We can’t always control what we think, for those with psychiatric disorders, this is especially challenging. Intrusive memories, flashbacks, and hallucinations are hallmark symptoms of a variety of mental health conditions. Although these symptoms are often attributed to problems with brain regions that help us inhibit unwanted thoughts—such as the prefrontal cortex—difficulties in controlling intrusive thoughts are also associated with chemical differences in the brain. Hippocampal hyperactivity arising from dysfunctions in neurons that relay GABA, an inhibitory neurotransmitter, have been linked to intrusive thought patterns. In this study, researchers aimed to clarify how hippocampal GABA contributes to stopping unwanted thoughts. Participants were shown reminders of unwanted thoughts, and then tried to suppress them, while being scanned using functional MRI. The act of thought suppression led to reduced hippocampal activity. Additionally, magnetic resonance spectroscopy revealed that greater resting concentrations of hippocampal GABA predicted better control over memories. The researchers concluded that GABA activity in the hippocampus is key in the inhibition of memories, and that interneurons within the hippocampus allow us to suppress intrusive thoughts. Since intrusive thoughts are implicated within a range of psychiatric disorders, it is important that researchers and clinicians understand their neural underpinnings. In the future, this may allow for the development of more effective pharmacological and psychological treatments for negative thought patterns that are difficult to control.
Citation: Schmitz, T.W., Correia, M.M., Ferreira, C.S., Prescot, A.P., & Anderson, M.C. (2017). Hippocampal GABA enables inhibitory control over unwanted thoughts. Nature Communications, 8, 1311.