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| 13. |
- Radovanovic, S., et al.
(författare)
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Comparison of brain activity during different types of proprioceptive inputs : a positron emission tomography study
- 2002
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Ingår i: Experimental Brain Research. - : Springer Science and Business Media LLC. - 0014-4819 .- 1432-1106. ; 143:3, s. 276-285
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Tidskriftsartikel (refereegranskat)abstract
- It has been shown that the primary and secondary somatosensory cortex, as well as the supplementary motor area (SMA), are involved in central processing of proprioceptive signals during passive and active arm movements. However, it is not clear whether different cortical areas are involved in processing of different proprioceptive inputs (skin, joint, muscle receptors), what their relative contributions might be, where kinesthetic sensations are formed within the CNS, and how they interact when the full peripheral proprioceptive machinery acts. In this study we investigated the representation of the brain structures involved in the perception of passive limb movement and illusory movement generated by muscle tendon vibration. Changes in cortical activity as indicated by changes in regional cerebral blood flow (rCBF) were measured using positron emission tomography (PET). Twelve subjects were studied under four conditions: (1) passive flexion-extension movement (PM) of the left forearm; (2) induced illusions of movements (VI) similar to the real PM, induced by alternating vibration of biceps and triceps tendons (70-80 Hz) at the elbow; (3) alternating vibration of biceps and triceps tendons (with 20-50 Hz) without induced kinesthetic illusions (VN); and (4) rest condition (RE). The results show different patterns of cortex activation. In general, the activation during passive movement was higher in comparison with both kinds of vibration, and activation during vibrations with induced illusions of movement was more prominent than during vibrations without induced illusions. When the PM condition was contrasted with the other conditions we found the following areas of activation -- the primary motor (MI) and somatosensory area (SI), the SMA and the supplementary somatosensory area (SSA). In conditions where passive movements and illusory movements were contrasted with rest, some temporal areas, namely primary and associative auditory cortex, were activated, as well as secondary somatosensory cortex (SII). Our data show that different proprioceptive inputs, which induce sensation of movement, are associated with differently located activation patterns in the SI/MI and SMA areas of the cortex. In general, the comparison of activation intensities under different functional conditions indicates the involvement of SII in stimulus perception generation and of the SI/MI and SMA areas in the processing of proprioceptive input. Activation of the primary and secondary auditory cortex might reflect the interaction between somatosensory and auditory systems in movement sense generation. SSA might also be involved in movement sense generation and/or maintenance.
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| 15. |
- Blesic, S., et al.
(författare)
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A random walk model analysis of spinal dorsalhorn neuron discharges
- 2000
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Konferensbidrag (refereegranskat)abstract
- Methods of statistical physics have been recently successfully ap- plied to the study of spatial ánd temporal randomness in various biological systems, like the analýsts of the DNA nucleotide sequences and the heartbeat time series. We study the interspike intervals (ISI) time series of the spinal dorsal horn nociceptive- responsive neurons (DHN) activity in decerebrate cats applying the detrended fluctuatìon analysis (DFA) that is a modification of the standard random walk model analysis. Specifically, we focus on ISI variability as an important quantity to help elucidate sensory coding and signal processing performed by DHN. DFA has been applied for it permtts quantification of correlation properties of a nonstationary time series of neuronal discharge, Changes in DHN activity were extracellularly recorded with high impedance glass microelectrodes from superficial laminae of the dorsal horn, during different experimentally simúlated conditions. We háve analyzed DHN discharge patterns during spontaneous activity, as well as in the presence of diflerent noxious and non- noxious mechanical stimuli. Application of DFA method showed significant changes in dynamics of neural discharge when the ex- ternal stimulus is appliéd. These findings demonstrate the relevance of the application of methods of statistical. physics to identify the changes in aflerent inflow, and to characterize temporal patterns of activity of neurons under study
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| 16. |
- Korotkov, A., et al.
(författare)
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Changes in human regional cerebral blood flow following hypertonic saline induced experimental muscle pain : a positron emission tomography study
- 2002
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Ingår i: Neuroscience Letters. - 0304-3940 .- 1872-7972. ; 335:2, s. 119-123
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Tidskriftsartikel (refereegranskat)abstract
- A positron emission tomography imaging study was performed on 16 healthy volunteers to reveal changes in cortical activation during acute muscle pain induced by intra-muscular injection of hypertonic saline into the left triceps brachii muscle. Changes in regional cerebral blood flow (rCBF) were measured with the use of [(15)O] labelled water during 'Rest1', 'Needle' (insertion of a needle without injection), 'Rest2' and 'Pain' conditions. Differences in rCBF were found in the comparison of Pain and Needle, and Pain and Rest2 conditions, revealing activation of the contralateral insula and putamen. The results are discussed with respect to possible differences in brain processing of muscle and cutaneous noxious inputs.
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| 17. |
- Ljubisavljevic, M, et al.
