examples-misc_current_clamp.txt

.. currentmodule:: brian

.. index::
   pair: example usage; NeuronGroup
   pair: example usage; run
   pair: example usage; plot
   pair: example usage; show
   pair: example usage; Equations
   pair: example usage; StateMonitor

.. _example-misc_current_clamp:

Example: current_clamp (misc)
=============================

An example of single-electrode current clamp recording
with bridge compensation (using the electrophysiology library).

::

    from brian import *
    from brian.library.electrophysiology import *
    
    taum = 20 * ms        # membrane time constant
    gl = 1. / (50 * Mohm)   # leak conductance
    Cm = taum * gl        # membrane capacitance
    Re = 50 * Mohm        # electrode resistance
    Ce = 0.5 * ms / Re      # electrode capacitance
    
    eqs = Equations('''
    dvm/dt=(-gl*vm+i_inj)/Cm : volt
    Rbridge:ohm # bridge resistance
    I:amp # command current
    ''')
    eqs += current_clamp(i_cmd='I', Re=Re, Ce=Ce, bridge='Rbridge')
    setup = NeuronGroup(1, model=eqs)
    soma = StateMonitor(setup, 'vm', record=True)
    recording = StateMonitor(setup, 'v_rec', record=True)
    
    # No compensation
    run(50 * ms)
    setup.I = .5 * nA
    run(100 * ms)
    setup.I = 0 * nA
    run(50 * ms)
    
    # Full compensation
    setup.Rbridge = Re
    run(50 * ms)
    setup.I = .5 * nA
    run(100 * ms)
    setup.I = 0 * nA
    run(50 * ms)
    
    plot(recording.times / ms, recording[0] / mV, 'b')
    plot(soma.times / ms, soma[0] / mV, 'r')
    show()