Proximal inhibition of Renshaw cells (Bui et al 2005)

 Download zip file 
Help downloading and running models
Accession:58957
Inhibitory synaptic inputs to Renshaw cells are concentrated on the soma and the juxtasomatic dendrites. In the present study, we investigated whether this proximal bias leads to more effective inhibition under different neuronal operating conditions. Using compartmental models based on detailed anatomical measurements of intracellularly stained Renshaw cells, we compared the inhibition produced by GABAA synapses when distributed with a proximal bias to the inhibition produced when the same synapses were distributed uniformly. See paper for more and details.
Reference:
1 . Bui TV, Dewey DE, Fyffe RE, Rose PK (2005) Comparison of the inhibition of Renshaw cells during subthreshold and suprathreshold conditions using anatomically and physiologically realistic models. J Neurophysiol 94:1688-98 [PubMed]
Model Information (Click on a link to find other models with that property)
Model Type: Neuron or other electrically excitable cell;
Brain Region(s)/Organism:
Cell Type(s):
Channel(s):
Gap Junctions:
Receptor(s): GabaA; Cholinergic Receptors; Glycine;
Gene(s):
Transmitter(s):
Simulation Environment: SABER;
Model Concept(s): Action Potential Initiation; Influence of Dendritic Geometry; Detailed Neuronal Models;
Implementer(s): Bui, Tuan V [tuan at biomed.queensu.ca]; Fyffe, Robert EW [robert.fyffe at wright.edu]; Dewey, Dianne E [dianne.dewey at wright.edu]; Rose, P Ken [ken at biomed.queensu.ca];
Search NeuronDB for information about:  GabaA; Cholinergic Receptors; Glycine;
Readme for the models associated with:

Bui, Tuan V., Diane E. Dewey, Robert E. W. Fyffe, and P. Ken
Rose (2005)  Comparison of the Inhibition of Renshaw Cells During 
Subthreshold and Suprathreshold Conditions Using Anatomically 
and Physiologically Realistic Models
J Neurophysiol 94: 1688-1698, 2005.

Inhibitory synaptic inputs to Renshaw cells are concentrated on the
soma and the juxtasomatic dendrites. In the present study, we 
investigated whether this proximal bias leads to more effective 
inhibition under different neuronal operating conditions. Using 
compartmental models based on detailed anatomical measurements of 
intracellularly stained Renshaw cells, we compared the inhibition 
produced by glycine/gamma-aminobutyric acid-A (GABAA) synapses when
distributed with a proximal bias to the inhibition produced when the 
same synapses were distributed uniformly (i.e., with no regional
bias). The comparison was conducted in subthreshold and suprathreshold
conditions. The latter were mimicked by voltage clamping the soma to 
-55 mV. The voltage clamp reduces nonlinear interactions between
excitatory and inhibitory synapses. We hypothesized that for
electrotonically compact cells such as Renshaw cells, the strength of
the inhibition would become much less dependent on synaptic location 
in suprathreshold conditions. This hypothesis was not confirmed. The 
inhibition produced when inhibitory inputs were proximally distributed
was always stronger than when the same inputs were uniformly
distributed. In fact, the relative effectiveness of proximally 
distributed inhibitory inputs over uniformly distributed synapses was
greater in suprathreshold conditions than that in subthreshold
conditions. The somatic voltage clamp minimized saturation of
inhibitory driving potentials. Because this effect was greatest near
the soma, the current produced by more distal synapses suffered a
greater loss because of saturation. Conversely, in subthreshold
conditions, the effectiveness of proximal synapses was substantially
reduced at high levels of background synaptic activity because of
saturation. Our results suggest glycine/GABAA synapses on Renshaw
cells are strategically distributed to block the powerful excitatory
drive produced by recurrent collaterals from motoneurons.

Four models for Renshaw cells (RC1a, RC2a, RC3a, and
RC4a) and three models for neck motoneurons (LAD5-4, LVN2-1 and
LVN4-1).  The models include a main template (starts with the name of
the cell followed by .sin).  Within each of these main templates is a
listing of the template for each primary subtree.  In the template of
each primary subtree is the listing of the membrane compartments that
make up the primary subtree.

The Renshaw cell models have glycinergic/GABAergic synapses and
cholinergic synapses in the distribution that we described in Bui et
al. (2005a) J. Neurophys.

The Renshaw cell models were produced by Dr. Robert Fyffe, 
Dianne Dewey, Dr. Ken Rose and Tuan Bui, while the motoneurons models 
were produced by Dr. Ken Rose and Tuan Bui.

These model files were contributed to ModelDB by Tuan Bui.

Tuan V. Bui
Queen's Univ
Dept Physiol
Botterell Hall
Kingston ON K7L 3N6
Canada
  	 
Work Phone: 613-533-6000 ext.74853
Fax: 613-533-6840
E-mail Address: tuan@biomed.queensu.ca

Loading data, please wait...