Functional Neuroanatomy

These experiments are designed to investigate the functions of neuroanatomical pathways using methods such as lesions and immediate early gene (IEG) expression. In the experiment below an anatomical tracer, biotinylated dextran amines was placed in one vocal control nucleus, MO. . The tracer backfilled neurons projecting to MO and was used, therefore, to identify the afferent inputs to MO. At the end of the experiment, the subject was placed in a social setting in which he could listen to other birds and vocalize in response. This induced production of the zenk (zif 268, egr1, NGF1A, Krox24) protein, an immediate early response gene (IEG) protein (i.e. a transcriptional regulator). IEGs including zenk are known to couple exogenous stimulation such as that related to vocalization or hearing novel or meaningful sounds, to synthesis of proteins necessary for  long term changes in neurons. Thus mapping of IEG expression can provide insights into the neuronal functions including those underlying perceptual and motor learning.

The figure depicts the main auditory streams to the vocal control nucleus MO in the budgerigar. For ease of readability pathways associated with the lateral MO are depicted on the right side of the drawing and those reaching the medial MO are decpited on the left side of the drawing. The reader is also referred to specific publications (Brauth et al, 2001; Brauth et al, 2002; Durand et al, 1997; Wild and Farabaugh, 1997; Striedter, 1994) for more information.

In these experiments we measured zenk protein expression in each auditory nucleus in response to presentation of an unfamiliar contact call and a contact call the birds were previously familiarized with due to repeated presentation.