 However, a lack of melanin "per se" does not appear to be directly responsible for deafness associated with hypopigmentation, as most individuals lacking the enzymes required to synthesize melanin have normal auditory function.Instead the absence of melanocytes in the stria vascularis of the inner ear results in cochlear impairment, though why this is, is not fully understood.In Parkinson's disease, a disorder that affects neuromotor functioning, there is decreased neuromelanin in the substantia nigra and locus coeruleus as consequence of specific dropping out of dopaminergic and noradrenergic pigmented neurons.