In 20 arms from 10 healthy subjects, the orthodromic median sensory volleys crossing the wrist gave rise to a stationary, biphasic potential rendering the forearm initially positive (Pw) and subsequently negative (Nw) compared with the hand. A pair of electrodes located on each side of the wrist best detected the junctional potential, Pw-Nw, that developed across the partition. Here the hand and the forearm each, in effect, acted as a lead, connecting any points within the respective compartment to the voltage source. Thus, nearly the same potential difference appeared across the wrist regardless of the inter-electrode distance, allowing the detection of the voltage step in far-field derivation. Our data verify that not only positive but also negative peaks of scalp-recorded evoked responses could represent junctional potentials generated along the course of the conduction medium in the absence of fixed neural discharges.
ASJC Scopus subject areas
- Clinical Neurology