New Study Pinpoints the Part of the Brain That Helps Animals Make Smart Inferences

A new study from New York University has shed light on how animals navigate unpredictable environments by identifying a specific part of the brain responsible for making inferences. Instead of reacting blindly to whatever happens around them, animals constantly evaluate situations, connect past experiences with new cues, and make educated guesses about what’s likely to happen next. According to this research, the orbitofrontal cortex (OFC) is the region that acts as this internal inference engine.

This finding offers a straightforward but fascinating update to our understanding of brain function: the OFC does much more than track rewards. It helps animals update their beliefs when the world changes. The results also carry implications for understanding human neuropsychiatric conditions where inference abilities are affected.

Below is a breakdown of all the key details from the study, along with additional context that helps explain why this discovery matters.

How Animals Use Inference to Survive

In nature, signals are not always reliable. For instance, squirrels learn that certain bird calls are not associated with predators, allowing them to avoid unnecessary panic. This ability to interpret the meaning behind cues is an example of inference, a skill that helps animals navigate complex and shifting environments.

The NYU team wanted to understand how the brain supports this ability. They focused on the OFC because earlier studies hinted it might help animals evaluate outcomes and adjust expectations. But until now, there wasn’t direct evidence showing the OFC participates specifically in state inference, meaning figuring out the hidden conditions of the environment.

The Research Setup: What the Rats Had to Do

The researchers trained laboratory rats to perform a decision-making task involving water rewards. Every detail of this setup was designed to reveal whether the animals were just reacting to the reward amounts or actually inferring the state of their environment.

Here’s how the experiment worked:

• Rats received water rewards delivered through ports.
• Each reward came in small, discrete quantities ranging from 5 to 80 microliters.
• The environment could be in one of three hidden “states”: low, mixed, or high, each defined by how much water was typically available.
• Crucially, some reward amounts appeared in multiple states. For example:
  • 10 microliters appeared in both low and mixed states.
  • 20 microliters appeared in all three states.
• Because of this overlap, rats couldn’t simply judge the environment from the reward amount alone—they would need to infer the overall state.

This task mimics what economists refer to as a willingness-to-pay setup, except the rats paid with time instead of money. The question was simple: How long are the rats willing to wait for a certain amount of water?

If they were using inference, their waiting time should depend on the state they believed they were in, not just the volume of water.

What the Rats’ Behavior Revealed

The rats who had been trained to understand the task behaved exactly as the researchers predicted:

• In a low state, where water was scarce, rats waited longer for a 20-microliter reward.
• In a high state, where water was plentiful, they waited less for the same 20 microliters because they expected better options ahead.

This showed that the rats weren’t simply reacting—they were estimating the broader reward conditions and evaluating how worthwhile it was to wait.

On the other hand, untrained rats failed to show such nuanced behavior. They did not infer hidden states and responded only to immediate cues or simple reward statistics.

Recording the Brain: Over 10,000 Neurons Studied

The researchers recorded activity from more than 10,000 OFC neurons while the rats performed the task. Their recordings showed:

• OFC activity patterns shifted depending on the rats’ beliefs about the reward state.
• These neural signals corresponded to how the rats updated their understanding as conditions changed.

But the strongest evidence came from disrupting the OFC directly.

What Happened When the OFC Was Disrupted

When the scientists selectively interfered with the OFC:

• Trained rats lost their ability to infer the environment’s hidden state.
• They no longer adjusted their waiting behavior based on whether water was abundant or scarce.
• They treated identical reward amounts the same across all states, which is what would happen without inference.

This demonstrated that the OFC doesn’t just contribute to inference—it is necessary for state updating in uncertain environments.

What Makes This Discovery Important

Understanding how brains make inferences has implications far beyond animal behavior. Humans also rely heavily on inference for daily decision-making: understanding social cues, anticipating outcomes, and navigating unpredictable situations.

Here’s why the findings are significant:

• Cognitive insight: They reinforce the idea that the OFC is not only about reward processing but also about representing hidden states.
• Neuropsychiatric relevance: Disorders like schizophrenia and bipolar disorder often involve impaired inference, leading to difficulty interpreting situations. Learning how the OFC supports inference could help researchers explore more effective treatments.
• Artificial intelligence inspiration: Understanding biological inference processes may help inspire new models in machine learning that deal with uncertainty.
• Comparative cognition: This work strengthens the view that sophisticated reasoning abilities are not exclusive to humans.

Additional Context: What Exactly Is the Orbitofrontal Cortex?

The orbitofrontal cortex, located just above the eyes, has long been associated with:

• Tracking rewards and punishments
• Evaluating choices
• Emotional decision-making

But recent research increasingly shows the OFC is involved in:

• Representing task states
• Integrating past experiences
• Predicting future outcomes

This new NYU study adds a major piece to that picture by demonstrating that the OFC actively updates beliefs when hidden aspects of the environment change.

Why Hidden-State Inference Matters in Nature

Animals rarely get perfect information. Most cues in the wild are ambiguous or unreliable. Hidden-state inference allows animals to:

• Detect predators without always seeing them
• Search for food efficiently
• Interpret calls, smells, and signals correctly
• Adapt when conditions shift unexpectedly

For example:

• Birds infer changing weather patterns from wind and pressure cues.
• Wolves infer herd movement from distant noises.
• Primates infer group dynamics from subtle social signals.

This built-in “inference engine” is essential for survival. The new study shows that the OFC plays a direct role in powering this mechanism.

Final Thoughts

This research delivers a clear and well-supported conclusion: the orbitofrontal cortex is central to how animals update their beliefs about their environment, especially when the important information is not directly observable. The combination of behavioral analysis, neural recordings, and targeted disruptions provides compelling evidence that the OFC enables flexible, inference-based decision-making.

By mapping this cognitive ability to a specific brain region, the study opens new doors for understanding both healthy cognition and the origins of disorders that disrupt it. It also deepens our appreciation for the sophisticated decision-making abilities found across the animal kingdom.

Research Paper:
The orbitofrontal cortex updates beliefs for state inference
https://www.cell.com/neuron/fulltext/S0896-6273(25)00805-0