An international group of neuroscientists from Sweden and Brazil has found that some cells in a brain area called hippocampus play a key role in risk-taking behavior and anxiety.
Microscopy image of OLM cells. Scale bar – 20 µm. Image credit: Mikulovic et al, doi: 10.1038/s41467-018-05907-w.
The team, led by Uppsala University researcher Dr. Sanja Mikulovic and Dr. Richardson Leao, a scientist in the Brain Institute at the Federal University of Rio Grande do Norte, found that brain cells known as oriens-lacunosum-moleculare (OLM) interneurons, when stimulated, produce a brain rhythm that is present when animals feel safe in a threatening environment.
The researchers also showed that anxiety and risk-taking behavior can be controlled by the manipulation of OLM cells.
“To find a pathway that quickly and robustly modulates risk-taking behavior is very important for treatment of pathological anxiety since reduced risk-taking behavior is a trait in people with high anxiety levels,” they said.
“Adaptive (or normal) anxiety is essential for survival because it protects us from harm. Unfortunately, in a large number of people, anxiety can be dysfunctional and severely interfere with daily life.”
“In these cases, doctors often rely on antidepressants to help patients recover from the dysfunctional state. However, these drugs act in the entire brain and not only in the areas where it is needed and may therefore have severe side-effects.”
“Thus, to act in a single brain region and in a very specific group of cells to control anxiety may be a major breakthrough in treating anxiety and associated disorders like depression.”
Another interesting finding in the study is that OLM cells can also be controlled by pharmacological agents.
In the past, the same team found that OLM cells were the gatekeepers of memories in the hippocampus and that these cells were very sensitive to nicotine.
“This finding may explain why people binge-smoke when they are anxious,” Dr. Leao said.
“It is fascinating how different regions of the same brain structure control distinct behaviors and how they interact with each other,” Dr. Mikulovic said.
“Identifying specific circuits that underlie either cognitive or emotional processes is crucial for the general understanding of brain function and for more specific drug development to treat disorders.”
“The discovery of these neurons and their role in anxiety and risk-taking may open a path for the development of highly efficient anxiolytics and antidepressants without common side-effects, such as apathy.”
The results appear in the journal Nature Communications.
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Sanja Mikulovic et al. 2018. Ventral hippocampal OLM cells control type 2 theta oscillations and response to predator odor. Nature Communications 9, article number: 3638; doi: 10.1038/s41467-018-05907-w
