Role of asymmetry and external noise in the development and synchronization of oscillations in the analog Hopfield neural networks with time delay.

The analog Hopfield neural network with time delay and random connections has been studied for its similarities in activity to human electroencephalogram and its usefulness in other areas of the applied sciences such as speech recognition, image analysis, and electrocardiogram modeling. Our goal here is to understand the mechanisms that affect the rhythmic activity in the neural network and how the addition of a Gaussian noise contributes to the network behavior. The neural network studied is composed of ten identical neurons.

Mathematical modeling physiological effects of the overexpression of β-adrenoceptors in mouse ventricular myocytes.

Transgenic (TG) mice overexpressing β-adrenergic receptors (β-ARs) demonstrate enhanced myocardial function, which manifests in increased basal adenylyl cyclase activity, enhanced atrial contractility, and increased left ventricular function in vivo. To gain insights into the mechanisms of these effects, we developed a comprehensive mathematical model of the mouse ventricular myocyte overexpressing β-ARs. We found that most of the β-ARs are active in control conditions in TG mice.

Distinct physiological effects of β- and β-adrenoceptors in mouse ventricular myocytes: insights from a compartmentalized mathematical model.

The β- and β-adrenergic signaling systems play different roles in the functioning of cardiac cells. Experimental data show that the activation of the β-adrenergic signaling system produces significant inotropic, lusitropic, and chronotropic effects in the heart, whereas the effects of the β-adrenergic signaling system is less apparent. In this paper, a comprehensive compartmentalized experimentally based mathematical model of the combined β- and β-adrenergic signaling systems in mouse ventricular myocytes is developed to simulate the experimental findings and make testable predictions of the behavior of the cardiac cells under different physiological conditions.