Skip to main content
. 2012 Apr 30;7(4):e36203. doi: 10.1371/journal.pone.0036203

Figure 8. Temporal course of amplitude changes in CAP, CM and ACEP before, during and after auditory cortex cooling at 8° and 4°C with cryoloops.

Figure 8

In this experiment 3 kHz stimuli were presented at different sound pressure levels, represented by symbols sizes increasing in 10 dB steps from 40 to 90 dB SPL. Light blue and cyan shaded areas illustrate periods of cortical cooling at 8° and 4°C respectively. A. Cochlear potentials amplitude changes. Note that there is a significant reduction in CAP and CM amplitudes (F = 113.74, p<0.001 and F = 40.55, p<0.001 respectively) at 8° and 4°C. Tukey post-hoc test revealed CAP amplitude differences between the four periods studied (baseline, cooling at 8°, at 4°, and recovery), but, in the case of CM amplitude changes, only for baseline against all other periods. After turning off the cryoloop pump, there was a recovery of CM for responses obtained at 80 and 90 dB SPL. In all other cases, the amplitudes of cochlear responses remained reduced even two hours after the cerebral blood flow restored the normal auditory cortex temperature (passive warming). B. ACEP amplitude changes. Note that auditory cortex cooling at 8°C was sufficient to reduce auditory-cortex potentials. Cooling at 4°C produced a greater decrease in cortical evoked potentials, and fifty to sixty minutes after the end of cortical cooling there was a complete recovery of ACEP amplitudes.