Research Methods : Tract-tracing

In addition to labeling tissue for peptides that are present, we inject tracers that allow us to examine the connections between different populations of neurons in the brain.

ctb_in_scn

Tissue labeled for cholera toxin beta, a retrograde tract tracer. This injection is centered on the suprachiasmatic nucleus.

Typical chemical tracers used in our laboratory include biotinylated dextran amine (BDA) and cholera toxin beta (CTb). By combining immunohistochemical and stereotaxic techniques we can examine neural connections between cells expressing specific proteins. Current projects include the use of light or confocal microscopy to study contacts between tracer-labeled fibers and cells labeled using standard immunohistochemistry.

nixon_ctb_oxa

Fluorescent labeling for the tracer CTb (green) and the peptide orexin (red). The CTb injection was centered on the intergeniculate leaflet in the thalamus.