Impact of background input on memory consolidation in In-Vitro neural networks

Memory consolidation is a complex process, that can be divided into two stages: first, memories are temporary stored in hippocampus and in the second stage, repeated replay slowly transfers memories to the neo-cortex for long-term consolidation. This 2nd stage occurs during slow wave sleep, a phase characterized in the cortex by low cholinergic tone and low afferent input.  A recent in-vitro study showed that high cholinergic tone hampers memory consolidation, probably due to lowered network excitability (defined as the mean network response to one neuron spiking). Here we investigate whether low background input contributes to memory consolidation.
We used cortical neuronal networks on multi electrode arrays to study memory. When input deprived, these networks develop an activity-connectivity balance. Focal stimuli initially disrupt the existing balance,  inducing connectivity changes. When repeated, this effect fades and the response becomes part of spontaneous patterns (memory format..., , , # Impact of Background Input on Memory Consolidation in In-Vitro Neural Networks

[https://doi.org/10.5061/dryad.f1vhhmh4m](https://doi.org/10.5061/dryad.f1vhhmh4m)

Our goal was to answer the following questions: given the important role of slow wave sleep in memory consolidation, and that one of the main characteristics of this sleep phase is the presence of low afferent input, which effects would have the application of background inputs on memory consolidation? To answer this question we applied focal electrical stimulation through one electrode to networks plated on micro electrodes array (MEAs), with or without contemporary background inputs. The application of background afferent inputs was done using optogenetic stimulation, which implies the use of an AAV virus in cultures in order to bring to expression channel rhodopsin 2 (ChR2). So first we checked the effects of expression of ChR2 alone on memory consolidation. 

Stimulation protocol for memory: acquisition of 1h spontaneou...