Synaptic Connections Between Identified Elements

The investigation of synaptic relationships in the cerebral cortex has recently entered a most productive era with the introduction and increasing application of combined light and electron microscopic methods that for the first time have enabled the synaptic relationships of identified neuronal elements to be determined reliably and on a regular basis. The methods currently employed combine the identification with the light micoscope of neurons impregnated by the Golgi method (e.g., Blackstad, 1965; Fairen et al., 1977) or labeled by the retrograde transport (e.g., White et al., 1980) or intracellular injection (e.g., McGuire et al., 1984) of horseradish peroxidase (HRP) followed by the analysis of their synaptic connections with the electron microscope.