GABAergic effects on the slow oscillatory neural activities in the procerebrum of Limax valentianus. Short communication.

We examined GABAergic modulation on "slow" oscillation (<1.0 Hz) of the procerebrum in the terrestrial mollusk, Limax valentianus. Short application of GABA-receptor agonists slightly increased the frequency of a periodic oscillation in the procerebrum, whereas persistent application decreased it. GABA-receptor antagonists decreased the oscillatory frequency. The GABA-like immunoreactivities were found in the neuropil and the cell body layers of the procerebrum. Because GABAergic inhibition is known to be essential for the generation of "fast" synchronous neuronal oscillation in the CNSs in othre many animals, our present findings are first evidence suggesting that GABA modulates 'slow' oscillation in the CNS.