README file for the simulation of spatio-temporal distribution of synaptic potentials over an identified nonspiking interneuron in crayfish using the GENESIS simulator by Akira Takashima, Ryou Hikosaka and Masakazu Takahata. 1. This GENESIS simulation show how a single or compound excitatory synaptic potentials evoked by mechanosensory stimulation spreads over the dendrites of the LDS interneuron that is identified in the terminal abdominal ganglion of crayfish Procambarus clarkii. 2. The model is based on physiological experiments carried out by Akira Takashima using single-electrode voltage clamp techniques and 3-D morphometry of the interneuron carried out by Ryou Hikosaka using confocal laser scanning microscope techniques. The physiological and morphological studies were coordinated by Masakazu Takahata. Details on the simulation are described in: Takashima, A., Hikosaka, R. and Takahata, M. (2006) J. Neurophysiol. 96: 3157-3169. Details on the physiological characterization of the LDS interneuron including Hodgkin-Huxley type description of active membrane conductances are described in: Takashima, A. and Takahata, M. (2000) J. Compt. Neurosci. 9: 187-205. Details on the 3-D morphometry of the interneuron are described in: Hikosaka, R. Takahashi, M. and Takahata, M. (1996) Zool. Sci. 13: 69-78 and Hikosaka, R. and Takahata, M. (1998) J. Comp. Neurol. 392: 373-389. (Raw materials on the 3-D morphometry of the LDS interneuron will be available in the spring of 2007 at http://crayfish3.sci.hokudai.ac.jp/index.html.) 3. The input synapses from mechanosensory afferents are pre-deterimined in this simulation. Users can choose from one, 5, 10, 21 and 94 regions for the input sites on the same ipsilateral to the cell body of the LDS interneuron. Users then select one region of interest to calculate the membrane potential change there due to the synaptic activity chosen. The result of calculation will be displayed on the window. 4. In order to run the simulation, you will need these: 1) a fast computer (Pentium 3 or higher) with enough memory (at least 256 Mb) 2) Linux 2.X installed correctly 3) GENESIS 2.2 or later installed correctly 4) a graphical display with at least a resolution of 1024 x 768 5. In order to test the simulation, follow these steps: 1) Make room on the display for he graphical output: move your shell window to the bottom of your display. 2) Change to the directory where the TEST.g scripts reside. 3) At the shell prompt, type "genesis". If you have not set PATH to the directory where the genesis command resides, type whole PATH to that directory. 4) If you can get started GENESIS simulator, then type "TEST". After a short period, two windows will appear: "control" window for setting parameters and "LDS" window for displaying the calculation result. 5) To further explore the simulation, please read "Instruction.txt". 6. Correspondence e-mail address is: takashim@sci.hokudai.ac.jp (Akira Takashima)