US researchers study brain’s behavior with micro LEDs

Some US researchers have studied the brain’s reward and aversion behavior with micro LEDs. The new research explained why treatments for drug addiction or depression do not work for some patients. This is because of reward and aversion responses in the brain. Researchers at Washington University School of Medicine in St. Louis, while working on mice, have discovered that brain pathways are linked to reward and aversion behaviors that are in close proximity and can get unintentionally activated at the same time. The researchers studied mice genetically engineered so that some of their brain cells could be activated with light. Using tiny, implantable LED devices to shine a light on the neurons, they stimulated cells in a region of the brain called the nucleus accumbens, producing a reward response. Cells in that part of the brain are dotted with kappa opioid receptors, which are involved in addiction and depression. The mice returned over and over again to the same part of a maze when the researchers stimulated the brain cells to produce a reward response. But activating cells a millimeter away resulted in robust aversion behavior, causing the mice to avoid these areas. Photo caption: In brain cells, a neurotransmitter (in red) is known to activate aversion behavior, but Washington University neuroscientists have found that in cells just a millimeter away the same neurotransmitter can activate reward behavior. Photos courtesy: Bruchas Laboratory