Definition of opacity for English Language Learners. : 1  the quality of a material that does not allow light to pass through it : the quality of being opaque. : 2  the quality of being difficult to understand or explain.
Research has shown that this is not true, and that brain cells can and do regenerate, especially in the areas related to learning, decision-making, visual recognition, and the way people perceive objects in space.weet. For a long time, scientists thought that it was impossible for brain cells to regenerate because they assumed that any new cells would disrupt the order of the brain.
Your brain's hippocampus, i.e. the memory center, is especially able to grow new cells and it's now known that your hippocampus regenerates throughout your entire lifetime (even into your 90s), provided you give it the tools to do so.