The membrane chamber: a new type of in vitro recording chamber.

In vitro brain slice electrophysiology is a powerful and highly successful technique where a thin slice is cut from the brain and kept alive artificially in a recording chamber. The design of this recording chamber is pivotal to the success and the quality of such experiments. Most often one of two types of chambers is used today, the interface chamber or the submerged chamber. These chambers, however, have the disadvantage that they are limited in either their experimental or their physiological properties respectively. Here we present a new working principle for an in vitro chamber design which aims at combining the advantages of the classical designs whilst overcoming their disadvantages. This is achieved by using a semipermeable membrane on which the slice is placed. The membrane allows for a fast flow of artificial cerebrospinal fluid of up to at least 17 ml/min. Due to a Bernoulli effect, this high speed flow also causes a 64% increase in flow of solution across the membrane on which the slice rests. The fact that the membrane is transparent introduces the possibility of wide field inverted optical imaging to brain slice electrophysiology. The utility of this setup was demonstrated in the recording of local field potential, single cell and voltage sensitive dye imaging data simultaneously from an area smaller then 1/8mm(2). The combination of all these features in the membrane chamber make it a versatile and promising device for many current and future in vitro applications, especially in the regard to optical imaging.