Integrative modeling of Paramecium, a "swimming neuron"

Paramecium is a unicellular organism that swims in fresh water using cilia. When it is stimulated (mechanically, chemically, optically, thermally, etc.), it often swims backward then turns and swims forward again: this is called the avoiding reaction. This reaction is triggered by a calcium-based action potential. For this reason, it enjoyed a period of glory in the 1970s as a model organism for neuroscience – some authors called it the "swimming neuron". Paramecium has considerable experimental advantages: it can be easily mass cultured in days, it is accessible to intracellular electrophysiology, its genome has been sequenced and it benefits from many techniques such as RNA interference.

Because Paramecium is both a cell and an organism, it becomes possible to develop quantitative models that link physiology and behavior, cellular plasticity and behavioral plasticity (including learning), theoretical neuroscience and systems biology. I will describe our first efforts to develop such models, based on electrophysiological and behavioral data.