Dependence of Skin Conductance Reactions and Skin Resistance Reactions Upon Previous Level

When results from an earlier investigation of skin resistance reaction and skin conductance reaction taken from parallel sites were reanalyzed, a surprising discrepancy between these measures was noted. At high levels of noise stimuli (90dB and above), skin resistance reaction amplitudes decrease with the number of trials whereas skin conductance reaction amplitudes increase. This divergence can be understood in terms of level dependence of both skin conductance reaction and skin resistance reaction. Because of opposite trends in resistance and conductance level shifts in the course of the experiment, skin resistance reaction measures yield decreasing values, even if the “true” reaction were constant, whereas SCR measures tend to overestimate the reaction. After a correction based upon empirically-determined level dependence the two measures give comparable results. Theoretical considerations underlying the empirical correction procedures are discussed based upon a simple electrical model of the skin, and recommendations are made for use of AC measurement in electrodermal activity research.     

Experimenter and Subject Sex Effects In the Skin Conductance Response

The present study was designed to determine the significance of the experimenter's sex on the subject's skin conductance responsiveness and to ascertain the nature and extent of sex differences in basal skin conductance, skin conductance response (SCR) magnitude, and spontaneous skin resistance (SRR) activity. The responses of 30 male and 30 female Ss were recorded by 3 male and 3 female experimental assistants. Following a brief adaptation period, all Ss received 20 5-sec bursts of 75 dB white noise. Variable stimulus intervals were employed. Male Ss serving in the female E condition evidenced significantly higher basal conductance levels and a more rapid decrease in basal conductance levels over trials. Skin resistance response magnitude data showed a significant Experimenter Sex X Trials interaction such that all Ss serving in the female E condition failed to habituate. An analysis of spontaneous SRR activity showed that Ss serving in the other-sex E condition emitted more spontaneous responses. All Ss showed a significant decrease in spontaneous activity across trials.     

Another Look at the Relationship of Electrodermal Activity to Electrode Contact Area

The present study was undertaken lo reexamine the hypothesis that the relationship between skin conductance and electrode size is monotonic and linear. Skin conductance activity was recorded from 48 right-handed male subjects using 6 different sixes of electrode collars ranging in exposed surface area from .131 cm² to .786 cm². The dependent measures were skin conductance level (SCL); skin conductance response (SCR) amplitude to a series of 8 loud tones; latency, rise time, and recovery half-time of the first tone elicited response; (he largest self-generated SCR; and the number of nonspecific responses. The results indicated a significant linear relationship between contact area and SCL, stimulus and self-generated SCR amplitude, and the number of nonspecific responses. Latency was not affected by electrode size although the other time-based measures were. Differences in skin conductance activity were found among different palmar recording sites. The observed linear relationship between electrode size and electrodermal measures has implications for current models of electrodermal activity and for the comparison of results across studies in which different electrode contact areas are used.     

Skin sympathetic nerve activity and effector function during sleep in humans

Multi-unit sympathetic skin nerve activity (SSA) in the peroneal nerve was recorded together with electrical skin resistance, skin blood flow and (in some subjects) finger blood pressure during sleep in 22 sleep-deprived healthy subjects. The average strength of sympathetic activity in different sleep stages was measured during 5-min periods as the area-under-curve of the integrated neurogram. Stage 2 sleep was reached by 15 subjects, stages 3–4 by nine and rapid eye movement (REM) sleep by six subjects. Non-REM sleep was always associated with an increased skin resistance, which was larger in glabrous than in hairy skin (293±48 vs. 175±4% of awake control level, n= 10, P < 0.05). Skin blood flow also increased during sleep, with a mean maximal increase of 397±79% of the awake control level (n= 11, P < 0.05). In spite of these changes of effector function no significant difference in mean SSA was found between the awake control period and periods of non-REM sleep, but during REM sleep SSA increased with 34% (P < 0.05) compared with the immediately preceding stage 2 period. In stage 2 sleep, K-complexes were associated with bursts of SSA followed by transient changes of skin resistance, blood flow and arterial blood pressure. When both skin resistance and blood flow were recorded within the innervation area of the impaled fascicle, single bursts or short periods of increased SSA could be succeeded by increased skin blood flow without concomitant skin resistance change. This indicates the existence of specific sympathetic vasodilator fibres in the skin. Therefore the unchanged strength of multiunit SSA during non-REM sleep in the face of increases of skin resistance and blood flow may be a consequence of an increased sympathetic vasodilator nerve activity combined with decreases of vasoconstrictor and sudomotor traffic.     

