image: This is a schematic diagram illustrating the dynamic of the synaptic connectivity in a neural network recruited during the formation of a new memory. Before learning the neural network presents a connectivity arrangement characterized by a mix of potentiated (thick black lines) and unpotentiated (thin black lines) synapses. During memory encoding, a sparse number of cells (engram cells, red) are recruited giving rise to new connections or activating preexisting ones (dashed red line). Immediately after encoding the process of memory consolidation enables the stabilization of the new connections (thick red line). The stabilization is characterized by a permanent enhancement of the synaptic strength and is fundamental for memory retrieval. Disruption of the consolidation process by intervention such as protein synthesis inhibitors impairs the stabilization potentiation of the new synaptic connections (thin red line) resulting in retrograde amnesia. The synaptic connectivity provides a substrate for memory storage whereas the potentiation of the synapses is required for memory retrieval. This material relates to a paper that appeared in the May 29, 2015 issue of Science, published by AAAS. The paper, by T.J. Ryan at Massachusetts Institute of Technology in Cambridge, MA, and colleagues was titled, "Engram cells retain memory under retrograde amnesia." view more
Credit: [Credit: Michele Pignatelli]