Subnetwork-Specific Homeostatic Plasticity in Mouse Visual Cortex In Vivo

Samuel J Barnes,Rosanna P Sammons,R Irene Jacobsen,Jennifer Mackie,Georg B Keller,Tara Keck

doi:10.1016/j.neuron.2015.05.010

Samuel J Barnes, Rosanna P Sammons + Show 4 more

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https://doi.org/10.1016/j.neuron.2015.05.010

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Abstract

SummaryHomeostatic regulation has been shown to restore cortical activity in vivo following sensory deprivation, but it is unclear whether this recovery is uniform across all cells or specific to a subset of the network. To address this issue, we used chronic calcium imaging in behaving adult mice to examine the activity of individual excitatory and inhibitory neurons in the same region of the layer 2/3 monocular visual cortex following enucleation. We found that only a fraction of excitatory neurons homeostatically recover activity after deprivation and inhibitory neurons show no recovery. Prior to deprivation, excitatory cells that did recover were more likely to have significantly correlated activity with other recovering excitatory neurons, thus forming a subnetwork of recovering neurons. These network level changes are accompanied by a reduction in synaptic inhibition onto all excitatory neurons, suggesting that both synaptic mechanisms and subnetwork activity are important for homeostatic recovery of activity after deprivation.

Highlights

Homeostatic plasticity is thought to be essential for maintaining the firing rate of neurons and preventing aberrantly low or high network activity (Turrigiano and Nelson, 2004)
To investigate the role of subnetworks of cells in homeostatic plasticity, we first measured the responses of individual excitatory and inhibitory neurons in the same cortical region of the mechanisms, we found that following deprivation, synaptic inhibition was reduced onto both putative recovering and inactive layer 2/3 (L2/3) excitatory neurons
We found that individual excitatory neurons in L2/3 could be divided into two groups: (1) those that become completely inactive after deprivation and (2) those that homeostatically recover activity, i.e., those in which a period of reduced activity is followed by a gradual recovery of activity over a period of 48–72 hr

Summary

SUMMARY

Homeostatic regulation has been shown to restore cortical activity in vivo following sensory deprivation, but it is unclear whether this recovery is uniform across all cells or specific to a subset of the network. To address this issue, we used chronic calcium imaging in behaving adult mice to examine the activity of individual excitatory and inhibitory neurons in the same region of the layer 2/3 monocular visual cortex following enucleation. Excitatory cells that did recover were more likely to have significantly correlated activity with other recovering excitatory neurons, forming a subnetwork of recovering neurons. These network level changes are accompanied by a reduction in synaptic inhibition onto all excitatory neurons, suggesting that both synaptic mechanisms and subnetwork activity are important for homeostatic recovery of activity after deprivation

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