Explain why a gustatory hallucination is described as often occurring together with an olfactory hallucination, despite being conceptually distinct from it.

Taste and smell are closely linked senses physiologically, with much of what is ordinarily experienced as taste actually depending heavily on smell, so a disturbance affecting one sensory pathway commonly co-occurs with a disturbance affecting the other. Despite this frequent co-occurrence, the two remain conceptually distinct hallucinated experiences, one occurring specifically in the mouth as a taste and the other specifically as a smell with no external source, and either can occur without the other. Recognising them as distinct, even when they appear together, matters because a patient's account may emphasise one modality over the other, and each should be characterised and documented in its own right.