One of my favorite organs in the human body is the brain. It is a marvelous creation, firing electrical impulses at a 100 m/s and essentially controlling the functioning of the entire corps. But there is an issue that comes with the magnitude of this organ- something that has stumped researchers for ages. Why does the brain require so much energy at rest?
Researchers at Weill Cornell Medicine may have just figured out the answer to this question. While the brain reduces its capacity to 50% when at rest, this value is still higher than all other organs. The primary consumers of this energy are neurotransmitters. Neurotransmitters are chemicals released by neurons into the synaptic cleft (the junction between 2 neurons) and are responsible for the transmission of electrical impulses. The mode of action that these neurotransmitters adopt requires a great deal of energy- exocytosis. This involves the membrane forming a vesicle around the neurotransmitter and releasing it into the synapse. This process requires energy. But how does this answer the question at hand?
Turns out that the process is inherently leaky- energy-wise. This means it continues to consume energy even when the vesicles are replenished and synaptic terminals are dormant. This also explains why we feel 'brain-dead' when we have a limited fuel supply. So how does this work? The novel study shows that the vesicles are pre-filled during inactivity and prepared to release them into the synapse during transmission. To maintain these vesicles proton pumps, are required. This is a form of active transport, which requires energy. This mechanism allows for a speedier reaction when in use, as now a lower threshold potential needs to be achieved to bring about an action.
This research gives great insight into understanding the functioning of the human brain. Moreover, it opens up another door for understanding neurodegenerative diseases such as Parkinson's and Alzheimer's diseases, both of which reflect metabolic deficiencies.
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