The Brain Compensates for Losing the Amygdala

A team of investigators for the University of California in Los Angeles (UCLA) has recently determined that the human brain is capable of compensating for the loss of one of its regions. The group learned that the cortices of individuals who had lost a portion of the brain called the amygdala – which plays an important part in the formation of emotional content-filled memories – were perfectly capable of compensating for that loss. In order to do that, the brain rewired itself so that other regions were used for the job, the UCLA scientists say.

“Our findings show that when the amygdala is not available, another brain region called the bed nuclei can compensate for the loss of the amygdala,” UCLA professor of psychology Michael Fanselow explains. He is a member of the UCLA Brain Research Institute, and also the senior author of a new paper detailing the findings. The work appears in the latest online issue of the esteemed journal Proceedings of the National Academy of Sciences (PNAS). The new data are in direct contradiction of past theories elaborated by neuroscientists, who believed that the loss of the amygdala would result directly in that person's inability to form new memories featuring emotional content.

“The bed nuclei are much slower at learning, and form memories only when the amygdala is not learning. However, when you do not have an amygdala, if you have an emotional experience, it is like neural plasticity (the memory-forming ability of brain cells) and  the bed nuclei spring into action. Normally, it is as if the amygdala says, 'I'm doing my job, so you shouldn't learn.' With the amygdala gone, the bed nuclei do not receive that signal and are freed to learn,” Fanselow explains. He adds that the amygdala plays a very important role in determining the human body's response to times of danger, when quick reactions are needed.

“Our results suggest some optimism that when a particular brain region that is thought to be essential for a function is lost, other brain regions suddenly are freed to take on the task. If we can find ways of promoting this compensation, then we may be in a better position to help patients who have lost memory function due to brain damage, such as those who have had a stroke or have Alzheimer's disease,” the UCLA expert adds. Funding for the investigation was obtained via a grant from the US National Institute of Mental Health (NIMH).