We derive the Kuramoto model (KM) corresponding to a population of weakly coupled, nearly identical quadratic integrate-and-fire (QIF) neurons with both electrical and chemical coupling. The ratio of chemical to electrical coupling determines the phase lag of the characteristic sine coupling function of the KM and critically determines the synchronization properties of the network. We apply our results to uncover the presence of chimera states in two coupled populations of identical QIF neurons. We find that the presence of both electrical and chemical coupling is a necessary condition for chimera states to exist. Finally, we numerically demonstrate that chimera states gradually disappear as coupling strengths cease to be weak.

1.
Y.
Kuramoto
, “Self-entrainment of a population of coupled non-linear oscillators,” in International Symposium on Mathematical Problems in Theoretical Physics, Lecture Notes in Physics, Vol. 39, edited by H. Araki (Springer, Berlin, 1975), pp. 420–422.
2.
Y.
Kuramoto
,
Chemical Oscillations, Waves, and Turbulence
(
Springer-Verlag
,
Berlin
,
1984
).
3.
K.
Glomb
,
J.
Cabral
,
A.
Cattani
,
A.
Mazzoni
,
A.
Raj
, and
B.
Franceschiello
, “
Computational models in electroencephalography
,”
Brain Topogr.
2021
,
1
20
.
4.
C. W.
Lynn
and
D. S.
Bassett
, “
The physics of brain network structure, function and control
,”
Nat. Rev. Phys.
1
,
318
332
(
2019
).
5.
M.
Breakspear
,
S.
Heitmann
, and
A.
Daffertshofer
, “
Generative models of cortical oscillations: Neurobiological implications of the Kuramoto model
,”
Front. Hum. Neurosci.
4
,
190
(
2010
).
6.
J.
Cabral
,
E.
Hugues
,
O.
Sporns
, and
G.
Deco
, “
Role of local network oscillations in resting-state functional connectivity
,”
NeuroImage
57
,
130
139
(
2011
).
7.
P.
Villegas
,
P.
Moretti
, and
M. A.
Muñoz
, “
Frustrated hierarchical synchronization and emergent complexity in the human connectome network
,”
Sci. Rep.
4
,
5990
(
2014
).
8.
A.
Ponce-Alvarez
,
G.
Deco
,
P.
Hagmann
,
G. L.
Romani
,
D.
Mantini
, and
M.
Corbetta
, “
Resting-state temporal synchronization networks emerge from connectivity topology and heterogeneity
,”
PLoS Comput. Biol.
11
,
e1004100
(
2015
).
9.
P.
Sanz-Leon
,
S. A.
Knock
,
A.
Spiegler
, and
V. K.
Jirsa
, “
Mathematical framework for large-scale brain network modeling in the virtual brain
,”
NeuroImage
111
,
385
430
(
2015
).
10.
R.
Schmidt
,
K. J. R.
LaFleur
,
M. A.
de Reus
,
L. H.
van den Berg
, and
M. P.
van den Heuvel
, “
Kuramoto model simulation of neural hubs and dynamic synchrony in the human cerebral connectome
,”
BMC Neurosci.
16
,
54
(
2015
).
11.
S.
Petkoski
,
A.
Spiegler
,
T.
Proix
,
P.
Aram
,
J.-J.
Temprado
, and
V. K.
Jirsa
, “
Heterogeneity of time delays determines synchronization of coupled oscillators
,”
Phys. Rev. E
94
,
012209
(
2016
).
12.
R. G.
Andrzejak
,
C.
Rummel
,
F.
Mormann
, and
K.
Schindler
, “
All together now: Analogies between chimera state collapses and epileptic seizures
,”
Sci. Rep.
6
,
23000
(
2016
).
13.
S.
Petkoski
,
J. M.
Palva
, and
V. K.
Jirsa
, “
Phase-lags in large scale brain synchronization: Methodological considerations and in-silico analysis
,”
PLoS Comput. Biol.
14
,
1006160
(
2018
).
14.
J. A.
Roberts
,
L. L.
Gollo
,
R. G.
Abeysuriya
,
G.
Roberts
,
P. B.
Mitchell
,
M. W.
Woolrich
, and
M.
Breakspear
, “
Metastable brain waves
,”
Nat. Commun.
10
,
1
(
2019
).
15.
H.
Choi
and
S.
Mihalas
, “
Synchronization dependent on spatial structures of a mesoscopic whole-brain network
,”
PLoS Comput. Biol.
