Overviews of Human (Evoked) Spinal Cord Potentials (SCPs): Recording Methods and Terminology

Abstract

Since Gasser and Graham (1933) first recorded the segmental spinal cord potential (SCP) from the dorsal surface of the cord in response to stimulation of the dorsal roots, its origin has been investigated by many neurophysiologists (Armett et al., 1961; Austin and McCouch, 1955; Barron and Matthews, 1938; Beall et al., 1977; Bernhard, 1953; Campbell, 1945; Carpenter and Rudomín, 1973; Fitzgerald and Wall, 1980; Howland et al., 1955; Lindblom and Ottoson, 1953a,b; Lupa and Niechaj, 1977). The fundamental pattern of the segmental SCP consists of an initially positive spike and subsequent slow negative (N) and positive (P) waves (refer to basic physiology, Chapter 2). It is generally agreed that the initially positive spike and N- and P-waves reflect the incoming afferent volleys along the root, the activities of interneurons in the dorsal horn, and the generation of primary afferent depolarization (PAD), respectively (Anders-Trelles, 1976; Barron and Matthews, 1938; Bernhard, 1953; Eccles and Malcolm, 1946; Eccles et al., 1963a; Fernandez de Molina and Gray, 1957; Fitzgerald and Wall, 1980; Hughes and Gasser, 1934a,b; Koketsu, 1956a,b; Mendell, 1972; Wall, 1958) (Fig. 4.1). The N-wave has been subdivided into two (Austin and McCouch, 1955; Bernhard, 1953) or three components (Beall et al., 1977; Christensen and Perl, 1970), the origins of which are variously interpreted.