diff --git a/docs/index.rst b/docs/index.rst index bb525d6a9fab551c3d3e196c82af8213d9af8dc3..8e36a24fb1fc749b99ba7658590ed5b96014e5b3 100644 --- a/docs/index.rst +++ b/docs/index.rst @@ -45,6 +45,7 @@ Contents: introduction/index user/py/quickstart/index + user/py/rdesigneur/index user/py/cookbook/index user/py/builtins/index user/py/classes/index diff --git a/docs/user/py/rdesigneur/index.rst b/docs/user/py/rdesigneur/index.rst new file mode 100644 index 0000000000000000000000000000000000000000..9579b0a89372c15c81b5da6c1639ac863c1df901 --- /dev/null +++ b/docs/user/py/rdesigneur/index.rst @@ -0,0 +1,770 @@ +-------------- + +**Rdesigneur: Building multiscale models** +========================================== + +Upi Bhalla + +Dec 28 2015. + +-------------- + +Contents +-------- + +Introduction +------------ + +**Rdesigneur** (Reaction Diffusion and Electrical SIGnaling in NEURons) +is an interface to the multiscale modeling capabilities in MOOSE. It is +designed to build models incorporating biochemical signaling pathways in +dendrites and spines, coupled to electrical events in neurons. +Rdesigneur assembles models from predefined parts: it delegates the +details to specialized model definition formats. Rdesigneur combines one +or more of the following cell parts to build models: + +- Neuronal morphology +- Dendritic spines +- Ion channels +- Reaction systems + +Rdesigneur's main role is to specify how these are put together, +including assigning parameters to do so. Rdesigneur also helps with +setting up the simulation input and output. + +Quick Start +----------- + +Here we provide a few use cases, building up from a minimal model to a +reasonably complete multiscale model spanning chemical and electrical +signaling. + +Bare Rdesigneur: single passive compartment +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +If we don't provide any arguments at all to the Rdesigneur, it makes a +model with a single passive electrical compartment in the MOOSE path +``/model/elec/soma``. Here is how to do this: + +:: + + import moose + import rdesigneur as rd + rdes = rd.rdesigneur() + rdes.buildModel() + +To confirm that it has made a compartment with some default values we +can add a line: + +:: + + moose.showfields( rdes.soma ) + +This should produce the output: + +:: + + [ /model[0]/elec[0]/soma[0] ] + diameter = 0.0005 + fieldIndex = 0 + Ra = 7639437.26841 + y0 = 0.0 + Rm = 424413.177334 + index = 0 + numData = 1 + inject = 0.0 + initVm = -0.065 + Em = -0.0544 + y = 0.0 + numField = 1 + path = /model[0]/elec[0]/soma[0] + dt = 0.0 + tick = -2 + z0 = 0.0 + name = soma + Cm = 7.85398163398e-09 + x0 = 0.0 + Vm = -0.06 + className = ZombieCompartment + idValue = 465 + length = 0.0005 + Im = 1.3194689277e-08 + x = 0.0005 + z = 0.0 + +Simulate and display current pulse to soma +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +A more useful script would run and display the model. Rdesigneur can +help with the stimulus and the plotting. This simulation has the same +passive compartment, and current is injected as the simulation runs. +This script displays the membrane potential of the soma as it charges +and discharges. + +:: + + import moose + import rdesigneur as rd + rdes = rd.rdesigneur( + stimList = [['soma', '1', 'inject', '(t>0.1 && t<0.2) * 2e-8']], + plotList = [['soma', '1', 'Vm', 'Soma membrane potential']], + ) + rdes.buildModel() + moose.reinit() + moose.start( 0.3 ) + rdes.display() + +The *stimList* defines a stimulus. Each entry has four arguments: + +:: + + `[region_in_cell, region_expression, parameter, expression_string]` + +- ``region_in_cell`` specifies the objects to stimulate. Here it is + just the soma. +- ``region_expression`` specifies a geometry based calculation to + decide whether to apply the stimulus. The value must be >0 for the + stimulus to be present. Here it is just 1. +- ``parameter`` specifies the simulation parameter to assign. Here it + is the injection