Effect of ketamine on the limb withdrawal reflex evoked by transcutaneous electrical stimulation in ponies anaesthetised with isoflurane

The purpose of this study was to evaluate the anti-nociceptive activity of ketamine and isoflurane in horses using a limb withdrawal reflex (WR) model. Single and repeated stimulations were applied to the digital nerve of the left forelimb in ponies anaesthetised with isoflurane before, during and after intravenous administration of racemic ketamine. Surface electromyographic activity was recorded from the deltoid muscle. Higher stimulation intensity was required to evoke a reflex during ketamine administration. Furthermore, the amplitudes of response to stimulations were significantly and dose-dependently depressed and a flattening of the stimulus-response curves was observed. The reflex activity recovered partially once the ketamine infusion finished. The results demonstrated that the limb WR can be used to quantify the temporal effect of ketamine on the sensory-motor processing in ponies anaesthetised with isoflurane.

The effects of isoflurane minimum alveolar concentration on withdrawal reflex activity evoked by repeated transcutaneous electrical stimulation in ponies

The aim of this study was to quantify the effects of isoflurane at approximately the minimum alveolar concentration (peri-MAC) on the temporal summation (TS) of reflex activity in ponies. TS was evoked by repeated electrical stimulations applied at 5 Hz for 2 s on the digital nerve of the left forelimb of seven ponies. Surface electromyographic activity was recorded from the deltoid and common digital extensor muscles. TS thresholds and amplitude of response to stimulations of increasing intensities were assessed during anaesthesia at 0.85, 0.95 and 1.05 times the individual MAC, and after anaesthesia in standing animals. Under isoflurane anaesthesia, TS thresholds increased significantly in a concentration-dependent fashion and at each isoflurane MAC, the responses increased significantly for increasing stimulation intensities. A concentration-dependent depression of evoked reflexes with a reduction in the slopes of the stimulus-response function was observed for both muscles. The results demonstrated that with this model it is possible to describe and quantify the effects of anaesthetics on spinal sensory-motor processing in ponies.

Evaluation of administration of isoflurane at approximately the minimum alveolar concentration on depression of a nociceptive withdrawal reflex evoked by transcutaneous electrical stimulation in ponies

OBJECTIVE: To investigate effects of isoflurane at approximately the minimum alveolar concentration (MAC) on the nociceptive withdrawal reflex (NWR) of the forelimb of ponies as a method for quantifying anesthetic potency. ANIMALS: 7 healthy adult Shetland ponies. PROCEDURE: Individual MAC (iMAC) for isoflurane was determined for each pony. Then, effects of isoflurane administered at 0.85, 0.95, and 1.05 iMAC on the NWR were assessed. At each concentration, the NWR threshold was defined electromyographically for the common digital extensor and deltoid muscles by stimulating the digital nerve; additional electrical stimulations (3, 5, 10, 20, 30, and 40 mA) were delivered, and the evoked activity was recorded and analyzed. After the end of anesthesia, the NWR threshold was assessed in standing ponies. RESULTS: Mean +/- SD MAC of isoflurane was 1.0 +/- 0.2%. The NWR thresholds for both muscles increased significantly in a concentration-dependent manner during anesthesia, whereas they decreased in awake ponies. Significantly higher thresholds were found for the deltoid muscle, compared with thresholds for the common digital extensor muscle, in anesthetized ponies. At each iMAC tested, amplitudes of the reflex responses from both muscles increased as stimulus intensities increased from 3 to 40 mA. A concentration-dependent depression of evoked reflexes with reduction in slopes of the stimulus-response functions was detected. CONCLUSIONS AND CLINICAL RELEVANCE: Anesthetic-induced changes in sensory-motor processing in ponies anesthetized with isoflurane at concentrations of approximately 1.0 MAC can be detected by assessment of NWR. This method will permit comparison of effects of inhaled anesthetics or anesthetic combinations on spinal processing in equids.

