The amygdala ― a brain area known for emotional control and regulation ― also unexpectedly responds specifically to animal pictures reports a paper published online in Nature Neuroscience this week.
Florian Mormann and colleagues obtained recordings of neural activity from a rare group of human patients, who had to undergo brain surgery to control drug-resistant epilepsy. Before such surgery can be carried out, doctors implant recording electrodes in the brain, to find out which brain areas are triggering the epilepsy attacks, so that the surgery can be targeted to these areas. The authors took advantage of this pre-surgery monitoring to look how activity in the implanted electrodes changed when the patients looked at pictures of animals, landmarks, objects or people. They found that activity in the amygdala on the right side of the brain was greater when the patients were looking at pictures of animals. The neural responses were also faster for these pictures. Using non-invasive functional magnetic resonance imaging, the authors were also able to see such specific responses to animal pictures in the right amygdala of people who were not suffering from epilepsy as well.
It is unclear why they should be such specific responses to animal pictures in the brain. The authors suggest that one possible explanation is that during our evolutionary history, seeing another animal (which could represent either predator or prey) may have been especially significant and thus trigger emotional responses to the stimuli.