BIRS Workshop Lecture Videos

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BIRS Workshop Lecture Videos

Homeostatic control of neuronal firing rate and correlation: scaling of synaptic strength with network size Reyes, Alex


Features of sensory input are represented as the spatiotemporal activities of neuronal population. This network dynamics depends on the balance of excitatory (E) and inhibitory (I) drives to individual neurons. Maintaining balance in the face of continuously changing nervous system is vital for preserving the response properties of neurons and preventing neuropathologies. While homeostatic processes are in place to maintain excitatory level, the conditions for maintaining stable responses are yet unclear. Here, we used a culture preparation to systematically vary the density of the network. Using optogenetic techniques to stimulate individual neurons in the network with high spatial and temporal resolution, we were able to systematically vary the number and correlation of external inputs. We found that the average firing rate and the correlation structure of synaptic inputs are invariant with network size. Finally, we used paired recordings to measure the synaptic strengths and connection probability between excitatory (E) and inhibitory (I) neurons. We confirmed experimentally a long standing theoretical assumption that synaptic strength scales with the number of connections per neuron ($N$) closer to $N^{-1/2}$ than to $N^{-1}$ .

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