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Multi-stability of in-phase and anti-phase activity patterns in neural networks with inhibitory and electrical synapses

Ostaszewski H., Meyrand P., Branchereau P., Hallam J., Bem T.

Biocybernetics and Biomedical Engineering

2010

Vol. 30, no. 3

3-17

As shown in modeling and experimental studies, network comprised of spiking cells interconnected by inhibitory and electrical synapses may express different activity patterns without any change of the network topology or parameters. In this study we confirm robust-ness of this phenomenon by demonstrating multi-stability of hybrid networks consisting of biological neurons of different types. Moreover we show here, using relaxation oscillator model cells, that multi-stability of in-phase (IP) and anti-phase (AP) patterns may be expressed in a network fully connected by instantaneous synaptic inhibition and electrical coupling independently of the network size. In such a network a stimulus of a given profile, consisting of depolarizing and hyperpolarizing signals sent to different subpopulations of cells, can evoke direct switching between IP and AP patterns. We also show that similar phenomenon occurs in more realistic network models with sparse connectivity. Our results suggest that transient signals if arriving in a proper time window may instantaneously reconfigure a given spatio-temporal activity pattern expressed by the network into another stable pattern without any change of the network properties.

Electrical coupling and bistability in inhibitory neuronal networks

Bem T., Hallam J., Meyrand P., Rinzel J.

Biocybernetics and Biomedical Engineering

2006

Vol. 26, no. 2

3-14

The role of gap junction-mediated electrical coupling in oscillatory networks is not yet fuIly understood. Such coupling is widespread in developing nervous systems and in many structures of the adult brain where it coexists with synaptic inhibition. Our results, both modeling and experimental, indicate that the effect of electrical coupling in networks of rhythmic inhibitory neurons is crucially dependent on the cells' duty cycle. In the Stomatogastric Nervous System, in which ceIls with large duty cycle are interconnected by reciprocal inhibition, electrical coupling may be responsible for masking adult-like properties of the embryonic network by coordinating the neuronal activity into a single rhythm with different phases. In a two-ceIl half-center oscillator model short duty cycle destabilizes antiphase activity which can be re-established by adding electrical coupling. Moreover, such a network expresses bistability of the in-phase and anti-phase patterns in some range of coupling strengths. AIso in a large-scale model network, in which ceIls are interconnected electrically and by synaptic inhibition, multistability of the in-phase and different anti-phase patterns may occur. A possible function of the multistability in the controI of movement is discussed.