Astrocyte as Spatiotemporal Integrating Detector of Neuronal Activity

Abstract

The functional role of astrocyte calcium signaling in brain information processing was intensely debated in recent decades. This interest was motivated by high resolution imaging techniques showing highly developed structure of distal astrocyte processes. Another point was the evidence of bi-directional astrocytic regulation of neuronal activity. To analyze the effects of interplay of calcium signals in processes and in soma mediating correlations between local signals and the cell-level response of the astrocyte we proposed spatially extended model of the astrocyte calcium dynamics. Specifically, we investigated how spatiotemporal properties of Ca 2+ dynamics in spatially extended astrocyte model can coordinate (e.g., synchronize) networks of neurons and synapses.

Integrated Information in the Spiking–Bursting Stochastic Model

“…The model provides a basis for possible modifications in order to apply integrated information concepts to systems exhibiting similar, but more complicated behavior (in particular, to neuronal [ 26 , 27 , 28 , 29 ] and neuron–astrocyte [ 24 , 30 ] networks). Such modifications might incorporate non-trivial spatial patterns in bursting, and causal interactions within and between the spiking and bursting subsystems.…”

“…The mentioned conditions were derived under the assumption of absent correlation between spontaneous activity in individual bits (24). If correlation exists and is positive, then s 1 > s A s B , or s B < s 1 /s A .…”

“…Empirical “whole minus sum” II, as defined in [ 13 ], was calculated in [ 19 ] from the time series produced by a biologically realistic model of neuro-astrocytic networks. A simplified, analytically tractable stochastic “spiking–bursting” model (in complement to the realistic one) was designed to describe a specific type of activity in neuro-astrocytic networks which manifests itself as a sequence of intermittent system-wide excitations of rapid pulse trains (“bursts”) on the background of random “spiking” activity in the network [ 23 , 24 ]. The spiking–bursting model is a discrete-time, discrete-state stochastic process which mimics the main features of this behavior.…”

Astrocytes Organize Associative Memory

“…It was shown that astrocyte can act as temporal and spatial integrator, hence, detecting the level of spatio-temporal coherence in the activity of accompanying neuronal network. Currently actively discussed hypothesis is that the astrocytic calcium activity can induce spatial synchronization in neuronal circuits defined by the morphological territory of the astrocyte [2][3][4]. In other words one can draw an analogy with the Hopfield network.…”

Editorial: New Insights on Neuron and Astrocyte Function From Cutting-Edge Optical Techniques

“…In particular, in thin dendritic branches of neurons and astrocytes, optical measurements perform better than electrode recordings, in terms of calcium activity (Schiller et al, 1995; Kampa et al, 2006), membrane potential transients (Zhou et al, 2008), and also for recording ion currents (Jaafari et al, 2014; Jaafari and Canepari, 2016; Ait Ouares et al, 2019). In summary, the places where electrodes cannot go, optical measurements are taking over (Popovic M. A. et al, 2015; Bindocci et al, 2017; Gordleeva et al, 2019).…”