Gadgets Manual

The PSMI Patch Slice Micro-Incubator is a unique environmental control unit that with its matching temperature controller (TC-202A) enables patch clamp recordings to be made from a brain slice using an upright microscope with water immersion objective.

Tissue slices (principally from the brain) are increasingly being used for electrophysiological and optical studies. Although this preparation offers an environment in which the majority of synaptic connections are maintained, less consideration has been given to the microscope’s environment where experimental examination takes place. One reason for this is the design problem associated with providing environ- mental conditioning, without limiting optical or electrode access or reducing the quality of any electrical recordings. This problem is acute with “patch slice recording” in which a water immersion microscope objective is used. The recording and cleaning pipettes need access at very shallow angles with respect to the horizontal axis, and continuous perfusion is required to maintain oxygenation within the slice.

The PSMI permits control of temperature of both a perfused liquid and overlying gaseous medium for the submerged tissue slice. Application of drugs or a change in the ionic composition is achieved without disturbing the set temperature or any electrodes. The tissue chamber for the PSMI is the PS-CSD with two replaceable 22 mm diameter cover slips, one for the floor of the slice chamber and one below it to prevent condensation that would otherwise block/distort condenser illumination from below.

The PSMI uses Peltier devices to drive the heat exchange. APPENDIX 3 describes their operation and identifies their advantages in this application. The design of the PSMI avoids the normal need for Peltier cooling water except at the lowest control temperatures.

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