The effect of emotional stressors on postoperative skin conductance indices: a prospective cohort pilot study / Efeito dos estressores emocionais nos índices de condutância cutânea no pós-operatório: estudo piloto de coorte prospectivo

Abstract Background: Skin conductance response reflects the activity of the sympathetic nervous system and is used to measure acute pain. This pilot study examines correlations of skin conductance response with emotional stressors postoperatively. Methods: The correlation of skin conductance response with pain, anxiety, nausea and intellectual task performance was analyzed in postoperative patients. Results: Significant correlations were observed between anxiety and pain during physical activity on both postoperative day 1 and 2. No significant correlations were found between skin conductance response versus mild pain, nausea, anxiety or intellectual task performance. Conclusion: This pilot study suggests that when the pain is well-controlled in the early postoperative period, skin conductance response monitoring may not be influenced by other emotional stressors.

Resumo Justificativa: A variação da condutância da pele reflete a atividade do sistema nervoso simpático e é usada para avaliar dor aguda. Este estudo piloto examinou as correlações entre a variação da condutância da pele e estressores emocionais no pós-operatório. Método: A correlação entre a variação da condutância da pele e dor, ansiedade, náusea e desempenho de tarefa intelectual foi analisada em pacientes no pós-operatório. Resultados: Correlações significantes foram observadas entre ansiedade e dor durante atividade física nos dias 1 e 2 pós-operatórios. Não foram encontradas correlações significantes entre a variação da condutância da pele e dor leve, náusea, ansiedade ou desempenho de tarefa intelectual. Conclusão: Este estudo piloto sugere que, quando a dor é bem controlada no pós-operatório inicial, o monitoramento empregando a variação da condutância da pele pode não ser influenciado por outros estressores emocionais.

Full-field electroretinogram recorded with skin electrodes in normal adults / Eletrorretinograma de campo total registrado com eletrodos de pele em adultos normais

ABSTRACT Purpose: Alternative recording methods have been tested to allow the electroretinogram (ERG) recording in uncooperative patients and/or patients with palpebral alterations, including recordings with skin electrodes. The purpose of this study was to compare ERG recorded with skin electrodes and well-established microfiber electrodes and to determine normative values of ERG parameters for recording with skin electrodes. Methods: Fifty healthy volunteers (17-26 years; mean 20.63 ± 2.01 years) participated in the study. A gold disk skin electrode was placed on the lower orbital rim of a randomly chosen eye. On the contralateral eye, a microfiber electrode was positioned in the lower conjunctival sac. Gold disc electrodes were positioned at the ipsilateral outer canthus of both eyes acting as reference electrodes for the creation of a potential difference. Two ground electrodes were placed on the lobe of each ear. ERGs were recorded according to the International Society of Clinical Electrophysiology Visual (ISCEV) protocol using the VERIS 5.1.9 system for data acquisition and analysis. Results: Both types of electrodes showed similar wave response morphologies. The implicit time of responses between the two electrodes was comparable. On peak-to-peak amplitude, skin electrode recordings showed an amplitude reduction of 61.4% for rod responses, 61.5% for maximal responses, 46.2% for oscillatory potentials, 57.4% for cone responses, and 54.4% for 30Hz-flicker responses, when compared with microfiber electrode recordings. Based on these findings, normative values for peak-to-peak amplitude and implicit time to be used as a reference for ERGs recorded with skin electrodes were determined. Conclusions: ERGs recorded with skin electrodes presented lower peak-to-peak amplitude compared with microfiber electrodes. However, using appropriate normative values, skin electrodes may be useful for specific target populations such as uncooperative infants and/or patients with ocular surface alterations.

