Figure 1.

Experimental setup and experimental paradigm description. (a) Mice were placed under a fluorescence microscope for virus injection in barrel cortex as well as during experiments to identify the expressing region in the somato-sensory cortex for placement of the photo-stimulation optic fiber (473 nm light delivery, blue cylinder) and laser Doppler flowmeter (LDF, red probe) for CBF measurements. LDF and the optic fiber were positioned at a 60° angle to facilitate placement under the microscope. (b) Sample image taken under green-yellow light (570 nm) of the mouse brain, while under the microscope illustrating virus injection as well as optic fiber and LDF probe placements (these took place separately during surgical preparation and experimental data collection, respectively). Whiskers were also stimulated by air puffs at 30 psi. (c) Description of the photo-stimulation and whisker-stimulation paradigm. Stimulation was delivered over D seconds every ISI seconds. Trains of stimulation pulses were delivered with duration (d), interval (I) and amplitude (A), repeated N times to match the stimulation period duration (D).