Shining a Light on the Brain

©2004 Elsevier Science

Scientists can now watch the mouse brain in action thanks to a new technique that lights up specific populations of neurons as they fire.¹ Because the fluorescent marker responsible is genetically encoded, it now will be possible to follow an animal throughout its life to see how activity changes during development and learning, says neurobiologist and coauthor Matt Wachowiak of Boston University.

Wachowiak and colleagues targeted a pH-sensitive fluorescent marker called synapto-pHluorin (spH) to the synaptic vesicles of mouse olfactory neurons. These neurons send information to the olfactory bulb through vesicular neurotransmitter release. Because they are acidic, these vesicles remain dark until neurons are activated and their contents are disgorged into the extracellular space, where the higher pH activates the marker's fluorescence. Exposing the mice to scents caused parts of the olfactory bulb to light up; the pattern of fluorescence depended on what the animal...