current to the compartment. +- ``expression_string`` calculates the value of the parameter, + typically as a function of time. Here we use the function sign(x), + where sign(x) == +1 for x > 0, 0 for x = 0 and -1 for x < 0. + +To summarise this, the *stimList* here means *inject a current of 20nA +to the soma between the times of 0.1 and 0.2 s*. + +The *plotList* defines what to plot. It has a similar set of arguments: + +:: + + `[region_in_cell, region_expression, parameter, title_of_plot]` + +These mean the same thing as for the stimList except for the title of +the plot. + +The *rdes.display()* function causes the plots to be displayed. + +.. figure:: ../../images/rdes2_passive_squid.png + :alt: Plot for current input to passive compartment + + Plot for current input to passive compartment +When we run this we see an initial depolarization as the soma settles +from its initial -65 mV to a resting Em = -54.4 mV. These are the +original HH values, see the example above. At t = 0.1 seconds there is +another depolarization due to the current injection, and at t = 0.2 +seconds this goes back to the resting potential. + +HH Squid model in a single compartment +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Here we put the Hodgkin-Huxley squid model channels into a passive +compartment. The HH channels are predefined as prototype channels for +Rdesigneur, + +:: + + import moose + import pylab + import rdesigneur as rd + rdes = rd.rdesigneur( + chanProto = [['make_HH_Na()', 'Na'], ['make_HH_K()', 'K']], + chanDistrib = [ + ['Na', 'soma', 'Gbar', '1200' ], + ['K', 'soma', 'Gbar', '360' ]], + stimList = [['soma', '1', 'inject', '(t>0.1 && t<0.2) * 1e-8' ]], + plotList = [['soma', '1', 'Vm', 'Membrane potential']] + ) + + rdes.buildModel() + moose.reinit() + moose.start( 0.3 ) + rdes.display() + +Here we introduce two new model specification lines: + +- **chanProto**: This specifies which ion channels will be used in the + model. Each entry here has two fields: the source of the channel + definition, and (optionally) the name of the channel. In this example + we specify two channels, an Na and a K channel using the original + Hodgkin-Huxley parameters. As the source of the channel definition we + use the name of the Python function that builds the channel. The + *make\_HH\_Na()* and *make\_HH\_K()* functions are predefined but we + can also specify our own functions for making prototypes. We could + also have specified the channel prototype using the name of a channel + definition file in ChannelML (a subset of NeuroML) format. +- **chanDistrib**: This specifies *where* the channels should be placed + over the geometry of the cell. Each entry in the chanDistrib list + specifies the distribution of parameters for one channel using four + entries: + + ``[object_name, region_in_cell, parameter, expression_string]`` + + In this case the job is almost trivial, since we just have a single + compartment named *soma*. So the line + + ``['Na', 'soma', 'Gbar', '1200' ]`` + + means *Put the Na channel in the soma, and set its maximal + conductance density (Gbar) to 1200 Siemens/m^2*. + +As before we apply a somatic current pulse. Since we now have HH +channels in the model, this generates action potentials. + +.. figure:: ../../images/rdes3_squid.png + :alt: Plot for HH squid simulation + + Plot for HH squid simulation +Reaction system in a single compartment +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Here we use the compartment as a place in which to embed a chemical +model. The chemical oscillator model is predefined in the rdesigneur +prototypes. + +:: + + import moose + import pylab + import rdesigneur as rd + rdes = rd.rdesigneur( + turnOffElec = True, + diffusionLength = 1e-3, # Default diffusion length is 2 microns + chemProto = [['make_Chem_Oscillator()', 'osc']], + chemDistrib = [['osc', 'soma', 'install', '1' ]], + plotList = [['soma', '1', 'dend/a', 'conc', 'a Conc'], + ['soma', '1', 