After single-neuron data collection, the probe and underlying PTV were cooled (within 2 min) to 10°C and kept at this temperature throughout the period (15–18 min) of repeated data collection. Subsequently, the probe and underlying PTV was rapidly (~2 min) rewarmed back to 36°C. Then at set times (10, 30, 45 and if necessary 60 min) after rewarming PTV covering probe to 36°C, the same tests were repeated again.