Name: Micro-Drive System Assembly and Electrode Array Implantation for Multichannel Recording in Mice
Uploaded: 2023-05-26T12:20:00
Description: Watch this Scientific Journal Video about Micro-Drive System Assembly and Electrode Array Implantation for Multichannel Recording in Mice at JoVE.com

micro-drive system assembly and electrode array implantation for multichannel recording in mice

Extracellular Electrophysiological Recording in the Motor Cortex of Mice

The local field potential (LFP), an important component of extracellular signals, reflects the synaptic activity of large populations of neurons, which form the neural code for multiple behaviors1. Spikes generated by neuronal activity are considered to contribute to the LFP and are important for neural coding2. Alterations in spikes and LFPs have been proven to mediate several brain diseases, such as Alzheimer&#39;s disease, as well as emotions such as fear, etc.3,4. It is worth noting that many studies have highlighted that spike activity significantly differs between awake and anesthetized states in animals5. Although recordings in anesthetized animals offer an opportunity to assess LFPs with minimal artifacts in highly defined cortical synchronization states, the results differ to some extent from what can be found in awake subjects6,7,8. Thus, it is more meaningful to detect neural activity over long time scales and large spatial scales in various diseases in an awake brain state using electrodes implanted in the brain. This manuscript provides information for beginners on how to make the micro-drive system and set the parameters using common software for computing the spike and LFP signals in a fast and straightforward way in order to get the recording and analysis started.
Although the non-invasive recording of brain functions, such as by using electroencephalograms (EEGs) and event-related potentials (ERPs) recorded from the scalp, has been used extensively in human and rodent studies, EEG and ERP data have low spatial and temporal properties and, thus, cannot detect the precise signals produced by nearby dendritic synaptic activity within a specific brain area1. Currently, by taking advantage of multichannel recording in conscious animals, neural activity in the deeper layers of the brain can be recorded chronically and progressively by implanting a micro-drive system into the brains of primates or rodents during multiple behavioral tests1,2,3,4,5,6,7,8,9. Briefly, researchers can construct a micro-drive system that can be used for the independent positioning of the electrodes or tetrodes to target different parts of the brain10,11. For example, Chang et al. described techniques to record spikes and LFPs in mice by assembling a light and compact micro-drive12. In addition, micro-machined silicon probes with custom-made accessory components are commercially available for recording multiple single neurons and LFPs in rodents during behavioral tasks13. Although various designs have been used for assembling micro-drive systems, these still have limited success in terms of the complexity and weight of the whole micro-drive system. For example, Lansink et al. showed a multichannel micro-drive system with a complex structure for recording from a single brain region14. Sato et al. reported a multichannel micro-drive system displaying an automatic hydraulic positioning function15. The main disadvantages of these micro-drive systems are that they are too heavy for mice to move freely and are difficult to assemble for beginners. Although multichannel extracellular recording has been shown to be a suitable and efficient technology for measuring neural activity during behavioral tests, it is not easy for beginners to record and analyze the signals acquired by the complex micro-drive system. Given that it is difficult to get the entire operation process of the multichannel extracellular recording and data analysis started in freely moving mice16,17, this present article presents simplified guidelines to introduce the detailed process of making the micro-drive system using commonly available components and settings; the parameters in the common software for computing the spike and LFP signals in a fast and straightforward way are also provided. Additionally, in this protocol, the mouse can move freely due to the use of a helium balloon, which contributes to offsetting the weight of headstage and micro-drive system. Generally, in the present study, we describe how to easily build a micro-drive system and optimize the processes of recording and data analysis.

Author Spotlight: Advancements in Multichannel Extracellular Recording for Studying Neuronal Activity in Freely Moving Mice 

Multichannel Extracellular Recording in Freely Moving Mice

We aim to uncover the properties of neuronal firing and network local field potentials in behaving mice carrying out specific tasks by correlating the electrophysiological signal with behaviors. Multichannel extracellular recording by the micro-drive system has been shown to be a suitable and a efficient technology for neural activity during behavioral tests. Multichannel recording in free-moving mice has been deemed to be a useful technology in neuroscience studies, but it's still quite challenging for beginners to acquire and analyze the signals.We introduced how to perform the multichannel extracellular recording in freely-moving mice with a more steady and lightweight micro-drive system, and optimize the processes of recording and data analysis for the beginners. We are going to increase the number of channels and reduce the volume of micro-driver system in a new version.

Watch this Scientific Journal Video about Micro-Drive System Assembly and Electrode Array Implantation for Multichannel Recording in Mice at JoVE.com

Micro-Drive System Assembly and Electrode Array Implantation for Multichannel Recording in Mice  

Begin by assembling the Microdrive system. Connect two computer-designed boards using two stulls and a screw that holds the movable Microdrive, and attach the connector to one board. Ensure the Microdrive can carry two sets of eight guide tubes for each side of the motor cortex or MC region.Cut the guide tubes to the same length. Cut 16 nichrome wires, each measuring approximately five centimeters long and 35 micrometers in diameter. Load the wires into the guide tubes and apply glue to fix them.Strip the wire insulation and twine each exposed wire to each pin from the connector following the channel map and the reference and ground electrodes, then slowly coat conducting paint onto each pin. Cover the pins using epoxy resin, then perform gold plating via an impedance tester to reduce the impedance of the electrode tips to approximately 350 kiloohms. For electrode array implantation, fix the anesthetized mouse in a stereotaxic apparatus and use a temperature controller to maintain its rectal temperature at 37 degrees Celsius.Then make a small midline incision to expose the skull. Remove the residual tissue using scissors and clean the skull with sterile saline-soaked cotton buds. Using a glass microelectrode filled with ink, mark the desired locations of the bilateral MC for implantation.Next, using a skull drill, carefully drill two small holes on both the left and right sides of the coordinated skull in the MC regions. Gently remove the dura mater from the holes with fine forceps. Then insert the Microdrive system into the center of the holes, using a micromanipulator at 10 micrometers per second.After finishing the insertion, fill the petroleum jelly into the dental cement walls and join the bottom plate of the Microdrive system and the dental cement walls with the mixed dental cement.

Research

JoVE Journal

Neuroscience

The protocol aims to uncover the properties of neuronal firing and network local field potentials (LFPs) in behaving mice carrying out specific tasks by ...