Image by pchow98 via Flickr One of the cool things about the brain & one of the ways in which it differs markedly from our current computer systems is that cells and synapses are living dynamic entities that grow and sprout new connections in response to experience. Since the 1980′s studies using protein synthesis inhibitors have shown that protein synthesis is necessary for an organism to store, recall and re-store, etc. various aspects of memory. The question for some time has been, “well, what protein(s) exactly ?” In their paper entitled, “ERK-dependent PSD-95 induction in the gustatory cortex is necessary for taste learning, but not retrieval” [DOI:10.1038/nn.2190], Elkobi et al., examine the role of PSD-95 a sort of general purpose scaffolding protein expressed in post-synaptic membranes that anchors the many molecular components that make up the synaptic machinery. They show that PSD-95 is indeed upregulated in the rat gustatory cortex after exposure to a novel stimulus (flavor) and that when it is selectively down-regulated via lentiviral expressed siRNA, that the creation of long term memories was disrupted. Interestingly, the paper shows a 3-hr time lag in the induction of PSD-95 after exposure to the memorable stimulus. Wow, that means I have 3 hours to selectively block long-term memories … I wonder what would be worth not remembering ?
Archive for the ‘PSD95’ Category
Image via Wikipedia From time to time, it just seems hopeless to adhere to a reductionist strategy in the area of psychiatry and psychology. How, indeed, can our infinitely complex mind be understood in terms of tiny chemical bits ? Just when you’re ready to give up and bid adieu to Descartes and his mechanisms, along comes a reinvigorating paper like Professor Morgan Sheng’s, “Synaptic Accumulation of PSD-95 and Synaptic Function Regulated by Phosphorylation of Serine-295 of PSD-95” (DOI). This paper demonstrates that the the addition and removal of a single – that’s right, a single – phosphate group to Serine 295 of the PSD-95 protein is sufficient to activate or inhibit the recruitment of synaptic proteins such as AMPA receptors and potentiate excitatory post-synaptic current. Given that many complex mental illnesses are associated with synaptic deterioration, there seems to be great therapeutic significance to this finding. [Neuron, Vol 56, 488-502, 08 November 2007]