15
,
e1006978
(
2019
).
16.
A.
Ziaeemehr
,
M.
Zarei
,
A.
Valizadeh
, and
C. R.
Mirasso
, “
Frequency-dependent organization of the brain’s functional network through delayed-interactions
,”
Neural Netw.
132
,
155
165
(
2020
).
17.
R.
Noori
,
D.
Park
,
J. D.
Griffiths
,
S.
Bells
,
P. W.
Frankland
,
D.
Mabbott
, and
J.
Lefebvre
, “
Activity-dependent myelination: A glial mechanism of oscillatory self-organization in large-scale brain networks
,”
Proc. Natl. Acad. Sci. U.S.A.
117
,
13227
13237
(
2020
).
18.
K.
Jung
,
S. B.
Eickhoff
, and
O. V.
Popovych
, “
Tractography density affects whole-brain structural architecture and resting-state dynamical modeling
,”
NeuroImage
237
,
118176
(
2021
).
19.
P. K.
Tewarie
,
B.
Prasse
,
J. M.
Meier
,
Á.
Byrne
,
M. D.
Domenico
,
C. J. K.
Stam
,
M. J.
Brookes
,
A.
Hillebrand
,
A.
Daffertshofer
,
S.
Coombes
, and
P. V.
Mieghem
, “
Interlayer connectivity reconstruction for multilayer brain networks using phase oscillator models
,”
New J. Phys.
23
,
063065
(
2021
).
20.
G.
Ódor
,
J.
Kelling
, and
G.
Deco
, “
The effect of noise on the synchronization dynamics of the Kuramoto model on a large human connectome graph
,”
Neurocomputing
461
,
696–704
(
2021
).
21.
J. C.
Pang
,
L. L.
Gollo
, and
J. A.
Roberts
, “
Stochastic synchronization of dynamics on the human connectome
,”
NeuroImage
229
,
117738
(
2021
).
22.
G.
Weerasinghe
,
B.
Duchet
,
C.
Bick
, and
R.
Bogacz
, “
Optimal closed-loop deep brain stimulation using multiple independently controlled contacts
,”
PLoS Comput. Biol.
17
,
e1009281
(
2021
).
23.
X.-J.
Wang
, “
Neurophysiological and computational principles of cortical rhythms in cognition
,”
Physiol. Rev.
90
,
1195
1268
(
2010
).
24.
C.
Börgers
,
An Introduction to Modeling Neuronal Dynamics
(
Springer
,
2017
), Vol. 66.
25.
B.
Ermentrout
, “
Type I membranes, phase resetting curves, and synchrony
,”
Neural Comput.
8
,
979
1001
(
1996
).
26.
B.
Ermentrout
and
N.
Kopell
, “
Parabolic bursting in an excitable system coupled with a slow oscillation
,”
SIAM J. Appl. Math.
46
,
233
253
(
1986
).
27.
E. M.
Izhikevich
,
Dynamical Systems in Neuroscience
(
The MIT Press
,
Cambridge, MA
,
2007
).
28.
H.
Sakaguchi
,
S.
Shinomoto
, and
Y.
Kuramoto
, “
Mutual entrainment in oscillator lattices with nonvariational type interaction
,”
Prog. Theor. Phys.
79
,
1069
1079
(
1988
).
29.
H.
Sakaguchi
and
Y.
Kuramoto
, “
A soluble active rotator model showing phase transitions via mutual entrainment
,”
Prog. Theor. Phys.
76
,
576
581
(
1986
).
30.
A. S.
Pikovsky
,
M. G.
Rosenblum
, and
J.
Kurths
,
Synchronization, a Universal Concept in Nonlinear Sciences
(
Cambridge University Press
,
Cambridge
,
2001
).
31.
S. H.
Strogatz
, “
From Kuramoto to Crawford: Exploring the onset of synchronization in populations of coupled oscillators
,”
Physica D
143
,
1
20
(
2000
).
32.
A.
Pikovsky
and
M.
Rosenblum
, “
Dynamics of globally coupled oscillators: Progress and perspectives
,”
Chaos
25
,
097616
(
2015
).
33.
X.-J.
Wang
and
G.
Buzsáki
, “
Gamma oscillation by synaptic inhibition in a hippocampal interneuronal network model
,”
J. Neurosci.
16
,
6402
6413
(
1996
).
34.
H. R.
Wilson
and
J. D.
Cowan
, “
Excitatory and inhibitory interactions in localized populations of model neurons
,”
Biophys. J.
