Mitochondria are known as the power plants that keep cells running. In the brain, where neurons are powered by mitochondria, mapping the location of mitochondria can reveal how they support brain function. A new study from Yale, published in the journal Science, shows that mitochondria are organized inside neurons in patterns that reflect not just the neuron’s type but also which neurotransmitter it uses and how it connects to larger brain circuits.
For the study, a research team led by the lab of Yale’s Damon Clark used what is known as a connectome dataset — an ultra-detailed electron microscopy map of a large brain region that shows how neurons are wired together while also revealing each neuron’s internal anatomy. By applying a massive fruit fly dataset of about 25,000 neurons, the team was able to measure hundreds of thousands of mitochondria across neural networks throughout the fly brain.
They found that mitochondria aren’t randomly scattered inside neurons. Their placement, size, shape, and complexity differ depending on the neuron’s type and the neurotransmitter it uses. Later, researchers found that what held true in the fruit fly brain held up when researchers looked for the same patterns in a mouse data set.
Together, the findings suggest that mitochondria shape and location are tightly linked to circuit structure. They’re built precisely into the logic of neural circuits and offer a new window into understanding how brain circuits are organized, the researchers said.
“One thing that made this research possible was just the massive amount of structural data, which allowed us to connect mitochondrial organization to many different aspects of circuit structure in the brain,” said Clark, the study’s senior author and a member of Yale’s Faculty of Arts and Sciences (FAS) who is a professor of molecular, cellular and developmental biology and of physics and of neuroscience.