Background and aims: The method of limits (MLi) is the most commonly used paradigm to measure the threshold of thermal stimuli. However, the measured threshold in MLi is reaction time (RT) dependent and may induce an overestimation of the thermal threshold in the elderly. The use of the method of levels (MLe), a method independent of RT would be more suitable for evaluating thermal threshold in the elderly. The purpose of the present study was to provide a new comparison of the two methods (MLi and MLe) of measuring the cold perception threshold in the elderly, using a high-speed (300°C/sec) thermal stimulator.
Methods: Eleven elderly subjects and 14 younger adults were recruited for this study. In the MLi session, we used two experimental conditions, referring to 2 cooling ramps: 2°C/sec and 4°C/sec. In the MLe session, we defined three experimental conditions, regarding the duration of stimulation: 50, 100, 300 ms.
Results: Results showed that the MLe method allows a threshold measurement accuracy gain greater than 2°C compared to the MLi in the elderly. In addition, our data with the MLe confirm the existence of a change in the cold perception threshold with age, but this modification seems less important than that measured with MLI. 
Conclusions: The use of MLe with high cooling rate opens new perspectives for the study of mechanisms underlying the alteration of thermal perception with age, including in pain perception.

STUDY OF THE EFFECTS OF THERMOSENSORY AGING BY COLD STIMULATIONS WITH HIGH TEMPORAL RESOLUTION