Figure 4. Effects of temperature in the barrel cortex of awake mice imaged through a reinforced thinned skull.

(a) Left, schematics of the preparation. The thermosensor was placed in the cortex superficial layers (II to IV). Right, the sensor core and tips (white arrow and arrow head, respectively) are observable as a dark shadow below the bone and the surface vessels, that were injected with texas red and imaged through the reinforced thinned-skull with a stereoscope. (b) Imaging with the cool water immersion objective causes a decrease of brain temperature (T°b2), which partially recovers upon heating the objective (T°b3). (c) Resting Po2, blood flow and velocity increase upon heating the objective (velocity, n = 8 capillaries, four mice; blood flow and Po2, n = 6 capillaries, three mice). See Materials and methods for the statistical tests. **, *** for p<0.01, 0.001, respectively.