THE EFFECTS OF ACETYLCHOLINE, DOPAMINE AND NORADRENALINE ON THE VISCERAL GANGLION OF HELIX-POMATIA .2. STIMULUS EVOKED FIELD POTENTIALS

1. Neurophysiological effects of acetylcholine (ACh), dopamine (DA) and noradrenaline (NA) on stimulus evoked field potentials in the Helix pomatia visceral ganglion were investigated. Electrical stimuli were applied to nerve trunks. 2. For frequency analysis of evoked potentials (EPs) the Fourier transform was performed. For quantification of pre- as well as poststimulus activities, root-mean-square (RMS)-voltages of digitally filtered signals were used. 3. ACh at 10(-4)-10(-3) M selectively enhances the 4-15 Hz as well as the 30-70 Hz components and DA at 10(-5)-10(-3) M increases the 30-70 Hz activity. NA at 10(-5)-10(-4) M augments the 15-30 Hz response and only at 10(-5) M increases the 30-48 Hz response. 4. All transmitters at 10(-2) M show a strong tendency to suppression. 5. Prestimulus activities of ACh and DA are damped by 40-50% compared to the ongoing induced activities in the non-stimulus study (cf. Part I). These damped prestimulus activities may be considered as a late part of the prolonged evoked activity. 6. The 4-15, 15-30 and 30-70 Hz responses selectively increased by the transmitters may be compared to theta-alpha combined rhythm, beta-rhythm and 40 Hz rhythm in the mammalian EEG.