"""
Miguel Capllonch Juan
30 September 2018
Draw together all the LFPs computed with the different methods:
- Results from the simulations (RN model)
- Using the VC conductor theory
"""
import numpy as np
import matplotlib.pyplot as plt
import csv
# Recording electrodes
rec_els = {
'E': {'pos': (250, 0, 19000),
'lfp_indiv_ly1': {}, 'lfp_indiv_ly2': {},
'lfp_total_ly1': None, 'lfp_total_ly2': None,
'color': 'r'},
'S': {'pos': (0, -250, 19000),
'lfp_indiv_ly1': {}, 'lfp_indiv_ly2': {},
'lfp_total_ly1': None, 'lfp_total_ly2': None,
'color': 'g'},
'W': {'pos': (-250, 0, 19000),
'lfp_indiv_ly1': {}, 'lfp_indiv_ly2': {},
'lfp_total_ly1': None, 'lfp_total_ly2': None,
'color': 'b'},
'N': {'pos': (0, 250, 19000),
'lfp_indiv_ly1': {}, 'lfp_indiv_ly2': {},
'lfp_total_ly1': None, 'lfp_total_ly2': None,
'color': 'k'}
}
# Stimulating electrode (amp in mA)
delay = 0.1
dur = 0.2
amp = -15.e-3
stimcurrent = None
stimelpos = (250, 0, 100)
# Medium conductivity tensor (1/(Ohm*um))
sigma_x = 1. / (1.211e3 * 1.e-6)
sigma_y = 1. / (1.211e3 * 1.e-6)
sigma_z = 1. / (0.175e3 * 1.e-6)
# Functions
def compute_lfp(currents, elpos):
""" Compute the LFP from a time series of currents as recorded by
a point electrode situated at elpos
The equation is taken from:
Nicholson & Freeman (1975)
The current sources are all the segments in the axon """
dx = x - elpos[0]
dy = y - elpos[1]
dz = z - elpos[2]
denominator = 4. * np.pi * np.sqrt\
(\
sigma_y * sigma_z * dx ** 2 + \
sigma_z * sigma_x * dy ** 2 + \
sigma_x * sigma_y * dz ** 2\
)
# denominator = np.tile(denominator, nt).reshape(currents.shape)
denominator = denominator.repeat(nt).reshape(currents.shape)
# print dz.shape, (dz ** 2).shape, currents.shape
return (currents / denominator).sum(axis=0)
def compute_lfp_fromtimeseries(currents, srcpos, elpos):
""" Compute the LFP from a time series of currents as recorded by
a point electrode situated at elpos
The equation is taken from:
Nicholson & Freeman (1975)
This time, there is only one current point source """
dx = srcpos[0] - elpos[0]
dy = srcpos[1] - elpos[1]
dz = srcpos[2] - elpos[2]
denominator = 4. * np.pi * np.sqrt\
(\
sigma_y * sigma_z * dx ** 2 + \
sigma_z * sigma_x * dy ** 2 + \
sigma_x * sigma_y * dz ** 2\
)
# denominator = np.tile(denominator, nt).reshape(currents.shape)
# denominator = denominator.repeat(nt).reshape(currents.shape)
# denominator = denominator.repeat(nt)
# print dz.shape, (dz ** 2).shape, currents.shape
return currents / denominator
# Declare arrays
names = {}
ily1 = {}
ily2 = {}
balancely1 = {}
balancely2 = {}
lfp_indiv_ly1 = {}
lfp_indiv_ly2 = {}
x = []
y = []
z = []
ii_fibs = []
# Other parameters
dt = 0.005
# Get recordings from file
recs = []
# with open('./recordings_R0P0_noartefacts.csv', 'r') as f:
with open('./recordings_R0P0_withartefacts.csv', 'r') as f:
frl = list(csv.reader(f))
for row in frl[1:]:
recs.append(float(row[1]))
recs = np.array(recs)
# Get currents from file
with open('./membranecurrents.csv', 'r') as f:
frl = list(csv.reader(f))
for i, row in enumerate(frl[1:]):
ifib = int(row[0])
ii_fibs.append(ifib)
name = row[1]
data = row[5:]
ndata = len(data) / 2
dataly1 = np.array([float(item) for item in data[:ndata]])
dataly2 = np.array([float(item) for item in data[ndata:]])
try:
ily1[ifib].append(dataly1.copy())
ily2[ifib].append(dataly2.copy())
names[ifib].append(name)
except KeyError:
names[ifib] = [name]
ily1[ifib] = [dataly1]
ily2[ifib] = [dataly2]
x.append(float(row[2]))
y.append(float(row[3]))
z.append(float(row[4]))
# Positions from lists to arrays
x = np.array(x)
y = np.array(y)
z = np.array(z)
# Finish setting parameters that depend on the data
tarray = np.arange(0, dt * ndata, dt)
nt = len(tarray)
nsegstotal = len(z)
stimcurrent = amp * np.ones_like(tarray)
# stimcurrent[np.where(tarray < delay + dur)] = amp
stimcurrent[np.where(tarray < delay)] = 0.
