A recent study led by Dr. Sameer Sheth, professor and vice chair of research in the Department of Neurosurgery at Baylor College of Medicine, has identified beta frequency neural activity in the anterior cingulate cortex (ACC) of the brain’s frontal lobe as a key neural signature associated with recognizing rewards and determining subsequent choices. This discovery could have significant implications for understanding and treating depression.
The study, published in Nature Communications, reveals that this neural signature is altered in patients with depression. "We found that the unequal assignment of reward between two correct responses in this task produced a response bias toward the more frequently rewarded stimulus," said lead author Dr. Jiayang Xiao.
Anhedonia, or the loss of ability to feel joy, is a primary symptom of depression and other psychiatric conditions such as schizophrenia and bipolar disorder. Traditional treatments often fail to address this symptom adequately. A better understanding of anhedonia can guide the development of targeted treatments for these conditions.
To identify the neural basis for anhedonia, Sheth's team recorded neural activity from four brain regions of 15 patients with medication-resistant epilepsy who were undergoing invasive monitoring. These patients performed a perceptual discrimination task called the probabilistic reward task (PRT), which measures anhedonia by observing changes in behavior related to reward.
The researchers found that beta frequency oscillations originating from the ACC showed a strong correlation with reward bias behavior. "Our study has addressed a longstanding fundamental question in neuroscience – which specific brain region and signal regulates the classic reward bias response," said co-senior author Dr. Benjamin Hayden.
In individuals with severe treatment-resistant depression, Sheth's team observed altered reward processing in the ACC during PRT tasks. These individuals did not exhibit typical behavioral responses favoring more frequently rewarded choices, suggesting reduced anticipation for rewards.
"In this study, we identified beta activity in the ACC as a potential biomarker for anhedonia," said Sheth. "Such a biomarker could improve diagnosis and monitoring symptoms of patients with severe depression."
The research was supported by funding from various sources including the National Institutes of Health Brain Research Through Advancing Innovative Neurotechnologies Initiative (BRAIN Initiative). "This study exemplifies how BRAIN-funded research is already having an impact in the clinic today," said Dr. John Ngai, director of NIH BRAIN Initiative.
Further information about other authors involved in this study can be found here.
