and they may in certain instances, resolve over time, if triggering cues are removed (Key Figure, Figure 2B–E). In this regard, it may be useful to regard differentially expressed genes and other molecular changes as interchangeable tools used by the same astrocyte subtypes as required in different contexts and induced by different triggers, rather than as markers of different astrocyte subtypes. Thus, reactive astrocytes that do not change their basic subtype may exhibit substantially different changes in gene expression and cell function over time during the same disorder, or in response to different disorders. Understanding the potential for diversity and subtilty of different astrocyte reactivity states is only beginning and is an important topic for future research.
