A key process of human cognition has been identified

Human behavioral patterns are based on such parameters as motivation, trust, anxiety, risk assessment, and so on. Although these personality traits are relatively well understood psychologically, their cerebral origin is much less so. Professor Adam Kepecs, of the Cold Spring Harbor Laboratory, answered some of these questions in a new study published in Nature . The results could lead to the development of more effective treatments for obsessive-compulsive disorder, gambling addiction and other psychiatric disorders.

The team studied the orbitofrontal cortex, a critical area for decision making in humans and animals. The damage of this area of ​​the brain is detrimental to decision-making. In a famous example, Phineas Gage, a railway worker, survived extreme damage in this area when an iron rod pierced his skull during an explosion. Gage survived, but his personality and decision-making skills were profoundly altered.

Kepecs and his lab have sought to clarify how neurons in the orbitofrontal cortex encode mental variables such as motivation or confidence. " We wanted to understand how neurons code for these mysterious entities, what is the logic behind that, what is the architecture of the orbitofrontal cortex, " says Kepecs.

By monitoring neural activity in the brains of rats making complex decisions, the team identified a new, unexpected structure in the functional organization of the orbitofrontal cortex.

The role of orbitofrontal neurons in behavioral management

The key idea was to use mathematical models of decision-making behavior to calculate "confidence in decision". This approach produced fairly accurate predictions of what a representation of confidence in observed variables looks like, such as the difficulty of the decision or the choice that was made. It turned out that many orbitofrontal neurons were consistent with these predictions, their activity increasing or decreasing with a formally defined decision confidence.

Previous studies on the orbitofrontal cortex have identified similar mental variables, but unlike other brain regions such as the visual cortex, there was no order in their responses and the coding complexity was confusing.

Junya Hirokawa, of Doshisha University in Kyoto, recorded large populations of neurons in the orbitofrontal cortex and used sophisticated machine learning techniques to understand their activity patterns.

Orbitofrontal cortex. This area of ​​the brain is heavily involved in decision making. Credits: Jonathan D. Wallis

The team discovered that the neurons belonged to distinct functional groups. And each group of neurons has coded for different mental variables, like decision confidence or reward value, revealing a highly structured organization hitherto unsuspected.

Towards new psychiatric treatments

Finally, Kepecs wondered whether these functional groups were supported by a specialized anatomical structure. To do this, the team used artificial viruses to target a specific group of neurons, those that send connections to the striatum, an important part of the brain to update or rethink the value of a choice. They monitored the activity of these neurons and found that they were coding for another mental variable, the reward value, increasing activity when the expected reward was low.

Deconstructing this logical relationship between the functioning of neurons during different tasks and their physical structure in the brain could also open up possibilities such as the treatment of psychiatric disorders, for example by means of more precise stimulation of the brain of patients suffering from severe depression, Parkinson's and other types of illness.


Frontal cortex neuron types categorically encode single decision variables

Junya Hirokawa, Alexander Vaughan, Adam Kepecs

Nature (2019)


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