How astrocytes stabilize mature brain circuits

A good brain somehow balances plasticity (the ability to change) with stability (the need to maintain information and structure). Our brains famously lose some of their plasticity when we become adults, and we more seasoned adults sometimes lament the reduced plasticity that accompanies our hard-earned wisdom. We also wonder how the whole dance is controlled.

Figure 5q: Schematic summarizing mechanisms of CCN1 action.

A new paper in Nature, in a technical tour de force, shows that astrocytes (those long-neglected, oft-forgotten glial cells) are central players in the dance of plasticity and stability. Using a classic example of that dance—the stabilization of binocular visual system circuits after birth, in response to experience with light—the authors looked for astrocyte genes whose expression suggests involvement in that process. They turned up a signaling protein called CCN1, which was previously almost completely unknown in the nervous system. Through CCN1, astrocytes control the stability of brain circuits by controlling the actions of multiple other cell types. Their role is truly central, and here is how the authors summarize the findings:

Most of the changes that arise after manipulating CCN1 expression in vivo do not require plasticity induction to be revealed, highlighting the role of CCN1 in regulating circuit stability during normal visual experience. We find that CCN1 acts on multiple cell types—excitatory neurons, inhibitory neurons, oligodendrocytes and microglia—underscoring the complex regulation of plasticity and stability by astrocytes (Fig. 5q). Overall, we have identified that CCN1 coordinates the maturational changes that occur in multiple cell types underlying the loss of plasticity in adulthood, highlighting the role of astrocytes as a hub for these effects.

You can see Figure 5q above, with astrocytes claiming the role of hubmaster. The data supporting its roles is extensive and diverse, somehow presented in five figures! It all adds up to a great new (to us) role for astrocytes in the lifelong dance of plasticity and stability. 

Astrocyte CCN1 stabilizes neural circuits in the adult brain
In Nature, 17 December 2025
From the group of Nicola Allen at the Salk Institute

Snippet by Stephen Matheson

Image credit: Figure 5q from Sancho et al. cited above (CC BY-NC-ND). Cropped from the full figure.

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