Figure 1.

Initial sensitivity to thermal stimulation. Thermal sensitivity was assessed in adult (12–16 months old) and aged (27–31 months old) rats. During 600-second sessions, the duration of time spent on either the 30°C or “comparison” floor plate was determined. The figure shows the time spent on the “comparison” plate as a function of that temperature. In general, the intermediate temperatures resulted in near equal times (∼300 seconds) spent in each compartment (ie, there was no preference). As the temperature of the floor plate increased or decreased, less time was spent in that compartment (ie, the temperature was aversive). Brackets indicate an overall significant main effect of age; * indicates a significant difference from 27°C; and + indicates a significant difference from 33°C.