Researchers believe they may have found out which part of the brain helps people ignore distractions, according to research published in Nature. The recent study may help experts understand how defects in the brain, particularly the thalamus might dominate symptoms noted in patients with autism, attention-deficit hyperactivity disorder (ADHD) and schizophrenia.
Medical News Today reported that lead author Dr. Michael Halassa, PhD, from New York University's Langone Medical Center, explains that people use a very small portion of incoming sensory stimuli to lead their behavior, successfully filtering out what is unimportant. In most neurological disorders, this function may be broken; leading to an insufficient control over sensory input so the brain becomes overloaded.
Neuroscientists have long considered that the prefrontal cortex (PFC), an area at the very front of the brain, selects what information to focus on, but until now they still don't know how this happens. One theory is that neurons in the PFC send signals to cells in the sensory cortices, which is on the outer part of the brain. Dr. Halassa's team however, believes that these neurons may send signals to inhibitory thalamic reticular nucleus (TRN) cells, which can be found deep inside the brain instead.
To prove this theory, they devised a test that challenged mice to focus and ignore distractions. They trained mice to either use a light or a sound to discover which of two doors hid a milk reward. Before the mice decide each time, they hear a noise telling them to wait for the light or the sound that would lead them to the correct door. They had to use the correct hint and ignore the irrelevant one to get their reward. They found that the mice made more mistakes when neurons in the prefrontal area were silenced while waiting for the cue. They always chose the wrong door, meaning they could not concentrate when the PFC neurons were silenced. Silencing the neurons of the visual cortex on the other hand, the part of the brain that processes visual information, at the moment of anticipation, had no effect on attention.