"It was hard to come to mutual understanding..." - Multidimensionality of social learning processes in natural resource use in India, Africa and Latin America

Sustainable natural resource use requires that multiple actors reassess their situation in a systemic perspective. This can be conceptualised as a social learning process between actors from rural communities and the experts from outside organisations. A specifically designed workshop oriented towards a systemic view of natural resource use and the enhancement of mutual learning between local and external actors, provided the background for evaluating the potentials and constraints of intensified social learning processes. Case studies in rural communities in India, Bolivia, Peru and Mali showed that changes in the narratives of the participants of the workshop followed a similar temporal sequence relatively independently from their specific contexts. Social learning processes were found to be more likely to be successful if they 1) opened new space for communicative action, allowing for an intersubjective re-definition of the present situation, 2) contributed to rebalance the relationships between social capital and social, emotional and cognitive competencies within and between local and external actors.

Effects of butorphanol on the withdrawal reflex using threshold, suprathreshold and repeated subthreshold electrical stimuli in conscious horses

OBJECTIVE: To assess the effects of a single intravenous dose of butorphanol (0.1 mg kg(-1)) on the nociceptive withdrawal reflex (NWR) using threshold, suprathreshold and repeated subthreshold electrical stimuli in conscious horses. STUDY DESIGN: 'Unblinded', prospective experimental study. ANIMALS: Ten adult horses, five geldings and five mares, mean body mass 517 kg (range 487-569 kg). METHODS: The NWR was elicited using single transcutaneous electrical stimulation of the palmar digital nerve. Repeated stimulations were applied to evoke temporal summation. Surface electromyography was performed to record and quantify the responses of the common digital extensor muscle to stimulation and behavioural reactions were scored. Before butorphanol administration and at fixed time points up to 2 hours after injection, baseline threshold intensities for NWR and temporal summation were defined and single suprathreshold stimulations applied. Friedman repeated-measures analysis of variance on ranks and Wilcoxon signed-rank test were used with the Student-Newman-Keul's method applied post-hoc. The level of significance (alpha) was set at 0.05. RESULTS: Butorphanol did not modify either the thresholds for NWR and temporal summation or the reaction scores, but the difference between suprathreshold and threshold reflex amplitudes was reduced when single stimulation was applied. Upon repeated stimulation after butorphanol administration, a significant decrease in the relative amplitude was calculated for both the 30-80 and the 80-200 millisecond intervals after each stimulus, and for the whole post-stimulation interval in the right thoracic limb. In the left thoracic limb a decrease in the relative amplitude was found only in the 30-80 millisecond epoch. CONCLUSION: Butorphanol at 0.1 mg kg(-1) has no direct action on spinal Adelta nociceptive activity but may have some supraspinal effects that reduce the gain of the nociceptive system. CLINICAL RELEVANCE: Butorphanol has minimal effect on sharp immediate Adelta-mediated pain but may alter spinal processing and decrease the delayed sensations of pain.

Electrical neuroimaging in the time domain

A publication entitled “A default mode of brain function” initiated a new way of looking at functional imaging data. In this PET study the authors discussed the often-observed consistent decrease of brain activation in a variety of tasks as compared with the baseline. They suggested that this deactivation is due to a task-induced suspension of a default mode of brain function that is active during rest, i.e. that there exists intrinsic well-organized brain activity during rest in several distinct brain regions. This suggestion led to a large number of imaging studies on the resting state of the brain and to the conclusion that the study of this intrinsic activity is crucial for understanding how the brain works. The fact that the brain is active during rest has been well known from a variety of EEG recordings for a very long time. Different states of the brain in the sleep–wake continuum are characterized by typical patterns of spontaneous oscillations in different frequency ranges and in different brain regions. Best studied are the evolving states during the different sleep stages, but characteristic EEG oscillation patterns have also been well described during awake periods (see Chapter 1 for details). A highly recommended comprehensive review on the brain's default state defined by oscillatory electrical brain activities is provided in the recent book by György Buzsaki, showing how these states can be measured by electrophysiological procedures at the global brain level as well as at the local cellular level.

