multichannel recording in the bilateral mc in free-moving mice and neurophysiological data analysis

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 Multichannel Recording in the Bilateral MC in Free-Moving Mice and Neurophysiological Data Analysis at JoVE.com

Multichannel Recording in the Bilateral MC in Free-Moving Mice and Neurophysiological Data Analysis  

For the multi-channel recording, move down the electrode arrays by twisting the screw on the movable part of the micro-drive system one day in advance. Hold the head of an awake mouse lightly and carefully. Then, link the center of the head stage and a helium balloon with a thread to offset the weight of the head stage and the micro-drive system.Capture raw signals using the recording electrodes and multi-channel systems by sampling at 30 kilohertz in the recording software. Then digitize using a digital analog converter from the multi-channel systems. Extract the local field potential, or LFP signals, from the raw data by re-sampling at 10 kilohertz.Then, using a notch filter, remove the 50-hertz line noise. For spike sorting and analysis, in the spike sorting software, click on File, then Open, and nev files to open the spike data sampled at 30 kilohertz. Click on Info to select the unsorted channel.Then choose Sort, Change Sort Method, and Use K-Means. Press the button Valley Seeking Sort, then K-Means Sorting to obtain the sorted units. Next, in the neurophysiological data analysis software, open the sorted spike file by clicking on File, Import Data, and BlackRock File.To obtain the autocorrelogram for the selected unit, click on Analysis, then Autocorrelograms, and set the parameters. Load the sorted spike data. Then, click on Analysis, and Interspike Interval Histograms to obtain the interspike interval histogram, and then set the desired parameters.Click on Analysis, then Crosscorrelograms to obtain the crosscorrelogram between two sorted unit events. And then set the reference events and parameters. For LFP analysis, click on File, Import Data, and BlackRock File, to open the continuous signal data sampled at 10 kilohertz.Then, by clicking Analysis and Spectrum for Continuous, analyze the power spectrum for the LFP from the selected channel. Next, click on Analysis, then Coherence for Continuous to analyze the coherence for two LFPs from the left and right sides of the MC.Then, click on Analysis, followed by Correlation with Continuous Variables to analyze the correlation between two LFPs from the left and right sides of the MC.Once done, click on Results, then Numerical Results to save the Power Spectrum Density, Coherence, and Correlation with a xls file name extension. To analyze correlations between the spike and LFP, click on File, then Import Data and BlackRock File to open the continuous signal data and spike data.Then, click on Analysis and Coherence Analysis to analyze the coherence between the spikes and LFP from the selected channel. Finally, click on Results, then Numerical Results to save the results of the spike field coherence with a xls file name extension. The valley width and waveform duration of the units in the MC of the mouse showed that both the valley width and waveform duration of the MC putative pyramidal neurons in mice are higher than those of the putative interneurons.The crosscorrelogram between putative pyramidal neurons and interneurons indicated that the putative pyramidal neurons spiking occurs before the putative interneurons with a window of 18 milliseconds. In the LFP analysis, the LFPs of the left and right MC in normal mice were similar in the power spectrum, suggesting synchronized activities between the left and right MC.Further, the coherence and correlation between the left and right MC were calculated. The curve of spike field coherence in the MC of a normal mouse showed a stronger low gamma coherence for the putative interneurons compared to the pyramidal neurons.

multichannel-recording-bilateral-mc-free-moving-mice

Research

JoVE Journal

Neuroscience

216 조회수.  South China Normal University. 다중 채널 기록의 경우 하루 전에 마이크로 드라이브 시스템의 가동 부분에 있는 나사를 비틀어 전극 어레이를 아래로 이동합니다. 깨어 있는 쥐의 머리를 가볍고 조심스럽게 잡습니다. 그런 다음 헤드 스테이지의 중앙과 헬륨 풍선을 나사산으로 연결하여 헤드 스테이지와 마이크로 드라이브 시스템의 무게를 상쇄합니다.기록 전극과 다중 채널 시스템을 사용하여 기록...