'dend/b', 'conc', 'b Conc']] + ) + rdes.buildModel() + b = moose.element( '/model/chem/dend/b' ) + b.concInit *= 5 + moose.reinit() + moose.start( 200 ) + + rdes.display() + +In this special case we set the turnOffElec flag to True, so that +Rdesigneur only sets up chemical and not electrical calculations. This +makes the calculations much faster, since we disable electrical +calculations and delink chemical calculations from them. + +We also have a line which sets the ``diffusionLength`` to 1 mm, so that +it is bigger than the 0.5 mm squid axon segment in the default +compartment. If you don't do this the system will subdivide the +compartment into 2 micron voxels for the purposes of putting in a +reaction-diffusion system, which we discuss below. + +There are a couple of lines to change the initial concentration of the +molecular pool b. It is scaled up 5x to give rise to slowly decaying +oscillations. + +.. figure:: ../../images/rdes4_osc.png + :alt: Plot for single-compartment reaction simulation + + Plot for single-compartment reaction simulation +Reaction-diffusion system +~~~~~~~~~~~~~~~~~~~~~~~~~ + +In order to see what a reaction-diffusion system looks like, delete the +``diffusionLength`` expression in the previous example and add a couple +of lines to set up 3-D graphics for the reaction-diffusion product: + +:: + + import moose + import pylab + import rdesigneur as rd + rdes = rd.rdesigneur( + turnOffElec = True, + chemProto = [['make_Chem_Oscillator()', 'osc']], + chemDistrib = [['osc', 'soma', 'install', '1' ]], + plotList = [['soma', '1', 'dend/a', 'conc', 'Concentration of a'], + ['soma', '1', 'dend/b', 'conc', 'Concentration of b']], + moogList = [['soma', '1', 'dend/a', 'conc', 'a Conc', 0, 360 ]] + ) + + rdes.buildModel() + bv = moose.vec( '/model/chem/dend/b' ) + bv[0].concInit *= 2 + bv[-1].concInit *= 2 + moose.reinit() + + rdes.displayMoogli( 1, 400, 0.001 ) + +This is the line we deleted. + +:: + + `diffusionLength = 1e-3,` + +With this change we permit *rdesigneur* to use the default diffusion +length of 2 microns. The 500-micron axon segment is now subdivided into +250 voxels, each of which has a reaction system and diffusing molecules. +To make it more picturesque, we have added a line after the plotList, to +display the outcome in 3-D: + +:: + + 'moogList = [['soma', '1', 'dend/a', 'conc', 'a Conc', 0, 360 ]]' + +This line says: take the model compartments defined by ``soma`` as the +region to display, do so throughout the the geometry (the ``1`` +signifies this), and over this range find the chemical entity defined by +``dend/a``. For each ``a`` molecule, find the ``conc`` and dsiplay it. +There are two optional arguments, ``0`` and ``360``, which specify the +low and high value of the displayed variable. + +In order to initially break the symmetry of the system, we change the +initial concentration of molecule b at each end of the cylinder: + +:: + + bv[0].concInit *= 2 + bv[-1].concInit *= 2 + +If we didn't do this the entire system would go through a few cycles of +decaying oscillation and then reach a boring, spatially uniform, steady +state. Try putting an initial symmetry break elsewhere to see what +happens. + +To display the concenctration changes in the 3-D soma as the simulation +runs, we use the line + +:: + + `rdes.displayMoogli( 1, 400, 0.001 )` + +The arguments mean: *displayMoogli( frametime, runtime, rotation )* +Here, + +:: + + frametime = time by which simulation advances between display updates + runtime = Total simulated time + rotation = angle by which display rotates in each frame, in radians. + +When we run this, we first get a 3-D display with the oscillating +reaction-diffusion system making its way inward from the two ends. After +the simulation ends the plots for all compartments for the whole run +come up. + +.. figure:: ../../images/rdes5_reacdiff.png + :alt: Display for oscillatory reaction-diffusion simulation + + Display for