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Thermal stimuli were applied to the upper surface of the tongue of the cat. The stimuli ranged from 40°C to 10°C and were changed in cold steps of 5°C, each temperature lasting 2 min. Afferent impulses of single specific cold fibers from the lingual nerve were analysed by a computer program. About 90% of the fibers showed bursts under static conditions. The bursts began as doublets at the temperature of maximal average frequency. This temperature varied from 40°C to 15°C in different fibers, the average being 30°C. The parameters burst period, burst duration, pause duration, intraburst interval and spikes per burst increased monotonically from 30°C to 15°C. The possible physiological significance of the burst pattern is discussed.

Static and dynamic discharge patterns of bursting cold fibers in the lingual nerve of the cat were analysed at temperatures between 10 and 40°C. The period of the static burst discharge depends only on temperature and is not affected by the number of spikes per burst. The termination of an intraburst sequence of impulses can be predicted by the duration of the intraburst intervals. Irregular impulse patterns at low static temperatures show a unimodal interval distribution, whereas the interval histograms from irregular spike sequences at high temperatures have multiple peaks with nearly equal distances.