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

Summary

We have developed a simplified and cost-effective approach for electrode fabrication and conducted recordings of signals across multiple regions in freely moving mice. Utilizing optogenetics, alongside multi-region electrophysiology and calcium signal recording, enabled the revelation of neuronal activities across regions in the seizure kindling model.

Abstract

Epilepsy is a neurological disorder characterized by synchronized abnormal discharges involving multiple brain regions. Focal lesions facilitate the propagation of epileptic signals through associated neural circuits. Therefore, in vivo recording of local field potential (LFP) from the critical brain regions is essential for deciphering the circuits involved in seizure propagation. However, current methods for electrode fabrication and implantation lack flexibility. Here, we present a handy device designed for electrophysiological recordings (LFPs and electroencephalography [EEG]) across multiple regions. Additionally, we seamlessly integrated optogenetic manipulation and calcium signaling recording with LFP recording. Robust after-discharges were observed in several separate regions during epileptic seizures, accompanied by increasing calcium signaling. The approach used in this study offers a convenient and flexible strategy for synchronous neural recordings across diverse regions of the brain. It holds the potential for advancing research on neurological disorders by providing insights into the neural profiles of multiple regions involved in these disorders.

Introduction

Epilepsy is a common neurological condition characterized by recurrent seizures, which manifest as convulsions, sensory disturbances, and loss of consciousness¹. The pathophysiological mechanisms underlying epilepsy are complex and involve multiple interconnected brain regions^2,3. Recent advances in neuroimaging have shed light on the large-scale networks involved in epilepsy^4,5. However, understanding of the intricate circuitry and network mechanisms underlying the generation and propagation of epilepsy remains limited, partly ....

Protocol

This protocol received approval from the Animal Care and Use Committee at Fudan University and was conducted following the guidelines and regulations designed by the National Institutes of Health Guide for Care and Use of Laboratory Animals. All possible measures were implemented to minimize the number of animals utilized in this study. The time required to perform each step is included in the respective steps.

1. Preparation of electrodes (Figure 1.......

Discussion

Here, we employed a self-made optrode device for in vivo neural signal recording across multiple regions. The feasibility of this system for simultaneous optogenetic stimulation, calcium signal recording, and electrophysiological recording has been validated. The electrode preparation method described herein is efficient and cost-effective. According to the experimental design, we could record signals from relevant brain regions. The strategic arrangement of optrodes allows for the potential extraction of abunda.......

Materials

Name	Company	Catalog Number	Comments
8-32 adapter	Plexon	Custom ordered	Connect the female connector and headstage
AAV-CaMKIIα-ChrimsonR-mcherry	Taitool Bioscience	S0371-9	4 x 1012 VG/mL
AAV-hsyn-Gcamp6m	Taitool Bioscience	S0471-9	4 x 1012 VG/mL
DAPI	Sigma	236276	Titered 1:500
Dental Cement	New Century Dental	430205
Electrophysiological recordings system	Plexon	Omniplex
Enameled wire	N/A	Custom ordered	Diameter = 0.2 mm
Female connector	N/A	Custom ordered	1.25 mm pitch
Glue	Loctite	45282
Laser	Changchun New Industries	BH81563	635 nm
MATLAB	MathWorks	R2021b
Microdrill	RWD	78001
Multichannel fiber photometry	ThinkerTech	FPS-SS-MC-LED
Optical fiber	Xi'an Bogao	L-200UM	Select the appropriate fiber length based on the depth of the targeted brain regions.
PFA-Coated Tungsten wire	A-M System	795500	Bare 0.002"; Coated 0.0040"
Power meter	Thorlabs	PM100D
Stereotaxic Fxrame	RWD	68807
Tissue adhesive	3M	1469SB