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2026-09-30 07:23:09 +08:00

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Python

import pandas as pd
from textwrap import dedent
# brian 2
from brian2 import NeuronGroup, Synapses, PoissonInput, SpikeMonitor, Network
from brian2 import mV, ms, Hz
# file handling
from pathlib import Path
# parallelization
from joblib import Parallel, delayed, parallel_backend
from time import time
default_params = {
# trials
't_run' : 1000 * ms, # duration of trial
'n_run' : 30, # number of runs
# network constants
# Kakaria and de Bivort 2017 https://doi.org/10.3389/fnbeh.2017.00008
'v_0' : -52 * mV, # resting potential
'v_rst' : -52 * mV, # reset potential after spike
'v_th' : -45 * mV, # threshold for spiking
't_mbr' : 20 * ms, # membrane time scale (capacitance * resistance = .002 * uF * 10. * Mohm)
# Jürgensen et al https://doi.org/10.1088/2634-4386/ac3ba6
'tau' : 5 * ms, # time constant
# Lazar et al https://doi.org/10.7554/eLife.62362
't_rfc' : 2.2 * ms, # refractory period
# Paul et al 2015 doi: 10.3389/fncel.2015.00029
't_dly' : 1.8*ms, # delay for changes in post-synaptic neuron
# Free parameter
'w_syn' : .275 * mV, # weight per synapse (note: modulated by exponential decay)
# Default activation rates
'r_poi' : 150*Hz, # default rate of the Poisson inputs
'r_poi2' : 0*Hz, # default rate of a 2nd class of Poisson inputs
'f_poi' : 250, # scaling factor for Poisson synapse; 250 is sufficient to cause spiking
# equations for neurons # alpha synapse https://doi.org/10.1017/CBO9780511815706; See https://brian2.readthedocs.io/en/stable/user/converting_from_integrated_form.html
'eqs' : dedent('''
dv/dt = (v_0 - v + g) / t_mbr : volt (unless refractory)
dg/dt = -g / tau : volt (unless refractory)
rfc : second
'''),
# condition for spike
'eq_th' : 'v > v_th',
# rules for spike
'eq_rst' : 'v = v_rst; w = 0; g = 0 * mV',
}
#######################
# brian2 model setup
def poi(neu, exc, exc2, params):
'''Create PoissonInput for neurons.
For each neuron in 'names' a PoissonInput is generated and
the refractory period of that neuron is set to 0 in NeuronGroup.
Parameters
----------
neu : NeuronGroup
Defined brian2.NeuronGroup object
exc : list
Indices of neurons for which to create Poisson input
exc2 : list
Indices of neurons for which to create Poisson input with `r_poi`
params : dict
Constants and equations that are used to construct the brian2 network model
Returns
-------
pois : list
PoissonInput objects for each neuron in 'exc'
neu : NeuronGroup
NeuronGroup with adjusted refractory periods
'''
pois = []
for i in exc:
p = PoissonInput(
target=neu[i],
target_var='v',
N=1,
rate=params['r_poi'],
weight=params['w_syn']*params['f_poi']
)
neu[i].rfc = 0 * ms # no refractory period for Poisson targets
pois.append(p)
for i in exc2:
p = PoissonInput(
target=neu[i],
target_var='v',
N=1,
rate=params['r_poi2'],
weight=params['w_syn']*params['f_poi']
)
neu[i].rfc = 0 * ms # no refractory period for Poisson targets
pois.append(p)
return pois, neu
def silence(slnc, syn):
'''Silence neuron by setting weights of all synapses from it to 0
Parameters
----------
slnc : list
List of neuron indices to silence
syn : brian2.Synapses
Defined synapses object
Returns
-------
syn : brian2.Synapses
Synapses with modified weights
'''
for i in slnc:
syn.w[' {} == i'.format(i)] = 0*mV
return syn
def create_model(path_comp, path_con, params):
'''Create default network model.
Convert the "completeness materialization" and "connectivity" dataframes
into a brian2 neural network model. Network constants and equations
are defined at the beginning of this file.
Parameters
----------
path_comp : str
path to "completeness materialization" dataframe
path_con : str
path to "connectivity" dataframe
params : dict
Constants and equations that are used to construct the brian2 network model
Returns
-------
neu : NeuronGroup
brian2.NeuronGroup object with neurons as in 'path_comp'
syn : Synapses
brian2.Synapses object with connections as in 'path_con'
spk_mon : SpikeMonitor
brian2.SpikeMonitor object, which records time of spike events
'''
# load neuron connectivity dataframes
df_comp = pd.read_csv(path_comp, index_col=0)
df_con = pd.read_parquet(path_con)
neu = NeuronGroup( # create neurons
N=len(df_comp),
model=params['eqs'],
method='linear',
threshold=params['eq_th'],
reset=params['eq_rst'],
refractory='rfc',
name='default_neurons',
namespace=params,
)
neu.v = params['v_0'] # initialize values
neu.g = 0
neu.rfc = params['t_rfc']
# create synapses
syn = Synapses(neu, neu, 'w : volt', on_pre='g += w', delay=params['t_dly'], name='default_synapses')
# connect synapses
i_pre = df_con.loc[:, 'Presynaptic_Index'].values
i_post = df_con.loc[:, 'Postsynaptic_Index'].values
syn.connect(i=i_pre, j=i_post)
# define connection weight
syn.w = df_con.loc[:,'Excitatory x Connectivity'].values * params['w_syn']
# object to record spikes
spk_mon = SpikeMonitor(neu)
return neu, syn, spk_mon
#####################
# running simulations
def get_spk_trn(spk_mon):
'''Extracts spike times from 'spk_mon'
The spike times recorded in the SpikeMonitor object during
simulation are converted to a list of times for each neurons.
