.. currentmodule:: brian

.. index::
   pair: example usage; NeuronGroup
   pair: example usage; run
   pair: example usage; Synapses
   pair: example usage; StateMonitor

.. _example-synapses_short_term_plasticity:

Example: short_term_plasticity (synapses)
=========================================

Example with short term plasticity.

::

    from brian import *
    
    tau_e = 3 * ms
    taum = 10 * ms
    A_SE = 250 * pA
    Rm = 100 * Mohm
    N = 10
    
    eqs = '''
    dx/dt=rate : 1
    rate : Hz
    '''
    
    input = NeuronGroup(N, model=eqs, threshold=1., reset=0)
    input.rate = linspace(5 * Hz, 30 * Hz, N)
    
    eqs_neuron = '''
    dv/dt=(Rm*i-v)/taum:volt
    di/dt=-i/tau_e:amp
    '''
    neuron = NeuronGroup(N, model=eqs_neuron)
    
    taud=1*ms
    tauf=100*ms
    U=.1
    #taud=100*ms
    #tauf=10*ms
    #U=.6
    S=Synapses(input,neuron,
               model='''x : 1
                        u : 1
                        w : 1''',
               pre='''u=U+(u-U)*exp(-(t-lastupdate)/tauf)
                      x=1+(x-1)*exp(-(t-lastupdate)/taud)
                      i+=w*u*x
                      x*=(1-u)
                      u+=U*(1-u)''')
    S[:,:]='i==j' # one to one connection
    S.w=A_SE
    # Initialization of STP variables
    S.x = 1
    S.u = U
    
    trace = StateMonitor(neuron, 'v', record=[0, N - 1])
    
    run(1000 * ms)
    subplot(211)
    plot(trace.times / ms, trace[0] / mV)
    title('Vm')
    subplot(212)
    plot(trace.times / ms, trace[N - 1] / mV)
    title('Vm')
    show()