High-Quality Seizure-Like Activity from Acute Brain Slices Using a Complementary Metal-Oxide-Semiconductor High-Density Microelectrode Array System

Summary

Here, we outline a protocol for using complementary metal-oxide-semiconductor high-density microelectrode array systems (CMOS-HD-MEAs) to record seizure-like activity from ex vivo brain slices.

Abstract

Complementary metal-oxide-semiconductor high-density microelectrode array (CMOS-HD-MEA) systems can record neurophysiological activity from cell cultures and ex vivo brain slices in unprecedented electrophysiological detail. CMOS-HD-MEAs were first optimized to record high-quality neuronal unit activity from cell cultures but have also been shown to produce quality data from acute retinal and cerebellar slices. Researchers have recently used CMOS-HD-MEAs to record local field potentials (LFPs) from acute, cortical rodent brain slices. One LFP of interest is seizure-like activity. While many users have produced brief, spontaneous epileptiform discharges using CMOS-HD-MEAs, few users reliably produce quality seizure-like activity. Many factors may contribute to this difficulty, including electrical noise, the inconsistent nature of producing seizure-like activity when using submerged recording chambers, and the limitation that 2D CMOS-MEA chips only record from the surface of the brain slice. The techniques detailed in this protocol should enable users to consistently induce and record high-quality seizure-like activity from acute brain slices with a CMOS-HD-MEA system. In addition, this protocol outlines the proper treatment of CMOS-HD-MEA chips, the management of solutions and brain slices during experimentation, and equipment maintenance.

Introduction

Commercially available high-density microelectrode array (HD-MEA) systems, which include an MEA chip with thousands of recording points^1,2 and an MEA platform to amplify and digitize the data, are an emerging tool for electrophysiological research. These HD-MEA systems use complementary metal-oxide-semiconductor (CMOS) technology to record electrophysiological data with high sensitivity from cell cultures and ex vivo brain slice preparations. These MEA systems afford unprecedented spatial and temporal resolution to neurophysiological research via high electrode density and quality signal-to-noise rati....

Protocol

Procedures involving mice were approved by the Institutional Animal Care and Use Committee (IACUC) at Brigham Young University. Male and female (n = 8) C57BL/6 mice aged to at least P21 were used in the following experiments.

Figure 1: Schematic figure of CMOS-HD-MEA experimentation. (A) The brain sl.......

Discussion

This protocol includes specific guidelines related to acute brain slice management that address common problems faced by CMOS-HD-MEA users, namely noise development under the brain slice and maintaining a healthy environment for the brain slice. Noise development under the slice occurs when the slice is not properly adhered to the array; if the brain slice is not adequately adhered, air pockets can form underneath the slice, which results in noise. This will result in the inability to acquire data. To mitigate these chal.......

Materials

Name	Company	Catalog Number	Comments
2D Workbench	Cloudray	LM04CLLD26B
4-Aminopyridine	Sigma-Aldrich	275875
Accura Chip	3Brain	Accura HD-MEA	CMOS-HD-MEA chip
Agarose	Thermo Fisher Scientific	BP160-100
Vibration isolation table	Kinetic Systems	91010124
Beaker for the slice holding chamber, 270 mL	VWR	10754-772
BioCam	3Brain	BioCAM DupleX	CMOS-HD-MEA platform
Brainwave Software	3Brain	Version 4	CMOS-HD-MEA software
Calcium Chloride	Thermo Fisher Scientific	BP510-500
Carbogen	Airgas	X02OX95C2003102
Carbogen	Airgas	12005
Carbogen Stones	Supelco	59277
Compresstome	Precissionary	VF-300-0Z
Computer	Dell	Precission3650
Crocodile Clip Grounding Cables	JWQIDI	B06WGZG17W
Detergent	Metrex	10-4100-0000
D-Glucose	Macron Fine Chemicals	4912-12
Dihydrogen Sodium Phosphate	Thermo Fisher Scientific	BP329-500
DinoCam	Dino-Lite	AM73915MZTL
Ethanol	Thermo Fisher Scientific	A407P-4
Forceps	Fine Science Tools	11980-13
Hot plate	Thermo Fisher Scientific	SP88857200
Ice Machine	Hoshizaki	F801MWH
Inflow and outflow needles	Jensen Global	JG 18-3.0X
Inline Solution Heater	Warner Instruments	SH-27B
Isofluorine	Dechra	08PB-STE22002-0122
Kim Wipes	Thermo Fisher Scientific	06-666
Magnesium Chloride	Thermo Fisher Scientific	FLM33500
Micropipets	Gilson	F144069
Mili-Q Water Filter	Mili-Q	ZR0Q008WW
Paintbrush	Daler Rowney	AF85 Round: 0
Paper Filter	Whatman	EW-06648-24
Parafilm	American National Can	PM996
Perfusion System	Multi Channel System	PPS2
Pipetor	Thermo Fisher Scientific	FB14955202
Platinum Harp	3Brain	3Brain
Potassium Chloride	Thermo Fisher Scientific	P330-3
Razor blade	Personna	BP9020
Scale	Metter Toledo	AB204
Scissors	Solingen	92008
Slice Holding Chamber	Custom	Custom	Custom 3D Printer Design, available upon request
Sodium Bicarbonate	Macron Fine Chemicals	7412-06
Sodium Chloride	Thermo Fisher Scientific	S271-3
Temperature Control Box	Warner Instruments	TC344B
Transfer Pipettes	Genesee Scientific	30-200
Tubing	Tygon	B-44-3 TPE
Vibratome VZ-300	Precissionary	VF-00-VM-NC
Weigh Boat	Electron Microscopy Sciences	70040