Brain electrical microstates in subjects with panic disorder

Brain electrical microstates represent spatial configurations of scalp recorded brain electrical activity and are considered to be the basic elements of stepwise processing of information in the brain. In the present study, the hypothesis of a temporo-limbic dysfunction in panic disorder (PD) was tested by investigating the topographic descriptors of brain microstates, in particular the one corresponding to the Late Positive Complex (LPC), an event-related potential (ERP) component with generators in these regions. ERPs were recorded in PD patients and matched healthy subjects during a target detection task, in a central (CC) and a lateral condition (LC). In the CC, a leftward shift of the LPC microstate positive centroid was observed in the patients with PD versus the healthy control subjects. In the LC, the topographic descriptor of the first microstate showed a rightward shift, while those of both the second and the fourth microstate, corresponding to the LPC, revealed a leftward shift in the PD patients versus the healthy control subjects. These findings indicate an overactivation of the right hemisphere networks involved in early visual processing and a hypoactivation of the right hemisphere circuits involved in LPC generators in PD. In line with this interpretation, the abnormal topography of the LPC microstate, observed in the CC, was associated with a worse performance on a test exploring right temporo-hippocampal functioning. Topographical abnormalities found for the LPC microstate in the LC were associated with a higher number of panic attacks, suggesting a pathogenetic role of the right temporo-hippocampal dysfunction in PD.

Association of congenital, diffuse electrical disease in children with normal heart: sick sinus syndrome, intraventricular conduction block, and monomorphic ventricular tachycardia.

INTRODUCTION Rhythm disturbances in children with structurally normal hearts are usually associated with abnormalities in cardiac ion channels. The phenotypic expression of these abnormalities ("channelopathies") includes: long and short QT syndromes, Brugada syndrome, congenital sick sinus syndrome, catecholaminergic polymorphic ventricular tachycardia, Lènegre-Lev disease, and/or different degrees of cardiac conduction disease. METHODS The study group consisted of three male patients with sick sinus syndrome, intraventricular conduction disease, and monomorphic sustained ventricular tachycardia. Clinical data and results of electrocardiography, Holter monitoring, electrophysiology, and echocardiography are described. RESULTS In all patients, the ECG during sinus rhythm showed right bundle branch block and long QT intervals. First-degree AV block was documented in two subjects, and J point elevation in one. A pacemaker was implanted in all cases due to symptomatic bradycardia (sick sinus syndrome). Atrial tachyarryhthmias were observed in two patients. The common characteristic ventricular arrhythmia was a monomorphic sustained ventricular tachycardia, inducible with ventricular stimulation and sensitive to lidocaine. In one patient, radiofrequency catheter ablation was successfully performed. No structural abnormalities were found in echocardiography in the study group. CONCLUSION Common clinical and ECG features suggest a common pathophysiology in this group of patients with congenital severe electrical disease.

Theories of Militancy in Practice: Explanations of Muslim Terrorism in India

This article analyzes the interaction between theories of radicalization and state responses to militancy in India. Focusing on the interpretation of the increased frequency of terrorist attacks in Indian metropolises in the last decade, the article examines the narratives surrounding those classified as terrorists in the context of rising Muslim militancy in the country. Different state agencies operate with different theories about the links between processes of radicalization and terrorist violence. The scenarios of radicalization underlying legislative efforts to prevent terrorism, the construction of motives by the police, and the interpretation of violence by the judiciary all rely on assumptions about radicalization and violence. Such narratives are used to explain terrorism both to security agencies and to the public; they inform the categories and scenarios of prevention. Prevention relies on detection of future deeds, planning, intentions, and even potential intentions. "Detection" of potential intentions relies on assumptions about specific dispositions. Identification of such dispositions in turn relies on the context-specific theories of the causes of militancy. These determine what "characteristics" of individuals or groups indicate potential threats and form the basis for their categorization as "potentially dangerous." The article explores the cultural contexts of theories of radicalization, focusing on how they are framed by societal understandings of the causes of deviance and the relation between the individual and society emerging in contemporary India. It examines the shift in the perception of threat and the categories of "dangerous others" from a focus on role to a focus on ascriptive identity.