The human body is made up of trillions of cells; cells of the nervous system are known as nerve cells or neurons. The cerebral cortex, also known as the gray matter, is the outer cover of the two brain hemispheres, and is densely packed with neurons.
Sensory neurons send information from sensory receptors such as skin, eyes, nose, tongue, and ears, to the central nervous system. A study conducted by neuroscientists at New York University (NYU) Langone Medical Center and its Neuroscience Institute discovered specialized nerve cells known as Somatostatin-expressing (SST) interneurons in the outer part of the cerebral cortex. These cells play a key role in the flow of information to the brain when it is awake and alert.
Experiments have been carried out on mice and rats since their brains have much in common with the human brain. The research found that the activity of SST interneurons changes when the animal’s whiskers move from the resting state to the active state; a process known as whisking. The team discovered that the cortex contains a diverse set of SST interneuron subsets that reach into different layers of the cortex. Some of the subtypes turn on while others turn off during whisking. Through this process, SST interneurons selectively block or activate the flow of information to the brain in a way that seems to help animals make guided movements.
“We have long wondered how the cerebral cortex can process and integrate separate information lines coming in from different brain structures, or from other areas of the cortex, and how it sorts out what information is relevant at any given moment” said senior study investigator Bernardo Rudy, Professor of Neuroscience and Physiology at NYU Langone. “We now know that SST interneurons operate like a switchboard that controls the flow of these information lines” he added.
Rudy explains that neurons in the cortex are known to have major roles in sensory perception, memory formation, and learning. However, it was the first time to notice that they operate like a switchboard in the cortex. This major discovery will increase the scientists understanding of how the brain processes sensing. The findings may speed up the research on drug therapies for diseases that affect the senses, such as Alzheimer’s, schizophrenia, and autism.
Scientists say that the discovery of the mice’s different responses to whisking makes it ideal to study nerve cell activity during the change in brain processing modes. Mice’s and rats’ whiskers are their most important sensory organ; they use them to make sense of their surroundings and guide their movements in the dark. The team inserted probes into the mice brains that allowed them to competently identify and record the activity of SST interneurons, which are integrated with other types of neurons.
Using the new mechanism, the researchers’ next step is to analyze the activity of SST interneurons and other kinds of neurons in the cerebral cortex during more advanced and complex behaviors, aiming to understand their role in the processing of sensory information in the brain.
The human brain is a mysterious vault that gradually unravels its secrets to the world of science.
Reference
psychologytoday.com
sciencedaily.com