Race Differences and Experimenter Race Effect in Galvanic Skin Response

The present study was designed to ascertain whether racial differences exist in the several components of the skin resistance response and to assess the importance of the role of the experimenter's race in determining the subject's responsiveness. Basal measures, GSR magnitude, and spontaneous GSR activity of 12 Negro and 12 Caucasian Ss were recorded by 2 Negro and 2 Caucasian experimental assistants matched for age, physical stature, and dress. Following a 15 min resting phase, all Ss received 14 1-sec bursts of 75 dB white noise. Variable stimulus intervals were employed. Significant subject-race effects, but no experimenter-race effects, were found for base level measures. Negro Ss evidenced significantly higher basal resistance levels. Conversely, experimenter-race effects, but no subject-race effects, were apparent in the GSR magnitude data. White Ss showed a significantly slower rate of response magnitude decrease over trials when paired with black Es. A significant decrease in spontaneous activity over time was observed for all Ss.     

Active Circuits for Direct Linear Measurement of Skin Resistance and Conductance

Passive voltage-divider circuitries typically used for measuring skin resistance and conductance provide only indirect measures of these variables. Although the resulting errors of nonlinearity may not be critical for some research purposes, there is no reason why they should be tolerated, because it is possible to design simple active circuitry which avoids the errors by measuring skin resistance and conductance directly. Two such circuits are presented: a) a variable-gain voltage amplifier for direct linear measurement of skin resistance; and b) a current-to-voltage transducer for direct linear measurement of skin conductance. A combined working circuit, suitable for practical research applications, is also presented.     

Psychological Correlates of Nonspecific Skin Conductance Responses

Previous research has indicated that the frequency of skin conductance responses without external stimulation or motor activity is a reliable indicator of psychophysiological states and traits. Some authors have suggested that cognitions elicit nonspecific skin conductance responses. These cognitions may resemble the stimuli that evoke a specific skin conductance response. In a within subjects design (n = 31 graduate students) the onset of nonspecific skin conductance responses triggered a signal for the subject to rate cognitions on several indices. These ratings ("absent" to "fully present") were compared with samples in the absence of phasic electrodermal activity. The subjects' current concerns, negative emotion, subjective arousal, and inner speech were rated to be significantly more intense at the time of nonspecific skin conductance responses compared to electrodermal nonresponding periods. Cognitive processes seem to be concomitants of nonspecific skin conductance responses.     

Psychological sweating from glabrous and nonglabrous skin surfaces under thermoneutral conditions

Recent experiments revealed psychological sweating to be a ubiquitous phenomenon in passively heated individuals. Since heating potentiates sweating, and since most research into psychological sweating was not conducted in this thermal state, these observations required thermoneutral verification. Thermoneutral subjects performed mental arithmetic (at 26^oC) with psychological sweating evaluated from nine sites (ventilated capsules, skin conductance). Discharged sweating was evident from three glabrous sites (P < .05). However, significant sweating was evident from two nonglabrous surfaces (P < .05), and skin conductance increased at the volar and dorsal finger surfaces (P < .05). Each of these changes occurred while core and skin temperatures remained stable (P > .05). These thermoneutral observations further refute the proposition that psychological sweating in humans is restricted to the glabrous skin surfaces.     

Anxiety and the Habituation of the Skin Conductance Response

The effect of threat of shock on the habituation of the skin conductance response (SCR) to a series of auditory stimuli was assessed. Skin resistance and heart rate were recorded during the presentation of 20, 1 sec, 1000 Hz tones in a control session and in a session at the end of which subjects were led to expect a painful electric shock. The effects of the threat of shock consisted of recovery of the SCR and an increase in skin conductance level and heart rate. They were restricted to the period during which subjects believed the shock to be imminent. Two possible reasons for the SCR recovery were offered, one in terms of Lader and Mathews' (1968) ‘maximal habituation’ hypothesis and a second in terms of a change in the stimulus complex.     

SIGNIFICANCE AND RELIABILITY OF SHOCK-INDUCED CHANGES IN BASAL SKIN CONDUCTANCE

Once weekly for 5 weeks, 15 adult male postaddicts were given 12 to 15 shocks of 5.0 to 8.0 ma. Basal skin conductance (BSC) was recorded during the 25-min weekly sessions. Increases in BSC during each session and the week-to-week reliabilities of the increases were determined. After the first week, subsequent increases showed reliability coefficients which ranged from 0.69 to 0.95 (P < 0.01). The reliabilities of the increases in BSC produced by shock were considered favorable for the use of change in BSC as a dependent variable in designs requiring repeated measurements on the same Ss at weekly intervals.     

