Intracellular Electrophysiological Techniques

The technique of intracellular recording is useful in studies seeking information about the functioning of individual neurons, their place in neuronal circuitry, and their membrane properties. For some of the just named applications, intracellular recording is the only method for obtaining the desired information. The functional significance of neurons is examined in the whole animal in intracellular experiments studying the responses of neurons during behavioral tasks or following sensory stimulation. The role of neurons in networks is studied by observing the synaptic responses generated by stimulation of connected structures. There are several standard tests of connectivity that can be made using intracellular recording techniques:

1.	Verification of a projection through antidromic activation can be made (e.g., Andersen et al., 1964 ; Kitai et al., 1972 ). This is usually done as a screening procedure to select projection neurons during an experiment.
2.	The nature of synaptic inputs can be examined. Here the sign (inhibitory or excitatory) of an input, its mechanism (i.e., ionic specie, conductance increase, disfacillitation, and so on, and, in many cases, the neurotransmitter can be learned (e.g., Coombs et al., 1955 , Kita et al., 1983 ;).