Inhibitory and excitatory networks balance cell coupling in the suprachiasmatic nucleus: A modeling approach. (21st May 2016)

• Record Type: Journal Article
• Authors: Kingsbury, Nathaniel J.; Taylor, Stephanie R.; Henson, Michael A.
• Is Part Of: Journal of theoretical biology. Volume 397(2016)
• Page Start: 135
• Page End: 144
• Publication Date: 2016-05-21
• Subjects: Circadian rhythms -- Coupling -- Gamma-aminobutyric acid -- Mathematical modeling -- Suprachiasmatic nucleus; Biology -- Periodicals; Biological Science Disciplines -- Periodicals; Biology -- Periodicals; Biologie -- Périodiques; Theoretische biologie; Biology; Periodicals; 571.05
• DOI: 10.1016/j.jtbi.2016.02.039
• Languages: English
• ISSNs: 0022-5193

Abstract

Abstract: Neuronal coupling contributes to circadian rhythms formation in the suprachiasmatic nucleus (SCN). While the neurotransmitter vasoactive intestinal polypeptide (VIP) is considered essential for synchronizing the oscillations of individual neurons, γ-aminobutyric acid (GABA) does not have a clear functional role despite being highly concentrated in the SCN. While most studies have examined the role of either GABA or VIP, our mathematical modeling approach explored their interplay on networks of SCN neurons. Tuning the parameters that control the release of GABA and VIP enabled us to optimize network synchrony, which was achieved at a peak firing rate during the subjective day of about 7 Hz. Furthermore, VIP and GABA modulation could adjust network rhythm amplitude and period without sacrificing synchrony. We also performed simulations of SCN networks to phase shifts during 12 h:12 h light-dark cycles and showed that GABA networks reduced the average time for the SCN model to re-synchronize. We hypothesized that VIP and GABA balance cell coupling in the SCN to promote synchronization of heterogeneous oscillators while allowing flexibility for adjustment to environmental changes. Highlights: Predicted how changes in VIP and GABA release rates influence circadian networks. A balance between inhibitory and excitatory networks was required for synchronization. Over-excitation increased the time required for adjustment to changing light schedules. Increased GABA network activity could assist with light shifts for high VIP levels.