Fig. 1. (A) The neuronal conduction velocity of axons in the leg nerves of marine crustaceans increases with temperature. Electrical stimulation of the leg nerve at a proximal site produces a stimulus artefact (black arrowheads), and compound action potentials recorded at a distal site, the most rapid of which are indicated by open arrowheads. Traces are aligned to the stimulus artefact, indicated by the first broken line in each block. The first peak of the compound action potential occurs sooner as temperature increases (second broken line). Scale bar, 5 ms. (B,C) Increasing the stimulation voltage reveals a sharp threshold for eliciting a compound action potential (B), which does not change with temperature(C). Increasing the stimulus voltage further results in only a modest increase in the measured conduction velocity (B). The arrow indicates 130% of threshold, which is the stimulation level used throughout this study. Data in B are from one experiment in G. antarcticus. Data in C are from five experiments in G. antarcticus, denoted by different symbol types. Regression equation: y=–1.93x10^–3x+1.266, r²=0.033, P=NS.