Calcium makes a fast getaway

Dendrites are like a busy phone exchange. A single neuron can have thousands of synapses talking to its dendrites. Some dendrites are able to separate the input from neighboring synapses with spines that act as morphological barriers of synaptic input by restricting calcium diffusion. Many neurons lack spines, however, thus causing speculation that these dendrites might lack synaptic specificity. But Jesse Goldberg, Rafael Yuste (Columbia University, New York, NY), and colleagues now show that these aspiny dendrites are able to compartmentalize—by restricting calcium domains in space and time.

The group imaged calcium dynamics in aspiny dendrites, where synaptic activation created a fast, short-lived, and highly localized calcium influx. However, they saw no morphological structures that could contain the signal. Rather, says Goldberg, “the key to localization is fast...