About this Research Topic
The idea of this Research Topic theme, Activated Synapses, comes from the already probed hypothesis that only small subsets of neurons, called neuronal ensembles, play causal roles in mediating specific learned associations underlying learned behaviors. The specific neuronal ensemble activated during recall of a memory is determined by the specific pattern of activated afferent inputs that convey information about different cues and past experiences. Furthermore, different memories can be stored within the same brain area by different ensembles. While the cell bodies that make up neuronal ensembles are the critical integrators of information-specific input, long-lasting learning-induced alterations induced within synapses on these ensemble neurons are thought to be the primary mechanism for learned alterations underlying learned behaviors. Accordingly, there has been a recent shift from focusing on the alterations of ensemble cell bodies (cellular engram) to alterations of ensemble synapses (synaptic engram).
Synapses that are activated during learning are thought to undergo long-lasting alterations to form a long-lasting engram encoding the memory. Understanding the long-lasting changes as well the phenomenon of synaptic activation and the integration that triggers the final activation of a neuron are important biological questions that may be addressed with the use of suitable molecular and cellular techniques. Most of the current data about how the synapses are activated are obtained from neuronal cell culture or in slice preparations. However, the meaning of those changes and its translation to the brain system and to process of learning and memory is a challenge for the synaptic neuroscience field.
New advances in molecular, cellular, and imaging techniques and experimental designs for studying activated synapses in vivo have recently become available. These include the isolation and identification of markers of synaptic activity (e.g. by using RNAseq and proteomic broad spectrum analysis), and the use of genetic tools for visualization and modification of those activated synapses. These will lead us to understand the process of memory and eventually develop targeted genetic and pharmacological approaches to differentially strengthen or weaken those synapses with the aim to consolidate or erase memories underlying pathological or addictive conditions, respectively.
This Research Topic will focus on synaptic alterations and visualization of synaptic engrams as they relate to ensembles mediating different learned behaviors, including those involving drugs of abuse. We welcome original research and review articles, with specific themes of interest including the following:
• Local synaptic mRNA translation
• Regulation of intracellular cascades
• Calcium dynamics at synapses
• Synaptic receptor plasticity
• Markers of activated synapses
• New tools to study synapses in vivo
Keywords: learning, dendritic spines, synaptic engram, synaptic regulation, intracellular signaling
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