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Free keywords:
Action Potentials/*physiology
Animals
Auditory Cortex/*physiology
Calcium Signaling
Evoked Potentials
Excitatory Postsynaptic Potentials/*physiology
Inhibitory Postsynaptic Potentials/*physiology
Long-Term Potentiation/physiology
Mice
Neural Inhibition/*physiology
Neuronal Plasticity/*physiology
Patch-Clamp Techniques
Pyramidal Cells/*physiology
Synapses/physiology
*Ca(2+) signaling
*ltp
*stdp
*cortex
*excitatory-inhibitory balance
*inhibition
*modeling
*plasticity
Abstract:
Excitation in neural circuits must be carefully controlled by inhibition to regulate information processing and network excitability. During development, cortical inhibitory and excitatory inputs are initially mismatched but become co-tuned or balanced with experience. However, little is known about how excitatory-inhibitory balance is defined at most synapses or about the mechanisms for establishing or maintaining this balance at specific set points. Here we show how coordinated long-term plasticity calibrates populations of excitatory-inhibitory inputs onto mouse auditory cortical pyramidal neurons. Pairing pre- and postsynaptic activity induced plasticity at paired inputs and different forms of heterosynaptic plasticity at the strongest unpaired synapses, which required minutes of activity and dendritic Ca(2+) signaling to be computed. Theoretical analyses demonstrated how the relative rate of heterosynaptic plasticity could normalize and stabilize synaptic strengths to achieve any possible excitatory-inhibitory correlation. Thus, excitatory-inhibitory balance is dynamic and cell specific, determined by distinct plasticity rules across multiple excitatory and inhibitory synapses.
