Paired recording is a powerful and versatile tool to examine communica
tion between and within neurones. This technique has provided new insi
ghts in studies of synaptic function and plasticity, of neuronal integ
ration, and of the decoding of neuronal circuits. Recent studies using
dual recordings in combination with morphology have successfully dete
rmined the number of transmitter release sites between synaptically co
nnected neurones. Important progress in understanding the dynamics of
signal transmission within individual cells has been made possible usi
ng infra-red microscopy, which permits dual recordings from visualized
somatic and dendritic sites on a single neurone.