Summary: A new study in rhesus macaques reveals how the brain regulates depression-like states. Researchers have discovered that a specific brain circuit connecting the dorsolateral prefrontal cortex (dlPFC) and the cingulo-striatal network plays a crucial role in emotional regulation.
Disruptions in this circuit, particularly in beta oscillations, were associated with pessimistic decision-making and depression-like behaviors. These findings pave the way for targeted therapies for major depressive disorder.
Highlights:
- The dorsolateral prefrontal cortex regulates depression-like states via the cingulo-striatal network.
- Beta oscillations in fronto-striatal circuits are crucial for encoding positive decision-making.
- Disturbances in this circuit can lead to pessimistic decision-making, characteristic of depression.
Source: Kyoto University
Understanding and treating depression, a potentially debilitating mental health problem that affects millions of people worldwide, remains a major priority for researchers in the field of neuroscience.
For example, major depressive disorder (MDD) affects approximately 33 million people and up to 5% of the global adult population.
Emotion regulation is a crucial function of the brain to suppress emotions and depression-like states and has been considered one of the defense mechanisms in MDD. However, the neurobiological mechanisms underlying how the brain regulates this depression-like state still remain unclear.
To explore this problem, a recent study led by Satoko Amemori and Ken-ichi Amemori and published in Natural communications studied how specific brain circuits regulate emotional responses, providing new insights into the neural basis of depression.
In this study, researchers focused on the dorsolateral prefrontal cortex (dlPFC), long known to play a role in emotion regulation. Researchers examined how the dlPFC signal changes in a depression-like state and revealed the mechanism by which the dlPFC regulates the cingulo-striatal network.
Elucidating the neural mechanisms underlying depression-like behavior in primates could lay the foundation for the development of new therapeutic approaches targeting specific brain circuits.
The research examined the so-called “top-down” influence of the dlPFC on the cingulo-striatal network, a brain network commonly associated with depression, in emotional regulation. They then examined how these circuits affect decision-making and emotional responses.
Using microstimulation techniques, researchers modulated neuronal activity in the subgenual anterior cingulate cortex (sgACC) of rhesus macaques (Macaca mulatta) and were able to experimentally induce pessimistic decision-making and depression-like states.
During these stimulation experiments, the researchers additionally recorded local field potentials (LFPs) to analyze the top-down influence of the dlPFC on the cingulo-striatal network.
They found that experimentally induced pessimistic decision-making was accompanied by a decrease in the top-down influence of the dlPFC on cingulo-striatal regions.
This finding suggests that disruption of the top-down signal from cognition to emotion could lead to pessimistic decision-making, a hallmark of MDD.
One of the main findings of the study was the role of beta oscillations in fronto-striatal circuits. Beta oscillations have long been associated with motor control and attention, and more recently they also play a role in cognitive functions such as working memory.
In this new study, effective microstimulation of the sgACC, which led to a depression-like state, reduced the magnitude of beta oscillations encoding positive decision-related variables.
This reduction in beta oscillations is important because it suggests a link between sgACC activity and negative biases in decision-making, providing a potential mechanism for how the brain processes positive and negative values.
The study also explored interactions between areas of the fronto-cingulo-striatal network. By examining factors such as consistency and Granger causality (a statistical test for whether a variable can be meaningfully described as a dependent variable), researchers found that effective microstimulation of the sgACC altered these interactions, reflecting the involvement of the network in decision-making. process.
They found that the “top-down” influence of the dlPFC on the cingulo-striatal network was encoded by the beta oscillation of the LFP, and that the reduction in top-down influence was associated with the experimentally induced depression-like state.
These results highlight the important role this network plays in emotion regulation and decision-making and how its dysfunction could lead to depression-like behavior.
This study provides valuable insights into the neural basis of depression, highlighting the role of specific brain circuits in regulating emotional responses. Of note, the study created a model of depression in primates and revealed that front-cingulo circuits are involved in regulating the limbic system via beta oscillations.
Importantly, researchers were able to demonstrate that monkeys exhibit depression-like behavior when this regulation is absent. By uncovering the mechanisms underlying depression-like behaviors in primates, this research opens new avenues for developing more effective treatments for MDD.
About this depression research news
Author: Satoko Amemori
Source: Kyoto University
Contact: Satoko Amemori – Kyoto University
Picture: Image is credited to Neuroscience News
Original research: Free access.
“Cingulate microstimulation induces negative decision-making via reduced top-down influence on the primate fronto-cingulo-striatal network” by Satoko Amemori et al. Natural communications
Abstract
Cingulate microstimulation induces negative decision making via reduced top-down influence on the primate fronto-cingulo-striatal network
The dorsolateral prefrontal cortex (dlPFC) is crucial for emotion regulation, known to contribute to the prevention of depression.
The broader fronto-cingulo-striatal (FCS) network, including the cognitive dlPFC and limbic cingulo-striatal regions, has been associated with a negative evaluative bias often observed in depression.
The mechanism by which the dlPFC regulates the limbic system remains largely unclear.
Here, we successfully induced a negative bias in decision-making in female primates performing a conflict decision-making task, by directly microstimulating the subgenual cingulate cortex while simultaneously recording local field potentials (LFPs) of the FCS.
The artificially induced negative bias in decision-making was associated with a significant decrease in functional connectivity from cognitive regions to limbic FCS, represented by a reduction in Granger causality in LFPs from the beta range of the dlPFC to other regions.
We suggest that the loss of top-down directional influence from cognitive to limbic regions could underlie negative biases in decision-making, as observed in depressive states.
News Source : neurosciencenews.com
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