oscillatory reaction-diffusion simulation +Make a toy multiscale model with electrical and chemical signaling. +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Now we put together chemical and electrical models. In this toy model we +have an HH-squid type single compartment electrical model, cohabiting +with a chemical oscillator. The chemical oscillator regulates K+ channel +amounts, and the average membrane potential regulates the amounts of a +reactant in the chemical oscillator. This is a recipe for some strange +firing patterns. + +:: + + import moose + import pylab + import rdesigneur as rd + rdes = rd.rdesigneur( + # We want just one compartment so we set diffusion length to be + # bigger than the 0.5 mm HH axon compartment default. + diffusionLength = 1e-3, + chanProto = [['make_HH_Na()', 'Na'], ['make_HH_K()', 'K']], + chanDistrib = [ + ['Na', 'soma', 'Gbar', '1200' ], + ['K', 'soma', 'Gbar', '360' ]], + chemProto = [['make_Chem_Oscillator()', 'osc']], + chemDistrib = [['osc', 'soma', 'install', '1' ]], + # These adaptor parameters give interesting-looking but + # not particularly physiological behaviour. + adaptorList = [ + [ 'dend/a', 'conc', 'Na', 'modulation', 1, -5.0 ], + [ 'dend/b', 'conc', 'K', 'modulation', 1, -0.2], + [ 'dend/b', 'conc', '.', 'inject', -1.0e-7, 4e-7 ], + [ '.', 'Vm', 'dend/s', 'conc', 2.5, 20.0 ] + ], + plotList = [['soma', '1', 'dend/a', 'conc', 'a Conc'], + ['soma', '1', 'dend/b', 'conc', 'b Conc'], + ['soma', '1', 'dend/s', 'conc', 's Conc'], + ['soma', '1', 'Na', 'Gk', 'Na Gk'], + ['soma', '1', '.', 'Vm', 'Membrane potential'] + ] + ) + + rdes.buildModel() + moose.reinit() + moose.start( 250 ) # Takes a few seconds to run this. + + rdes.display() + +We've already modeled the HH squid model and the oscillator +individually, and you should recognize the parts of those models above. +The new section that makes this work the *adaptorList* which specifies +how the electrical and chemical parts talk to each other. This entirely +fictional set of interactions goes like this: + +:: + + [ 'dend/a', 'conc', 'Na', 'modulation', 1, -5.0 ] + +- *dend/a*: The originating variable comes from the 'a' pool on the + 'dend' compartment. + + *conc*: This is the originating variable name on the 'a' pool. + + *Na*: This is the target variable + + *modulation*: scale the Gbar of Na up and down. Use 'modulation' + rather than direct assignment of Gbar since Gbar is different for + each differently-sized compartment. + + *1*: This is the initial offset + + *-5.0*: This is the scaling from the input to the parameter updated + in the simulation. + +A similar set of adaptor entries couple the molecule *dend/b* to the K +channel, *dend/b* again to the current injection into the soma, and the +membrane potential to the concentration of *dend/s*. + +.. figure:: ../../images/rdes6_multiscale.png + :alt: Plot for toy multiscale model + + Plot for toy multiscale model +Morphology: Load .swc morphology file and view it +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Here we build a passive model using a morphology file in the .swc file +format (as used by NeuroMorpho.org). The morphology file is predefined +for Rdesigneur and resides in the directory ``./cells``. We apply a +somatic current pulse, and view the somatic membrane potential in a +plot, as before. To make things interesting we display the morphology in +3-D upon which we represent the membrane potential as colors. + +:: + + import moose + import rdesigneur as rd + rdes = rd.rdesigneur( + cellProto = [['./cells/h10.CNG.swc', 'elec']], + stimList = [['soma', '1', '.', 'inject', 't * 25e-9' ]], + plotList = [['#', '1', '.', 'Vm', 'Membrane potential'], + ['#', '1', 'Ca_conc', 'Ca', 'Ca conc (uM)']], + moogList = [['#', '1', '.', 'Vm', 'Soma potential']] + ) + + rdes.buildModel() + + moose.reinit() + rdes.displayMoogli( 0.0002, 0.1 ) + +Here the new concept is the cellProto line, which loads in the specified +cell model: + +:: + + `[ filename, cellname ]` + +The system recognizes the filename extension and builds a model from the +swc file. It uses the cellname **elec** in this example. + +We use a similar line as in the reaction-diffusion example, to build up +a Moogli display of the cell model: + +:: + + `moogList = [['#', '1', '.', 'Vm', 'Soma potential']]` + +Here we have: + +:: + + *#*: the path to use for selecting the compartments to display. + This wildcard means use all compartments. + *1*: The expression to use for the compartments. Again, `1` means use + all of them. + *.