OPTICAL RECORDING OF NEURONAL ACTIVITY IN ORGANOTYPIC SLICE CULTURES

Previously, multi-site recordings of neuronal activity using voltage-sensitive fluorescent dyes have been obtained from a variety of preparations. We report here the application of this technique to organotypic cultures of rat hippocampus and cerebellum. These cultures offer unique opportunities since optical signals with a high signal-to-noise ratio could be recorded from single neurons which were integrated in complex synaptic networks.

For optical mapping with high temporal resolution (0.2 ms), a 10 x 10 photo-diode array was used. With this detector, we recorded synaptically evoked activity from single cerebellar Purkinje cells and population responses from the more densely packed hippocampal pyramidal neurons using dye RH 414.

Optical imaging with high spatial resolution (256 x 244 points) was achieved with a charge coupled device (CCD). At present, the temporal resolution of our CCD detector is too low (20 ms) to resolve single action potentials. The CCD allows, however, mapping of slow synaptic potentials, while their time course could be recorded with the diode-array.

This work shows that using a combination of diodes and a CCD allows recording with high temporal, as well as spatial, resolution neuronal activity in organotypic slice cultures.