The nucleus accumbens It is a brain structure that plays a leading role in the experimentation of pleasure and reward. Thanks to this region of the brain, among others, we are able to experience positive sensations and learn about pleasant and negative events, and even fall into addictions. Today, we delve into the anatomy and the main functions that this important structure has.
- 1 Where is the nucleus accumbens?
- 2 Its structure is divided into two parts
- 3 What is the main function of the nucleus accumbens?
- 4 The nucleus accumbens and drug addiction
Where is the nucleus accumbens?
Previously, this set of neurons used to be called nucleus accumbens septi, which means "nucleus resting on the septum." Exists a nucleus accumbens in each hemisphere and are located in the area of the subcortical brain (inside the brain), specifically between the caudate nucleus and the putamen, constituting the area ventral striatum and being, therefore, part of the basal ganglia.
The nucleus accumbens is part of the mesolimbic pathway, one of the important ways dopaminergic of the brain that are associated with the responses we generate to stimuli that produce us motivation and pleasure. The main entries of the nucleus accumbens come from the prefrontal cortex, theamygdalaand the ventral tegmental area and its projections are directed towards the basal ganglia, and the pale globe, which in turn reaches the prefrontal cortex and the striatum, forming a sophisticated circuit.
Its structure is divided into two parts
- Layer or crust: It is the outer part of the nucleus accumbens. It consists of medium spiny neurons, mostly with dopamine D1 and D2 receptors and have fewer terminal segments and dendrites than those in the body area. It seems that synapse that happen in the D1 neurons of the cortex are responsible for the Immediate reward for drugs. This is why addictive drugs have a greater effect on the layer than on the body of the nucleus accumbens.
- Body or core: It is the central part of the nucleus accumbens; It contains spiny neurons with dopamine receptors type D1 and D2 that project to other areas such as pale balloon wave black substance thanks to GABA receivers among others.
What is the main function of the nucleus accumbens?
Although the nucleus accumbens is involved in multiple tasks, its main recognized function has always been the important role it plays in the brain reward circuit. Within the mesolimbic pathway, this nucleus has always been considered a mediator in these reward processes: Imagine you do something that gives you pleasure, such as eating chocolate. The dopaminergic neurons of ventral tegmental area of your brain would be activated by projecting into the nucleus accumbens, which automatically increases the levels of dopamine, producing that sense of reward in a pleasant situation.
That is why scientists used to consider the nucleus accumbens a center whose function was to mediate the reward. However, it has subsequently been found that the nucleus accumbens increase your dopamine levels both in pleasant situations and in aversive situations. This has suggested that the role that both the nucleus accumbens and dopamine play in the brain has more to do with the ability to store information in the face of positive and negative events so that these can then be remembered as such.
Although neuroscientists are still looking for the exact answers about the role of the nucleus accumbens in these processes, what is clear is that this structure is very important for the processing and generation of important memories that the context gives us, both positive and negative. as well as learning through reinforcement and pleasure experimentation.
The nucleus accumbens and drug addiction
As we had previously commented, drugs such as cocaine, amphetamines or morphine, dopamine levels increase in the nucleus accumbens. This increase is more evident in the part of the layer or crust than in the center of the region, although amphetamine manages to increase levels in both areas.
The increase in dopamine in the nucleus accumbens not only occurs when drugs are used, but also when it is experienced any positive experience. However, when this increase is produced by drugs repeatedly, the habit it creates is more resistant And it is harder to extinction of this association between brain reward-drug.
That is why this important role is still being studied that the nucleus accumbens has in reference to the addiction that certain drugs create in the brain, since understanding their role can be important in controlling these harmful situations. Although the brain is still a great stranger today and its operation is still largely unknown, researching its depths is vital to understanding and improving people's lives.