12
,
1
24
(
1972
).
35.
J. I.
Nagy
,
A. E.
Pereda
, and
J. E.
Rash
, “
Electrical synapses in mammalian CNS: Past eras, present focus and future directions
,”
Biochim. Biophys. Acta Biomembr.
1860
,
102
123
(
2018
).
36.
G.
Deco
,
G.
Tononi
,
M.
Boly
, and
M. L.
Kringelbach
, “
Rethinking segregation and integration: Contributions of whole-brain modelling
,”
Nat. Rev. Neurosci.
16
,
430
439
(
2015
).
37.
B.
Pietras
,
F.
Devalle
,
A.
Roxin
,
A.
Daffertshofer
, and
E.
Montbrió
, “
Exact firing rate model reveals the differential effects of chemical versus electrical synapses in spiking networks
,”
Phys. Rev. E
100
,
042412
(
2019
).
38.
E.
Montbrió
and
D.
Pazó
, “
Exact mean-field theory explains the dual role of electrical synapses in collective synchronization
,”
Phys. Rev. Lett.
125
,
248101
(
2020
).
39.
E.
Montbrió
,
D.
Pazó
, and
A.
Roxin
, “
Macroscopic description for networks of spiking neurons
,”
Phys. Rev. X
5
,
021028
(
2015
).
40.
E.
Montbrió
,
J.
Kurths
, and
B.
Blasius
, “
Synchronization of two interacting populations of oscillators
,”
Phys. Rev. E
70
,
056125
(
2004
).
41.
D. M.
Abrams
,
R.
Mirollo
,
S. H.
Strogatz
, and
D. A.
Wiley
,
Phys. Rev. Lett.
101
,
084103
(
2008
).
42.
C. R.
Laing
, “
Chimera states in heterogeneous networks
,”
Chaos
19
,
013113
(
2009
).
43.
E. A.
Martens
,
C.
Bick
, and
M. J.
Panaggio
, “
Chimera states in two populations with heterogeneous phase-lag
,”
Chaos
26
,
094819
(
2016
).
44.
D.
Pazó
and
E.
Montbrió
, “
Low-dimensional dynamics of populations of pulse-coupled oscillators
,”
Phys. Rev. X
4
,
011009
(
2014
).
45.
E.
Montbrió
and
D.
Pazó
, “
Kuramoto model for excitation-inhibition-based oscillations
,”
Phys. Rev. Lett.
120
,
244101
(
2018
).
46.
More recently, a similar derivation has been obtained for populations of heterogeneous Winfree oscillators with sinusoidal infinitesimal phase resetting curves (iPRCs).44 When the oscillators have the iPRC of the QIF neuron, the population of Winfree oscillators can be well approximated to a population of QIF neurons with (weak) chemical synapses.45
47.
N.
Kopell
and
B.
Ermentrout
, “
Chemical and electrical synapses perform complementary roles in the synchronization of interneuronal networks
,”
Proc. Natl. Acad. Sci. U.S.A.
101
,
15482
15487
(
2004
).
48.
C. R.
Laing
, “
Exact neural fields incorporating gap junctions
,”
SIAM J. Appl. Dyn. Syst.
14
,
1899
1929
(
2015
).
49.
F. C.
Hoppensteadt
and
E. M.
Izhikevich
,
Weakly Connected Neural Networks
(
Springer-Verlag
,
New York
,
1997
).
50.
B.
Pietras
and
A.
Daffertshofer
, “
Network dynamics of coupled oscillators and phase reduction techniques
,”
Phys. Rep.
819
,
1
105
(
2019
).
51.
A. T.
Winfree
, “
Biological rhythms and the behavior of populations of coupled oscillators
,”
J. Theor. Biol.
16
,
15
42
(
1967
).
52.
For g=0, the natural frequencies in Refs. 44 and 45 differ from Eq. (18). The reason for this discrepancy is that Refs. 44 and 45 consider the Winfree model with distributed natural frequencies Ωi, while here, we study the QIF model with distributed currents ηi.
53.
B.
Blasius
and
R.
Tönjes
, “
Quasiregular concentric waves in heterogeneous lattices of coupled oscillators
,”
Phys. Rev. Lett.
95
,
084101
(
2005
).
54.
D.
Hansel
,
G.
Mato
, and
C.
Meunier
, “
Synchrony in excitatory neural networks
,”
Neural Comput.
7
,
307
337
(
1995
).
55.
