Observing neural signals in real time offers an important
glimpse into how brains perceive the outside world. In the new
study, researchers developed a way to follow these signals in
the brain of a zebrafish larva, using a sensitive fluorescent
marker. "It's a breakthrough," molecular and cell biologist
Florian Engert of Harvard University, who was not involved in
the study, told LiveScience. "No one else can look at neuronal
activity with fluorescence microscopy in a freely swimming
zebrafish larva" with such good resolution. Zebrafish are widely
used to study genetics and development in vertebrates. Their
larvae are ideal for neuroimaging because they have translucent
heads, and scientists can literally peer into their brains. To
see what was actually going on in those fish noggins,
researchers developed a genetically engineered protein, called
GCaMP7a, that lights up under a fluorescent microscope when
neurons, or brain cells, fire. Transgenic zebrafish were bred to
express this protein in a brain region c