Washington, March 3 : The brain and the heart can work in tandem to produce anxiety, according to a new mice study. The study, published in the journal Nature, detangles the link whether emotions drive bodily functions or vice versa. It showed that while fear and anxiety can make your heart beat faster, the reverse is also true. To understand, the team increased the heart rate of a mouse. The results showed that speeding up a mouse's heart rate made otherwise calm animals act more anxious. The finding suggests that lowering heart rate may be a way to treat mood disorders such as anxiety and depression. Karl Deisseroth, a neuroscientist at Stanford University in California and his colleagues bioengineered mice to make muscle cells in the rodents' hearts sensitive to light. The team also designed tiny vests for the animals that emitted red light, which could pass through the rodents' bodies all the way to their hearts. When a mouse's vest emitted a pulse of light, the animal's engineered heart muscles fired, causing the heart to beat. The team trained the animals to expect a shock if they pressed a lever for a water reward. Using the optogenetic system, the team raised the animals' heart rates from their normal 660 beats per minute to 900. When their hearts started racing, mice became less willing to press the lever or to explore open areas, suggesting that they were more anxious. But for animals in other contexts, the externally increased heart rate had no effect, suggesting that the brain and the heart worked together to produce anxiety, Nature reported. The finding could have implications for the treatment of chronic anxiety conditions, Sahib Khalsa, a psychiatrist at the Laureate Institute for Brain Research in Tulsa, Oklahoma, was quoted as saying. /IANS