RESUMEN
There has been a continuing interest in many areas of psychophysiological research in the quantification of slow wave bioelectric potentials recorded from the surface of the skin. However, surprisingly little research has focused specifically on methods for stabilizing and minimizing the offset potentials of the sintermetallic Ag/AgCl surface electrodes commonly used in such noninvasive bioelectric measurement. To provide empirically based recommendations in this regard, we contrasted the effects of three common storage methods (air dry vs. saline vs. carbon rod) on the two distinct types of Ag/AgCl surface electrodes (sintermetallic vs. electrolytic) under simulated experimental conditions. The obtained results confirm that minimum offset potentials and maximum stability for electrolytic Ag/AgCl electrodes are obtained when they are stored in a 0.9% NaCl solution with their leads shorted together and connected in parallel to a carbon rod partially immersed in the solution (cf. Cooper, 1956). In addition, the pattern of results suggested that the inter-session unshorted storage of sintermetallic electrodes in a mild saline solution is to be recommended over either shorted saline storage in parallel with a carbon rod or unshorted dry storage.
Asunto(s)
Electrodos , Psicofisiología/instrumentación , Procesamiento de Señales Asistido por Computador/instrumentación , Compuestos de Plata , Plata , Conductividad Eléctrica , HumanosRESUMEN
The historical beginnings of the scientific discipline of psychophysiology are traced back to the first published English definition by Dr. Samuel Adams, M.D.
Asunto(s)
Hipnosis/historia , Psicofisiología/historia , Europa (Continente) , Historia del Siglo XIX , Historia del Siglo XX , Humanos , Estados UnidosRESUMEN
Despite the burgeoning literature using facial electromyography (EMG) to study cognitive and emotional processes, the psychometric properties of facial EMG measurement have received little attention. Two experiments were conducted to assess the reliability and validity of facial EMG as a measure of specific facial actions. In Experiment 1, two recording sites in the brow region were compared for their ability to differentiate facial actions hypothesized to be due to the activation of the corrugator supercilii from facial actions presumed to be due to the activation of proximate muscles (e.g. depressor supercilii, procerus, frontalis, levator labii superioris alaeque nasi, orbicularis oculi), and four sites in the infraorbital triangle were compared for their ability to differentiate facial actions hypothesized to be due to the activation of the zygomaticus major from facial actions presumed to be due the activation of proximate muscles (e.g. zygomaticus minor, risorius, buccinator, orbicularis oculi, orbicularis oris). Fifteen subjects were instructed to pose a series of facial actions while EMG activity was sampled simultaneously at all sites. In Experiment 2, 5 subjects returned to the laboratory for a more extensive investigation of surface EMG activity over the zygomaticus major muscle region. The results of this experiment confirmed the findings of Experiment 1. Overall, the results demonstrate that certain recording sites located over specific facial muscle regions are more sensitive and valid indices of particular facial actions than other nearby sites.