A major turning point in the use of electrophysiology to study the cerebral cortex occurred in the late 1930s with the introduction of surface electrodes to record the activity of neurons in a large volume of cortex. In a series of pioneering studies, Woolsey et al. (e.g., 1942; and see Woolsey, 1964) placed wire electrodes on the pial surface of cat and monkey somatosensory cortex and recorded the electrical responses of neurons following stimulation of peripheral tissue. The results of these studies showed that cortical neurons are activated by discrete peripheral stimuli and that coherent maps in the brain can be produced by relating a region on the body surface to the point of maximal evoked activity in the cortex. Similar evoked-potential maps were produced for other cortical areas and in other species, including the somatosensory cortex of the human (Penfield and Boldrey, 1937), the gustatory cortex of the rat (Benjamin and Pfaffamann, 1955), and the visual cortex of the monkey (Marshall and Talbot, 1942) and human (Blakemore and Campbell, 1969).
KeywordsVisual Cortex Cortical Neuron Receptive Field Pyramidal Neuron Somatosensory Cortex
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