.. currentmodule:: brian2

.. Rossant_et_al_2011bis:

Example: Rossant_et_al_2011bis
==============================


        .. only:: html

            .. |launchbinder| image:: http://mybinder.org/badge.svg
            .. _launchbinder: https://mybinder.org/v2/gh/brian-team/brian2-binder/master?filepath=examples/frompapers/Rossant_et_al_2011bis.ipynb

            .. note::
               You can launch an interactive, editable version of this
               example without installing any local files
               using the Binder service (although note that at some times this
               may be slow or fail to open): |launchbinder|_

        

Distributed synchrony example
=============================
Fig. 14 from:

    Rossant C, Leijon S, Magnusson AK, Brette R (2011).
    "Sensitivity of noisy neurons to coincident inputs".
    Journal of Neuroscience, 31(47).

5000 independent E/I Poisson inputs are injected into a leaky integrate-and-fire neuron.
Synchronous events, following an independent Poisson process at 40 Hz, are considered, 
where 15 E Poisson spikes are randomly shifted to be synchronous at those events.
The output firing rate is then significantly higher, showing that the spike timing of
less than 1% of the excitatory synapses have an important impact on the postsynaptic firing.

::

    from brian2 import *
    
    # neuron parameters
    theta = -55*mV
    El = -65*mV
    vmean = -65*mV
    taum = 5*ms
    taue = 3*ms
    taui = 10*ms
    eqs = Equations("""
                    dv/dt  = (ge+gi-(v-El))/taum : volt
                    dge/dt = -ge/taue : volt
                    dgi/dt = -gi/taui : volt
                    """)
    
    # input parameters
    p = 15
    ne = 4000
    ni = 1000
    lambdac = 40*Hz
    lambdae = lambdai = 1*Hz
    
    # synapse parameters
    we = .5*mV/(taum/taue)**(taum/(taue-taum))
    wi = (vmean-El-lambdae*ne*we*taue)/(lambdae*ni*taui)
    
    # NeuronGroup definition
    group = NeuronGroup(N=2, model=eqs, reset='v = El',
                        threshold='v>theta',
                        refractory=5*ms, method='exact')
    group.v = El
    group.ge = group.gi = 0
    
    # independent E/I Poisson inputs
    p1 = PoissonInput(group[0:1], 'ge', N=ne, rate=lambdae, weight=we)
    p2 = PoissonInput(group[0:1], 'gi', N=ni, rate=lambdai, weight=wi)
    
    # independent E/I Poisson inputs + synchronous E events
    p3 = PoissonInput(group[1:], 'ge', N=ne, rate=lambdae-(p*1.0/ne)*lambdac, weight=we)
    p4 = PoissonInput(group[1:], 'gi', N=ni, rate=lambdai, weight=wi)
    p5 = PoissonInput(group[1:], 'ge', N=1, rate=lambdac, weight=p*we)
    
    # run the simulation
    M = SpikeMonitor(group)
    SM = StateMonitor(group, 'v', record=True)
    BrianLogger.log_level_info()
    run(1*second)
    # plot trace and spikes
    for i in [0, 1]:
        spikes = (M.t[M.i == i] - defaultclock.dt)/ms
        val = SM[i].v
        subplot(2, 1, i+1)
        plot(SM.t/ms, val)
        plot(tile(spikes, (2, 1)), 
             vstack((val[array(spikes, dtype=int)],
                     zeros(len(spikes)))), 'C0')
        title("%s: %d spikes/second" % (["uncorrelated inputs", "correlated inputs"][i], 
                                        M.count[i]))
    tight_layout()
    show()
    

.. image:: ../resources/examples_images/frompapers.Rossant_et_al_2011bis.1.png