RESUMO Objetivo: O eletrorretinograma de campo total (ERG) em pacientes não colaborativos e/ou com alterações palpebrais pode ser registrado com diferentes métodos de captação de respostas, dentre eles os eletrodos de pele. O objetivo deste estudo foi comparar o eletroretinograma obtido com eletrodos de pele e eletrodos de microfibra, determinando valores normativos para os parâmetros registrados com eletrodos de pele. Métodos: Cinquenta voluntários saudáveis (17-26 anos; média 20,63 ± 2,01) participaram deste estudo. Um eletrodo de cúpula de ouro foi aderido à pele na margem orbital inferior de um dos olhos escolhido ao acaso. No olho contralateral, um eletrodo de microfibra foi posicionado no saco conjuntival inferior. Eletrodos de cúpula de ouro foram posicionados na região lateral de cada olho para a formação da diferença de potencial com o eletrodo ativo. Dois eletrodos terra foram posicionados no lobo de cada orelha. O eletrorretinograma foi registrado de acordo com o protocolo da ISCEV (Sociedade Internacional de Eletrofisiologia Visual), com o sistema VERIS 5.1.9 para aquisição e análise dos registros. Resultados: Os dois tipos de eletrodos apresentaram morfologias de onda similares. O tempo implícito das respostas foi comparável entre os dois tipos de eletrodo. Os registros feitos com eletrodo de pele quando comparados aos registros com eletrodos de microfibra mostraram reduções na amplitude das ondas, de 61,4% para resposta de bastonetes, 61,5% para resposta máxima, 46,2% para potenciais oscilatórios, 57,4% para resposta de cones, e 54,4% para flicker 30Hz. Baseado nestes resultados, foram determinados valores normativos para amplitude e tempo de implícito para ERGs obtidos com eletrodos de pele. Conclusões: ERGs registrados com eletrodos de pele apresentam respostas com amplitudes menores quando comparados aos registrados com eletrodos de microfibra. No entanto, usando valores normativos apropriados, os eletrodos de pele podem ser uma alternativa útil para populações especificas como pacientes não colaborativos e/ou com alterações palpebrais.

Potencial evocado miogenico vestibular (VEMP) com estimulo galvanico em individuos normais / Vestibular evoked myogenic potential (VEMP) with galvanic stimulation in normal subjects

Introdução: O potencial evocado miogênico vestibular (VEMP) gerado por estimulação galvânica (GVS) reflete uma resposta vestíbulo-espinhal. A resposta obtida no músculo sóleo é bifásica, primeiro com componente de curta latência (CL), em torno de 60 ms, e depois com o de média latência (ML), em torno de 100 ms. O componente de CL associa-se à função otolítica (sáculo e utrículo), e o de ML, aos ductos semicirculares. Objetivo: Descrever os valores de referência do VEMP com estimulação galvânica em indivíduos normais. Casuística e método: Forma de estudo transversal; o VEMP foi gerado por GVS de 2mA/400 ms, aplicada bilateralmente, sob frequência de 5-6 ms. Testou-se resposta no músculo sóleo de 13 sujeitos saudáveis, com idade média de 56 anos. Os sujeitos permaneceram de pé, com cabeça girada contralateral ao GVS aplicado na mastoide. Na configuração catodo direito, anodo esquerda, 30 GVS foi aplicado, seguidos de mais 30 com configuração inversa. Os componentes de CL e de ML da resposta vestibular foram analisados. Resultado: Os componentes de CL e de ML foram semelhantes em ambas as pernas. O valor médio de CL foi 54 ms, e o de ML, 112 ms. Conclusão: Os componentes de CL e de ML do VEMP solear foram replicáveis, sendo medidas úteis de função do trato vestíbulo-espinhal. .

Introduction: The vestibular evoked myogenic potential (VEMP) generated by galvanic vestibular stimulation (GVS) is related to the vestibulo-spinal pathway. The response recorded from soleus muscle is biphasic with onset of short latency (SL) component around 60 ms and medium latency (ML) component around 100 ms. The first component reflects otolith function (sacule and utricle) and the last deals with semicircular canals. Aim: To describe VEMP generated by GVS. Methods: In this cross-sectional clinical study, VEMP was generated by 2mA/400 ms binaural GVS, frequency of 5-6 ms that was recorded from soleus muscles of 13 healthy adults, mean age 56 years. The subjects remained standing, head turned contralateral to the GVS applied to the mastoid. Thirty GVS were applied to the mastoid in the position cathode right anode left, followed by 30 in inverted position. SL and ML were measured. Results: SL and ML components were recorded from both legs of all participants and were similar. The average of SL component was 54 ms and of ML was 112 ms. Conclusion: The components SL and ML of the VEMP response in soleus were reproducible and are useful measures of vestibular-spinal function. .

