Optical physiology in living fish

 

Imaging activity: The transparency of the zebrafish offers a unique opportunity to study the activity of neurons in the living animal during behavior. By filling the nerve cells with fluorescent calcium indicators, which increase in brightness as calcium flows into electrically active nerve cells, we can literally watch the neurons light up when they are active. The movie shows a series of images of a nerve cell in spinal cord that is activated during an escape produced by a touch on the head of the fish. The brightness of the neuron is color coded, with the cell turning more red when it is electrically active in association with the movement of the escape.

 

 

Imaging molecules: One of the key features of the nervous system is the ability to change the strength of the connections between nerve cells. These changes are essential, as they alter the wiring, and are the foundation for our ability to learn and remember. The changes are accomplished by molecules that move around inside the cells to alter the strength of the synapses -the connections between neurons.

We have tagged these molecules with a fluorescent marker, which allows us to watch the molecules move to the locations of synaptic connections as they play their roles in altering the strength of the connections. The movie shows the accumulation of one of these molecules, calcium calmodulin dependent protein kinase II, at synapses on a process (dendrite) of a neuron in a living fish. The accumulations, which are the green patches, occur in response to a stimulus on the skin, which activates connections onto the neuron. The ability to watch movements of molecules in living animals offers the possibility to link molecular events to changes in synapses, circuits, and behavior, which is a major goal of neuroscience.