Meeting Abstract

57.6  Tuesday, Jan. 5   Organization and function of lateral line afferent neurons in larval zebrafish LIAO, James C.; The Whitney Laboratory for Marine Biosciences, U. Florida jliao@whitney.ufl.edu

Afferent neurons of the zebrafish posterior lateral line relay hydrodynamic signals sensed along the body to the hindbrain. We labeled individual neurons to reveal their connections to single and multiple neuromasts along the body. Electroporation of Alexa 647 in HUC-Kaede fish, a transgenic line expressing a photo-convertible protein under control of a pan-neuronal promotor, indicates that single and multiple-neuromast afferent neurons correspond to later and early-born cells, respectively. We normalized ganglion area across individuals and plotted position of afferent neurons to show that early-born cells are located centrally in the ganglion, with newly developing cells added to the periphery. Whole-cell recordings of afferent neurons show an inverse relationship between soma area and input resistance, where input resistance is a proxy for excitability. Taken together, a picture is emerging that large, early-born cells are less excitable and may therefore fire only to strong hydrodynamic stimuli across the whole body, while small, later-born cells that are more excitable sense local flows. We hypothesize that large, coarse coding afferents innervating multiple hair cells are critical for initiating powerful escape responses while small, fine coding afferents are responsible for modulating routine motor behaviors such as swimming. Aspiration of ganglia led to the inability of animals to avoid a constant flow source in the absence of light compared to control animals, indicating that the posterior lateral line is required for rheotaxis.