Galvanic vestibular stimulation: a novel modulatory countermeasure for vestibular-associated movement disorders / Estimulacao galvanica vestibular para corrigir transtornos neurologicos associados a disfuncao vestibular

Motion sickness or kinetosis is the result of the abnormal neural output originated by visual, proprioceptive and vestibular mismatch, which reverses once the dysfunctional sensory information becomes coherent. The space adaptation syndrome or space sickness relates to motion sickness; it is considered to be due to yaw, pith, and roll coordinates mismatch. Several behavioural and pharmacological measures have been proposed to control these vestibular-associated movement disorders with no success. Galvanic vestibular stimulation has the potential of up-regulating disturbed sensory-motor mismatch originated by kinetosis and space sickness by modulating the GABA-related ion channels neural transmission in the inner ear. It improves the signal-to-noise ratio of the afferent proprioceptive volleys, which would ultimately modulate the motor output restoring the disordered gait, balance and human locomotion due to kinetosis, as well as the spatial disorientation generated by gravity transition.

A cinetose ou doença do movimento resulta de uma resposta neural anormal originada do desequilíbrio entre estímulos visuais, proprioceptivos e vestibulares, que melhora quando esse desequilíbrio é corrigido. A síndrome de adaptação espacial ou doença do espaço está relacionada à doença do movimento e é desencadeada por mudanças bruscas de direção, inclinação e rotação da cabeça. Têm sido propostas várias medidas comportamentais e farmacológicas para controlar esses transtornos do movimento associados com o sistema vestibular, mas sem sucesso. A estimulação galvânica vestibular pode regular o desequilíbrio sensitivo-motor causado pela cinetose e pela doença do espaço modulando os canais iônicos GABA, relacionados à transmissão de impulsos nervosos no ouvido interno. Essa estimulação melhora a relação sinal-ruído dos impulsos proprioceptivos que acabam modulando a resposta motora, restabelecendo o equilíbrio e a marcha, recuperando a desorientação espacial causada pelos diversos gradientes de gravidade.

Habituation of the eyeblink response in humans with stimuli presented in a sequence of incremental intensity

In an experiment we examined whether the repeated presentation of tones of gradually increasing intensities produces greater decrement in the eyeblink reflex response in humans than the repetition of tones of constant intensities. Two groups of participants matched for their initial level of response were exposed to 110 tones of 100-ms duration. For the participants in the incremental group, the tones increased from 60- to 90- dB in 3-dB steps, whereas participants in the constant group received the tones at a fixed 90-dB intensity. The results indicated that the level of response in the last block of 10 trials, in which both groups received 90-dB tones, was significantly lower in the incremental group than in the constant group. These findings support the data presented by Davis and Wagner (7) with the acoustic response in rats, but differ from several reports with autonomic responses in humans, where the advantage of the incremental condition has not been observed unambiguously. The discussion analyzes theoretical approaches to this phenomenon and the possible involvement of separate neural circuits.

