Leech Mechanosensory Neurons: Synaptic Facilitation by Reflected APs (Baccus 1998)

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This model by Stephen Baccus explores the phenomena of action potential (AP) propagation at branch boints in axons. APs are sometimes transmitted down the efferent processes and sometimes are reflected back to the axon of AP origin or neither. See the paper for details. The model zip file contains a readme.txt which list introductory steps to follow to run the simulation. Stephen Baccus's email address: baccus@fas.harvard.edu
1 . Baccus SA (1998) Synaptic facilitation by reflected action potentials: enhancement of transmission when nerve impulses reverse direction at axon branch points. Proc Natl Acad Sci U S A 95:8345-50 [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): Leech pressure (P) mechanosensory neuron;
Channel(s): I K; I K,Ca; I Sodium; I Calcium; I Potassium;
Gap Junctions:
Simulation Environment: NEURON;
Model Concept(s): Action Potential Initiation; Pattern Recognition; Activity Patterns; Spatio-temporal Activity Patterns; Influence of Dendritic Geometry; Detailed Neuronal Models; Synaptic Plasticity; Short-term Synaptic Plasticity; Axonal Action Potentials; Action Potentials; Facilitation; Invertebrate;
Implementer(s): Baccus, Stephen [Baccus at fas.Harvard.edu];
Search NeuronDB for information about:  I K; I K,Ca; I Sodium; I Calcium; I Potassium;
TITLE gkca.mod   
UNITS {          
   (uM) = (micro/liter)          
   (mM) = (milli/liter)          
   (mA) = (milliamp)          
   (mV) = (millivolt)   
NEURON {          
   SUFFIX gkca         
   USEION ca READ cai      
   USEION k READ ek WRITE ik          
   RANGE gkcabar, ikca
   GLOBAL cinf, cexp

INDEPENDENT { t FROM 0 TO 1 WITH 1 (ms) }          
PARAMETER {          
   celsius = 20 (degC)
   dt (ms)
   v (mV) 
   gkcabar = 0.0008 (mho/cm2)    
   ikca (ma/cm2)
   ek = -68 (mV)           
ASSIGNED {          
   ik  (mA/cm2)          
   cai (mM)          
   cinf cexp

LOCAL tinc, q10, alpha, beta, sum

BREAKPOINT {          
        q10 = 3^((celsius - 20)/10)
        tinc = -dt * q10
        alpha = 0.1 * (cai / 0.01)
        beta =  0.1 
        sum = alpha + beta
        cinf = alpha/sum
        cexp = 1 - exp(tinc*sum)
        c = c + cexp*(cinf-c)
        ikca = gkcabar * c * (v-ek)
        ik = ikca

        alpha = 0.1 * (cai / 0.01)
        beta =  0.1 
        sum = alpha + beta
        cinf = alpha/sum
        c = cinf     

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