# -*- coding: utf-8 -*-
#
# brette_gerstner_fig_2c.py
#
# This file is part of NEST.
#
# Copyright (C) 2004 The NEST Initiative
#
# NEST is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 2 of the License, or
# (at your option) any later version.
#
# NEST is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with NEST.  If not, see <http://www.gnu.org/licenses/>.

"""
Testing the adapting exponential integrate and fire model in NEST (Brette and Gerstner Fig 2C)
----------------------------------------------------------------------------------------------

This example tests the adaptive integrate and fire model (AdEx) according to
Brette and Gerstner [1]_ reproduces Figure 2C of the paper.
Note that Brette and Gerstner give the value for `b` in `nA`.
To be consistent with the other parameters in the equations, `b` must be
converted to `pA` (pico Ampere).

References
~~~~~~~~~~

.. [1] Brette R and Gerstner W (2005). Adaptive exponential integrate-and-fire model as an effective
       description of neuronal activity J. Neurophysiology. https://doi.org/10.1152/jn.00686.2005

"""


import nest
import nest.voltage_trace
import matplotlib.pyplot as plt

nest.ResetKernel()

###############################################################################
# First we make sure that the resolution of the simulation is 0.1 ms. This is
# important, since the slop of the action potential is very steep.

nest.resolution = 0.1
neuron = nest.Create("aeif_cond_alpha")

###############################################################################
# `a` and `b` are parameters of the adex model. Their values come from the
# publication.

neuron.set(a=4.0, b=80.5)

###############################################################################
# Next we define the stimulus protocol. There are two DC generators,
# producing stimulus currents during two time-intervals.

dc = nest.Create("dc_generator", 2)
dc.set(amplitude=[500.0, 800.0], start=[0.0, 500.0], stop=[200.0, 1000.0])

###############################################################################
# We connect the DC generators.

nest.Connect(dc, neuron, 'all_to_all')

###############################################################################
# And add a ``voltmeter`` to sample the membrane potentials from the neuron
# in intervals of 0.1 ms.

voltmeter = nest.Create("voltmeter", params={'interval': 0.1})
nest.Connect(voltmeter, neuron)

###############################################################################
# Finally, we simulate for 1000 ms and plot a voltage trace to produce the
# figure.

nest.Simulate(1000.0)

nest.voltage_trace.from_device(voltmeter)
plt.axis([0, 1000, -80, -20])
plt.show()
