A side-by-side comparison of blood flow in a healthy mouse brain vs. a mouse brain exposed to cocaine. The image on the left (a) shows the mouse brain blood vessels before cocaine. The image on the right (b) shows the blood vessels after, revealing that many of the vessels are now darker, which signifies lower blood flow. FOV:1.2 x 2.0 x1.0 mm3. Credit Biomedical Optics Express.