The thalamus was involved in making probabilistic decisions

Decision making in a changing probability of occurrence of events defined by the functional connections between the prefrontal parts of the brain and the thalamus, which sends signal from the sense organs to the cerebral cortex. It found the German scientists, they conducted an experiment in which participants had to choose which sensory stimulation they receive, based on information about the stimulation obtained before. The work of scientists, published in Cerebral Cortex, clarifies the role of the thalamus in the decision-making process.

Every event that occurs in a person’s life, there is a certain probability. Predicting it accurately is impossible practically never, but you can roughly estimate it, it grows or decreases depending on third-party events are those that occur simultaneously, or those that occurred earlier. For example, if you want to buy a chocolate bar, the likelihood, will you be able to get it today, will decline over time as the store closes, say, at ten o’clock.

Of course, such external events and factors should affect the decision-making process: it is unlikely that people who left five minutes to walk to the store for the chocolate, decide not to jump further. Such a mechanism of adaptation, on the one hand, requires the prefrontal cortex (just as she is responsible for making decisions), and on the other its relationship with other areas of the brain, particularly motor cortex.

To examine these relations more decided Won Bin (Bin Wang) and Pleger Burkhard (Burkhard Pleger) from the Ruhr University Bochum. In their experiment, they used the tactile stimulator is a small device with eight plastic retractable lugs arranged in two rows. Depending on the conditions of the experiment (total of two) stimulator put forward either the upper or lower four tip, and the participants kept the finger of his right hand on the stimulator and was able to feel it.

Experiment with 28 participants was held with the use of fMRI: first, after stimulation, participants had to press the other hand on one of the two buttons — top or bottom — depending on what kind of stimulation they received. After that, the participants had to choose which is the next stimulation — of the same or different. Volunteers were asked not to guess, and consider how the changing stimulation and predict the next. The probability of occurrence of a particular stimulation (90 to 10, 70 to 30 and 50 to 50 percent) of the participants was unknown.

The more correct answers the participants gave in the case, if the probability of occurrence of one event was high (90 percent), and in this case faster chose the right variant (p < 0.001). In cases where the participants did not change their decision in their brain was observed attenuated functional connectivity between the ventromedial part of the prefrontal cortex and secondary somatosensory cortex, and the weaker was the relationship, the faster the participants made the decision, not adapting it.

On the contrary, in the case where participants estimated the probability of events and changed their decision, there was increased functional connectivity between the orbitofrontal cortex (another part of the prefrontal cortex) and one of the nuclei of the thalamus. Again, if participants were confident in his original decision and not adapted it, the relationship was weaker.

The authors concluded that the adaptive decision-making requires well-established and strong functional connections between the thalamus and the prefrontal parts of the brain. One of the functions of the thalamus — signal transmission from sensory organs to the cerebral cortex, mainly in the engine Department, which is in the process of decision making contact with departments prefrontal cortex. The thalamus thus serves another function — manages the decision making in that case, if the initially selected strategy needs to change: if she really is changed, the functional relationship between it and other departments is becoming stronger.

The fact that not only the prefrontal cortex is involved in the decision-making process, scientists have shown before: for example, premotor cortex, apparently, for this process not even the right signals from other parts of the cerebral cortex — at least, that showed an experiment on mice.

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