BMI SEMINAR // Tara Keck - Synapse specific homeostatic responses to sensory deprivation

Homeostatic compensation of neural activity is necessary to prevent aberrant activity levels. Compensatory mechanisms can take several forms, including synaptic scaling, where synaptic weights are changed by an equal fraction across the spatial scale of the cell or dendritic branch and in a way that is anti-correlated with the changes in activity. Our previous work has shown that not all synapses undergo synaptic scaling, but the functional properties of the affected synapses are not clear. Based on studies of metaplasticity, one prediction is that the synapses that lose the most activity would have the largest increase in activity following deprivation. Here we show that the synapses that undergo compensatory increases in synaptic strength following sensory deprivation are more strongly correlated with the activity intrinsic to the network prior to deprivation, whereas the spines that received sensory input prior to deprivation do not strengthen over the time course of synaptic scaling. These results suggest that homeostatic synaptic compensation in vivo may be implemented specifically in the subset dendritic spines whose inputs reflect intrinsic network activity, rather than feedforward sensory inputs. This would serve to preserve input-output relationships while regulating cortical activity levels.