A TISSUE recording chamber for very small volumes
Electrophysiological recordings from brain slices are typically performed in small recording chambers that allow for the superfusion of the tissue with artificial extracellular solution (ECS), while the chamber holding the tissue is mounted in the optical path of a microscope to image neurons in the tissue. Most existing recording chambers continuously add fresh or reconditioned ACSF through one port of the chamber, while removing an equivalent amount of spent ACSF through a second port. Whenever expensive chemicals have to be added to the bath solution such as pharmacological agents or caged compounds, experimenters reduce the total volume of ACSF required for the experiment as much as possible to save on costs associated with the experiments. We developed a novel tissue recording chamber that reduces the amount of ACSF required for proper function down to 1.5 to 2.5 ml total. This reduction is accomplished by eliminating all tubing and holding containers, and instead oxygenating the ACSF directly in the recording chamber. The chamber was developed over the course of about 2 years from the initial idea to the final design. Multiple designs were drawn up, tested as first via computer simulation and the then in actual prototypes, followed by further modification of the design.