Journal of Neuroscience, Vol 4, 659-672, Copyright © 1984 by Society for Neuroscience
Optical measurements of potential changes in axons and processes of neurons of a barnacle ganglion
WN Ross and V Krauthamer
Optical techniques using voltage-sensitive dyes were used to record
electrical events simultaneously from many positions on certain neurons of
the barnacle supraesophageal ganglion. By signal-averaging, recordings with
good signal-to-noise ratios and time resolution were obtained from fine
dendritic processes as well as the axon and cell body. Controls established
that the optical signals faithfully matched recordings made with
intracellular electrodes for short times (5 to 10 msec), but deviations
were observed at longer times. Pharmacological effects and photodynamic
damage due to the dye were insignificant. The optical records were
correlated with positions on the stimulated cell determined from Lucifer
Yellow injections. This comparison demonstrated that signal-averaged
records with large signal-to-noise ratios were obtained from those parts of
the visual field which contained elements of the stimulated cell and hence
could be attributed to specific locations on the cell. The quality of the
optical signals were adequate to: (a) determine variations in the shape of
action potentials in different parts of the cell; (b) demonstrate
electrotonic spread of hyperpolarizing pulses; (c) determine the direction
and velocity of action potential propagation, and (d) in some
circumstances, using reasonable assumptions, estimate variations in the
amplitude of action potentials or electrotonic pulses in different regions
of the cell.