Skin Conductance Recovery and Pupillometrics in Chronic Schizophrenia

A group of 31 chronic male shizopherics were found to be heterogeneous with respect to skin conductance recovery, when response was made to non-signal tones. Fast skin conductance recovery was related to slow pupillary constriction in the light/dark reflex. Conversely, slow skin conductance recovery was related to fast pupillary constriction in the light/dark reflex. The cholinergic nature of pupillary constriction and the implications of these findings for a generalized cholinergic hypothesis of schizophrenia are discussed.     

Sympathetic Skin Nerve Discharges in Relation to Amplitude of Skin Resistance Responses

Sympathetic skin nerve action potentials were recorded in the median nerve of 5 healthy college students. A linear and significant correlation was found between the mean voltage amplitude of the sympathetic bursts and the amplitude of skin resistance responses (SRRs). Thus amplitude of skin resistance responses seems to be an index of sympathetic activity.     

Dependence of EDR Recovery Times and Other Electrodermal Measures on Scale of Measurement: A Methodological Clarification

Edelberg (1970) and Boucsein and Hoffmann (1979) found shorter recovery times with a constant voltage method as compared with a constant current method. In the present paper it is pointed out that this effect may be due to the use of different scales of measurement rather than to any electrophysiological aspects of the recording procedure. The mathematical relationship between resistance and conductance implies that recovery times are shorter for SCRs than for corresponding SRRs. For demonstration purposes, recovery times were computed from an SR record and compared with those computed from the same record after computerized transformation to SC. Research implications of the demonstrated effect are discussed, and the relevance of measurement scale to two other electrodermal measures, area below the curve and range-corrected amplitude, is pointed out.     

胸背血管蒂皮瓣的临床应用

目的：探讨胸背血管蒂皮瓣修复躯体组织缺损的疗效。方法：应用胸背血管蒂皮瓣修复头、颈、胸、上肢等不同部位软组织缺损，其中带蒂胸背血管蒂皮瓣修复4例，游离胸背血管蒂皮瓣修复6例。结果：术后9例胸霄血管蒂皮瓣均存活良好，修复效果满意，1例游离胸背血管蒂皮瓣坏死。随访1月～3a，受区外形及功能恢复满意，供区愈合良好。结论：胸背血管蒂皮瓣血供丰富，血管解剖恒定，血管蒂长，可切取面积大，形式灵活，是修复组织缺损常用的皮瓣之一。     

Orienting in Schizophrenia: Habituation to Auditory Stimuli of Constant and Varying Intensity in Patients High and Low in Skin Conductance Responsivity

Groups of schizophrenics and normal controls were exposed to different series of tones of constant (80dB) and variable intensity (60, 80, and 100 dB). Measurements included bilateral skin conductance, finger pulse volume, and heart rate. Both groups were split on the common median in skin conductance response to constant intensity tones to form matched patient and control groups of low and high responsivity. The low and high responsive schizophrenic groups were more clearly separated than the two control groups in rate of spontaneous skin conductance fluctuations, skin conductance magnitudes, and skin conductance levels, primarily because of generalized hyperactivity in high responsive patients. This pattern was clearest for the most intense tone and left hand recordings. High responsive schizophrenics also showed larger response amplitudes, shorter rise and recovery times, and a smaller ratio of elicited to spontaneous responses, than high responsive controls. Finger pulse volume responses recorded from the left hand were smaller in the patient groups, whereas patients and controls did not differ in right hand recordings. High skin conductance responsive subjects showed more heart rate deceleration than low responsive subjects, and schizophrenics had more decelerative responses than controls.     

Effects of epidermal hydration on skin conductance responses and levels

Simultaneous recordings of skin conductance responses (SCRs) and levels (SCLs) were obtained from four sites. A glycol solution at one site produced minimal hydration while agar jelly at another site which was presoaked with water produced maximal hydration. The other two sites were recorded with two standard electrolytes (agar jelly and Unibase cream). In separate experimentsra pid and slow recovery SCRs were elicited over a period of 20–25 min. It was concluded that Unibase and agar have very different effects on skin conductance (SC) measurements, and that the relationship between SC measures and hydration is not monotonic.     

Uncomfortably numb: new evidence for suppressed emotional reactivity in response to body-threats in those predisposed to sub-clinical dissociative experiences

ABSTRACT

Introduction: Depersonalisation and derealisation disorders refer to feelings of detachment and dissociation from one’s “self” or surroundings. A reduced sense of self (or “presence”) and emotional “numbness” is thought to be mediated by aberrant emotional processing due to biases in self-referent multi-sensory integration. This emotional “numbing” is often accompanied by suppressed autonomic arousal to emotionally salient stimuli.