F.
Devalle
,
A.
Roxin
, and
E.
Montbrió
, “
Firing rate equations require a spike synchrony mechanism to correctly describe fast oscillations in inhibitory networks
,”
PLoS Comput. Biol.
13
,
e1005881
(
2017
).
56.
E.
Ott
and
T. M.
Antonsen
, “
Low dimensional behavior of large systems of globally coupled oscillators
,”
Chaos
18
,
037113
(
2008
).
57.
E.
Montbrió
and
D.
Pazó
, “
Shear diversity prevents collective synchronization
,”
Phys. Rev. Lett.
106
,
254101
(
2011
).
58.
Y.
Kuramoto
and
D.
Battogtokh
, “
Coexistence of coherence and incoherence in nonlocally coupled phase oscillators
,”
Nonlinear Phenom. Complex Syst.
5
,
380
(
2002
).
59.
H.
Sakaguchi
, “
Instability of synchronized motion in nonlocally coupled neural oscillators
,”
Phys. Rev. E
73
,
031907
(
2006
).
60.
S.
Olmi
,
A.
Politi
, and
A.
Torcini
, “
Collective chaos in pulse-coupled neural networks
,”
Europhys. Lett.
92
,
60007
(
2010
).
61.
I.
Omelchenko
,
O. E.
Omel’chenko
,
P.
Hövel
, and
E.
Schöll
, “
When nonlocal coupling between oscillators becomes stronger: Patched synchrony or multichimera states
,”
Phys. Rev. Lett.
110
,
224101
(
2013
).
62.
A.
Vüllings
,
J.
Hizanidis
,
I.
Omelchenko
, and
P.
Hövel
, “
Clustered chimera states in systems of type-I excitability
,”
New J. Phys.
16
,
123039
(
2014
).
63.
J.
Hizanidis
,
V. G.
Kanas
,
A.
Bezerianos
, and
T.
Bountis
, “
Chimera states in networks of nonlocally coupled Hindmarsh–Rose neuron models
,”
Int. J. Bifurcation Chaos
24
,
1450030
(
2014
).
64.
M. J.
Panaggio
and
D. M.
Abrams
, “
Chimera states: Coexistence of coherence and incoherence in networks of coupled oscillators
,”
Nonlinearity
28
,
R67
(
2015
).
65.
S.
Majhi
,
B. K.
Bera
,
D.
Ghosh
, and
M.
Perc
, “
Chimera states in neuronal networks: A review
,”
Phys. Life Rev.
28
,
100
121
(
2019
).
66.
C. R.
Laing
, “
Dynamics and stability of chimera states in two coupled populations of oscillators
,”
Phys. Rev. E
100
,
042211
(
2019
).
67.
J.
Hizanidis
,
N. E.
Kouvaris
,
G.
Zamora-López
,
A.
Díaz-Guilera
, and
C. G.
Antonopoulos
, “
Chimera-like states in modular neural networks
,”
Sci. Rep.
6
,
19845
(
2016
).
68.
M.
Gerster
,
R.
Berner
,
J.
Sawicki
,
A.
Zakharova
,
A.
Škoch
,
J.
Hlinka
,
K.
Lehnertz
, and
E.
Schöll
, “
FitzHugh–Nagumo oscillators on complex networks mimic epileptic-seizure-related synchronization phenomena
,”
Chaos
30
,
123130
(
2020
).
69.
A.
Lucchetti
,
M. H.
Jensen
, and
M. L.
Heltberg
, “
Emergence of chimera states in a neuronal model of delayed oscillators
,”
Phys. Rev. Res.
3
,
033041
(
2021
).
70.
C.
Bick
,
M.
Goodfellow
,
C. R.
Laing
, and
E. A.
Martens
, “
Understanding the dynamics of biological and neural oscillator networks through exact mean-field reductions: A review
,”
J. Math. Neurosci.
10
,
9
(
2020
).
71.
O. E.
Omel’chenko
, “
The mathematics behind chimera states
,”
Nonlinearity
31
,
R121
(
2018
).
72.
S. W.
Haugland
, “
The changing notion of chimera states, a critical review
,”
J. Phys. Complex.
2
,
032001
(
2021
).
73.
A.
Byrne
,
J.
Ross
,
R.
Nicks
, and
S.
Coombes
, “
Mean-field models for EEG/MEG: From oscillations to waves
,”
Brain Topogr.
2021
,
1
18
.
74.