Proton magnetic resonance spectroscopy of the frontal, cingulate and perirolandic cortices and its relationship to skin conductance in patients with schizophrenia

The aim of the present study was to determine whether specific subgroups of schizophrenic patients, grouped according to electrodermal characteristics, show differences in the N-acetylaspartate/creatine plus choline (NAA / (Cr + Cho)) ratios in the frontal, cingulate and perirolandic cortices. Skin conductance levels (SCL) and skin conductance responses to auditory stimulation were measured in 38 patients with schizophrenia and in the same number of matched healthy volunteers (control). All subjects were submitted to multivoxel proton magnetic resonance spectroscopic imaging. When compared to the control group, patients presented significantly lower NAA / (Cr + Cho) ratios in the right dorsolateral prefrontal cortex (schizophrenia = 0.95 ± 0.03; control = 1.12 ± 0.04) and in the right (schizophrenia = 0.88 ± 0.02; control = 0.94 ± 0.03) and left (schizophrenia = 0.84 ± 0.03; control = 0.94 ± 0.03) cingulates. These ratios did not differ between electrodermally responsive and non-responsive patients. When patients were divided into two groups: lower SCL (less than the mean SCL of the control group minus two standard deviations) and normal SCL (similar to the control group), the subgroup with a lower level of SCL showed a lower NAA / (Cr + Cho) ratio in the left cingulate (0.78 ± 0.05) than the controls (0.95 ± 0.02, P < 0.05) and the subgroup with normal SCL (0.88 ± 0.03, P < 0.05). There was a negative correlation between the NAA / (Cr + Cho) ratio in the left cingulate of patients with schizophrenia and the duration of the disease and years under medication. These data suggest the existence of a schizophrenic subgroup characterized by low SCL that could be a consequence of the lower neuronal viability observed in the left cingulate of these patients.

Assessment of computer game as a psychological stressor.

To simulate the effects of acute psychological stress, the effects of stressful computer game in young adult subjects were assessed by various physiological, psychological and biochemical parameters. The results showed a significant increase in the physiological and psychological markers of stress. It is concluded from these results that computer game can be used as an acute laboratory psychological stressor for future studies on physiological effects of stress.

Sympathetic skin responses in hemiplegic patients with and without complex regional pain syndrome.

BACKGROUND AND AIMS: To investigate whether there were changes in the sympathetic skin responses (SSR) in the limbs with complex regional pain syndrome (CRPS) type I in hemiplegic patients. SETTING: A physical medicine and rehabilitation center in Turkey. MATERIALS AND METHODS: Sympathetic skin responses were evaluated in 69 stroke patients (41 with CRPS and 28 without CRPS) and 20 healthy volunteers. SSR were recorded on the paretic and healthy hands after stimulation of the ipsilateral median nerve. Patients' ages ranged from 33 to 77 years, with a mean of 60.0+/-12.9 years. RESULTS: The SSR were obtained in all patients with CRPS, whereas SSR was absent in 9 of 28 patients with hemiplegia who did not have CRPS after stimulation of the plegic side and the difference was statistically significant (P=0.023). SSR amplitudes were increased at the hemiplegic limbs in patients affected by CRPS compared to individuals unaffected; this group difference was statistically significant (P=0.014). The mean amplitude of the SSR in the advanced stage of CRPS was greater than lower stage and the difference was statistically significant (P=0.035). CONCLUSION: Our results suggest that SSR can be obtained in stroke patients with CRPS even in the early stages of CRPS. SSR acquirability and amplitude increase as the stage of the disease advances. As an electrophysiologic technique, SSR may be used in the evaluation of the sympathetic function in hemiplegic patients and also in the diagnosis of CRPS and in monitoring of its treatment.

Influence of alternate nostril breathing on cardiorespiratory and autonomic functions in healthy young adults.

