Assessing the Effects of Toxins on Chick Embryo Neural Network Development Using Multielectrode Arrays

Abstract

Source: Sanchez, K. R., et.al. Assessment of the Effects of Endocrine Disrupting Compounds on the Development of Vertebrate Neural Network Function Using Multi-electrode Arrays. J. Vis. Exp. (2018).

This video demonstrates the use of multi-electrode arrays (MEA) to study the effects of toxins on early embryonic chick neuronal cultures. By monitoring the synchronous activity of the neurons in the neuronal network, the MEA captures the functional dynamics of the neuronal network in response to toxin exposure. Reduced synchrony and firing rates upon toxin exposure highlight its detrimental impact on neuronal network maturation and function.

Protocol

1. Recording Neuronal Network Activity

1. On the day of acquisition, exchange the culture medium with fresh neurobasal medium and return the MEAs to the CO₂ incubator for a minimum of 2 h before recording. Start the recording software and set the temperature of the MEA to 37 °C by clicking on the temperature icon.
   NOTE: Recording can begin as early as day 3 of plating and can continue as long as the cultures are alive.
2. Set up the acquisition parameters by right-clicking on the "Muse" icon (under Streams in the left window panel) and select "Add Processing" and "Spike Detector" and click OK in the pop up window. "Spike Detector (6 x STD)" will appear below the file name.
3. Next right click on the Spike Detector, select "Add Processing" and "Burst Detector" and click OK in the pop up window. "Burst Detector" (ISI) will appear below the Muse icon.
4. Next right click on Burst Detector, select "Add Processing" and "Neural Statistics Compiler." In the pop up window, ensure that File Header, Aggregated Well Statistics and Synchrony are selected. Click OK. "Statistics Compiler" will appear below.
   NOTE: This will set the adaptive threshold crossing (6x STD filter), the inter-spike interval at 100 ms with a minimum number of spikes at 5, the mean firing rate detection at 10 s with a synchrony parameter at 20 ms, and the minimum spike rate at 0.083333 spikes per min.
5. Set up the scheduled recording for the recording time of 5 minutes (300,000 ms) by clicking on the clock icon at the bottom. This is achieved by changing the information in the setting section to record every 5.1 minutes and record for 5 minutes. This will be started immediately and will be executed once.
6. Ensure that the temperature of the MEA has reached 37 °C before moving the MEA. Remove the MEA from the incubator, place it on the recording unit, and lock down the MEA. Start recording the network activity by clicking on the start record in the scheduled recording section or the record icon in the "File Play" window. Typically, a recording time of 5 minutes (300,000 ms) is sufficient, although longer recordings of up to 10 minutes can be obtained.
7. After recording, return the MEA to the incubator.
   NOTE: Care must be taken to maintain sterility and to minimize the time the MEA is outside the incubator.

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Axion Muse MEA	Axion Biosystems	M64-GL1-30Pt200	Will be called MEA system in manuscript
Axis Software	Axion Biosystems		Will be called recording software in the manuscript
BPA	Sigma-Aldrich	239658-250g
EtOH	Sigma-Aldrich	64-17-5
Neurobasal medium	BrainBits	Nb4-500
Neuroexplorer statistical software	Nex Technologies	Neuroexplorer version 5