*: Which object in the compartment to display. Here we are using the + compartment itself, so it is just a dot. + *Vm*: Field to display + *Soma potential*: Title for display. + +.. figure:: ../../images/rdes7_passive.png + :alt: 3-D display for passive neuron + + 3-D display for passive neuron +Build an active neuron model by putting channels into a morphology file +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +We load in a morphology file and distribute voltage-gated ion channels +over the neuron. Here the voltage-gated channels are obtained from a +number of channelML files, located in the ``./channels`` subdirectory. +Since we have a spatially extended neuron, we need to specify the +spatial distribution of channel densities too. + +:: + + import moose + import rdesigneur as rd + rdes = rd.rdesigneur( + chanProto = [ + ['./chans/hd.xml'], + ['./chans/kap.xml'], + ['./chans/kad.xml'], + ['./chans/kdr.xml'], + ['./chans/na3.xml'], + ['./chans/nax.xml'], + ['./chans/CaConc.xml'], + ['./chans/Ca.xml'] + ], + cellProto = [['./cells/h10.CNG.swc', 'elec']], + chanDistrib = [ \ + ["hd", "#dend#,#apical#", "Gbar", "50e-2*(1+(p*3e4))" ], + ["kdr", "#", "Gbar", "p < 50e-6 ? 500 : 100" ], + ["na3", "#soma#,#dend#,#apical#", "Gbar", "850" ], + ["nax", "#soma#,#axon#", "Gbar", "1250" ], + ["kap", "#axon#,#soma#", "Gbar", "300" ], + ["kap", "#dend#,#apical#", "Gbar", + "300*(H(100-p*1e6)) * (1+(p*1e4))" ], + ["Ca_conc", "#", "tau", "0.0133" ], + ["kad", "#soma#,#dend#,#apical#", "Gbar", "50" ], + ["Ca", "#", "Gbar", "50" ] + ], + stimList = [['soma', '1', '.', 'inject', '(t>0.02) * 1e-9' ]], + plotList = [['#', '1', '.', 'Vm', 'Membrane potential'], + ['#', '1', 'Ca_conc', 'Ca', 'Ca conc (uM)']], + moogList = [['#', '1', 'Ca_conc', 'Ca', 'Calcium conc (uM)', 0, 120], + ['#', '1', '.', 'Vm', 'Soma potential']] + ) + + rdes.buildModel() + + moose.reinit() + rdes.displayMoogli( 0.0002, 0.052 ) + +Here we make more extensive use of two concepts which we've already seen +from the single compartment squid model: + +1. *chanProto*: This defines numerous channels, each of which is of the + form: + + ``[ filename ]`` + + or + + ``[ filename, channelname ]`` + +If the *channelname* is not specified the system uses the last part of +the channel name, before the filetype suffix. + +2. *chanDistrib*: This defines the spatial distribution of each channel + type. Each line is of a form that should be familiar now: + + ``[channelname, region_in_cell, parameter, expression_string]`` + +- The *channelname* is the name of the prototype from *chanproto*. This + is usually an ion channel, but in the example above you can also see + a calcium concentration pool defined. +- The *region\_in\_cell* is typically defined using wildcards, so that + it generalizes to any cell morphology. For example, the plain + wildcard ``#`` means to consider all cell compartments. The wildcard + ``#dend#`` means to consider all compartments with the string + ``dend`` somewhere in the name. Wildcards can be comma-separated, so + ``#soma#,#dend#`` means consider all compartments with either soma or + dend in their name. The naming in MOOSE is defined by the model file. + Importantly, in **.swc** files MOOSE generates names that respect the + classification of compartments into axon, soma, dendrite, and apical + dendrite compartments respectively. SWC files generate compartment + names such as: + + :: + + soma_<number> + dend_<number> + apical_<number> + axon_<number> + +where the number is automatically assigned by the reader. In order to +select all dendritic compartments, for example, one would use *"#dend#"* +where the *"#"* acts as a wildcard to accept any string. - The +*parameter* is usually Gbar, the channel conductance density in *S/m^2*. +If *Gbar* is zero or less, then the system economizes by not +incorporating this channel mechanism in this part of the cell. +Similarly, for calcium pools, if the *tau* is below zero then the +calcium pool object is simply not inserted into this part of the cell. - +The *expression\_string* defines the value of the parameter, such as +Gbar. This is typically a function of position in the cell. The +expression evaluator knows about several parameters of cell geometry. +All units are in metres: + +- *x*, *y* and *z* coordinates. +- *g*, the geometrical distance from the soma +- *p*, the path length from the soma, measured along the dendrites. +- *dia*, the diameter of the dendrite. +- *L*, The electrotonic length from the soma (no units). + +Along with these geometrical arguments, we make liberal use of the +Heaviside function H(x) to set up the channel distributions. The +expression evaluator also knows about pretty much all common algebraic, +trignometric, and logarithmic functions, should you wish to use these. + +Also note the two Moogli displays. The first is the calcium +concentration. The second is the membrane potential in each compartment. +Easy! + +.. figure:: ../../images/rdes8_active.png + :alt: 3-D display for active neuron + + 3-D display for active neuron +Build a spiny neuron from a morphology file and put active channels in it. +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +This model is one step elaborated from the previous one, in that we now +also have dendritic spines. MOOSE lets one decorate a bare neuronal +morphology file with dendritic spines, specifying various geometric +parameters of their location. As before, we use an swc file for the +morphology, and the same ion channels and distribution. + +:: + + import moose + import pylab + import rdesigneur as rd + rdes = rd.rdesigneur( + chanProto = [ + ['./chans/hd.xml'], + ['./chans/kap.xml'], + ['./chans/kad.xml'], + ['./chans/kdr.xml'], + ['./chans/na3.xml'], + ['./chans/nax.xml'], + ['./chans/CaConc.xml'], + ['./chans/Ca.xml'] + ], + cellProto = [['./cells/h10.CNG.swc', 'elec']], + spineProto = [['make_active_spine()', 'spine']], + chanDistrib = [ + ["hd", "#dend#,#apical#", "Gbar", "50e-2*(1+(p*3e4))" ], + ["kdr", "#", "Gbar", "p < 50e-6 ? 500 : 100" ], + ["na3", "#soma#,#dend#,#apical#", "Gbar", "850" ], + ["nax", "#soma#,#axon#", "Gbar", "1250" ], + ["kap", "#axon#,#soma#", "Gbar", "300" ], + ["kap", "#dend#,#apical#", "Gbar", + "300*(H(100-p*1e6)) * (1+(p*1e4))" ], + ["Ca_conc", "#", "tau", "0.0133" ], + ["kad", "#soma#,#dend#,#apical#", "Gbar", "50" ], + ["Ca", "#", "Gbar", "50" ] + ], + spineDistrib = [['spine', '#dend#,#apical#', '20e-6', '1e-6']], + stimList = [['soma', '1', '.', 'inject', '(t>0.02) * 1e-9' ]], + plotList = [['#', '1', '.', 'Vm', 'Membrane potential'], + ['#', '1', 'Ca_conc', 'Ca', 'Ca conc (uM)']], + moogList = [['#', '1', 'Ca_conc', 'Ca', 'Calcium conc (uM)', 0, 120], + ['#', '1', '.', 'Vm', 'Soma potential']] + ) + + rdes.buildModel() + + moose.reinit() + rdes.displayMoogli( 0.0002, 0.023 ) + +Spines are set up in a familiar way: we first define one (or more) +prototype spines, and then distribute these around the cell. Here is the +prototype string: + +:: + + [spine_proto, spinename] + +*spine\_proto*: This is typically a function. One can define one's own, +but there are several predefined ones in rdesigneur. All these define a +spine with the following parameters: + +- head diameter 0.5 microns +- head length 0.5 microns +- shaft length 1 micron +- shaft diameter of 0.2 microns +- RM = 1.0 ohm-metre