I am a
Home I AM A Search Login

Human Studies

Share this

The effects of unpredictability and negative affect on perception and neural gating in different interoceptive modalities.

Breathlessness and pain frequently co-occur in chronic conditions, and their unpredictability is often reported to amplify perception and negative affect (NA), however any common neural mechanisms remain largely unexplored. This study examined the effects of (unpredictable) bodily threat on perception and neural gating of respiratory and somatosensory stimuli. Healthy adults (N=51) experienced brief paired inspiratory occlusions and electrocutaneous stimuli, with their neural activity monitored via electroencephalography. Neural gating was measured as a ratio of the N1 response to the second relative to the first stimulus in a pair. In 4/6 blocks, threatening stimulation, in form of additional loaded breaths or electrocutaneous pulses, was presented predictably or unpredictably. Participants reported: perceived intensity and unpleasantness of all stimuli, fear, trait NA and intolerance of uncertainty (IU). Threatening stimulation increased perception, fear, and N1 amplitudes, without affecting neural gating. There was no group effect of unpredictability, though interactions were found with NA and IU. Cross-modal correlations revealed significant baseline relationships in neural gating and perception, though not in their modulation by threat. The present findings demonstrate that respiratory and somatosensory modalities relate in baseline perception and neural gating, and exhibit similar modulation effects by unpleasant stimulation, with significant changes in perception but not gating. Further research is encouraged to elucidate the underlying mechanisms of these relationships, and the potential interactions with stimulus unpredictability.

Learn More >

Alterations in pain processing circuitries in episodic migraine.

The precise underlying mechanisms of migraine remain unknown. Although we have previously shown acute orofacial pain evoked changes within the brainstem of individuals with migraine, we do not know if these brainstem alterations are driven by changes in higher cortical regions. The aim of this investigation is to extend our previous investigation to determine if higher brain centers display altered activation patterns and connectivity in migraineurs during acute orofacial noxious stimuli.

Learn More >

Facilitatory Effect of Intermittent Repetitive Transcranial Magnetic Stimulation on Perceptual Distortion of the Face.

Orofacial pain patients often report that the painful facial area is "swollen" without clinical signs – known as perceptual distortion (PD). The neuromodulatory effect of facilitatory repetitive transcranial magnetic stimulation (rTMS) on PD in healthy individuals was investigated, to provide further support that the primary somatosensory cortex (SI) is involved in facial PD. Participants were allocated to active (n=26) or sham (n=26) rTMS group in this case-control study. PD was induced experimentally by injecting local anesthesia (LA) in the right infraorbital region. PD was measured at baseline, 6 min after LA, immediately, 20 and 40 min after rTMS. Intermittent theta-burst stimulation (iTBS) as active rTMS and sham rTMS was applied to the face representation area of SI at 10 min after LA. The magnitude of PD was compared between the groups. The magnitude of PD significantly increased immediately after iTBS compared with sham rTMS (P=0.009). The PD was significantly higher immediately after iTBS compared to 6 min after LA (P=0.004) in the active rTMS group, but not in the sham rTMS group (P=0.054). iTBS applied to a somatotopic-relevant cortical region appears to facilitate facial PD further supporting the involvement of SI in the processing of one´s own face and PD. PERSPECTIVE: This study provides information on neural substrate responsible for processing of perceptual distortion of the face which is speculated to contribute to the chronification of orofacial pain. The findings of this study may aid in mechanism-based management of the condition in orofacial pain disorders and possibly other chronic pain states.

Learn More >

Association of plasma tryptophan concentration with periaqueductal gray matter functional connectivity in migraine patients.

Altered periaqueductal gray matter (PAG) functional connectivity contributes to brain hyperexcitability in migraine. Although tryptophan modulates neurotransmission in PAG projections through its metabolic pathways, the effect of plasma tryptophan on PAG functional connectivity (PAG-FC) in migraine has not been investigated yet. In this study, using a matched case-control design PAG-FC was measured during a resting-state functional magnetic resonance imaging session in migraine without aura patients (n = 27) and healthy controls (n = 27), and its relationship with plasma tryptophan concentration (TRP) was assessed. In addition, correlations of PAG-FC with age at migraine onset, migraine frequency, trait-anxiety and depressive symptoms were tested and the effect of TRP on these correlations was explored. Our results demonstrated that migraineurs had higher TRP compared to controls. In addition, altered PAG-FC in regions responsible for fear-cascade and pain modulation correlated with TRP only in migraineurs. There was no significant correlation in controls. It suggests increased sensitivity to TRP in migraine patients compared to controls. Trait-anxiety and depressive symptoms correlated with PAG-FC in migraine patients, and these correlations were modulated by TRP in regions responsible for emotional aspects of pain processing, but TRP did not interfere with processes that contribute to migraine attack generation or attack frequency.