Returns dict with "brian ID": "list of spike times".
Parameters
----------
spk_mon : SpikeMonitor
Contains recorded spike times
Returns
-------
spk_trn : dict
Mapping between brian neuron IDs and spike times
'''
spk_trn = {k: v for k, v in spk_mon.spike_trains().items() if len(v)}
return spk_trn
def construct_dataframe(res, exp_name, i2flyid):
'''Take spike time dict and collects spikes in pandas dataframe
Parameters
----------
res : list
List with spike time dicts for each trial
exp_name : str
Name of the experiment
i2flyid : dict
Mapping between Brian IDs and flywire IDs
Returns
-------
df : pandas.DataFrame
Dataframe where each row is one spike
'''
ids, ts, nrun = [], [], []
for n, i in enumerate(res):
for j, k in i.items():
ids.extend([j for _ in k])
nrun.extend([n for _ in k])
ts.extend([float(l) for l in k])
d = {
't': ts,
'trial': nrun,
'flywire_id': [i2flyid[i] for i in ids],
'exp_name': exp_name
}
df = pd.DataFrame(d)
return df
def run_trial(exc, exc2, slnc, path_comp, path_con, params):
'''Run single trial of coactivation/silencng experiment
During the coactivation experiment, the neurons in 'exc' are
Poisson inputs. The simulation runs for 't_run'.
Parameters
----------
exc: list
contains indices of neurons for PoissonInput
exc2: list
contains indices of neurons for PoissonInput of different frequency `r_poi2`
slnc: list
contains indices of neurons to silence
path_comp: Path
path to "completeness materialization" dataframe
path_con: Path
path to "connectivity" dataframe
params : dict
Constants and equations that are used to construct the brian2 network model
Returns
-------
spk_trn : dict
Mapping between brian neuron IDs and spike times
'''
# get default network
neu, syn, spk_mon = create_model(path_comp, path_con, params)
# define Poisson input for excitation
poi_inp, neu = poi(neu, exc, exc2, params)
# silence neurons
syn = silence(slnc, syn)
# collect in Network object
net = Network(neu, syn, spk_mon, *poi_inp)
# run simulation
net.run(duration=params['t_run'])
# spike times
spk_trn = get_spk_trn(spk_mon)
return spk_trn
def run_exp(exp_name, neu_exc, path_res, path_comp, path_con,
params=default_params, neu_slnc=[], neu_exc2=[],
n_proc=-1, force_overwrite=False):
'''
Run default network experiment
Neurons in `neu_exc` are Poisson external inputs
Neurons in `neu_slnc` are silenced
Parameters
----------
exp_name: str
name of the experiment
neu_exc: list
contains custom names or flywire IDs of neurons to be excited
path_res: str
path to the output folder where spike data is stored
path_comp: str
path to "completeness materialization" dataframe
path_con: str
path to "connectivity" dataframe
params : dict
Constants and equations that are used to construct the brian2 network model
neu_slnc : list (optional)
contains custom names or flywire IDs of neurons to be silenced
neu_exc2 : list (optional)
contains custom names or flywire IDs of neurons to be excited with different frequency
requires `r_poi2` to be defined in `params`
n_proc: int (optional)
number of cores to be used for parallel runs
default: -1 (use all available cores)
n_proc=1 is equivalent serial code
force_overwrite : bool (optional)
If True, overwrite output files, else skip simulation, by default False
'''
# convert to Path objects
path_res, path_comp, path_con = [ Path(i) for i in [path_res, path_comp, path_con] ]
# define output files
path_save = path_res / '{}.parquet'.format(exp_name)
if path_save.is_file() and not force_overwrite:
print('>>> Skipping experiment {} because {} exists and force_overwrite = {}'.format(exp_name, path_save, force_overwrite))
return
# load name/id mappings
df_comp = pd.read_csv(path_comp, index_col=0) # load completeness dataframe
flyid2i = {j: i for i, j in enumerate(df_comp.index)} # flywire id: biran ID
i2flyid = {j: i for i, j in flyid2i.items()} # brian ID: flywire ID
# print info
print('>>> Experiment: {}'.format(exp_name))
print(' Output file: {}'.format(path_save))
print(' Excited neurons: {}'.format(len(neu_exc + neu_exc2)))
if neu_slnc:
print(' Silenced neurons: {}'.format(len(neu_slnc)))
# start parallel calculation
n_run = params['n_run']
start = time()
with parallel_backend('loky', n_jobs=n_proc):
exc = [ flyid2i[n] for n in neu_exc ]
exc2 = [ flyid2i[n] for n in neu_exc2 ]
slnc = [ flyid2i[n] for n in neu_slnc ]
res = Parallel()(
delayed(
run_trial)(exc, exc2, slnc, path_comp, path_con, params) for _ in range(n_run))
# print simulation time
walltime = time() - start
print(' Elapsed time: {} s'.format(int(walltime)))
# dataframe with spike times
df = construct_dataframe(res, exp_name, i2flyid)
# store spike data
df.to_parquet(path_save, compression='brotli')