Why This Matters:
- Why this matters: Provides a neural explanation for how humans balance exploration and exploitation under both reward and loss conditions.
- How this aligns with previous research: Builds on evidence linking the amygdala to exploration and mood regulation but extends it to loss-avoidance contexts.
- Future implications: Could inform therapies that address altered exploration in psychiatric disorders, from depression to anxiety.
Summary: A new study shows that the brain uses two distinct mechanisms to drive exploration under uncertainty. Recording single-neuron activity during a learning task, researchers found that amygdala and temporal cortex neurons modulate their firing before exploration in both gain and loss situations.
Humans were more likely to explore when avoiding losses, a behavior linked to increased “noise” in amygdala activity. The findings reveal how the brain flexibly shifts strategies depending on whether decisions involve potential rewards or threats.
Key Facts
- Two Mechanisms: Exploration is guided by both a general rate signal and a valence-dependent noise signal in the amygdala.
- Loss Bias: Humans explore more when facing potential losses than when seeking rewards.
- Clinical Insight: Heightened amygdala activity in mood disorders may drive maladaptive exploration and pathological decision-making.
Source: Neuroscience News
Every day, humans and other animals face a fundamental choice: exploit the resources they already know or explore new possibilities that might offer greater benefits—or, conversely, avoid potential losses.
This “exploration–exploitation dilemma” has been extensively studied in positive settings, such as seeking rewards. However, exploration is equally important when navigating threats or losses, yet much less is known about how the brain handles these scenarios at the level of single neurons.
A new study brings clarity by showing that human exploration in both gain and loss contexts depends on distinct neural signals arising from the amygdala and temporal cortex. The findings point to two mechanisms—one general, the other specific to negative outcomes—that shape how people make decisions in uncertain environments.
Single-Neuron Activity in the Human Brain
Researchers recorded single-neuron activity from participants performing a probabilistic learning task that mixed trials involving potential gains and losses. The task required individuals to sometimes stick with a known option and sometimes try something new—mirroring real-world decision-making.
The data revealed that neurons in the amygdala and temporal cortex consistently altered their firing patterns just before participants chose to explore. This showed that the exploration process is actively prepared in the brain, rather than emerging randomly.
Losses Drive More Exploration
Interestingly, humans showed a stronger tendency to explore when trying to avoid losses than when seeking gains. At the neural level, this was linked to an increase in “noise” in amygdala activity. In neuroscience, noise often refers to random fluctuations in firing that reduce the predictability of neural responses. Here, that variability appears to push the brain toward riskier, exploratory behavior.
This discovery suggests that the brain has a built-in bias: when facing potential losses, it is more willing to take chances in hopes of avoiding a negative outcome.
Two Mechanisms, One Decision
Overall, the researchers identified two signals guiding exploration:
- A valence-independent rate signal, seen across contexts, that prepares neurons to shift into exploratory mode.
- A valence-dependent noise signal, specific to loss contexts, that increases variability in amygdala responses and encourages risk-taking.
By combining these signals, the brain flexibly adjusts how much exploration to engage in, depending on whether the stakes involve rewards or threats.
Implications for Mood Disorders
The findings also shed light on why exploration rates are often altered in psychiatric conditions. Heightened amygdala activity, long observed in mood disorders such as anxiety and depression, may amplify the noise signal.
This could contribute to maladaptive decision-making patterns—either excessive exploration that leads to instability or avoidance behaviors that become pathological.
By identifying the cellular mechanisms that underlie exploration in both positive and negative contexts, this study creates a foundation for linking mood disorders to specific disruptions in decision circuits.
Looking Ahead
Future research may investigate whether these neural dynamics can be modulated through targeted interventions—such as brain stimulation or pharmacological treatments—aimed at restoring balance in exploration versus exploitation.
The results also highlight the importance of considering both reward-seeking and loss-avoidance when designing tasks to study cognition and psychiatric illness.
By showing that the amygdala’s “noise” can shape decisions under threat, the study reframes exploration not just as curiosity-driven, but as a deeply survival-oriented process.
About this neuroscience research news
Author: Neuroscience News Editorial Team
Contact: Neuroscience News
Source: Neuroscience News Editorial Team – Neuroscience News
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Original Research: Closed access.
“Rate and noise in human amygdala drive increased exploration in aversive learning” by Tamar Reitich-Stolero et al. Nature
Abstract
Rate and noise in human amygdala drive increased exploration in aversive learning
To cope in uncertain environments, animals must balance their actions between using current resources and searching for new ones.
This exploration–exploitation dilemma has been studied extensively in paradigms involving positive outcomes, and neural correlates have been identified in frontal cortices and subcortical structures, including the amygdala.
Importantly, exploration is just as essential for survival or well-being when trying to avoid negative outcomes, yet we do not know whether the single-neuron mechanisms that drive exploration are shared across positive and negative environments.
Here we examined the dynamics of exploration when human participants engaged in a probabilistic learning task with intermixed loss and gain trials, while simultaneously recording single-neuron activity.
We show that neurons of the amygdala and temporal cortex modulate their activity before a decision to explore in both loss and gain.
Moreover, we find that humans exhibit more exploration when trying to avoid losses, and that an increase in the levels of noise in amygdala neurons contributes to this behaviour.
Overall, we report that human exploration is driven by two distinct neural mechanisms, a valence-independent rate signal and a valence-dependent global noise signal.
The results suggest a link between the heightened amygdala activity observed in mood disorders and higher exploration rates that underlie maladaptive and even pathological behaviours.
