Paired recordings from synaptically coupled neurones in acute neocortical slices

Abstract

The minimal element of a neuronal network is the microcircuit between a single pre- and postsynaptic neurone. To date, a detailed analysis of individual synaptic connections is only possible using paired or multiple recordings from synaptically coupled neurones. No other electrophysiological or optophysiological technique allows a correlated functional and structural characterization of both pre- and postsynaptic neurone, even down to the electron microscopic level. Paired recording studies have shown that a full identification of the neuronal elements in a synaptic microcircuit is necessary to fully understand its connectivity and synaptic dynamics. Furthermore, a description of the dendritic and axonal projection pattern makes it possible to elucidate synaptic connectivity rules, e.g., whether it is random or highly specific. Paired recordings can also be used in combination with pharmacological interventions, e.g., to characterize the role of different ion channel subtypes in synaptic transmission and their modulation. Finally, paired recordings also allow more challenging studies such as a quantal analysis of an identified synaptic connection or the regulation of synaptic transmission by neurotransmitters acting on G proteincoupled receptors. Taken together, paired recordings from synaptically coupled neurones are a powerful technique that helps to describe the properties of synaptic microcircuits, which are the basic building blocks of large-scale neuronal networks in the brain.