Right now, the grey matter right behind your forehead is calculating whether you should feel pleasantly content, or an irritating degree of contempt. If you also happen to experience chronic pain, one emotion will probably be more likely than the other. New research shows how pain affects the way our prefrontal lobe processes emotion at a fundamental level, finding tendencies to be more anxious or depressed are the result of disruptions to the way cells communicate. "Chronic pain is more than an awful sensation," says Sylvia Gustin, a neuroscientist and psychologist at the University of New South Wales and NeuRA, a neurological research institute in Australia. "It can affect our feelings, beliefs and the way we are." Gustin is the senior author of a recent study that used advanced imaging techniques to scan for concentrations of a specific neurotransmitter in volunteers with and without a history of chronic pain. That chemical, gamma-aminobutyric acid (GABA), is one of the big players in brain signaling, keeping a lid on neural activity broadly across the nervous system. Specifically in the brain's prefrontal cortex, GABA's dampening activity acts as a form of traffic control, limiting communication with other regions such as the amygdala. Working in balance with the stimulating neurotransmitter glutamate, this signal system ensures our emotions keep us motivated at the right moments without causing us undue stress. Painful situations could be regarded as a perfect moment to let our emotions run a little wild, either to encourage assistance or to help us run free. Studies on animal models have found significant variations in the amount of glutamate at work in the medial area of the prefrontal cortex when the subjects are in pain. Similarly, glutamate has been seen to drop in humans experiencing chronic pain, in line with a decline in their emotional regulation. Yet while changes in the amount of GABA have been observed in mice, this link hasn't been established in the human body until now. Knowing whether a neurotransmitter directly responsible for bringing down the boom gates on our deep sense of anxiety is in short supply when we're in pain might not only help us better understand our own brains, it could point the way to new methods for helping us get on top of our moods. In a sample of 48 participants with and without chronic pain, brain scans revealed significant contrasts in levels of GABA. While the number of volunteers isn't huge, it's significant enough to support the view that being in pain over the long term changes how our brain processes emotions by lowering inhibitory measures. "We have discovered, for the first time, that ongoing pain is associated with a decrease in GABA, an inhibitive neurotransmitter in the medial prefrontal cortex. In other words, there's an actual pathological change going on," says Gustin. Without GABA, computations carried out in the front part of our brain that deal with not only our emotional responses, but reasoned-out thoughts and actions, become amplified. Roughly one in ten people around the world deal with some degree of chronic pain each year, affecting more people than heart disease, diabetes, and cancer combined. In some regions that figure is as high as one in every four. Being such a prevalent experience, we ought to know more about ways to manage the worst of its effects. It's long been known that mood disorders and chronic pain go hand-in-hand, with up to half of those with bouts of pain lasting more than a few months also experiencing depression or anxiety. The consequences can be serious, impeding sleep, creating stress, and promoting feelings of guilt. Targeting specific shifts in neurochemistry in such a confined area of the brain is a challenge, especially when neurotransmitters like glutamate and GABA have such broad uses across the nervous system. But knowing there are physical changes linking chronic pain with managing emotions just might go some way to helping individuals regain a sense of perspective and control over their body. "The brain can't dampen down these feelings on its own, but it is plastic – and we can learn to change it," says Gustin. Source
