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Abstract:
We describe a method for the preparation and maintenance of the blowfly (Calliphora erythrocephala) brain in a recording chamber under in vitro
conditions in a semi-slice configuration. Large identified neurones in the posterior part of the 3rd optic lobe (lobula plate) can be penetrated easily with
microelectrodes. The so-called vertical system (VS) cells which respond to vertical image motion in vivo could be encountered best because their axons are
escorted individually by specific tracheae. Fluorescent stained cells show their natural shape as being in vivo. Electrophysiological properties of the cells
investigated so far, i.e., resting potential (about -40 mV) and firing properties (single rebound spikes), are comparable to recordings in intact flies. Initial
pharmacological experiments on VS cells in this preparation reveal that iontophoretical application of acetylcholine and carbamylcholine results in
depolarization. VS cells also respond to bath-applied nicotine (1 mu M) with a slow depolarization of their membrane potential in normal fly saline as well as
in a Ca2+-free saline, suggesting direct cholinergic input via nicotinic receptors. The suitability of the preparation for a wide range of electrophysiological
and pharmacological studies is discussed.