square +- RA = 1.0 ohm-meter +- CM = 0.01 Farads per square metre. + +Here are the predefined spine prototypes: + +- *make\_passive\_spine()*: This just makes a passive spine with the + default parameters +- *make\_exc\_spine()*: This makes a spine with NMDA and glu receptors, + and also a calcium pool. The NMDA channel feeds the Ca pool. +- *make\_active\_spine()*: This adds a Ca channel to the exc\_spine. + and also a calcium pool. + +The spine distributions are specified in a familiar way for the first +few arguments, and then there are multiple (optional) spine-specific +parameters: + +*[spinename, region\_in\_cell, spacing, spacing\_distrib, size, +size\_distrib, angle, angle\_distrib ]* + +Only the first two arguments are mandatory. + +- *spinename*: The prototype name +- *region\_in\_cell*: Usual wildcard specification of names of + compartments in which to put the spines. +- *spacing*: Math expression to define spacing between spines. In the + current implementation this evaluates to + ``1/probability_of_spine_per_unit_length``. Defaults to 10 microns. + Thus, there is a 10% probability of a spine insertion in every + micron. This evaluation method has the drawback that it is possible + to space spines rather too close to each other. If spacing is zero or + less, no spines are inserted. +- *spacing\_distrib*: Math expression for distribution of spacing. In + the current implementation, this specifies the interval at which the + system samples from the spacing probability above. Defaults to 1 + micron. +- *size*: Linear scale factor for size of spine. All dimensions are + scaled by this factor. The default spine head here is 0.5 microns in + diameter and length. If the scale factor were to be 2, the volume + would be 8 times as large. Defaults to 1.0. +- *size\_distrib*: Range for size of spine. A random number R is + computed in the range 0 to 1, and the final size used is + ``size + (R - 0.5) * size_distrib``. Defaults to 0.5 +- *angle*: This specifies the initial angle at which the spine sticks + out of the dendrite. If all angles were zero, they would all point + away from the soma. Defaults to 0 radians. +- *angle\_distrib*: Specifies a random number to add to the initial + angle. Defaults to 2 PI radians, so the spines come out in any + direction. + +One may well ask why we are not using a Python dictionary to handle all +these parameters. Short answer is: terseness. Longer answer is that the +rdesigneur format is itself meant to be an intermediate form for an +eventual high-level, possibly XML-based multiscale modeling format. + +.. figure:: ../../images/rdes9_spiny_active.png + :alt: 3-D display for spiny active neuron + + 3-D display for spiny active neuron +Build a spiny neuron from a morphology file and put a reaction-diffusion system in it. +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Rdesigneur is specially designed to take reaction systems with a +dendrite, a spine head, and a spine PSD compartment, and embed these +systems into neuronal morphologies. This example shows how this is done. + +The dendritic molecules diffuse along the dendrite in the region +specified by the *chemDistrib* keyword. In this case they are placed on +all apical and basal dendrites, but only at distances over 500 microns +from the soma. The spine head and PSD reaction systems are inserted only +into spines within this same *chemDistrib* zone. Diffusion coupling +between dendrite, and each spine head and PSD is also set up. It takes a +predefined chemical model file for Rdesigneur, which resides in the +``./chem`` subdirectory. As in an earlier example, we turn off the +electrical calculations here as they are not needed. Here we plot out +the number of receptors on every single spine as a function of time. + +(stuff here) + +Make a full multiscale model with complex spiny morphology and electrical and chemical signaling. +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +(stuff here)