How Your Brain Helps You Stop Thinking About Something

If you have been wondering if you'll ever be able to scrub unwanted thoughts from your memory, science says you actually might—if your hippocampus is well-stocked with a particular neurotransmitter.

The neurotransmitter responsible for inhibiting the actions of our nervous system is called gamma-Aminobutyric acid, or GABA. Previous research on human inability to suppress intrusive thoughts has focused on underperforming GABA in the prefrontal cortex, the part of your brain that controls decision-making and memory.

But a paper published today in the journal Nature Communications explains that the GABA that actually predicts our ability to control our thoughts is located in the hippocampus. The higher the concentrations of GABA you have in your hippocampus, the better-equipped your prefrontal cortex is to make unwanted thoughts go away.

“One of the things that really excites me is that it unifies these diverse observations of elevated hippocampal activity,” said senior author Michael Anderson“Which people have been noting for years, but why was that the case? And I think this provides an explanation.”

The findings should help explain why some people have trouble casting traumatic memories, worries or paranoia from their minds.  A psychologically healthy adult may still grow quiet every few weeks because of that time in 1997 when they called their teacher “mom,” but a more severe inability to suppress intrusive thoughts is a feature common to a number of psychiatric disorders.

41467_2017_956_Fig3_HTML Hippocampal GABA predicts DLPFC-Hippocampal connectivity during thought suppression. Anderson et al

Anderson and his coauthors combined an established method of measuring thought suppression called the Think/No-Think paradigm with multiple-phase memory tests. In some, participants were shown colored circles associated with two separate buttons to push, and after identifying the correct buttons were given two new colors and continued the process while the researchers recorded success rates. At times they were instructed to respond as quickly as possible, or to stop responding if they heard a beep first. Another phase included memory word pairs, where the participants engaged until they remembered at least 40 percent of the pairs. 

When the responses had been catalogued, the researchers processed the data through neuroimaging tools like MRI. They found that subjects whose brains contained more hippocampal GABA had better control of memory retrieval, supporting their theory that it’s crucial to the efficacy of the prefrontal cortex.

Theoretically, strengthening communication between GABA receptors in the hippocampus would give your prefrontal cortex the tools it needs to manage symptoms of conditions like schizophrenia, depression, anxiety, and Post-Tramatic Stress Disorder. The new study offers no specific therapy in and of itself, but it’s quite possible it could form the basis of trials for future treatments.

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