From decision to action: Detailed modelling of frog tadpoles reveals neuronal mechanisms of decision-making and reproduces unpredictable swimming movements in response to sensory signals
Fig 7
VT model: 3D body reconstruction and swimming in “water”.
a–c. Reconstruction of the 3D tadpole body from experimental images and body sections of the real tadpole (using the Blender software). Some body sections at different RC positions from head to tail are shown in (a). d. Scale diagram of a real tadpole (top) with the notochord (green) and muscle segments (yellow and orange) with a schematic representation of muscle segments 11 and 12) in Sibernetic (bottom-right). This simplified 3D construction includes particles (blue balls) connected by ordinary springs (green) and “elementary muscle fibers” (red) which can contract in response to motoneuron spiking. Bottom-left: Reconstructed 3D tadpole body (VT model) in the Sibernetic system. The 3D shape of the tadpole body (с) was loaded and visualized by Sibernetic to assist in building the VT model. The density of the VT model belly is higher (1060 kg/m3) than other tissues (1035 kg/m3). To simulate swimming the VT model is placed into a tank (18.4×3.7×3.7 mm) filled with “water” represented by ≈ 2 million liquid particles with density and dynamical viscosity (measured in the simulation using Stokes’ law) equal to those of water at 20°С. The swimming speed of the VT model ≈ 19.3 mm/s (tadpole length is 5 mm and period of muscle contraction on one body side is 100 ms), whereas the typical preferred speed of a real tadpole is ≈ 21 mm/s. The difference might be due to the skin cilia activity driving surface mucus caudally over the body which is not included to the model [20].