The researchers used MRI scanners to scan the brain activity in 39 depressed people (23 female 16 male) and 37 control subjects who were not depressed (14 female 23 male). The researchers found the fMRI scans revealed significant differences in the brain circuitry of the two groups. The greatest difference observed in the depressed patients was the uncoupling of the so-called "hate circuit" involving the superior frontal gyrus, insula and putamen. Other major changes occurred in circuits related to risk and action responses, reward and emotion, attention and memory processing.
The hate circuit was first clearly identified in 2008 by UCL Professor Semir Zeki who found that a circuit which seemed to connect three regions in the brain (the superior frontal gyrus, insula and putamen) when test subjects were shown pictures of people they hated.
The new University of Warwick led research found that in significant numbers of the depressed test subjects they examined by fMRI that this hate circuit had become decoupled. Those depressed people also seemed to have experienced other significant disruptions to brain circuits associated with; risk and action, reward and emotion, and attention and memory processing. The researchers found that in the depressed subjects:
- The Hate circuits were 92% per cent likely to be decoupled
- The Risk/Action circuit was 92% likely to be decoupled
- The Emotion/Reward circuit was 82% likely to be decoupled