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Abstract

Microelectrodes of different types are used by neurophysiologists to record the electrical activity of single nerve cells or groups of neurons, and it is often desirable to localize the structure producing the physiological response. Ideally the nerve cells whose activity is being monitored should be anatomically characterized. With intracellular recording of a single neuron, a stain can be iontophoretically injected into the neuroplasm, and the cell unambiguously identified. Such recordings, however, are very difficult to achieve in the mammalian brain, and most experimenters still rely on extracellular recordings for their physiological analysis. Although it is not generally possible to identify the recorded structure to the neuronal level using extracellular techniques, the ordered topology of some structures in the brain, such as cerebellum, hippocampus, and retina, may permit cellular identification if the tip position of the microelectrode can be accurately marked.