Injecting current into a neuron


Hi !

I am new to this platform

I am trying to Inject step current into a neuron using the following code which is pynn source code
for injecting step current

from neuron import h
import numpy
from pyNN.standardmodels import electrodes, build_translations, StandardCurrentSource
from pyNN.parameters import ParameterSpace, Sequence
from pyNN.neuron import simulator

class NeuronCurrentSource(StandardCurrentSource):
“”“Base class for a source of current to be injected into a neuron.”""

def __init__(self, **parameters):
    self._devices = []
    self.cell_list = []
    self._amplitudes = None
    self._times = None
    self._h_iclamps = {}
    parameter_space = ParameterSpace(self.default_parameters,
    parameter_space = self.translate(parameter_space)

def _h_amplitudes(self):
    if self._amplitudes is None:
        if isinstance(self.amplitudes, Sequence):
            self._amplitudes = h.Vector(self.amplitudes.value)
            self._amplitudes = h.Vector(self.amplitudes)
    return self._amplitudes

def _h_times(self):
    if self._times is None:
        if isinstance(self.times, Sequence):
            self._times = h.Vector(self.times.value)
            self._times = h.Vector(self.times)
    return self._times

def _reset(self):
    if self._is_computed:
        self._amplitudes = None
        self._times = None
    for iclamp in self._h_iclamps.values():
        self._update_iclamp(iclamp, 0.0)    # send tstop = 0.0 on _reset()

def _update_iclamp(self, iclamp, tstop):
    if not self._is_playable:
        iclamp.delay = self.start
        iclamp.dur = self.stop - self.start
        iclamp.amp = self.amplitude

    if self._is_playable:
        iclamp.delay = 0.0
        iclamp.dur = 1e12
        iclamp.amp = 0.0

        # check exists only for StepCurrentSource (_is_playable = True, _is_computed = False)
        # t_stop should be part of the time sequence to handle repeated runs
        if not self._is_computed and tstop not in self._h_times.to_python():
            ind = self._h_times.indwhere(">=", tstop)
            if ind == -1:   # tstop beyond last specified time instant
                ind = self._h_times.size()
            if ind == 0.0:    # tstop before first specified time instant
                amp_val = 0.0
                amp_val = self._h_amplitudes.x[int(ind)-1]
            self._h_times.insrt(ind, tstop)
            self._h_amplitudes.insrt(ind, amp_val), self._h_times)

def _check_step_times(self, times, amplitudes, resolution):
    # ensure that all time stamps are non-negative
    if not (times >= 0.0).all():
        raise ValueError("Step current cannot accept negative timestamps.")
    # ensure that times provided are of strictly increasing magnitudes
    dt_times = numpy.diff(times)
    if not all(dt_times>0.0):
        raise ValueError("Step current timestamps should be monotonically increasing.")
    # map timestamps to actual simulation time instants based on specified dt
    for ind in range(len(times)):
        times[ind] = self._round_timestamp(times[ind], resolution)
    # remove duplicate timestamps, and corresponding amplitudes, after mapping
    step_times = []
    step_amplitudes = []
    for ts0, amp0, ts1 in zip(times, amplitudes, times[1:]):
        if ts0 != ts1:
    return step_times, step_amplitudes

def set_native_parameters(self, parameters):
    for name, value in parameters.items():
        if name == "amplitudes": # key used only by StepCurrentSource
            step_times = parameters["times"].value
            step_amplitudes = parameters["amplitudes"].value
            step_times, step_amplitudes = self._check_step_times(step_times, step_amplitudes, simulator.state.dt)
            parameters["times"].value = step_times
            parameters["amplitudes"].value = step_amplitudes
        if isinstance(value, Sequence):  # this shouldn't be necessary, but seems to prevent a segfault
            value = value.value
        object.__setattr__(self, name, value)

def get_native_parameters(self):
    return ParameterSpace(dict((k, self.__getattribute__(k)) for k in self.get_native_names()))

def inject_into(self, cells):
    __doc__ = StandardCurrentSource.inject_into.__doc__
    for id in cells:
        if id.local:
            if not id.celltype.injectable:
                raise TypeError("Can't inject current into a spike source.")
            if not (id in self._h_iclamps):
                self.cell_list += [id]
                self._h_iclamps[id] = h.IClamp(0.5, sec=id._cell.source_section)

def record(self):
    self.itrace = h.Vector()
    self.record_times = h.Vector()

def _get_data(self):
    # NEURON and pyNN have different concepts of current initiation times
    # To keep this consistent across simulators, pyNN will have current
    # initiating at the electrode at t_start and effect on cell at next dt.
    # This requires removing the first element from the current Vector
    # as NEURON computes the currents one time step later. The vector length
    # is compensated by repeating the last recorded value of current.
    t_arr = numpy.array(self.record_times)
    i_arr = numpy.array(self.itrace)[1:]
    i_arr = numpy.append(i_arr, i_arr[-1])
    return (t_arr, i_arr)

class StepCurrentSource(NeuronCurrentSource, electrodes.StepCurrentSource):

__doc__ = electrodes.StepCurrentSource.__doc__

translations = build_translations(
    ('amplitudes',  'amplitudes'),
    ('times',       'times')

_is_playable = True
_is_computed = False

def _generate(self):

steps = StepCurrentSource(times=[5.0, 100.0],amplitudes=[i_min,0.0])

I am not sure about the above I am getting following error

OSError: NEURON mechanisms not found in /home/spinnaker/sPyNNakerGit/lib/python3.6/site-packages/pyNN/neuron/nmodl. You may need to run ‘nrnivmodl’ in this directory.

Is there any alternative for this ?

Thank you !