Date of Award

2011

Degree Type

Thesis

Degree Name

Master of Science

Program

Biology

Supervisor

Dr. Scott MacDougall-Shackleton

Abstract

The song-control system is a network of discrete nuclei in the songbird brain that controls the production and learning of birdsong, and exhibits some of the greatest neuroplasticity found in the adult brain. This plasticity is driven by the gonadal steroid testosterone. When acting on neural tissue, however, testosterone can be metabolized into 5a-dihydrotestosterone (DHT) or 17|3-estradiol (E2), which activate different hormonal signalling pathways. By treating adult starlings with both testosterone metabolites and metabolite antagonists, I isolated the effects of DHT and E2 treatment on neuroplasticity in the song-control system. E2 treatment induced some, but not all neuroplastic effects

reported with testosterone treatment. Conversely, DHT treatment induced no neuroplasticity. I documented the first evidence of sex-specific neuroplasticity in the songbird. These findings suggest that DHT and E2 signalling alone do not account for all songbird neuroplasticity and that future studies should account for species and sex differences in the brain.

Share

COinS
 
 

To view the content in your browser, please download Adobe Reader or, alternately,
you may Download the file to your hard drive.

NOTE: The latest versions of Adobe Reader do not support viewing PDF files within Firefox on Mac OS and if you are using a modern (Intel) Mac, there is no official plugin for viewing PDF files within the browser window.