Microelectrode Array-Based Assessment of Neuronal Networks in Mouse Spinal Cord Slices

To begin recording dorsal horn activity, transfer the slice from the incubator to the MEA well using a large-tip tip Pasteur pipette filled with artificial CSF, and add additional artificial CSF.

Use a fine, short-hair paintbrush to position the slice over the 60-electrode recording array. Then, place a weighted net over the tissue to hold it in place and promote good contact with MEA electrodes.

Place the MEA in the recording head stage. Check the position of the tissue over the electrodes using an inverted microscope to confirm that as many electrodes as possible are under the superficial DH. Ensure that at least two to six electrodes do not contact the slice.

After connecting the camera to the device, take a reference image of the slice relative to the MEA for use during the analysis. Then, press Start DAQ in the recording software and confirm that all electrodes receive a clear signal.

Next, attach the perfusion inlet and outlet lines to the MEA well filled with artificial CSF, and turn the perfusion system on. Check the flow rate and ensure that the outflow is sufficient to prevent overflow of the superfusate. After equilibrating the tissue for five minutes, record the raw baseline data for five minutes.

Move the perfusion inlet line from artificial CSF to a 4-aminopyridine solution, and wait for 12 minutes for the 4-aminopyridine-induced rhythmic activity to reach steady state. Then, record five minutes of 4-aminopyridine-induced activity, and be prepared for the subsequent recordings to test the drugs or check the stability of 4-aminopyridine.