10 research outputs found
Everyday Diplomacy: UKUSA Intelligence Cooperation and Geopolitical Assemblages
This article offers an alternative to civilizational thinking in geopolitics and international relations predicated on assemblage theory. Building on literature in political geography and elsewhere about everyday practices that produce state effects, this article theorizes the existence of transnational geopolitical assemblages that incorporate foreign policy apparatuses of multiple states. Everyday material and discursive circulations make up these assemblages, serving as conduits of affect that produce an emergent agency. To demonstrate this claim, I outline a genealogy of the UKUSA alliance, an assemblage of intelligence communities in the United States, United Kingdom, Canada, Australia, and New Zealand. I then trace the circulation of materialities and affectsâat the scales of individual subjects, technological systems of mediation, and transnational processes of foreign policy formation. In doing so, I offer a bottom-up process of assemblage that produces the emergent phenomena that proponents of civilizational thinking mistakenly attribute to macroscaled factors, such as culture
Investigating the potential role of arousal in multisensory hypersensitivity
Recent studies have shown that experimentally induced long-lasting sensitization of nociceptive pathways in healthy human volunteers not only leads to the typically-observed hypersensitivity to mechanical pinprick stimuli, but also to an enhanced processing of non-nociceptive stimuli, as shown by amplitude increases in the cortical responses to visual and vibrotactile stimuli presented on a sensitized as compared to a non-sensitized body part. These latter effects have been hypothesized to share similarities with the hypersensitivity to a plethora of sensory stimuli that has been reported for some chronic pain conditions, such as fibromyalgia. However, to date, the mechanisms leading to such multisensory hypersensitivity remain unexplained, since they cannot be accounted for by the spinal mechanisms that increase pain perception after sensitization. We will present a study protocol that investigates whether increased arousal, triggered by the intense stimulation of the nociceptors, may be a potential underlying mechanism of both nociceptive and non-nociceptive hypersensitivity. In a between-subject design, we will use two different sensitization procedures (burst vs. continuous electrical stimulation applied on the arm during two minutes) in healthy participants and investigate 1) whether burst stimulation, which typically leads to higher nociceptive hypersensitivity, is also associated with higher arousal than continuous stimulation, by testing differences in mechanical pinprick sensitivity and arousal, measured as skin conductance level (SCL) before, during and after the sensitization, between the two procedures; 2) differences in somatosensory evoked potentials (SEPs) to vibrotactile stimuli on the sensitized vs. control arm; 3) the relationship between SCL and SEPs/mechanical pinprick sensitivity
Phase-locked and non-phase-locked EEG responses to pinprick stimulation before and after experimentally-induced secondary hyperalgesia.
Pinprick-evoked brain potentials (PEPs) have been proposed as a technique to investigate secondary hyperalgesia and central sensitization in humans. However, the signal-to-noise (SNR) of PEPs is low. Here, using time-frequency analysis, we characterize the phase-locked and non-phase-locked EEG responses to pinprick stimulation, before and after secondary hyperalgesia. Secondary hyperalgesia was induced using high-frequency electrical stimulation (HFS) of the left/right forearm skin in 16 volunteers. EEG responses to 64 and 96mN pinprick stimuli were elicited from both arms, before and 20min after HFS. Pinprick stimulation applied to normal skin elicited a phase-locked low-frequency (<5Hz) response followed by a reduction of alpha-band oscillations (7-10Hz). The low-frequency response was significantly increased when pinprick stimuli were delivered to the area of secondary hyperalgesia. There was no change in the reduction of alpha-band oscillations. Whereas the low-frequency response was enhanced for both 64 and 96mN intensities, PEPs analyzed in the time domain were only significantly enhanced for the 64mN intensity. Time-frequency analysis may be more sensitive than conventional time-domain analysis in revealing EEG changes associated to secondary hyperalgesia. Time-frequency analysis of PEPs can be used to investigate central sensitization in humans
Cool evoked potentials: characterizing values for healthy subjects
Background: Laser evoked potentials are gold-standard for the assessment of spinothalamic tract integrity in neuropathic pain. However, they have several shortcomings. Cool evoked potentials might be an interesting technique to, at least, complement LEPs. Aims: The aim of this study was to characterise (latency, amplitude, topography) CEPs elicited by very fast cooling of the skin (up to 300°C/s) in healthy humans. Method : In a first experiment (21 participants aged 23.4 ± 4.8 years), cold stimuli (cooling the skin down to 10°C, slope: -300°C/s) were delivered using two surface areas: 38 and 115 mmÂČ. For each condition, 80 stimuli were applied to the volar forearm, with an inter-stimulus interval of, at least, 8s. Participants were asked to rate the intensity of the sensation elicited by every stimulus. In a second experiment (21 participants aged 24.8 ± 4.2 years), cold stimuli (surface area: 115 mm2) were delivered using four different temperature decreases (-5, -10, -15 and -20°C relative to baseline) and two different slopes (-133 and -200°C/s). For each condition, 20 stimuli were applied, with an inter-stimulus interval of approximatively 12 s. Intensity rating were asked after 5 stimulations of the same condition were delivered. Results : Clear CEPs were obtained in each participant and condition. The waveforms consisted of an early N1/P1 wave (â172 ms) maximal over contralateral parietal electrodes, followed by an N2 wave (â240 ms) also maximal over the contralateral hemisphere and a later P2 wave (â420 ms) maximal over the vertex
Does CRPS Impair The Perception of Somatosensory and Non-somatosensory Stimuli?
Background: Complex regional pain syndrome (CRPS) is a chronic pain condition associating sensory, motor, trophic and autonomic symptoms in one limb. Cognitive difficulties have also been reported, affecting the patientsâ ability to mentally represent, perceive and use their affected limb. However, the nature of these deficits is still a matter of debate. Recent studies suggested that cognitive deficits are limited to body-related information and body perception, while not extending to external space. Aims: Here we challenge that statement, by using temporal order judgment (TOJ) tasks with tactile (i.e. body) or visual (i.e. extra-body) stimuli in patients with upper-limb CRPS. Methods: TOJ tasks allow characterizing cognitive biases to the advantage of one of the two sides of space. Participants report which of two stimuli they perceive as presented first. In the tactile TOJ task, pairs of vibrotactile stimuli were presented, one stimulus applied to either hand. Patients performed the task with their arms either in a crossed or an uncrossed posture. In the visual TOJ task, pairs of visual stimuli were presented, one stimulus in either side of space, either close or far from the patientsâ hands. Results: While the tactile TOJ task did not show any significant results, significant cognitive biases were observed in the visual TOJ task, affecting mostly the perception of visual stimuli occurring in the immediate vicinity of the affected limb. Conclusion & implications: Our results clearly demonstrate the presence of visuospatial deficits in CRPS, supporting the utility of developing rehabilitation techniques modifying visuospatial abilities to treat chronic pain