soldering to establish a connection between the tungsten wire and the pin of the female connector.

According to the experimental design, solder the required number of optrodes. Next, cut the enameled wire to the appropriate length and burn off the insulation on both ends. Wrap one end of the enameled wire around the base of the screw and solder it.

After that, connect the other end of the enameled wire to the pins of the female connector via soldering iron. Then, apply hot-melt adhesive to the female connector's pin array to encapsulate the connector and ensure the solder joints are fully enveloped. Shape the adhesive using a plastic board during its solidification to minimize space occupancy during implantation.

Next, use a light intensity meter and digital multimeter to measure luminousness and conductivity. Once these tests are passed, the setup is ready for use. Before use, immerse the prepared electrodes in 75%alcohol for 15 minutes.

Then, transfer them to sterile saline. After securing the anesthetized animal in the stereotaxic apparatus, trim away the scalp along the edge of the skull. Then, wipe the skull surface with 75%alcohol to expose the positions of the bregma and lambda.

Using a micro drill, level the mouse and drill holes above the regions of interest. Then, inject the relevant viruses with a syringe pump. Now, hold the optrodes with a holder and move their tip to the bregma point, setting this position as zero.

Using the bregma point as the reference coordinate, move the optrodes to the target regions. Position the optrodes 0.3 millimeters above the virus injection site. After inserting the optic fibers into the corresponding brain areas, apply a small amount of tissue adhesive around them to cover the exposed tissue.

Sequentially apply additional adhesive and a little dental cement. After the dental cement solidifies, release the holder carefully. Once all optrodes are implanted, drill the holes behind the lambda point for ground and above the neocortex for EEG using a micro drill.

Insert skull screws into the hole above the cortex and behind the lambda point. Then, organize the tungsten and enameled wires so they are positioned above the implantation area and not exposed outside the skull. Secure the position of the female connector using a holder.

Now, fill the implantation site with dental cement to ensure a stable connection between the electrode device and the skull. Encapsulate the internal wires, leaving the female connector's insertion holes exposed for connection to the head stage. Once the dental cement hardens, apply iodine to the wound and place the animal on a warming pad.

To begin, implant the recording electrodes and inject the relevant viruses in the mouse skull. After anesthetizing the mice, connect the optical fibers sequentially in the order of the recording site before inserting the head stage. Then, set the 635 nanometer light pulse with a 10%duty cycle at 20 hertz and set up the light stimulation for 10 seconds during recording.

Set the intensity at the optical fiber tips at three milliwatts. Next, use a fiber photometry system to record GCaMP6m signals throughout the behavior testing. Simultaneously, record calcium signals, local field potentials, and electroencephalogram under optogenetic stimulation, along with corresponding behavioral performances.

Finally, employ transistor-transistor logic signal synchronization tagging to ensure temporal consistency in recorded data. Brief optogenetic stimulation elicited robust afterdischarges, along with remarkable increases in calcium activities in the target brain regions. A 30 hertz response was observed in the optostimulating region, induced by the activation of optogenetic proteins via blue light LED.