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
Scientists at the University of Basel identified a specific gene, neuroligin-3 which when absent in mice, interferes with neuronal signal transmission which leads to the development of behavior patterns typically found in autism. These adverse effects are associated with the increased production of a specific neuronal glutamate receptor which modulates the transmission of signals between neurons. Too much of this receptor prevents the adaptation of synaptic transmission during learning processes and disrupts the long term development and function of the brain. The scientists were also able to reverse these neuronal changes.
When they reactivated the production of neuroligin-3, the nerve cells scaled down the production of the glutamate receptors to a normal level and the structural defects in the brain typical for autism disappeared. These findings are an important step in drug development for the treatment for autism.
Baudouin SJ, Gaudias J, Gerharz S, Hatstatt L, Zhou K, Punnakkal P, Tanaka KF, Spooren W, Hen R, De Zeeuw CI, Vogt K, & Scheiffele P (2012). Shared synaptic pathophysiology in syndromic and nonsyndromic rodent models of autism. Science (New York, N.Y.), 338 (6103), 128-32 PMID: 22983708
Neuroscientists at the University of Rochester have discovered an alternative mechanism to clear extra-cellular proteins from the brain. Scientists studied the flow of cerebrospinal fluid (CSF) in living mouse brain. Cerebrospinal fluid acts as a cushion to protect the brain and also to “cleanse” the brain tissue. But how the fluid moves through the brain and clears waste wasn’t well understood. Scientists used a method called two-photon laser scanning microscopy to analyze the flow of CSF in living mouse brains. This new technology allowed the scientists to study the intact brain in real time.
They injected tracer molecules into the subarachnoid space, a cerebrospinal fluid-filled cavity between the membranes that cover the brain and spinal cord. This research conducted on mouse, is a sign of hope for people with neurodegenerative disorder.
Iliff JJ, Wang M, Liao Y, Plogg BA, Peng W, Gundersen GA, Benveniste H, Vates GE, Deane R, Goldman SA, Nagelhus EA, & Nedergaard M (2012). A paravascular pathway facilitates CSF flow through the brain parenchyma and the clearance of interstitial solutes, including amyloid β. Science translational medicine, 4 (147) PMID: 22896675