Learn More >

Pilot study for treatment of symptomatic shoulder arthritis utilizing cooled radiofrequency ablation: a novel technique.

To introduce cooled radiofrequency nerve ablation (C-RFA) as an alternative to managing symptomatically moderate to severe glenohumeral osteoarthritis (OA) in patients who have failed other conservative treatments and who are not surgical candidates or refuse surgery.

Learn More >

Risk for opioid misuse in chronic pain patients is associated with endogenous opioid system dysregulation.

µ-Opioid receptors (MOR) are a major target of endogenous and exogenous opioids, including opioid pain medications. The µ-opioid neurotransmitter system is heavily implicated in the pathophysiology of chronic pain and opioid use disorder and, as such, central measures of µ-opioid system functioning are increasingly being considered as putative biomarkers for risk to misuse opioids. To explore the relationship between MOR system function and risk for opioid misuse, 28 subjects with chronic nonspecific back pain completed a clinically validated measure of opioid misuse risk, the Pain Medication Questionnaire (PMQ), and were subsequently separated into high (PMQ > 21) and low (PMQ ≤ 21) opioid misuse risk groups. Chronic pain patients along with 15 control participants underwent two separate [C]-carfentanil positron emission tomography scans to explore MOR functional measures: one at baseline and one during a sustained pain-stress challenge, with the difference between the two providing an indirect measure of stress-induced endogenous opioid release. We found that chronic pain participants at high risk for opioid misuse displayed higher baseline MOR availability within the right amygdala relative to those at low risk. By contrast, patients at low risk for opioid misuse showed less pain-induced activation of MOR-mediated, endogenous opioid neurotransmission in the nucleus accumbens. This study links human in vivo MOR system functional measures to the development of addictive disorders and provides novel evidence that MORs and µ-opioid system responsivity may underlie risk to misuse opioids among chronic pain patients.

Learn More >

Exploring alterations in sensory pathways in migraine.

Migraine is a neurological disorder characterized by intense, debilitating headaches, often coupled with nausea, vomiting and sensitivity to light and sound. Whilst changes in sensory processes during a migraine attack have been well-described, there is growing evidence that even between migraine attacks, sensory abilities are disrupted in migraine. Brain imaging studies have investigated altered coupling between areas of the descending pain modulatory pathway but coupling between somatosensory processing regions between migraine attacks has not been properly studied. The aim of this study was to determine if ongoing functional connectivity between visual, auditory, olfactory, gustatory and somatosensory cortices are altered during the interictal phase of migraine.

Learn More >

Migraine in the Emergency Department: A Prospective Multinational Study of Patient Characteristics, Management, and Outcomes.

Migraine headache is commonly diagnosed in emergency departments (ED). There is relatively little real-world information about the epidemiology, investigation, management, adherence to therapeutic guidelines and disposition of patients treated in ED with a final diagnosis of migraine. The primary aim of the current study is to get a snapshot of assessment and management patterns of acute migraine presentations to the different settings of EDs with a view to raise awareness.

Learn More >

Prevalence and factors associated with sleep disturbance in adult patients with psoriasis.

Sleep, which is crucial for restoring of physiological functions and health, is reportedly impaired in psoriasis. The role of different potential sleep confounding factors, including detailed pruritus characteristics, and the complex interplay between psychological variables (anxiety and depression), pruritus and sleep disturbance in psoriasis remain insufficiently investigated.

Learn More >

Subepidermal Schwann cell counts correlate with skin innervation – an exploratory study.

Schwann cell clusters have been described at the murine dermis-epidermis border. We quantified dermal Schwann cells in the skin of patients with small fiber neuropathy (SFN) compared to healthy controls to correlate with the clinical phenotype.

Learn More >

Search