Alternate nostril breathing (ANB) may modulate cardio-respiratory and autonomic functions. However, the studies are scarce and results highly conflicting. The present study was conducted in healthy young volunteers comprising of males (n=20) and females (n=20) in range of 17-22 years. In both groups respiratory rate (RR/min), heart rate (HR/ min), systolic blood pressure (SBP; mm Hg), diastolic blood pressure (DBP; mm Hg), peak expiratory flow rate (PEFR; L/min) and galvanic skin resistance (GSR; microV) were recorded thrice; once as control and then after 15 min (acute exposure) and following 8 wks of training in ANB (15 min daily). In males the control RR was 16.60 +/- 2.01, HR 75.75 +/- 11.07, SBP-115.9 +/- 7.33, DBP 70.4 +/- 6.28 and PEFR 550.00 +/- 51.50. After 15 min of ANB-RR (14.75 +/- 1.41, P<0.001), HR (68.45 +/- 12.41, P<0.01) and SBP (113.6 +/- 6.04, P<0.05) fell significantly. After 8 wks of ANB training RR (12.35 +/- 1.35, P<0.0001), HR (63.20 +/- 11.11, P<0.001), SBP (109.5 +/- 5.61, P<0.001), declined to much greater extent and PEFR (571.50 +/- 46.26, P<0.01) rose significantly. In females the control RR was 17.25 +/- 1.89, HR-74.90 +/- 12.85, SBP-106.70 +/- 6.91, DBP-68.70 +/- 5.52 and PEFR-394.50 +/- 44.89. After 15 min of ANB RR (15.05 +/- 1.54, P<0.001) and HR (64.75 +/- 9.80, P<0.001) showed significant decline with concomitant rise in PEFR (407.00 +/- 2.31, P<0.05). Following 8 wks training the decrement in RR (12.60 +/-1.50, P<0.0001) and HR (63.30 +/- 8.65, P<0.001) was maintained. SBP (103.10 +/- 4.92, P<0.001) and DBP (65.8 +/- 5.54, P<0.001) decreased further and PEFR (421.00 +/- 38.51 P<0.001) rose, GSR was unaffected by ANB in both males and females. These results suggest that in general there is a tilt towards parasympathetic dominance by alternate nostril breathing. This breathing may be a useful adjuvant to medical therapy of hypertension and COPD.

The effects of right and left nostril breathing on cardiorespiratory and autonomic parameters.

The responses of right nostril breathing (RNB) and left nostril breathing (LNB) on cardio-respiratory and autonomic functions were investigated in healthy student volunteers of both sexes. The RNB and LNB groups comprised of 10 males and 10 females in each in age range of 17-22 years. Initially, in both groups control values of respiratory rate (RR), heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBF), peak expiratory flow rate (PEFR) and galvanic skin resistance (GSR) were recorded. The same parameters were recorded after 15 min (acute exposure) and 8 wks of training in RNB and LNB. In males RR (P<0.0001), SBP (P<0.05) and DBF (P<.05) fell significantly after 15 min of RNB. After 8 wks training in RNB, HR (P<0.01) decreased, SBP (P<0.001) declined more profoundly and RR (P<0.0001) and DBP (P<0.05) decrement was maintained. After 15 min of LNB, RR (P<0.01), HR (P<0.01), SBP (P<0.001) and DBP (P<0.01) declined significantly, on 8 wks training, RR (P<0.0001) and HR (P<0.001) decreased further, the decrement in SBP (P<0.001) and DBP (P<0.01) was the same. In females, RR alone fell significantly (P<0.05) after 15 min RNB. After 8 wks RR decrement was more profound (P<0.0001) and DBP also declined significantly (P<0.01). Similarly, 15 min LNB resulted in significant reduction in RR (P<0.001) and HR (P<0.05) only. Following 8 wks, of training in LNB, in addition to RR (P<0.0001) and HR (P<0.05) decrement, SBP (P<0.01) and DBP (P<0.05) also fell significantly. Both in males and females, GSR did not change significantly (P>0.05) either after RNB or LNB (15 min/8 wks). PEFR rose significantly (P<0.05) only in females after 8 wks of LNB. The results suggest that there are no sharp distinctions between effects of RNB and LNB either acute exposure (15 min) or after training (8 wks). However, there is a general parasympathetic dominance evoked by both these breathing patterns.

Effects of sirsasana (headstand) practice on autonomic and respiratory variables.

