Figure - available via license: Creative Commons Attribution-NonCommercial 4.0 International
Content may be subject to copyright.
Figure S9 | Further examples of isolated astrocytes (fluorescence average, left) together with the local delay maps (right). Extension of Fig. 6h. The color code (as in Fig. 6) indicates propagation of activity from distal to somatic compartments on a timescale of seconds. The side length of each FOV excerpt is approximately 55 µm.
Source publication
An essential feature of neurons is their ability to centrally integrate information from their dendrites. The activity of astrocytes, on the other hand, has been described to be mostly uncoordinated across the cellular compartments and therefore without central integration. Here, we describe conditional centripetal integration, a principle how astr...
Context in source publication
Context 1
... Fig. S8. Each delay map represents an entire imaging FOV (40x objective, 200 µm side length in x-direction). Yellow arrow heads highlight regions that are devoid of somata and thick processes, therefore mostly containing fine gliapil processes. Green arrow heads highlight astrocytic somata that are, unlike other soma examples shown in Fig. 6h and Fig. S9, not activated in a delayed manner with respect to the global mean activation. White arrow heads highlight astrocyte processes around blood vessels, exhibiting a very clear delayed activation with respect to the global mean activity. The red arrow head highlights an ectopically labeled interneuron; such interneuron pixels were blanked ...Citations
... Conversely, if sensory input is strong enough, it can trigger astrocytic Ca 2+ signaling without notable arousal. Intriguingly, our proposal is in congruence with recent preliminary work showing that the probability that astrocytic Ca 2+ signals originating in the processes will propagate to the soma increases during states of higher arousal [56], suggesting that arousal primes astrocytes to be more responsive to sensory input. ...
The integration of external information with the internal state of the body is central to the survival of virtually every multicellular organism. However, a complete picture of the mechanisms that govern this process is lacking. In this opinion article, we synthesize evidence demonstrating that astrocytes sense the momentary arousal state – through neuromodulator release – as well as the sensory inputs – through local synaptic activity – and respond to them with changes in calcium (Ca2+) signaling. We hypothesize that astrocytes integrate sensory signals with the internal state and that this process is necessary to secure optimal behavior. Finally, we argue that dysfunctional astrocytic Ca2+ signaling could be an underlying factor in disorders characterized by disrupted sensory processing.
Astrocytes, the most abundant non-neuronal cell type in the mammalian brain, are crucial circuit components that respond to and modulate neuronal activity through calcium (Ca²⁺) signalling1–7. Astrocyte Ca²⁺ activity is highly heterogeneous and occurs across multiple spatiotemporal scales—from fast, subcellular activity3,4 to slow, synchronized activity across connected astrocyte networks8–10—to influence many processes5,7,11. However, the inputs that drive astrocyte network dynamics remain unclear. Here we used ex vivo and in vivo two-photon astrocyte imaging while mimicking neuronal neurotransmitter inputs at multiple spatiotemporal scales. We find that brief, subcellular inputs of GABA and glutamate lead to widespread, long-lasting astrocyte Ca²⁺ responses beyond an individual stimulated cell. Further, we find that a key subset of Ca²⁺ activity—propagative activity—differentiates astrocyte network responses to these two main neurotransmitters, and may influence responses to future inputs. Together, our results demonstrate that local, transient neurotransmitter inputs are encoded by broad cortical astrocyte networks over a minutes-long time course, contributing to accumulating evidence that substantial astrocyte–neuron communication occurs across slow, network-level spatiotemporal scales12–14. These findings will enable future studies to investigate the link between specific astrocyte Ca²⁺ activity and specific functional outputs, which could build a consistent framework for astrocytic modulation of neuronal activity.
