Figure 1.
Subcellular patch-clamp recording from dendrites and axons of CA3 pyramidal neurons. (a-c) Dendritic recording from CA3 pyramidal neurons. A confocal image of a CA3 pyramidal cell filled with 100 μM Alexa Fluor 488 via the somatic recording pipette during the experiment is shown in a. The dendritic recording site is 218 μm from the soma. An infrared differential interference contrast video image of the soma (top) and the apical dendrite (bottom) of the same CA3 pyramidal neuron with the patch pipettes attached is shown in b. A light micrograph of a CA3 cell filled with biocytin during recording and labeled using 3,3′-diaminobenzidine (DAB) as chromogen is shown in c. The bottom panel shows an expanded view corresponding to the dashed box shown in the top panel. Arrowheads in c indicate thorny excrescences, the postsynaptic spines of hippocampal mossy fiber synapses. (d-f) Axonal recording from CA3 pyramidal neurons. A confocal image of a CA3 pyramidal neuron filled with 100 μM Alexa Fluor 488, showing an axon bleb at the surface of the slice, is presented in d. The axonal recording site is 90 μm from the soma. A corresponding infrared differential interference contrast video image is shown in e. Post hoc biocytin labeling of the same CA3 cell using DAB as chromogen is shown in f. The axon was unequivocally identified by the complete lack of spines. Arrowhead in f indicates axon bleb. Photomicrographs in a, d and f represent collages of images at slightly different focal planes. Images in a and b were obtained from the same cell; images in d-f were obtained from another cell.