Astrocytes are key regulators of brain homeostasis, equilibrating ion, water, and neurotransmitter concentrations and maintaining essential conditions for proper cognitive function. Recently, it has been shown that the excitability of the actin cytoskeleton manifests in second‐scale dynamic fluctuations and acts as a sensor of chemophysical environmental cues. However, it is not known whether the cytoskeleton is excitable in astrocytes and how the homeostatic function of astrocytes is linked to the dynamics of the cytoskeleton. Here it is shown that homeostatic regulation involves the excitable dynamics of actin in certain subcellular regions of astrocytes, especially near the cell boundary. The results further indicate that actin dynamics concentrate into “hotspot” regions that selectively respond to certain chemophysical stimuli, specifically the homeostatic challenges of ion or water concentration increases. Substrate topography makes the actin dynamics of astrocytes weaker. Super‐resolution images demonstrate that surface topography is also associated with the predominant perpendicular alignment of actin filaments near the cell boundary, whereas flat substrates result in an actin cortex mainly parallel to the cell boundary. Additionally, coculture with neurons increases both the probability of actin dynamics and the strength of hotspots. The excitable systems character of actin thus makes astrocytes direct participants in neural cell network dynamics.

Societies rely on individual contributions to sustain public goods that benefit the entire community. Several mechanisms, that specify how individuals change their decisions based on past experiences, have been proposed to explain how altruists are not outcompeted by selfish counterparts. A key aspect of such strategy updates involves a comparison of an individual's latest payoff with that of a random neighbour. In reality, both the economic and social milieu often shapes cooperative behaviour. We propose a new decision heuristic, where the propensity of an individual to cooperate depends on the local strategy environment in which she is embedded as well as her wealth relative to that of her neighbours. Our decision-making model allows cooperation to be sustained and also explains the results of recent experiments on social dilemmas in dynamic networks. Final cooperation levels depend only on the extent to which the strategy environment influences altruistic behaviour but are largely unaffected by network restructuring. However, the extent of wealth inequality in the community is affected by a subtle interplay between the environmental influence on a person's decision to contribute and the likelihood of reshaping social ties, with wealth-inequality levels rising with increasing likelihood of network restructuring in some situations.

Astrocytes are key regulators of brain homeostasis, which is essential for proper cognitive function. The role of cytoskeletal dynamics in this critical regulatory process is unknown. Here we find that actin is dynamic in certain subcellular regions, especially near the cell boundary. Our results further indicate that actin dynamics concentrates into hotspot regions that selectively respond to certain chemophysical stimuli, specifically the homeostatic challenges of ion or water concentration increases. Substrate topography makes actin dynamics more frequent yet weaker, and it also alters actin network structure. Superresolution images analyzed with a filament extraction algorithm demonstrate that surface topography is associated with a predominant perpendicular alignment of actin filaments near the cell boundary whereas flat substrates result in an actin cortex mainly parallel to the cell boundary. Thus, actin structure and dynamics together integrate information from different aspects of the environment that might steer the operation of neural cell networks.

All societies rely on individual contributions to sustain public goods that benefit the entire community. A variety of mechanisms, that specify how individuals change their decisions in response to past experiences and behavioral attributes of interacting partners, have been proposed to explain how altruists are not outcompeted by selfish counterparts. A key aspect of such strategyupdate processes involves only a comparison of an individual's latest payoff with that of a randomly chosen neighbor. In reality, both the economic and social milieu often shapes cooperative behavior. We propose a new decision heuristic in social dilemmas, where the propensity of an individual to cooperate depends on the local strategy environment in which she is embedded as well as her wealth relative to that of her connected neighbors. Our decision-making model allows cooperation to be sustained and also explains the results of recent behavioral experiments on cooperation in dynamic social networks. Final cooperation levels depend only on the extent to which the strategy environment influences altruistic behaviour but is largely unaffected by network restructuring. However, the extent of wealth inequality in the community is affected by a subtle interplay between the environmental influence on a person's decision to contribute and the likelihood of reshaping community ties through breaking old and making new links, with wealth-inequality levels rising with increasing likelihood of network restructuring in some situations.