In recent years, groundbreaking research revealed many surprising roles for astrocytes in addition to their well characterized supportive roles, in modulating neuronal activity and even behavior. I will talk on one hand about manipulating astrocytes to alter neuronal activity and behavior and on the other hand about imaging astrocytes in behaving animals.
We chronically imaged CA1 astrocytes using 2-photon microscopy when head-fixed mice were trained mice to run on a linear treadmill and proceed in a virtual environment to obtain water rewards. We found that astrocytic activity persistently ramps towards the reward location in a familiar environment. When the reward location was changed in the same environment or when mice were introduced to a novel context, the ramping was not apparent. Using linear decoders, we accurately reconstructed mice location trajectories in a familiar environment from astrocyte activity alone. This is the first indication that astrocytes can encode position related information in learnt spatial contexts, thus broadening their known computational abilities, and their role in cognitive functions.
To directly and specifically modulate astrocytic activity we employed a chemogenetic approach: We expressed the Gq-coupled designer receptor hM3Dq in astrocytes, which allowed their time-restricted manipulation, and discovered that astrocytic activation is sufficient to induce de-novo long term potentiation, enhance memory allocation and augment memory recall on the following day. I will talk about these published works and about non-published results on the role of astrocytes in Alzheimer's disease
