| OCR Text |
Show 95 interactions are almost definitely influenced by peripheral processes and interactions with the surrounding natural environment. The cell may not even be the true "building block" of the brain. A cell-centric view of the brain implies that non-cellular components, such as extracellular structural proteins, are not involved in active CNS processing. Unfortunately, the tools do not exist to test this hypothesis so it can only exist in the philosophical realm. Although the tools described here are extremely useful for monitoring calcium dynamics in the brain, there are still many limitations to fully describing how astrocytes, healthy or reactive, affect brain physiology. However, this work was one small step towards a complete understanding of the astrocyte response to brain insults. Currently, imaging of calcium dynamics in living tissue with decent temporal resolution via two-photon microscopy is limited to two dimensions. Activity obviously occurs in three dimensions, so we are only able to observe a small slice of calcium activity. It is probable that fast three-dimensional imaging will reveal novel cellular and network behavior. Even faster scan rates are desirable for detection of ephemeral calcium events. Many small calcium signals likely exist which are impossible to detect with current imaging technology. Indicator kinetics are limited by speed of conformational change and may give the impression that calcium transient activity is longer than it actually is. Synthetic dyes, maybe in the form of quantum dots, which could be delivered in vivo without the need to bulk load could solve this problem in the near future. Depth of imaging with current GECIs is limited by both excitation and emission wavelengths. Green indicators are not able to be imaged more than 500 µm deep in the rodent brain. Laser power could interfere with cellular dynamics. Even the small amount of absorption by water and tissue in the infrared range could lead to a response from |
