Re-Creating In Vivo-Like Activity and Investigating the Signal Transfer Capabilities of Neurons: Dynamic-Clamp Applications Using Real-Time Neuron

Abstract

Understanding the input–output transfer properties of NEURONs is a complex problem which requires detailed knowledge of the intrinsic properties of neurons, and how these intrinsic properties influence signal integration. More recently, it became clear that the transfer function of neurons also highly depends on the activity of the surrounding network, and in particular on the presence of synaptic background activity. We review here different in vitro techniques to investigate such problems in cortex, thalamus, and spinal cord, along three examples: First, by constructing “hybrid” networks with real and artificial thalamic neurons using dynamic clamp, it was possible to study how the state of the circuit influences spike transfer through the thalamus. Second, the dynamic clamp was used to study how the state of discharge of spinal neurons influences their information processing capabilities. Third, the dynamic-clamp experiments could re-create “in vivo-like” background synaptic activity by injection of stochastic excitatory and inhibitory conductances, and we showed that this activity profoundly modifies the input–output transfer function of thalamic and cortical neurons. We also illustrate how such applications are greatly facilitated by the use of a neuronal simulator to run the dynamic-clamp experiments, as shown here for RT-NEURON.