Neuroscience: A racing heart may influence anxiety-like behaviour in mice
March 2, 2023
An increased heart rate is linked to an increase in anxiety-related behaviours in mice, according to a study published in Nature. The findings demonstrate how signals from the body may influence affective behaviours relevant to emotions such as anxiety and fear.
Emotional states influence how the body functions. For example, anxiety and fear can cause the heart to beat faster. However, whether the reverse may be true — an increase in heart rate might induce anxiety or fear responses — has remained an unanswered question. One of the major challenges for evaluating the effects of heart rates on emotions is that the researchers lacked a proper tool to precisely control the heart rate without causing side effects or introducing confounding factors.
Karl Deisseroth and colleagues developed a non-invasive optical pacemaker, which uses light signals to target heart muscle cells, that can increase the heart rate of mice to 900 beats per minute (bpm), compared to baseline heart rates of 660 bpm. The authors found that an optically induced increase in heart rate enhanced anxiety-like behaviours and fear in mice, but only in potentially risky environments. To investigate the underlying mechanisms of this effect, the authors scanned the brain for changes in activity. They identified the posterior insular cortex, a region in the brain that receives and processes signals from around the body, as a potential mediator for the anxiety-like and apprehensive behaviours that were induced by increased heart rates. Moreover, inhibition of the posterior insula cortex was found to reduce the anxiety-like behaviours induced by optical cardiac pacing.
“This is an unequivocal demonstration that, at least in mice, heart rate can affect anxiety, and can probably influence other emotional behaviours, too,” write Yoni Coudec and Anna Beyeler in an accompanying News & Views article. Further studies are needed to identify the long-term effects of increased heart rates on the brain and affective behaviours, and to explore potential translational and therapeutic applications of these findings.
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