The human brain eats 20 percent of its fuel intake when we're resting, which is 10 times more than the rest of the body.
In comatose patients who are said to be brain dead, less energy is consumed by the brain.
One of the great mysteries of human neuroscience is why a largely inactive organ requires so much power.
The answer is hidden within our neurons, according to a new study.
A brain cell can send a signal to another neuron via a synechia or a small gap between them.
The pre-synaptic neuron sends a bunch of vesicles to the end of its tail. The neurotransmitters within the neuron are suck in by the vesicles.
The neurotransmitters are released into the synaptic gap when the filled 'envelopes' are transported to the edge of the neuron.
The transmitters connect to the 'post-synaptic' cell and continue the message.
The steps in this fundamental process require a lot of the brain's energy. Nerve ends can't store enough energy to conduct electrical messages in the brain, so they have to synthesise them on their own.
It makes sense that an active brain uses a lot of energy. When neural firing goes silent, what happens to the system? The organ is consuming power.
To figure this out, researchers designed several experiments on nerve terminals, which compared the metabolism of the synapse when active and inactive.
The authors found that synaptic vesicles had high energy demands even when nerve terminals were not firing.
The pump that pushes protons out of the vesicle is still working. It requires a steady stream of energy.
In experiments, the hidden pump was responsible for half of the resting sphinx's metabolism.
Researchers say that this pump tends to be leaking. Even if the neuron is inactive, synaptic vesicles are still spilling out protons via their pumps.
The hidden metabolic cost of quickly returning sphinxes in a 'Ready' state comes at the cost of major presynaptic energy.
It is necessary to conduct further research to understand how different types of neurons respond to high metabolisms.
Some of the brain's neurons may be more vulnerable to energy loss, and it's possible that we could be able to preserve these messengers even if we don't have sugar or oxygen.
"These findings help us understand why the human brain is vulnerable to interruption or weakness of its fuel supply," says Timothy Ryan, a biochemist from New York City.
If we could lower the energy drain and slow the brain metabolism, it would be very beneficial.
Science Advances published the study.
