Astrocytes are known to display dynamic intracellular Ca2+ signals, and it has recently been shown that astrocytes rapidly sense and regulate single synapses. Researchers could able to study astrocytic network using optical, pharmacological and genetic tools. Astrocytes in the hippocampus, found to be regulating neuronal conversations. Here, the flashes of light indicate changes in calcium levels within the astrocytes. When neurons show a burst of activity, calcium levels dramatically increase in the astrocyte, lighting up the entire cell.
Haustein MD, Kracun S, Lu XH, Shih T, Jackson-Weaver O, Tong X, Xu J, Yang XW, O’Dell TJ, Marvin JS, Ellisman MH, Bushong EA, Looger LL, & Khakh BS (2014). Conditions and constraints for astrocyte calcium signaling in the hippocampal mossy fiber pathway. Neuron, 82 (2), 413-29 PMID: 24742463
Neuroscientists at the Massachusetts Institute of Technology have identified the cells where memory traces are stored in the mouse hippocampus. In a study published recently, they reported to establish a population of cells in the dentate gyrus of the mouse hippocampus that encoded a particular context and were able to generate a false memory and study its neural and behavioral interactions with true memories. The researchers optogenetically activated the memory engram bearing cells in the hippocampus and these activated engrams were used to implant false memories in the mice’s brains.
It was demonstrated that the optogenetic reactivation of memory engram bearing cells was not only sufficient for the behavioral recall of that memory, but could also serve as a conditioned stimulus for the formation of an associative memory. The MIT team is now planning further studies of how memories can be distorted in the brain.
Ramirez S, Liu X, Lin PA, Suh J, Pignatelli M, Redondo RL, Ryan TJ, & Tonegawa S (2013). Creating a false memory in the hippocampus. Science (New York, N.Y.), 341 (6144), 387-91 PMID: 23888038