Post by SNNAP Board Admin on Nov 30, 2004 18:02:16 GMT -5
Posted by Doug Baxter
January 8, 2004
Subject: Summary of modulatory interactions
SNNAP simulates two types of intracellular modulatory agents: 1) second messengers (*.sm), and 2) ion pools (*.ion). The accumulation of second messengers is driven either by a treatment, which is specified in the *.trt file, and/or by the actions of a modulatory synapse (*.ms). [Note, *.ms can also incorporate a voltage dependence (*.fAvt). Thus, the accumulation of the second messenger will depend on both the actions of the modulatory synapse and the membrane potential of the target cell.] The accumulation of ions is driven by user-specified membrane conductances.
The various modulatory actions of second messengers and ion pools are indicated by the red arrows in the figure. A cell can contain any number of second messengers and ion pools. Both second messengers and ion pools can modulate membrane conductances and synaptic strength. In addition, both ion pools and second messengers can modulate the accumulation of second messengers. For example, the levels of intracellular calcium can modulate the accumulation of cAMP. These modulatory relationships provide opportunities to simulation many different types of nonassociative and associative neuronal and synaptic plasticity.
The modulatory relationships are defined by the equations in the *.fBr files, which provide the user with a selection of several nonlinear, increasing and decreasing functions. The nonlinearity of the modulatory functions can be increased by ‘daisy chaining’ several second messengers in series, which is the equivalent of increasing the Hill coefficient.
Simulations that illustrate each of these modulatory relationships can be found in the Example files, which are available for download.
Doug
January 8, 2004
Subject: Summary of modulatory interactions
SNNAP simulates two types of intracellular modulatory agents: 1) second messengers (*.sm), and 2) ion pools (*.ion). The accumulation of second messengers is driven either by a treatment, which is specified in the *.trt file, and/or by the actions of a modulatory synapse (*.ms). [Note, *.ms can also incorporate a voltage dependence (*.fAvt). Thus, the accumulation of the second messenger will depend on both the actions of the modulatory synapse and the membrane potential of the target cell.] The accumulation of ions is driven by user-specified membrane conductances.
The various modulatory actions of second messengers and ion pools are indicated by the red arrows in the figure. A cell can contain any number of second messengers and ion pools. Both second messengers and ion pools can modulate membrane conductances and synaptic strength. In addition, both ion pools and second messengers can modulate the accumulation of second messengers. For example, the levels of intracellular calcium can modulate the accumulation of cAMP. These modulatory relationships provide opportunities to simulation many different types of nonassociative and associative neuronal and synaptic plasticity.
The modulatory relationships are defined by the equations in the *.fBr files, which provide the user with a selection of several nonlinear, increasing and decreasing functions. The nonlinearity of the modulatory functions can be increased by ‘daisy chaining’ several second messengers in series, which is the equivalent of increasing the Hill coefficient.
Simulations that illustrate each of these modulatory relationships can be found in the Example files, which are available for download.
Doug