Cell Stem Cell on February 2, researchers show that brain organoids—clumps of lab-grown neurons—can integrate with rat brains and respond to visual stimulation like flashing lights. “We saw that a good number of neurons within the organoid responded to specific orientations of light, which gives us evidence that these organoid neurons were able to not just integrate with the visual system, but they were able to adopt very specific functions of the visual cortex. Now, we want to understand how organoids could be used in other areas of the cortex, not just the visual cortex, and we want to understand the rules that guide how organoid neurons integrate with the brain so that we can better control that process and make it happen faster