Intracellular recording of He-Ne laser effect on motoneuron action potential duration in crayfish

The motoneurons of crayfish were investigated for reactions to He-Ne laser energy in an attempt to artificially produce action potentials. Intracellular recordings were obtained in 18 motoneurons from 13 crayfish. Low level laser energy (LLLE) was directed via fiber optic material onto the ventral nerve cord motoneurons (VNC). The VNC was used as a system analogous to vertebrates. The recordings from spontaneously active motoneurons were evaluated on the basis of duration of synaptic potentials and reaction to laser energy. No action potentials were obtained at the amplitude of laser energy used. Significant increases in duration of synaptic potentials illustrated a stimulatory effect on the VNC motoneurons. The increase in synaptic potential duration suggest that laser energy effects changes in the cell membrane potentiating the ion channel activity of the motoneuron. Selective stimulation of motoneurons above 3.5 mW may produce action potentials