New research from Cedars-Sinai has identified neurons that play a role in how people recognize errors they make, a discovery that may have implications for the treatment of conditions including obsessive-compulsive disorder and schizophrenia.

Catching even small errors, such as making a typo while writing a letter, is a critical executive function that allows us to regulate behavior and make adjustments that can assure we don't repeat mistakes in the future.

When that process is short-circuited, however, serious issues may arise. Patients diagnosed with obsessive-compulsive disorder, for instance, may believe every action can contain an error, so they can get caught in a cycle of checking and rechecking their work. Patients diagnosed with schizophrenia may not be able to detect the mistakes at all.

Self-monitoring

"One of the brain areas that is known to be important for self-monitoring is the medial frontal cortex, but how exactly this process works and how it fails when it does not work remains poorly understood," said Ueli Rutishauser. The first author of the paper, Zhongzheng Fu. The study, published online in the journal Neuron, also offers a new level of understanding for what is called error-related negativity (ERN), which can be easily measured using an electroencephalogram (EEG) and could one day become standard clinical care in individuals with psychiatric disorders.

Stroop Test

The research underlying the study was conducted by having subjects take a Stroop Test, in which they are asked to identify the color ink in which a color word is printed. For instance, if the word "green" were published in red ink, the subject would have to identify it as red to register a correct answer. 

Subjects, however, sometimes give "green" as the answer, which is an error. In these cases, the error neurons would immediately react and thereby signal to the subject that he or she made a mistake. The error neurons could do so without relying on outside feedback, an ability called self-monitoring.

"These electrodes allow us to measure the electrical activity of individual neurons, a type of recording that is only possible because the patient is undergoing a neurosurgical procedure," said Adam Mamelak. "This setup provides precious new insights into the mechanisms by which humans engage executive control of their behavior, understanding of which is essential to develop new treatments for mental disorders."

The study found that during the Stroop Test, "error neurons" were mostly distinct from the neurons, signaling a conflict between the color word and the color of the ink shortly following stimulus onset, suggesting that the representation of conflict detection and error monitoring in the medial frontal cortex are mostly distinct.

The research paves the way for further testing to see whether the manipulation of these neurons, whether by suppressing or activating them, impairs or improves the self-monitoring of errors. This testing could yield new therapies to address cognitive problems such as memory disorders, psychiatric illnesses, and autism, the researchers said.