How the brain learns to reclassify danger and reward

Summary: The brain constantly evaluates if the stimuli are positive or negative, which causes an approach or avoidance behaviors that are essential for survival. A new study reveals that two types of neurons in the Accumbens nucleus, the neurons D1 and D2) respond to gratifying and aversive stimuli, but differently.

Using real -time images in mice, researchers found that D2 neurons are especially important to update the associations learned, such as recognizing when a threat is no longer dangerous. These ideas could help explain why people with anxiety or PTSD struggle to put aside negative memories and can lead to specific treatments.

Key facts:

Neurons D1 and D2: Both types of neurons respond to rewards and threats, but have different roles in learning. D2 The role in extinction: D2 neurons help extinguish negative associations when a stimulus is no longer aversive. Implications for mental health: Understanding the D2 function can inform new therapies for anxiety and PTSD.

Source: Bial Foundation

The human brain contains billions of neurons that continually receive information and stimuli from abroad. To make decisions, neurons evaluate at all times if the stimulus is positive or negative. If it is positive, there is a tendency to approach, while if it is negative, an aversion reaction arises, which helps guarantee survival.

The Accumbens nucleus (NAC) of the brain plays a central role in the process of evaluation and coding of stimuli, but how neuronal populations D1 and D2 of the NAC encodify appetizing or aversive stimuli is not yet completely understood.

To deepen knowledge in this area, a team of researchers coordinated by Ana João Rodrigues and Carina Soares-Cunha (ICVS, U.Minho), with the support of the Bial Base, studied the neurons D1 and D2 of the NAC to understand how they distinguish between stimuli and influence learning.

When tracking hundreds of neurons in mice exposed to appetizing and aversive stimuli in real time, the researchers first demonstrated that D1 and D2 responded together to both stimuli.

In the article, the dynamic representation of appetitive and aversive stimuli in the spinous neurons of the Accumbens D1 and D2 nucleus, published in the scientific journal Nature Communications, the researchers reveal that the use of advanced images in mice, could observe that during associative learning, that is, when a stimulus is associated with a reward or types of neurons, they are activated and working together And they work and work together, but they do it, but they do. But they do. But they do.

When associations change, such as when a negative stimulus no longer has an unpleasant consequence, D2 neurons are essential to extinguish that aversive association.

“Since the difficulties in modifying negative associations are related to posttraumatic anxiety and stress, the best understanding of the function of D2 neurons could help develop new treatments,” explains Carina Soares-Cunha.

“The same external stimulus can cause different reactions depending on the context and memories of the individual. For example, the sound of fireworks can evoke celebrations and joy. Even so, for an ancient combatant, it can trigger an anxiety crisis, bringing memories of war, even if it is in a safe environment,” he explies.

This study demonstrates the ability of the brain to constantly reclassify external stimuli based on previous experiences and adapt to new situations while demonstrating the complexity of the neuronal circuits involved in this type of memory.

The work was developed in association with Rui Costa and Gabriela Martins of the University of Columbia and the Allen Institute (USA).

Financing: In addition to the Bial Foundation, the investigation was co -financed by the European Research Council, the La Caixa Foundation and the Foundation for Science and Technology.

On this neuroscience research news

Author: Sandra Pinto
Source: Bial Foundation
Contact: Sandra Pinto – Bial Foundation
Image: The image is accredited to Neuroscience News

Original research: open access.
“Dynamic representation of appetizing and aversive stimuli in the spiny neurons of the nucleus Accumbens D1 and D2-Medio” by Carina Soares-Cunha et al. Nature communications

Abstract

Dynamic representation of appetitive and aversive stimuli in the nucleus Accumbens Shell D1 and D2-Medium Escinas Neuronas

The Nucleus Accumbens (NAC) is a key brain region for motivated behaviors, but how different neuronal populations encode appetizing or aversive stimuli remain undetermined.

Using microendoscopic calcium images in mice, we trace the activity of the spiny neurons of the Nac D1 or D2 (MSNS) housing during exposure to opposite valence stimuli and associative learning.

Despite the drift in the coding of individual neurons, the activity of population D1 and D2 was sufficient to discriminate the opposite valence unconditioned stimuli, but not predictive signs.

In particular, the D1 and D2-MSN were copulated in a similar way during the appetizing and aversive conditioning, which supports a concurrent role in associative learning.

On the contrary, when contingencies changed, there was an asymmetric response in the NAC, with more pronounced changes in the D2-MSNS activity. The optogenetic manipulation of D2-MSN provided causal evidence of the need for this population in the extinction of aversive associations.

Our results reveal how Concha Nac neurons encode Valencia, Pavlovian associations and their extinction, and the inauguration mechanisms underlying motivated behaviors.