Parallel Neuron: NetCon failed to connect different hosts
I am trying to create a basic ring network to run in parallel as in Hines & Carnevalle 2007 (see in http://www.neuron.yale.edu/neuron/nrnpubs) together with the help of Thomas McTavish tutorial on https://nn.med.yale.edu:8000 to implement it in Python. To become familiar with the parallel environment of NEURON, I wanted to create a simple ring of cells, with as many neurons as parallel processes. For that I first created a Cell class, with a synapse on the soma, and methods to get the vectors of time and voltage and to create a NetCon.
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""" morphology.py this file contains a class to create a very basic cell type to work in parallel """ from mpi4py import MPI # always load mpi4py before neuron from neuron import h import numpy as np class DummyCell(object): """ A dummy cell simply for testing """ def __init__(self): self.soma = h.Section(name ='soma', cell = self) self.soma.L = self.soma.diam = 30. self.soma.insert('hh') # create a synapse in soma self.syn = h.ExpSyn(self.soma(0.5), name='syn', sec=self.soma) self.syn.tau = 2. # assign gid to current thread/rank # because we did not start ParallelContext, we have to use # the MPI for getting the rank self.gid = MPI.COMM_WORLD.Get_rank() # time and voltage vectors self._time = h.Vector() self._time.record(h._ref_t) self._voltage = h.Vector() self._voltage.record(self.soma(0.5)._ref_v) # a list of the NetCons of this cell self.netcon =  def connect2target(self, target): """ connects the firing of this cell to a target via NetCon and appends the NetCon to the netcon list. """ source = self.soma(0.5)._ref_v netcon = h.NetCon(source, target, sec = self.soma) netcon.threshold = 10.0 netcon.delay = 3.1 netcon.weight = 0.04 self.netcon.append(netcon) return netcon def get_vectorlist(self, time=True, voltage=True): """ return a list of NumPy vectors with time and voltage at the soma """ vectorlist =  if time is True: vectorlist.append(np.array(self._time)) if voltage is True: vectorlist.append(np.array(self._voltage)) return vectorlist
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""" ring.py A class defining a network of N cells, where N is the number of process currently called in a parallel environment. Cell N will be connected to cell with gid =0. """ # this will initialize MPI from morphology import DummyCell as Cell from neuron import h class Ring(object): def __init__(self): """ creates a ring containing as many cells as parallel processes """ # list of cell objects self.cell = Cell() # create one cell in the current thread # lists of netcons on this host self.netcon =  # external stimulator to this cell only if gid=0 self.spk_generator = None self.nc_generator = None # external stimulator if self.cell.gid == 0: self.spk_generator = h.NetStim() self.spk_generator.number = 1 self.spk_generator.start = 20. self.nc_generator = h.NetCon(self.spk_generator, self.cell.syn) self.nc_generator.delay = 1. self.nc_generator.weight = 0.04 self.nc_generator.threshold = 10. self.pc = h.ParallelContext() # associate the gid of the cell with host's thread self.pc.set_gid2node(self.cell.gid, int(self.pc.id())) # attach NetCon source (spike detector) to cell.gid nc = self.cell.connect2target(None) self.pc.cell(self.cell.gid, nc) # ** Connection ** ncells = int(self.pc.nhost()) targid = (self.cell.gid+1)%ncells if self.pc.gid_exists(targid): # get the object associated with that gid ??? target = self.pc.gid2cell(targid) # and connect this gid to its synapse netcon = self.pc.gid_connect(self.cell.gid, target.syn) netcon.weight = 0.04 netcon.delay = 1. self.netcon.append(netcon) def get_cell(self, cell_gid=0): """ returns the object associated with the gid """ if self.pc.gid_exists(cell_gid): return self.pc.gid2cell(cell_gid) else: return None
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""" test_simulate.py execute with mpiexec -np 5 python test_simulate.py """" from ring import Ring h.load_file('stdrun.hoc') pc = h.ParallelContext() myring = Ring() # ** Simulation pc.set_maxstep(10) h.stdinit() h.dt = 0.025 pc.psolve(120) import numpy as np # read voltage cell = myring.get_cell(0) if cell is not None: t,v = cell.get_vectorlist() import matplotlib.pyplot as plt plt.plot(t,v) plt.show() pc.runworker() pc.done()
Thanks in advance!