IA and IT interact to set first spike latency (Molineux et al 2005)

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Accession:59479
Using patch clamp and modeling, we illustrate that spike latency characteristics are the product of an interplay between I(A) and low-threshold calcium current (I(T)) that requires a steady-state difference in the inactivation parameters of the currents. Furthermore, we show that the unique first-spike latency characteristics of stellate cells have important implications for the integration of coincident IPSPs and EPSPs, such that inhibition can shift first-spike latency to differentially modulate the probability of firing.
Reference:
1 . Molineux ML, Fernandez FR, Mehaffey WH, Turner RW (2005) A-Type and T-Type Currents Interact to Produce a Novel Spike Latency-Voltage Relationship in Cerebellar Stellate Cells. J Neurosci 25:10863-10873 [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): I Na,t; I T low threshold; I A; I K;
Gap Junctions:
Receptor(s):
Gene(s):
Transmitter(s):
Simulation Environment: MATLAB;
Model Concept(s): Action Potential Initiation; Coincidence Detection;
Implementer(s): Fernandez FR [ffernand at ucalgary.ca]; Mehaffey WH ;
Search NeuronDB for information about:  I Na,t; I T low threshold; I A; I K;
/
a_and_t
readme.txt
CerebStellate.m
m2.jpg
                            
This is the readme for the model associated with the paper:

Molineux ML, Fernandez FR, Mehaffey WH, Turner RW.
A-type and T-type currents interact to produce a novel spike 
latency-voltage relationship in cerebellar stellate cells.
J Neurosci. 2005 Nov 23;25(47):10863-73

Hotchkiss Brain Institute, University of Calgary, Calgary,
Alberta, Canada T2N 4N1.
rwturner@ucalgary.ca

The modification of first-spike latencies by low-threshold and
inactivating K(+) currents (I(A)) have important implications in
neuronal coding and synaptic integration. To date, cells in which
first-spike latency characteristics have been analyzed have shown
that increased hyperpolarization results in longer first-spike
latencies, producing a monotonic relationship between first-spike
latency and membrane voltage. Previous work has established that
cerebellar stellate cells express members of the K(v)4 potassium
channel subfamily, which underlie I(A) in many central neurons.
Spike timing in stellate cells could be particularly important to
cerebellar output, because the discharge of even single spikes
can significantly delay spike discharge in postsynaptic Purkinje
cells. In the present work, we studied the first-spike latency
characteristics of stellate cells. We show that first-spike
latency is nonmonotonic, such that intermediate levels of
prehyperpolarization produce the longest spike latencies, whereas
greater hyperpolarization or depolarization reduces spike
latency. Moreover, the range of first-spike latency values can be
substantial in spanning 20-128 ms with preceding membrane shifts
of <10 mV. Using patch clamp and modeling, we illustrate that
spike latency characteristics are the product of an interplay
between I(A) and low- threshold calcium current (I(T)) that
requires a steady-state difference in the inactivation parameters
of the currents. Furthermore, we show that the unique first-spike
latency characteristics of stellate cells have important
implications for the integration of coincident IPSPs and EPSPs,
such that inhibition can shift first-spike latency to
differentially modulate the probability of firing.

This model file was supplied by Dr Fernandez: 
ffernand@ucalgary.ca

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