Pain intensity signals in the brain identified

A new technique has been developed to detect the area of the brain involved in the process of pain intensity detection.

Neurologists at the Oxford Centre for Functional Magnetic Resonance Imaging of the Brain used a new brain imaging technique and identified that the activity in a brain area known as the dorsal posterior insula is directly related to the intensity of pain.

“We were able to find this area by developing a new method of tracking brain activity, based on a technique called arterial spin labelling. This allowed us to look at more complex brain states that stretch over much longer periods. By tracking pain felt over many hours, we were able to filter out more momentary experiences, such as variations in attention or fear,” said Professor Tracey.

In the study, published in the journal Nature Neuroscience, 17 healthy volunteers had a cream containing the active component of chillies – capsaicin – applied to their leg. The scientists tracked the brain activity from the burning sensation caused by the cream and asked the volunteers to indicate the level of pain.

When the pain began to fade, the researchers put a hot water bottle where the cream was applied to revive the sensation. Pain relief was provided a few minutes later by switching to a cooling water bottle and the volunteers' pain ratings accordingly went up and then down. These activity changes were tracked in the dorsal posterior insula.

“We have identified the brain area likely to be responsible for the core, 'it hurts', experience of pain. Pain is a complex, multidimensional experience, which causes activity in many brain regions involved with things like attention, feeling emotions such as fear, locating where the pain is, and so on. But the dorsal posterior insula seems to be specific to the actual 'hurt level' of pain itself,” said Professor Irene Tracey at the University of Oxford.

The study could help in detecting pain in people with limited communication abilities, such as those in a coma, small children and dementia patients.

Next, the team is planning to verify the results by attempting to switch off this brain region in relevant patients suffering from intractable pain. The scientists hope that changing activity in the dorsal posterior insula will help in pain treatment where other methods have failed.

Paper: http://www.nature.com/neuro/journal/vaop/ncurrent/full/nn.3969.html