Nell Beatty Cant

The long-term objective of Dr. Cant’s work is to understand the organization of the brainstem auditory pathways in terms of connections among the different neuronal types that form them. The goal of current research is to analyze the termination patterns of the axons of some specific cell types within the isofrequency contours of the inferior colliculus. There are four specific aims: 1) To characterize the organization of the bushy cell pathway from the cochlear nucleus to the superior olivary complex and from the superior olivary complex to the inferior colliculus; 2) To characterize the multipolar cell pathway from the ventral cochlear nucleus to the inferior colliculus; 3) To analyze the periolivary cell groups of the superior olivary complex in terms of specific cell types; and 4) To examine the organization of the isofrequency contours in the inferior colliculus in terms of the arborization patterns of lemniscal inputs from the bushy and multipolar cell pathways and from selected periolivary nuclei. The hypothesis is that although a number of lower brainstem auditory pathways converge on one isofrequency contour in the inferior colliculus, their terminal arborizations occupy different domains within that contour.

Methods used in Dr. Cant’s laboratory include: 1) Tracing techniques based on the anterograde and/or retrograde transport of biocytin, Phaseolus vulgaris-leucoagglutin, and a number of different fluorescent dyes, and 2) A fixed slice preparation in which the dendriticarborization patterns of neurons that project to known sources can be examined.

Neuroanatomical studies provide essential information relevant to the mechanisms of auditory processing. The neuronal activity that leads to functional expression is dependent on the precise and specific connectivities among hundreds of specialized neuronal types. Detailed understanding of these connectivities will not only help to interpret available functional data, it will also provide a basis for developing rational hypotheses about auditory function that can be tested further.