Transparent Zebrafish Shed Light on Brain Activity

To date, measuring neuronal activity in a large region of nerve cells simultaneously has been a significant stumbling block to understanding the inner workings of the brain. In order to overcome this problem researchers at Harvard University and the University of Cambridge have developed a novel technique to measure the simultaneous activity of up to 2,000 neurons in zebrafish at the resolution of individual cells.

In order to perform their experiments the team modified the genetic configuration of transparent zebrafish, causing their neurons to fluoresce when active. Owing to the transparency of the zebrafish, the research team was able to image this fluorescent neuronal activity using a scanning electron microscope.

The experimental setup was used to test the hypothesis that zebrafish adapt their behavior in response to changes in their environment, the results of which have been published in the journal Nature. Dr. Misha Ahrens, one of the lead investigators on the study, explains:

“The paralyzed fish in the virtual world do indeed adapt their behaviour, by adjusting the amount of impulses the brain sends to the muscles. They also ‘remember’ this change for a while. Imaging the brain everywhere during this behaviour, we identified certain brain regions that were involved, most notably the cerebellum and related structures. This technique opens the possibility that eventually, the behaviour may be used to gain insights into human motor control and motor control deficits.”

While the zebrafish model is a simplified version of functioning of the human brain the researchers believe that the new technique will go a long way towards illuminating the inner workings of the human brain.

Study abstract in Nature: Brain-wide neuronal dynamics during motor adaptation in zebrafish