tissue homovanillic acid amount forebrain homovanillic acid amount forebrain HVA amount The proportion, quantity or volume in the forebrain (part of the brain developed from the most rostral of the three primary vesicles of the embryonic neural tube from which the diencephalon and telencephalon are derived) of HVA, a catecholamine metabolite. Trait.ontology VT:0010849 caripark 2019-10-30T13:12:57Z CMO:0003097 brain homovanillic acid amount