• nsc203practice3

Practice Problem

Developmental changes in ifenprodil binding within a brain region involved in vocal learning

This experiment evaluated the effects of age and sex on the expression of NMDA receptors within a brain region (LMAN) that is necessary for normal song learning in songbirds. The experiment involved zebra finches, a songbird in which only males produce learned song. Juvenile male zebra finches normally imitate only songs heard during a sensitive period that occurs between 20 and 55 days after hatching. The hypothesis being tested was whether the sensitive period for song learning correlates with age-related changes in the expression of NMDA receptors.

NMDA receptors play a central role in synaptic and behavioral plasticity, and their activation is necessary for normal avian song learning. Native NMDA receptors consist of several different subunits, and in vertebrate forebrain regions, a developmental decrease in the propensity for NMDA receptor-mediated plasticity is associated with a reduction in NR2B subunit expression. Here, we tested whether there are age-related changes in the expression of the NR2B subunit of the NMDA receptor within the LMAN of male and female zebra finches. To assess NR2B expression, we measured specific binding of ifenprodil, a ligand that binds only to NMDA receptors that contain the 2B subunit.

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