Physiology and Morphology of Movement Sensitive Neurons in the crab Chasmagnathus (poster)

MARTÍN BERÓN DE ASTRADA Y DANIEL TOMSIC

University of Bonn, Germany

Congreso; 6th International Congress of Neuroethology; 2001

This study present a physiological description of movement sensitive neurons (MSNs) investigated by intracellular recordings in an intact and awaken living animal, and neuroanatomical data on MSNs in crustacea. The study was performed in the highly visual semiterrestrial crab Chasmagnathus granulatus, which displays a conspicuous escape response when stimulated by an object moving overhead. This escape response and a learning process elicited by a visual danger stimulus (VDS) has been under intensive investigation with behavioral, pharmacological and molecular approaches in our laboratory. Recently, we initiated an electrophysiological investigation of those neurons in the optic lobe of Chasmagnathus tunned to respond to the VDS. The response of MSNs to the VDS consists of a discharge of action potentials. However, many distinctions can be observed in the responses from different cells. The differences described here are related to the size of the spikes, the receptive fields, the preferred direction of movement, the response to a pulse of light, the mechanosensitivity and the possibility of having multiple spike initiation zones. The heterogeneity of the electrophysiological responses, is somehow less evident when analyzing the location and gross structure of the neurons. Lucifer Yellow injections revealed that all MSNs appear to present an extensive arborisation in the internal medulla and lateral protocerebrum, with their soma located in the cell body cluster laying beneath the internal medulla.