The present study had two aims: (1) To assess heart rate variability (HRV) along with non-specific autonomic measures (used in earlier studies), before and after two minutes of the head stand. (2) To compare changes in two categories of subjects, i.e., those who practiced the headstand in a traditional way (without any support) and those who used the support of the wall (a present day adaptation). The subjects were forty male volunteers (age range 19 to 36 years), with twenty subjects under each category. The following changes were significant after the practice, compared to values at baseline. (i) Both categories had an increase in the power of the low frequency component (LF) and a decrease in the high frequency component (HF) of the HRV spectrum, increased LF/HF ratio, and decreased heart rate. (ii) Subjects who practiced the head stand with the support of a wall showed reduced finger plethysmogram amplitude suggesting increased sympathetic vasomotor tone. (iii) Practicing the headstand without support was associated with an increase in the skin conductance level, suggestive of increased sympathetic sudomotor tone. Hence, both categories showed similar changes in the HRV components though changes in sympathetic vasomotor and sudomotor activity were different. These changes suggest sympathetic activation, irrespective of the method of practice.

Alteraçöes eletrodérmicas na esquizofrenia / Electrodermal abnormalities in schizophrenia

A atividade eletrodérmica tem sido, desde há muito tempo, foco de interesse dos pesquisadores no campo da esquizofrenia, devido a sua provável relaçäo com processos que säo considerados disfuncionais na esquizofrenia, como atençäo, processamento de informaçöes e emoçäo. O objetivo principal do presente trabalho foi fazer revisäo crítica da literatura sobre alteraçöes eletrodérmicas na esquizofrenia. Enfatizam-se as questöes metodológicas e as correlaçöes , com perfil de sintomas, desempenho neuropsicológico e imagem cerebral. A revisäo feita evidencia que os pacientes esquizofrênicos apresentam anormalidades na condutância da pele, incluindo maior incidência de hiporresponsividade eletrodérmica e habituaçäo mais lenta em resposta à apresentaçäo de estímulos neutros. Após discussäo destas questöes, os autores propöem encaminhamento para futuras pesquisas

Autonomic changes while mentally repeating two syllables--one meaningful and the other neutral.

Autonomic and respiratory variables were recorded in 12 volunteers in three types of sessions (1). Before, during and after a test period of mentally repeating a meaningful syllable 'OM' (MOM session) (2). A similar session except that the test period was spent mentally repeating a neutral work, 'one' (COM session) (3). A session with non-targeted thinking (NT session). The subjects were familiar with both syllables, and had been meditating on 'OM' for 20 days. During the test periods of both MOM and COM sessions the rate of respiration (RR) and heart rate (HR) decreased significantly [(two factor ANOVA (RR), paired t test (RR. HR)]. Compared to the pre period. Mental repetition of 'OM' (but not 'one') caused a significant decrease in skin resistance level (SRL) (paired t test). This was taken to mean that the subject recognized the significance of the syllable. No significant change occurred during NT sessions.

Sympathetic skin response and cardiovascular autonomic function tests in Parkinson's disease

Autonomic dysfunction commonly occurs in Parkinson's disease, but the pathogenesis of autonomic dysregulation remains uncertain. Autonomic functions regulating the cardiovascular system have been investigated in Parkinson's disease, but those involving the extremities has not been well demonstrated. To compare autonomic dysfunctions of the cardiovascular system with those of the extremities, we performed sympathetic skin response (SSR) and cardiovascular autonomic function tests (CAFT) - 30:15 ratio, E:I ratio, Valsalva ratio, isometric exercise test (IET) - in 37 patients with Parkinson's disease and 33 age- and sex-matched healthy controls. The patients were asked to stop antiparkinsonian medications for at least 12 hours prior to the tests. SSR was measured at the right hand and foot after electrical stimulation of the right median and posterior tibial nerves. Absent SSR at either one or both extremities and CAFT beyond normal ranges were regarded as abnormal. Abnormal SSR was observed in 59% of patients, while abnormal CAFT were found in the range of 32%-81%. Patients with abnormal SSR showed more frequent and severe CAFT abnormalities than did patients with normal SSR. Among the CAFT, IET was well correlated with the SSR. The results suggest that parkinsonian sympathetic dysfunction involving either the cardiovascular system or the extremities may have the same pathophysiology.

