Pound for pound, the brain consumes vastly more energy than other organs, and, puzzlingly, it remains a fuel-guzzler even when its neurons are not firing signals called neurotransmitters to each other. Now researchers at Weill Cornell Medicine have found that the process of packaging neurotransmitters may be responsible for this energy drain.

In their study, reported Dec. 3 in Science Advances, they identified tiny capsules called synaptic vesicles as a major source of energy consumption in inactive neurons. Neurons use these vesicles as containers for their neurotransmitter molecules, which they fire from communications ports called synaptic terminals to signal to other neurons. Packing neurotransmitters into vesicles is a process that consumes chemical energy, and the researchers found that this process, energy-wise, is inherently leaky—so leaky that it continues to consume significant energy even when the vesicles are filled and synaptic terminals are inactive.

These findings h ...

...