Skin Conductance Conditioning to Potentially Phobic Stimuli as a Function of Interstimulus Interval and Delay Versus Trace Paradigm

Because prepared learning has been defined in terms of response acquisition in spite of degraded input, it was expected that differences in resistance to extinction between skin conductance responses conditioned to potentially phobic and neutral stimuli would increase with increased interstimulus interval (ISI) and be larger with a trace than with a delay conditioning paradigm. Twelve groups with 10 subjects each were observed in a differential conditioning experiment manipulating ISI (2, 8, or 16 sec), paradigm (delay versus trace), and fear-relevance of the conditioned stimulus (potentially phobic versus neutral). The results showed highly reliable resistance to extinction of first-interval anticipatory responses to phobic stimuli, and no resistance to extinction of the corresponding responses to the neutral stimuli. This difference did not interact either with the ISI or the paradigm factor. Thus, although underscoring the reliability of the difference in conditioning to potentially phobic and neutral stimuli, the results did not support the specific hypothesis of conditioning to phobic stimuli as being less dependent on the ISI parameters than conditioning to neutral stimuli.     

Interaction of a Motor Response, and Reaction Time and Time Estimation Tasks, on Heart Rate and Skin Conductance

The influence of motor responding and typical psychophysiological tasks on heart rate was tested by manipulating motor requirements of reaction time (RT) and time estimation (TE) tasks. Thirty-four volunteers were assigned randomly to four groups. Two groups squeezed a hand dynamometer at the start of a trial and the other two groups squeezed at the finish of the trial. The force of the squeeze was also manipulated: either 3 kg (3) or 7 kg (7). The four groups were Start 3, Start 7, Finish 3, and Finish 7. All subjects participated in the TE and RT tasks. The dependent variables were measurements of forearm flexor muscle tension, heart rate and skin conductance. It was found that the manipulations of when and with what force a person squeezed the dynamometer resulted in reliable group differences in muscle tension. The magnitude of acceleratory components of the triphasic (acceleration-deceleration-acceleration) cardiac response was amplified by tension. The magnitude of the deceleratory component seemed to depend on both muscle tension and stimulus processing. Except for the magnitude of the response-bound deceleration, RT and TE produced very similar heart rate responses, and skin conductance did not differ among groups. The data were interpreted as providing evidence that motor response acts as an amplifier for the phasic HR produced by common psychological paradigms.     

Recommendations for the examination of peripheral nerve biopsies

 Peripheral nerve biopsy is now an established, valuable investigative procedure, but as it can give rise to significant residual symptoms it should only be undertaken after careful consideration of the indications and with informed consent from the patient. Nerve biopsies should only be processed and evaluated in a laboratory with the relevant particular expertise. It is generally recommended that a sural nerve biopsy be performed in combination with a muscle biopsy but not vice versa (muscle biopsies together with a nerve biopsy). Nerve biopsy is not the only means of sampling peripheral nerve tissue to study the peripheral nervous system. Examination of the innervation of the skin may be informative. The same is likely to be true for motor point muscle biopsy. Nerve biopsy is mainly used for morphology although molecular genetic techniques using fresh or archival nerve biopsies are increasingly available. Chemical analysis is undertaken mainly for research purposes. Received: 10 June 1997 / Accepted: 29 October 1997     

Effect of maximal arm exercise on skin blood flux in the paralyzed lower limbs in persons with spinal cord injury

 The purpose of the present study was to examine the effect of maximal arm exercise on the skin blood circulation of the paralyzed lower limbs in persons with spinal cord injury (PSCI). Eight male PSCI with complete lesions located between T3 and L1 performed graded maximal arm-cranking exercise (MACE) to exhaustion. The skin blood flux at the thigh (SBFT) and that at the calf (SBFC) were monitored using laser-Doppler flowmeter at rest and for 15 s immediately after the MACE. The subject's mean peak oxygen uptake and peak heart rate was 1.41 ± 0.22 l · min^–1 and 171.6 ± 19.2 beats · min^–1, respectively. No PSCI showed any increase in either SBFT or SBFC after the MACE, when compared with the values at rest. These results suggest that the blood circulation of the skin in the paralyzed lower limbs in PSCI is unaffected by the MACE. Accepted: 12 September 1996     