stimcurrent[np.where(tarray > delay + dur)] = 0.
# stimcurrent = stimcurrent()
# stimcurrent[np.where(delay < tarray < delay + dur)] = amp
# Positions of the nodes of Ranvier
zRN = {}
# and indices corresponding to them
indsRN = {}
for k, v in names.items():
zRN[k] = []
indsRN[k] = []
for i, vv in enumerate(v):
if 'node' in vv:
zRN[k].append(z[i])
indsRN[k].append(i)
for ifib in ii_fibs:
# Current balances
ily1[ifib] = np.array(ily1[ifib])
ily2[ifib] = np.array(ily2[ifib])
balancely1[ifib] = np.zeros(nt)
balancely2[ifib] = np.zeros(nt)
for i_t, t in enumerate(tarray):
balancely1[ifib][i_t] = ily1[ifib][:, i_t].sum()
balancely2[ifib][i_t] = ily2[ifib][:, i_t].sum()
# Individual LFPs
for k, re in rec_els.items():
re['lfp_indiv_ly1'][ifib] = compute_lfp(ily1[ifib], re['pos'])
re['lfp_indiv_ly2'][ifib] = compute_lfp(ily2[ifib], re['pos'])
# Finally, sum up the individual LFPs of the fibers into a total LFP
# for each electrode
for k, re in rec_els.items():
re['lfp_total_ly1'] = np.zeros(nt)
re['lfp_total_ly2'] = np.zeros(nt)
for ifib in ii_fibs:
re['lfp_total_ly1'] += re['lfp_indiv_ly1'][ifib]
re['lfp_total_ly2'] += re['lfp_indiv_ly2'][ifib]
# Add the contribution of the stimulating electrode
re['lfp_total_ly1'] += compute_lfp_fromtimeseries(stimcurrent,
stimelpos, re['pos'])
re['lfp_total_ly2'] += compute_lfp_fromtimeseries(stimcurrent,
stimelpos, re['pos'])
# What if I sum them?
resum = re['lfp_total_ly1'] + re['lfp_total_ly2']
# Now compare the two curves
resum_norm = resum / np.abs(resum.max() - resum.min())
recs_norm = recs / np.abs(recs.max() - recs.min())
###############################################################################
# Figures
# Time evolution at some point
fig, ax = plt.subplots()
ax.plot(tarray, recs, lw=3, label='RN model')
for k, re in rec_els.items():
ax.plot(tarray, re['lfp_total_ly1'], c=re['color'] , ls='-',
label=k + '. Layer 1')
ax.plot(tarray, re['lfp_total_ly2'], c=re['color'] , ls='--',
label=k + '. Layer 2')
ax.plot(tarray, resum, 'r', lw=3, label='Sum VC model')
ax.set_xlabel('Time (ms)')
ax.set_ylabel('Extracellular recordings (mV)')
ax.set_title('Extracellular recordings')
ax.legend()
fig.tight_layout()
# plt.show()
fig.savefig('recordings_all.png')
fig, ax = plt.subplots()
ax.plot(tarray, recs_norm, lw=3, label='RN model')
ax.plot(tarray, resum_norm, 'r', lw=3, label='Sum VC model')
ax.set_xlabel('Time (ms)')
ax.set_ylabel('Extracellular recordings (mV)')
ax.set_title('Extracellular recordings (normalised)')
ax.legend()
fig.tight_layout()
# plt.show()
fig.savefig('recordings_all_compare_RN_VC.png')