Método para el estudio de la resistencia eléctrica de la piel en ratas / Method for studying the electrical resistance of skin in rats

Se propone un método que permite estudiar el reflejo cutáneo galvánico en animales con el fin de analizar los diferentes factores que intervienen en su génesis. Para ello se estudiaron 3 grupos de ratas, las cuales fueron inyectadas con adrenalina, privadas de sueño MOR por 48 horas, y privadas de alimento y agua por 48 horas. Se midieron los valores de resistencia eléctrica de la piel con el método propuesto y se sometieron a pruebas estadísticas, con el objetivo de corroborar la utilidad del método

Influence of respiration on human sympathetic skin response.

Sympathetic skin response (SSR) is a reflexly elicited potential of the sweat glands, the afferent and efferent fibres of the reflex are cutaneous sensory fibres (if the SSR is elicited by electrical stimulus) and sympathetic sudomotor fibres respectively. Our earlier study indicated that latency, besides duration and amplitude, of SSR of a given normal individual showed significant variations between many trials of stimulation, even in a single sitting. Since deep inspiration is also an effective stimulus to elicite SSR, the present study was conducted to assess the influence of respiration on SSR. Thirty-four healthy students participated in the study. The skin of the forearm of the dominant hand was stimulated by electrical square pulse and SSR was recorded from the ipsilateral hand. SSR was elicited and recorded in each subject during the various phases of respiration, namely, end expiration (EE), end inspiration (EI), mid expiration (ME) and mid inspiration (MI). It was observed that the mean values of SSR latency during these respiratory phases (EE : 1.59, EI: 1.51, ME : 1.55, and MI: 1.56 sec) were similar, indicating that the normal respiration might not be responsible for the observed interstimulation variations in latency in any given individual.

Svara (nostril dominance) and bilateral volar GSR.

The Svara yoga concept of Ida, Pingala and Susumna svara representing rest, active and turbulent states was examined in this study by recording nostril dominance (svara) and bilateral volar GSR (galvanic skin resistance) as an indicator of sympathetic activity under field and laboratory conditions. The sympathetic activity was low in Ida svara, followed by Pingala svara and was maximum in Susumna svara group of subjects under both field and laboratory conditions which agreed with the traditional Svara yoga description. The volar GSR on the right side more readily varied with svara, particularly so in the physically relaxed subjects of laboratory condition than the left volar GSR. The latter observation was worth noting because the subjects were right handed. The right side could be recommended as the standard site for recording volar GSR to closely reflect the sympathetic activity, particularly so when physical rest was given to subjects.

Autonomic changes during "OM" meditation.

The autonomic and respiratory variables were studied in seven experienced meditators (with experience ranging from 5 to 20 years). Each subject was studied in two types of sessions--meditation (with a period of mental chanting of "OM") and control (with a period of non-targetted thinking). The meditators showed a statistically significant reduction in heart rate during meditation compared to the control period (paired 't' test). During both types of sessions there was a comparable increase in the cutaneous peripheral vascular resistance. Keeping in mind similar results of other authors, this was interpreted as a sign of increased mental alertness, even while being physiologically relaxed (as shown by the reduced heart rate).

Effect of Sahaja yoga practice on stress management in patients of epilepsy.

An attempt was made to evaluate the effect of Sahaja yoga meditation in stress management in patients of epilepsy. The study was carried out on 32 patients of epilepsy who were rendomly divided into 3 groups: group I subjects practised Sahaja yoga meditation for 6 months, group II subjects practised postural exercises mimicking Sahaja yoga and group III served as the epileptic control group. Galvanic skin resistance (GSR), blood lactate and urinary vinyl mandelic acid (U-VMA) were recorded at 0, 3 and 6 months. There were significant changes at 3 & 6 months as compared to 0 month values in GSR, blood lactate and U-VMA levels in group I subjects, but not in group II and group III subjects. The results indicate that reduction in stress following Sahaja yoga practice may be responsible for clinical improvement which had been earlier reported in patients who practised Sahaja yoga.