Methods: 118 participants completed the Cambridge Depersonalisation scale [Sierra, & Berrios, 2000. The Cambridge Depersonalisation Scale: A new instrument for the measurement of depersonalisation. Psychiatry Research, 93, 153–164)] as an index of dissociative anomalous experience. Participants took part in a novel “Implied Body-Threat Illusion” task; a pantomimed injection procedure conducted directly onto their real body (hand). Objective psychophysiological data were recorded via standardised threat-related skin conductance responses and finger temperature measures.

Results: Individuals predisposed to depersonalisation/derealisation revealed suppressed skin conductance responses towards the pantomimed body-threat. Although the task revealed a reliable reduction in finger temperature as a fear response, this reduction was not reliably associated with measures of dissociative experience.

Conclusions: The present findings significantly extend previous research by revealing emotional suppression via a more direct body-threat task, even for sub-clinical groups. The findings are discussed within probabilistic and predictive coding frameworks of multi-sensory integration underlying a coherent sense of self.     

Conductance Recording of Ionic Outflow from Frog Skin Glands during Nerve Stimulation

A method for continuous recording of the ionic efflux from frog skin glands has been developed which under given experimental conditions provides a convenient index on glandular secretion. A nerve skin preparation from the calf is mounted so that the outside of the skin forms the bottom of a small test compartment with distilled water while the corium side is bathing in Ringer's solution. After determination of the adequate nerve stimulus parameters for discernible gland secretion to occur, the skin nerve was stimulated at 10 Hz during varying periods and chemical control analyses performed of the changes in ionic content of the test compartment solution. The main ionic outflow consisted of Na⁺ and Cl^- in equal amounts, the outflow of other ions during stimulation being negligible. The concomitant conductance changes were measured as variations of absorption in a high-frequency field applied to a conductance probe placed in the test chamber. Determinations of the NaCl outflow based on the conductance changes were in good agreement with the values obtained by chemical analysis. The continuous conductance recordings proved to give approximative information of the quantities and time relations of the glandular secretion, allowing a direct comparison with, e.g., skin potential changes.     

Histomorphological and Angiogenic Analyzes of Skin Epithelium After Low Laser Irradiation in Hairless Mice

It is not well‐understood how low‐laser therapy affects the skin of the applied area. This study analyzes skin of the masseteric region of mice from the HRS/J strain after three different application regimens (three, six or ten applications per regimen) of low intensity laser at 20 J/cm² and 40 mW for 20 sec on alternate days. Three experimental groups according to the number of laser applications (three, six or ten) and three control groups (N = 5 animals for each group) were used. On the third day after the last irradiation, all animals were sacrificed and the skin was removed and processed to analyze the relative occupation of the test area by each epithelial layer and the aspects of neovascularization. Data were submitted to statistical analyzes. The irradiated groups compared to their respective controls at each period of time, showed no significant difference in relative occupation of the test area by the layers and epithelium areas for three and six applications, but for ten applications, a significant decrease (P < 0.05) in the basal and granulosum layers, and epithelium areas were found. From the comparisons of the three irradiated groups together, the group with six laser applications showed statistical difference (P < 0.05) in total epithelium and on the layers. Vascular endothelial growth factor (VEGF) and VEGFR‐2 immunoreactivities were similar for the control and irradiated groups. Results suggested a biostimulatory effect with low risks associated with superficial tissues, when the treatment aims the deeper layers after six applications. Anat Rec, 2011. © 2011 Wiley‐Liss, Inc.     

The Effect of Stimulus Significance on Skin Conductance Recovery

The relationship between skin conductance (SC) recovery time and stimulus meaning was investigated. Previous research has shown that a strong relationship between prestimulus electrodermal activity (prior activity) and recovery time makes it necessary to control prior activity before the relationship of recovery time and stimulus meaning can be evaluated properly. In this study prior activity was controlled by experimental design. We examined the effects of stimulus meaning on skin conductance recovery time and amplitude in 55 teenage and young adult subjects in a continuous performance paradigm. Tones were presented monaurally to left and right ears. Subjects were required to make a pedal press after any tone in the left or right ear that followed a right-ear tone. Recovery time was computed for left-ear and right-ear tones not requiring a press because they had been preceded by a left-ear tone. SC recovery was longer for signal (right-ear) than for nonsignal (left-ear) tones with the effects of prior SC activity and amplitude removed. These findings replicate those of a pilot study (Janes, 1982). We conclude that stimulus significance can affect SC recovery time and that in this paradigm differences in prior SC activity cannot account for the recovery time differences observed.