A group of nerve cells in the substantia Innominata of the basal forebrain that has wide projections to the Neocortex and is rich in acetylcholine and choline acetyltransferase. In parkinson’s disease and alzheimer’s disease, the nucleus undergoes degeneration. A decrease in acetylcholine production is seen in alzheimer’s disease, lewy body dementia, and some parkinson’s disease patients Showing abnormal brain function, leading to a general decrease of mental capacity and learning. Most pharmacological treatments of dementia focus on compensating for a faltering basal Nucleus function through artificially increasing acetylcholine levels.