Recording Neural Activity of Unfolded Hippocampal Tissue Using Penetrating Microelectrode Array

Take a recording chamber containing the penetrating microelectrode array or PMEA, which records electrical signals from neural tissue.

Connect the inlet to bottles containing oxygenated aCSF and oxygenated aCSF with 4-aminopyridine or 4-AP using a trivalve connector.

Attach the outlet to a vacuum tube.

Heat the pipeline between the inlet and trivalve to physiological temperature.

With the inlet and outlet closed, transfer the unfolded hippocampus into the chamber.

Under a microscope, position the hippocampus on the PMEA.

Remove the solution from the chamber.

Place a tissue anchor to hold the tissue onto the PMEA electrodes.

Open the inlet and outlet to start the aCSF flow.

Incubate the tissue with aCSF to allow neuronal acclimatization.

Then, flow in aCSF with 4-AP. The 4-AP blocks the neuronal potassium channels, extending the action potential duration.

The PMEA captures the electrical signals proportional to the enhanced neural firing from hippocampal neurons.

In this procedure, fill one bottle with normal aCSF and another bottle with 4-AP aCSF. Bubble the solutions with 95% oxygen, 5% carbon dioxide from the beginning of the experiments. Use a trivalve connector to control which