increased forebrain size forebrain hyperplasia 2013-10-09T15:20:00Z MP:0012140 MPheno.ontology csmith hyperplastic forebrain hyperplastic prosencephalon overdevelopment or increased size, usually due to a increased number of cells, of the anterior of the three primary divisions of the developing chordate brain or the corresponding part of the adult brain (in vertebrates, includes especially the cerebral hemispheres, the thalamus, and the hypothalamus and especially in higher vertebrates is the main control center for sensory and associative information processing, visceral functions, and voluntary motor functions) prosencephalon hyperplasia