
Synesthesia is a neurological condition where the stimulation of one sensory or cognitive pathway leads to involuntary experiences in another pathway, such as perceiving colors when hearing music or associating specific tastes with words.

Vitamin B12, or cobalamin, is a water‑soluble vitamin essential for neurologic function, red blood cell formation, and DNA synthesis. It is naturally present in animal-derived foods and certain fortified products, absorbed in the ileum via an intrinsic factor–mediated process, and functions as a cofactor for methionine synthase and methylmalonyl‑CoA mutase. Deficiency can cause megaloblastic anemia and neuropathy and is most common in older adults, people with malabsorption, and individuals following strict vegan diets.