Mechanotransduction in spider slit sensilla

Mechanoreception is a vital constituent of several sensory modalities and a wide range of internal regulatory processes, but fundamental mechanisms for neural detection of mechanical stimuli have been difficult to characterize because of the morphological properties of most mechanoreceptors and the nature of the stimulus itself. An invertebrate preparation, the VS-3 lyriform slit sense organ of the spider, Cupiennius salei, has proved useful because it possesses large mechanosensory neurons, whose cell bodies are close to the sites of sensory transduction, and accessible to intracellular recording during mechanotransduction. This has made it possible to observe and experiment with all the major stages of mechanosensation. Here, we describe several important findings from this preparation, including the estimated number, conductance and ionic selectivity of the ion channels responsible for mechanotransduction, the major voltage-activated ion channels responsible for action potential encoding and control of the dynamic properties of the neurons, the location of action potential initiation following mechanical stimulation, and the efferent control of mechanoreception. While many details of mechanosensation remain to be discovered, the VS-3 system continues to offer important opportunities to advance our understanding of this crucial physiological process.