Cholinergic modulation of the locomotor network in the lamprey spinal cord.

Acetylcholine (ACh) was found here to be a strong modulator of swimming activity in the isolated spinal cord preparation of the adult lamprey (Ichthyomyzon unicuspis). During fictive swimming induced with either D-glutamate or N-methyl-D-aspartate, addition of ACh (200 microM) significantly reduced the cycle period of ventral root bursts to 54%, intersegmental phase lag to 32%, and ventral root burst proportion to 80% of control levels. Effects of ACh were apparent at concentrations as low as 1 microM.