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- Donadio, V., et al.
(författare)
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Muscle sympathetic response to arousal predicts neurovascular reactivity during mental stress
- 2012
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Ingår i: Journal of Physiology-London. - : Wiley. - 0022-3751. ; 590:12, s. 2885-2896
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Tidskriftsartikel (refereegranskat)abstract
- Key points Mental stress (MS) is often initiated by a sensory or cognitive stimulus, which induces a brief arousal reaction followed by a longer stress phase. Both phases induce blood pressure (BP) increases whereas effects on muscle sympathetic nerve activity (MSNA) vary: in approximately 50% of healthy subjects (responders) arousal induces a brief MSNA reduction, which is absent in the remaining 50% (non-responders). We now report a link between the arousal response and neurovascular effects of MS in healthy males. Our data show that during MS, responders to arousal exhibited a significant decrease of MSNA and a lesser BP increase compared to non-responders. The whole material displayed a positive correlation between MSNA responses induced by arousal and MS. In addition, arousal induced MSNA changes correlated positively with BP changes during MS. We conclude that the MSNA response to arousal predicts MSNA and BP responses to MS.
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| 2. |
- Persson, Mikael, 1959, et al.
(författare)
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Microwave-Based Stroke Diagnosis Making Global Prehospital Thrombolytic Treatment Possible
- 2014
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Ingår i: IEEE Transactions on Biomedical Engineering. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9294 .- 1558-2531. ; 61:11, s. 2806-2817
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Tidskriftsartikel (refereegranskat)abstract
- Here, we present two different brain diagnostic devices based on microwave technology and the associated two first proof-of-principle measurements that show that the systems can differentiate hemorrhagic from ischemic stroke in acute stroke patients, as well as differentiate hemorrhagic patients from healthy volunteers. The system was based on microwave scattering measurements with an antenna system worn on the head. Measurement data were analyzed with a machine-learning algorithm that is based on training using data from patients with a known condition. Computer tomography images were used as reference. The detection methodology was evaluated with the leave-one-out validation method combined with a Monte Carlo-based bootstrap step. The clinical motivation for this project is that ischemic stroke patients may receive acute thrombolytic treatment at hospitals, dramatically reducing or abolishing symptoms. A microwave system is suitable for prehospital use, and therefore has the potential to allow significantly earlier diagnosis and treatment than today.
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| 3. |
- Thordstein, Magnus, et al.
(författare)
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Individual effects of varying stimulation intensity and response criteria on area of activation for different muscles in humans. A study using navigated transcranial magnetic stimulation
- 2013
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Ingår i: Brain Stimulation. - : Elsevier BV. - 1935-861X. ; 6:1, s. 49-53
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Tidskriftsartikel (refereegranskat)abstract
- Background When using transcranial magnetic stimulation, a stimulation intensity defined as a certain level above the threshold for activation of a hand muscle is commonly used, disregarding the fact that the areas of activation for different muscles may have varying response characteristics intra- and interindividually. Objective To study the response characteristics of different muscles and compare them within and between individuals. Also to investigate the effect of varying stimulation intensity (defined in two different ways) and amplitude criterion for response, on the sizes of the activation areas for different muscles. Methods A system of transcranial magnetic stimulation with navigation capacity where the stimulation intensity can be defined in terms of the electric field strength in the tissue was used. Four different muscles were investigated in healthy adults. The threshold for activation at rest (RMT) of the different muscles and their respective areas of activation were quantified using three different stimulus intensities (100, 110 and 120% RMT) and two criteria for response amplitude (20 and 50 μV). Results Responses could readily be determined using 20 μV as response limit. The RMTs for different muscles varied within and between individuals. The degree to which the area depended on stimulation intensity differed between muscles intra- and interindividually. All results were statistically significant (P < 0.05 or less). Conclusions The response characteristics vary between muscles within an individual and between individuals for a certain muscle. Thus, for optimal accuracy when delineating the activation area, the investigation should be adapted to each particular muscle.
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| 4. |
- Wallin, Gunnar B, 1936, et al.
(författare)
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Sympathetic single axonal discharge after spinal cord injury in humans: activity at rest and after bladder stimulation
- 2014
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Ingår i: Spinal Cord. - : Springer Science and Business Media LLC. - 1362-4393 .- 1476-5624. ; 52:6, s. 434-438
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Tidskriftsartikel (refereegranskat)abstract
- Study design: Clinical experimental mechanistic study. Objectives: (1) To determine in three spinal cord-injured patients whether individual muscle sympathetic nerve fibres below the level of the spinal lesion display spontaneous activity. (2) To determine in these patients if individual sympathetic vasoconstrictor fibres show a prolonged discharge following a bladder stimulus. Methods: Microneurographic recordings of action potentials from individual muscle nerve sympathetic fibres in a peroneal nerve. Recordings of skin blood flow and electrodermal responses in a foot. Results: In all patients, there was sparse ongoing spontaneous impulse traffic in individual sympathetic fibres. Brisk mechanical pressure over the urinary bladder evoked a varying number of action potentials in individual fibres, but the activity was brief and did not continue after the end of the evoked multiunit burst. Conclusion: Prolonged discharges in individual sympathetic fibres are unlikely to contribute to a long duration of blood pressure increases induced by brief bladder stimuli.
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