The Role of Gene Regulation in Neural Circuit Development: Studies in the Zebra Finch

173 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1997.The oscine songbird zebra finch learns to sing in a "critical period" in adolescence. Song acquisition and production are controlled by the brain song circuit which consists of auditory and motor pathways. The purpose of this thesis is to study genomic mechanisms underlying zebra finch song circuit formation. First, the expression of genes encoding synaptic proteins was measured by in situ hybridization during the "critical period" for song learning in the motor control pathway. Three genes: canarigranin, GAP-43 and synelfin were tested, and changes in mRNA level were observed in all three cases, each at a specific song control nucleus. Behavioral isolations which delay the "critical period" for song learning did not delay the changes of the expression of these gene. In order to gain more insights on how experience affect brain development, specifically at the molecular level, the responsiveness of an immediate early gene ZENK was measured from 20 days post-hatch (immediately prior to song learning) to adulthood (after learning is completed), following either singing or playback of tape-recorded song. No significant differences were observed in the patterns of expression between adults and juveniles. However, a developmental difference was detected on the ZENK inducibility after song playback. A large age-dependent decline in basal ZENK expression which associated with the progression of the "critical period" was also detected. Behavioral isolations delayed the development of ZENK responsiveness to song playback and the decline of basal ZENK mRNA levels. The results presented in this thesis demonstrate dynamic changes in gene regulation in the zebra finch song control system at the time of juvenile song learning. The changes in gene expression can be placed into two categories: the experience-independent and the experience-dependent. These two forms of gene regulation work in concert to define species specific features of the brain and to direct formation and modification of the neural circuitry based upon external stimuli.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD