NEURODEVELOPMENT

Asymmetrical circuits reduce anxiety

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Science  01 Jan 2016:
Vol. 351, Issue 6268, pp. 38-39
DOI: 10.1126/science.351.6268.38-d

Brain asymmetry regulates anxiety in zebrafish

PHOTO: MARK SMITH/SCIENCE SOURCE

Although fish are overall bilaterally symmetrical, the devil is in the details. For instance, in zebrafish, a part of the forebrain called the epithalamus exhibits asymmetry. However, this orientation is reversed in the brains of a small percentage of zebrafish. Facchin et al. asked whether this matters to the fish. They found that fish with brains of the minority configuration showed signs of increased anxiety when compared to their majority-configuration siblings. But their brains were not simply flipped. Within the epithalamus, neuronal axons projected in unusual patterns. The results suggest that asymmetries in how the brain processes rewards and aversions may favor neuronal circuits to organize in one way over another.

J. Neurosci. 35, 15847 (2015).

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