Abstract
Aim: A pilot study to compare skin blood flow (SBF) as measured by laser Doppler flowmetry (LDF) with measures of skin conductance.
Method: Changes in SBF and skin conductance in response to a variety of stimuli were investigated in twelve healthy volunteers. The stimuli included three manoeuvres – breath holding, Valsalva and head turning – and a series of auditory and shock stimuli. Evidence of correlation between the two measures as well as evidence of habituation were investigated.
Results: A simultaneous reduction in SBF and increase in skin conductance followed each manoeuvre and stimulus. A significant correlation between the two responses was found (p < .001). Habituation of skin conductance to shock stimuli was demonstrated and found to be statistically significant. Habituation of skin conductance through the course of the protocols (comparing the first auditory stimulus to the last shock stimulus) was demonstrated and found to be statistically significant. Habituation of SBF was not evident in terms of diminution of responses but was evident in terms of reduced recovery times over the course of the protocols.
Conclusions: The results support a significant correlation between SBF and skin conductance in response to autonomic nervous system related manoeuvres and alerting stimuli. Habituation was evident for electrodermal activity but not for vasomotor activity. The criticism that vasomotor activity habituates too rapidly for it to be a useful measure was not supported by this study. The findings suggest that the vasomotor response may habituate at a slower or delayed rate. LDF measures of SBF compare favourably to skin conductance measurement in the investigation of autonomic function and might have several advantages over skin conductance measurement. The poster will discuss these advantages and the possible implication for research into autonomic arousal and related disorders. Further investigation is warranted to investigate the SBF responses in anxious versus normal subjects.