The highway of the brain: How does the uncinate fasciculus change with depression?
What is the uncinate fasciculus?
The nerve cells in the brain are said to number over 110 billion, counting the cerebrum and the cerebellum, and they process information rapidly.
Because the brain can process information rapidly like this, we know that it has an extremely effective network structure.
When we drive a long way, we usually use highways. On highways, we do not need to stop at traffic signals and can move around very efficiently. The brain also has pathways equivalent to highways, one of which is the uncinate fasciculus.
As you can see in the image, the uncinate fasciculus is like a broad main highway that links the frontal lobe and the temporal lobe.
How does depression change the uncinate fasciculus?
Depression does not just make the sufferer feel sad: they also have poorer memory and attention. So, how does depression change the uncinate fasciculus?
The paper I discuss today investigates the relationship between major depressive disorder and the uncinate fasciculus. In the experiment, 18 participants with major depressive disorder and a control group of 24 healthy participants were shown emotional images and their brain activity was measured closely using functional magnetic resonance imaging (fMRI). The results showed:
- in participants with major depressive disorder, the part equivalent to the uncinate fasciculus was structurally weaker than in the control group; and
- in participants with major depressive disorder, the functional connections in the part equivalent to the uncinate fasciculus were stronger.
These results appear to contradict each other.
In other words, the results showed that the uncinate fasciculus was structurally weaker but transmissions of information were more active, and the authors hypothesized that the reason for this outcome could be that people with major depressive disorder have stronger functional connections to make up for the structural weakness.
I thought that the brain is well made, and also that the reason you get worn out just from everyday life when you have depression could be because the brain is using all its strength to keep everything balanced, despite the structural weakening.
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see also: Relation between structural and functional connectivity in major depressive disorder.