NMMs for QIF neurons are derived after adopting the thermodynamic limit, N, and under the assumption Vr and Vp; see Refs. 38 and 39. If neurons are fully synchronized, [Vi(t)=Vj(t),i,j], the population of QIF neurons behaves as a single neuron. Therefore, in QIF-NMM, the mean voltage [Eq. (3)] diverges when all neurons fire a spike—in Refs. 48 and 90, the mean-field variable v is approximated to avoid this divergence; see also Ref. 37.
75.
C.-U.
Choe
,
J.-S.
Ri
, and
R.-S.
Kim
, “
Incoherent chimera and glassy states in coupled oscillators with frustrated interactions
,”
Phys. Rev. E
94
,
032205
(
2016
).
76.
A.
Pikovsky
and
M.
Rosenblum
, “
Partially integrable dynamics of hierarchical populations of coupled oscillators
,”
Phys. Rev. Lett.
101
,
264103
(
2008
).
77.
S.
Watanabe
and
S. H.
Strogatz
, “
Constant of motion for superconducting Josephson arrays
,”
Physica D
74
,
197
253
(
1994
).
78.
Y.
Kawamura
,
H.
Nakao
,
K.
Arai
,
H.
Kori
, and
Y.
Kuramoto
, “
Phase synchronization between collective rhythms of globally coupled oscillator groups: Noiseless nonidentical case
,”
Chaos
20
,
043110
(
2010
).
79.
E. J.
Doedel
, “AUTO: A program for the automatic bifurcation analysis of autonomous systems,”
Congr. Numer
30
(265–284),
25–93
(
1981
).
80.
Figures 4(b)–4(f) in Ref. 43 show a bifurcation scenario with a transcritical bifurcation that is not observed in Fig. 3. This bifurcation occurs for αs>π/2, and these values of the phase lag parameter are unreachable in the QIF model, where αs(π/2,0) for inhibitory coupling and αs(0,π/2) for excitatory coupling; see Eq. (29).
81.
For n, this corresponds to a Lorentzian distribution of voltages ρ(V)=πτr/[(Vv)2+(πτr)2], see Ref. 39, and to uniformly distributed constants of motion in the Watanabe–Strogatz theory.70,76,91
82.
We cannot discount that the collective dynamics of the QIF [Eq. (26)] is chaotic, as it also occurs in coupled populations of Winfree oscillators.44 
83.
A similar approach has been applied to the leaky integrate-and-fire model. In this case, the approximated phase model is not the KM, but it contains higher harmonics in the coupling function.92 
84.
D.
Pazó
, “
Thermodynamic limit of the first order phase transition in the Kuramoto model
,”
Phys. Rev. E
72
,
046211
(
2005
).
85.
L. F.
Lafuerza
,
P.
Colet
, and
R.
Toral
, “
Nonuniversal results induced by diversity distribution in coupled excitable systems
,”
Phys. Rev. Lett.
105
,
084101
(
2010
).
86.
O. E.
Omel’chenko
and
M.
Wolfrum
, “
Nonuniversal transitions to synchrony in the Sakaguchi-Kuramoto model
,”
Phys. Rev. Lett.
109
,
164101
(
2012
).
87.
E. A.
Martens
,
E.
Barreto
,
S. H.
Strogatz
,
E.
Ott
,
P.
So
, and
T. M.
Antonsen
, “
Exact results for the Kuramoto model with a bimodal frequency distribution
,”
Phys. Rev. E
79
,
026204
(
2009
).
88.
D.
Pazó
and
E.
Montbrió
, “
Existence of hysteresis in the Kuramoto model with bimodal frequency distributions
,”
Phys. Rev. E
80
,
046215
(
2009
).
89.
B.
Pietras
,
N.
Deschle
, and
A.
Daffertshofer
, “
First-order phase transitions in the Kuramoto model with compact bimodal frequency distributions
,”
Phys. Rev. E
98
,
062219
(
2018
).
90.
B.
Ermentrout
, “
Gap junctions destroy persistent states in excitatory networks
,”
Phys. Rev. E
74
,
031918
(
2006
).
91.
C. R.
Laing
, “
The dynamics of networks of identical theta neurons
,”
J. Math. Neurosci.
8
,
4
(
2018
).
92.
A.
Politi
and
M.
Rosenblum
, “
Equivalence of phase-oscillator and equivalence of phase-oscillator and integrate-and-fire models
,”
Phys. Rev. E
91
,
042916
(
2015
).
You do not currently have access to this content.