A Network Architecture for Bidirectional Neurovascular Coupling in Rat Whisker Barrel Cortex

Abstract

The neurovascular coupling is mostly considered as a master-slave relationship between the neurons and the cerebral vessels: the neurons demand energy which the vessels supply in the form of glucose and oxygen. In the recent past both theoretical and experimental studies have suggested that the neurovascular coupling is a bidirectional system, a loop that includes a feedback signal from the vessels influencing neural firing and plasticity. An integrated model of bidirectionally connected neural network and vascular network is hence required to understand the relationship between the informational and metabolic aspects of neural dynamics. In this study, we present a computational model of the bidirectional neurovascular system in the whisker barrel cortex and study the effect of such coupling on neural activity and plasticity as manifest in the map formation. In this model, a biologically plausible self-organizing network model of rate coded, dynamic neurons is nourished by a network of vessels modeled using the biophysical properties of blood vessels. The neural layer which is designed to simulate the whisker barrel cortex of rat transmits the vasodilatory signals to the vessels. The feedback from the vessels is in the form of available oxygen for oxidative metabolism whose end result is the ATP necessary to fuel neural firing. The model captures the effect of the feedback from the vascular network on the neuronal map formation in the whisker barrel model under normal and pathological (Hypoxia and Hypoxia-Ischemia) conditions.\n\nAuthor SummaryAlthough neurovascular coupling is typically depicted as a unidirectional influence originating from the neurons and acting on the cerebral vessels, in reality it forms a bidirectional system, consisting of neuronal energy demand signals transmitted to the vessels, and a feedback of metabolic substrates from the vessels, that influence the neural firing and plasticity. We present a computational model of the bidirectional neurovascular coupling in the whisker barrel cortex of rats and study the effect of such coupling on neural activity and plasticity as manifest in the map formation. The model consists of a biologically plausible self-organizing dynamic, neural network model and a biophysical vascular network model that nourishes the neural network in the form of oxygen necessary for neural oxidative metabolism. The model reproduces the spatio-temporal hemodynamic responses observed in rat whisker barrel cortex. It also demonstrates the essentiality of the vascular feedback on the whisker barrel map formation under normal and pathological conditions.