This question is mainly about neurochemistry and molecular neuroscience! Clarification supposedly suggested by Arnon Weinberg.
I thoroughly and extensively read Philosophy, Neuroscience, Psychology, Neurobiology and Molecular Biology textbooks along with much existentialist, liberalist and classic literature and ncbi, pubmed regarding them https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4104996/ https://www.ncbi.nlm.nih.gov/pubmed/16166028 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5871756/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1804747/
My problem is that only senses(particularly taste and smell) are explained in my textbooks by molecular biology and physical movements(Heart Beats, Respiration, Blinking, Voluntary Movements)
What I often see is Neuroanatomy, Neurophysiology, Neuroimmunology, Neurogenetics(this one quitte uninformative like simply stating X gene is linked with Y symptom). Nonetheless Molecular Biology is a distinct textbook. How( including which) chemical reactions explain desires.