Researchers have succeeded in deciphering how the brain moves from decision-making to acting out, a discovery that could significantly improve the use of targeted therapy for patients suffering from sensory and motor brain deficits.
- A cortical region traditionally defined as the motor cortex is more directly related to the execution process.
- Our brain represents sensory and motor information in more than one place and often redundantly for multiple purposes such as fine-tuning future movements, enhancing perception, or storing memory.
When we make a decision, a sequence of events unfolds at lightning speed in the brain. A team of American neuroscientists from the University of California at Riverside has managed to dissect them and identify the part of the brain responsible for the passage to the act which remained unknown until then. A discovery that could significantly improve the use of targeted therapy for patients with sensory and motor brain deficits. The results were presented on January 25 in the journal in Euro.
Transforming the electrical activities of neurons into numbers
The researchers took the example of the red light to illustrate their study: when we drive and the light in front of us turns red, a multitude of reactions occur in our brain. The image of the traffic light is transferred from our eyes to the visual cortex, which, in turn, communicates with the premotor cortex, a section of the brain involved in planning and executing limb movements. A signal is then sent to our foot to press the brake. The region of the brain that helps the body move from “seeing” to “executing” was unknown. To unpack this “black box,” the researchers conducted experiments on mice to identify the region of the brain that functions beyond sensory coding and motor coding.
For the experiment, the scientists trained mice to detect a slight deflection on one side of their whiskers and report if they detected it while licking a water port. “We recorded neuronal activity from certain regions of the brain that could convey this sensory-motor transformation using the ‘language of neurons’ – the electrical signals – generated when the mouse performs the stimulus detection task.”, clarified Zhaoran Zhang, co-first author of the research. The researchers then used mathematical tools to turn the electrical activities of neurons into numbers that describe how well neurons sense sensory input, how well they reflect upcoming movement outputs, and how well they predict whether the information sensory input can be successfully transformed into correct behavior.
Improving targeted therapies
The researchers report that a cortical region traditionally defined as the whisker motor cortex in mice is more directly related to the execution process. “We have located a region of the brain traditionally defined as the motor whisker cortex, which was previously believed to influence how a mouse moves its whiskerscontinues Behzad Zareian, co-first author of the study. We found that this cortical region is able to transform sensory input from whisker deflection into a general movement action – licking in this case – rather than just moving whiskers..”
One of the difficulties in finding brain regions that effect sensory-motor transformation is that, although scientists can easily measure sensory-motor brain activities in the laboratory, the internal process that drives sensory-motor transformation in the brain is elusive. and difficult to quantify. “Our brain represents sensory and motor information in more than one place and often redundantly for multiple purposes such as fine-tuning future movements, enhancing perception, or storing memory.explains Edward Zagha, assistant professor of psychology and principal researcher of the team. Thus, scientists are now able to distinguish between the location of the transformation and regions that merely reflect sensory or motor information for other purposes. This can significantly improve the use of targeted therapy for patients with sensory and motor brain deficits.”