International journal of psychophysiology : official journal of the International Organization of Psychophysiology
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Int J Psychophysiol · Dec 2008
Effects of nocturnal railway noise on sleep fragmentation in young and middle-aged subjects as a function of type of train and sound level.
Due to undisputable effects of noise on sleep structure, especially in terms of sleep fragmentation, the expected development of railway transportation in the next few years might represent a potential risk factor for people living alongside the rail tracks. The aim of this study was to compare the effects of different types of train (freight, automotive, passenger) on arousal from sleep and to determine any differential impact as a function of sound level and age. Twenty young (16 women, 4 men; 25.8 years+/-2.6) and 18 middle-aged (15 women, 3 men; 52.2 years+/-2.5) healthy subjects participated in three whole-night polysomnographic recordings including one control night (35 dBA), and two noisy nights with equivalent noise levels of 40 or 50 dB(A), respectively. ⋯ Awakenings (>10 s) were produced more frequently by freight train than by automotive and passenger trains. Normal age-related changes in sleep were observed, but they were not aggravated by railway noise, thus questioning whether older persons are less sensitive to noise during sleep. These evidences led to the conclusion that microscopic detection of sleep fragmentation may provide advantageous information on sleep disturbances caused by environmental noises.
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Int J Psychophysiol · Dec 2008
You can see pain in the eye: pupillometry as an index of pain intensity under different luminance conditions.
Pupil dilation is regulated autonomically and it may be a valid measure of pain, but pupillometry for pain intensity recordings has not been evaluated under different luminance conditions. We hypothesized that the pupil response may serve as an objective indicator of pain intensity even if luminance conditions differ which is often the case in experiments with pictures. In 20 healthy females we applied a tonic pressure pain to the fingers (20 s). ⋯ While this maximum pupil dilation did not differ with pressure intensity, the pupil dilation was larger for the higher pressure intensity in the period from 10 s after pressure onset to pressure offset. Even under different luminance conditions, pupillometry can serve as an objective indicator of pressure pain intensity. Thus, it seems promising to use pupillometry with complex experimental designs combining pain and pictorial stimuli.
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Int J Psychophysiol · Aug 2008
Randomized Controlled TrialEffects of opioid blockade on nociceptive flexion reflex thresholds and nociceptive responding in hypertensive and normotensive individuals.
Hypertension and risk for hypertension have been associated with reduced pain sensitivity. It has been hypothesised that endogenous opioids contribute to this hypertensive hypoalgesia. ⋯ Neither nociceptive flexion reflex thresholds nor nociceptive responding differed between hypertensives and normotensives during placebo or naltrexone. These data provide no support for the hypothesis that essential hypertension is characterised by higher levels of endogenous opioids in the central nervous system and reveal no association between blood pressure status and nociceptive flexion reflex responses.
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Int J Psychophysiol · Jul 2008
Randomized Controlled Trial Controlled Clinical TrialTaxometric analysis of biceps femoris EMG following electrocutaneous stimulation over the sural nerve: determining the latent structure of the nociceptive flexion reflex (NFR).
The nociceptive flexion reflex (NFR) is a polysynaptic withdrawal reflex typically assessed from biceps femoris electromyogram (EMG) following noxious stimulation of the ipsilateral sural nerve. Electrophysiological evidence suggests the reflex is elicited following the activation of small diameter A-delta afferents. As a result, the NFR is assumed to be a categorically distinct construct that emerges from EMG activity only following nociceptor activation. ⋯ Results suggested the presence of a taxon in the covariance of biceps femoris EMG and stimulus intensity that is likely to be the NFR. Furthermore, preliminary analyses suggested the best method of scoring NFR magnitude was using Cohen's d. Implications of these results are discussed.
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Int J Psychophysiol · May 2008
Magnetoencephalography-guided epilepsy surgery for children with intractable focal epilepsy: SickKids experience.
We introduced magnetoencephalography (MEG)-guided epilepsy surgery for children with intractable focal epilepsy at The Hospital for Sick Children (SickKids) in Toronto, Canada. Surgical candidacy and decisions on surgical procedure for children with intractable focal epilepsy are based on long-term scalp video EEG (VEEG) results, magnetic resonance imaging (MRI) findings, and the distribution of MEG spike sources. After multidisciplinary discussion at the seizure conference, for the patients requiring intracranial VEEG, custom-made subdural electrode grids are designed using three-dimensional MRI superimposed with MEG spike sources to cover the area of clustered MEG spike sources. ⋯ At the second surgery, the area of seizure onset and active interictal spike discharges on the intracranial VEEG recording, which usually correlates with the zone of clustered MEG spike sources, is resected. This combination leads to successful surgical outcome to control seizures in these challenging paediatric patients. MEG is a useful tool in children with intractable focal epilepsy to determine the surgical candidacy and focal cortical resection to stop seizures.