RELATION OF ELECTROTACTUAL THRESHOLD TO BASAL SKIN CONDUCTANCE.

Abstract

thresholds (ETT) of the human neonate over the first 4 days of life. 53 infants were studied in 4 age groups, there being approximately equal numbers of males and females in each. Results showed a significant negative correlation between BSC and ETT, but a covariance analysis of effects of age on threshold, with effects of BSC statistically controlled, supported their independent decrease over time. It is suggested that both factors are related to one or more other factors. Standardized methods and uses for the threshold determinations are briefly discussed. Two recent studies of electrotactual threshold (ETT) (6, io) have shown that a population of clinically normal neonates show decreasing behavioral thresholds as a function of age over the first four days of life. Lipsitt and Levy used a toe electrode with foot withdrawal as the sign of threshold. They suggested that possible parameters determining this early developmental change include: increased wakefulness over the four-day test period; decreases in the effects of maternal anesthesia and analgesia; and increasing recovery from perinatal anoxia in part of the tested population. Graham et al. (6) also demonstrated this developmental phenomenon, using stimulation applied to either calf and measuring leg withdrawal as the response. They found that thresholds tended to be higher for apparently traumatized infants when compared with normals. However, the distribution for the traumatized group was bimodal, so that a large number of the group fell within the range of normal threshold distribution. One important factor not controlled in the Lipsitt and Levy study was that of possible change in skin conductance over time (2, 12). In his work with animals, Bishop placed a 3 megohm resistor in series with his Ss to minimize effects of intersubject and intrasubject differences in basal skin resistance. Graham (5), utilizing a stimulator designed by Bishop (2), used only a .5 megohm resistor in series. Darrow et al. (4) have reported nonpalmar and nonplantar resistances to DC which are exceptionally high, and