ReMoto - Simulation system of spinal cord motor nuclei
This project was developed
by Rogerio R. L. Cisi and Andre F. Kohn, from the Biomedical Engineering Laboratory - University of Sao Paulo, Brazil,
under the financing of FAPESP (Sao Paulo, Brazil). The paper describing the
system is:
Cisi, R.R.L., Kohn, A. F.
“Simulation system of spinal cord motor nuclei and associated nerves and
muscles, in a web-based architecture”. Journal of Computational Neuroscience, 2008 [http://dx.doi.org/10.1007/s10827-008-0092-8].
The system is available for anyone to use it, provided
a citation of the paper above is given in any publication that relies on
results obtained from this simulator. Any suggestions for improvement are extremely
welcome. Please contact: rcisi@leb.usp.br or andfkohn@leb.usp.br.
This site is best viewed with a resolution of
1280x1024 or 1024x768.
The code of the system is available to those
interested in expanding the system. The idea would be to keep expanding the system,
while making it available to everyone.
Click here to download the code.
ReMoto is a Web-based neuronal simulation
system, intended for studying spinal cord neuronal networks responsible for
muscle control. These networks are subjected to descending drive, afferent
drive and/or electrical stimulation. The simulator should be helpful in
activities such as interpretation of results obtained from neurophysiological
experiments in humans, proposal of hypotheses or testing models or theories on
neuronal dynamics or neuronal network processing, validation of experimental
protocols and teaching neurophysiology.
Stimuli can be applied to the neural circuits by
appropriate selection in the configuration windows. Neuronal or synaptic
properties can be modified to simulate normal or adverse conditions, mimicking
real or idealized experiments. The human-machine interface is user-friendly.
The elements that take part in the system belong
to the following classes: motoneurons, muscle fibers (electrical activity
and force generation), Renshaw cells, Ia Inhibitory Interneuron, Ib Inhibitory
Interneuron, Ia and Ib afferents. The neurons are interconnected by chemical
synapses, which can be chosen to have depression.
The system simulates the following nuclei
involved in flexion and extension of the human or cat ankle:
· Medial gastrocnemius (MG).
· Lateral gastrocnemius (LG).
· Soleus (SOL).
· Tibialis anterior (TA).
The figure below shows a general view of two
antagonistic neural nuclei, in the so-called reciprocal inhibition pathway.

The next figure shows the inner structure of a neural nucleus. The motoneuron
pool receives synaptic inputs from a few independent pathways: corticospinal,
rubrospinal (excitatory and inhibitory) and Ia afferents. The user can select
which type of MN will receive these inputs and calibrate the synaptic strength
by altering the value of the default synaptic conductances. The RCs were
associated with the nearest MNs and IaIn interneurons. Other inputs are also
connected to the MN pool, as described in the Synapses window.

The default number of neurons for the human ankle flexor-extensor system is
summarized below. Users can change these numbers, and chose how many nuclei
will take part in a simulation.
|
|
MN S |
MN FR |
MN FF |
AF Ia |
AF Ib |
|
SOL |
800 |
50 |
50 |
400 |
200 |
|
MG |
250 |
125 |
125 |
80 |
40 |
|
LG |
200 |
100 |
100 |
76 |
38 |
|
TA |
250 |
50 |
50 |
280 |
140 |
|
|
IN RC |
IN IaIn |
IN IbIn |
Flexion
|
350 |
350 |
350 |
|
Extension |
350 |
350 |
350 |
This program is free software under the terms of the GNU General Public License
as published by the Free Software Foundation, either version 3 of the License,
or any later version.
A copy of the GNU General Public License can be obtained at http://www.gnu.org/licenses/.