Electrolyte Medium Effects on Measurements of Palmar Skin Potential

Two experiments with 12 subjects each compared skin potential recordings taken simultaneously with four different electrolytes. These were polyethylene glycol, hydrated agar (at a site presoaked with water), fresh agar (i.e., not presoaked), and Unibase. The glycol controlled epidermal hydration at a minimal level, while presoaking produced a high level of hydration at the hydrated agar site. Fresh agar and Unibase represented normal recording conditions for these two electrolytes which have been recommended as “standard” for electrodermal measurements. This design permitted a comparison of two standard electrolytes with each other and with recordings from hydrated and unhydrated sites. These comparisons were made for both monophasic negative SPRs and positive SPRs and the prestimulus levels associated with each. The results replicated previous studies in showing a large effect of epidermal hydration on skin potential measurements. Recordings with agar and Unibase did not differ significantly. The effects of hydration were interpreted in terms of a reduction in the resistance of the stratum corneum and of alterations in the functioning of the dermal and epidermal membranes as a result of blockage of the sweat gland pore. In the light of this interpretation, it was suggested that both agar and Unibase substantially alter the functioning of the sweat glands under some conditions, and neither may be entirely suitable for skin potential measurements.     

84例变应性鼻炎患儿过敏原皮内试验结果分析

目的 了解新疆地区变应性鼻炎患儿气传过敏原的分布状况,探讨气传变应原分布的地区差异及产生原因,为本地区儿童变应性鼻炎的防治方案提供客观依据.方法 采用阿罗格(NHD)点刺液进行皮肤点刺试验84例变应性鼻炎患儿进行气传变应原测试.结果 84例变应性鼻炎患儿吸入变应原测试总阳性率96.4%(81例),以藜属花粉最高70.2%(59例),蒿属植物次之42.9%(36例),其后依次为杨树27.4%(23例),榆树25.0%(21例),槭树17.8%(15例),柳树11.9%(10例),豚草(巨大豚草、普通豚草)11.9%(10例),粉螨10.7%(9例),尘螨9.5%(8例),交链孢霉8.3%(7例),特异青霉7.1%(6例),白色念珠菌4.8%(4例)等.81例对不同变应原过敏,其中42例(51.9%)患儿对2种或2种以上变应原过敏.点刺试验皮肤反应强度蒿属最明显,强阳性占蒿属过敏病人的50.0%,藜属次之,强阳性占藜属过敏病人的40.7%.结论 藜属和蒿属为新疆地区变应性鼻炎患儿最主要的变应原,在治疗过程中对这类变应性鼻炎患儿可采取有效的避、忌、替、移等措施,明确变应原后对特异性免疫治疗具有重要的指导意义.     

Skin Conductance Responses to Stimulus "Energy" Decreases Following Habituation

Two experiments are reported in which a reduction in tone intensity or duration followed habituation. Experiment I, which employed 120 subjects, assessed the effects of type of stimulus change (intensity or duration) and trial of change (trial 5 or trial 22) on orienting response (OR) recovery. Experiment II employed 131 subjects, and examined the effects of reduction of stimulus intensity on trial 22 or after subjects reached a predetermined habituation criterion. Experiment I demonstrated OR reappearance following the offset of a shortened stimulus. The combined findings of Experiments I and II suggest that the effects of reducing stimulus intensity depend on when the change is made. In Experiment I, reducing stimulus intensity on trial 5 led to a significant decrease in OR magnitude. In Experiment II, increases in OR magnitude were produced by reducing stimulus intensity either after reaching a criterion or after 21 habituation trials. These findings suggest a Sokolovian view of the development of the generalization gradient of habituation. Results also revealed large individual differences in responding to the stimulus change in Experiment II. Multiple regression analyses of these data were therefore conducted, which allowed two further conclusions to be drawn: First, initial electrodermal state can be used to predict responding on the stimulus change trial. Second, with long habituation training (21 trials), the role of the initial state variables diminishes while other variables representing change over the experimental session become more prominent in predicting responding to stimulus change.     

Localized polyarteritis nodosa: cases involving the lower extremities and the breast

Summary Two patients with cutaneous polyarteritis nodosa with nodules in the lower extremities and another patient with an unusual presentation of polyarteritis nodosa involving only the arteries of the breast are reported.