(författare)
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Changes in fusimotor activity during repetitive lengthening muscle contractions in decerebrate cats
- 1998
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Ingår i: Neuroscience. - 0306-4522 .- 1873-7544. ; 86:4, s. 1337-1342
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Tidskriftsartikel (refereegranskat)abstract
- Responses of fusimotor neurons to lengthening vs isometric contractions have been studied in decerebrate cats. Spike discharges of fusimotor neurons to the medial gastrocnemius muscle were recorded from this muscle nerve filament during sequences of contractions and/or stretches of the lateral gastrocnemius and soleus muscles. The sequences lasted for 250-450s (duty cycle 4:2 s). Isometric contractions were elicited by electrical stimulation (40 Hz, 1.3 times motor threshold) of the muscle nerves. Lengthening contractions were elicited in the same way while the muscles were stretched by 4 mm at a velocity of 1 mm/s. Of 25 fusimotor neurons studied, 23 responded to muscle contractions with an increase in firing rate, subsiding towards the end of the sequence. The increase was either modulated with each subsequent contraction or smooth throughout the sequence. Approximately 64% of fusimotor neurons, responding to muscle contractions, responded in a similar way to the sequences of muscle stretches, applied alone. Responses to sequences of the lengthening contractions were significantly larger, on average, than those to the isometric ones, but smaller than the sum of the responses to the contractions and stretches applied separately. On the other hand, they were also larger in fusimotor units, showing no overt responses to muscle stretches alone.
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| 18. |
- Stevanovic, D., et al.
(författare)
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Assessing the symptoms of Internet Gaming Disorder among college/university students: An international validation study of a self-report
- 2020
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Ingår i: Psihologija. - : National Library of Serbia. - 0048-5705 .- 1451-9283. ; 53:1, s. 43-63
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Tidskriftsartikel (refereegranskat)abstract
- The present study evaluated the psychometric properties of a self-report scale for assessing Internet Gaming Disorder (IGD) symptoms according to the DSM-5 and ICD-11 among 3270 college/university students (2095 [64.1%] females; age mean 21.6 [3.1] years) from different countries worldwide. Croatian, English, Polish, Portuguese, Serbian, Turkish, and Vietnamese versions of the scale were tested. The study showed that symptoms of IGD could be measured as a single underlying factor among college/university students. A nine item-symptom scale following DSM-5, and a short four-item scale representing the main ICD-11 symptoms, had sound internal consistency and construct validity. Three symptom-items were found non-invariant across the language samples (i.e., preoccupation with on-line gaming, loss of interests in previous hobbies and entertainment, and the use of gaming to relieve negative moods). This study provides initial evidence for assessing IGD symptoms among college/university students and will hopefully foster further research into gaming addiction in this population worldwide especially with taking into account language/cultural differences.
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| 19. |
- Claeys, M. J., et al.
(författare)
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Organization of intensive cardiac care units in Europe : Results of a multinational survey
- 2020
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Ingår i: European Heart Journal. - : Oxford University Press (OUP). - 2048-8726 .- 2048-8734. ; 9:8, s. 993-1001
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Tidskriftsartikel (refereegranskat)abstract
- Background: The present survey aims to describe the intensive cardiac care unit organization and admission policies in Europe. Methods: A total of 228 hospitals (61% academic) from 27 countries participated in this survey. In addition to the organizational aspects of the intensive cardiac care units, including classification of the intensive cardiac care unit levels, data on the admission diagnoses were gathered from consecutive patients who were admitted during a two-day period. Admission policies were evaluated by comparing illness severity with the intensive cardiac care unit level. Gross national income was used to differentiate high-income countries (n=13) from middle-income countries (n=14). Results: A total of 98% of the hospitals had an intensive cardiac care unit: 70% had a level 1 intensive cardiac care unit, 76% had a level 2 intensive cardiac care unit, 51% had a level 3 intensive cardiac care unit, and 60% of the hospitals had more than one intensive cardiac care unit level. High-income countries tended to have more level 3 intensive cardiac care units than middle-income countries (55% versus 41%, p=0.07). A total of 5159 admissions were scored on illness severity: 63% were low severity, 24% were intermediate severity, and 12% were high severity. Patients with low illness severity were predominantly admitted to level 1 intensive cardiac care units, whereas patients with high illness severity were predominantly admitted to level 2 and 3 intensive cardiac care units. A policy mismatch was observed in 12% of the patients; some patients with high illness severity were admitted to level 1 intensive cardiac care units, which occurred more often in middle-income countries, whereas some patients with low illness severity were admitted to level 3 intensive cardiac care units, which occurred more frequently in high-income countries. Conclusion: More than one-third of the admitted patients were considered intermediate or high risk. Although patients with higher illness severity were mostly admitted to high-level intensive cardiac care units, an admission policy mismatch was observed in 12% of the patients; this mismatch was partly related to insufficient logistic intensive cardiac care unit capacity.
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| 20. |
- Kolte, Dhaval, et al.
(författare)
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Culprit Vessel-Only Versus Multivessel Percutaneous Coronary Intervention in Patients With Cardiogenic Shock Complicating ST-Segment-Elevation Myocardial Infarction : A Collaborative Meta-Analysis
- 2017
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Ingår i: Circulation. Cardiovascular Interventions. - : LIPPINCOTT WILLIAMS & WILKINS. - 1941-7640 .- 1941-7632. ; 10:11
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Tidskriftsartikel (refereegranskat)abstract
- Background The optimal revascularization strategy in patients with multivessel disease presenting with cardiogenic shock complicating ST-segment-elevation myocardial infarction remains unknown. Methods and Results Databases were searched from 1999 to October 2016. Studies comparing immediate/single-stage multivessel percutaneous coronary intervention (MV-PCI) versus culprit vessel-only PCI (CO-PCI) in patients with multivessel disease, ST-segment-elevation myocardial infarction, and cardiogenic shock were included. Primary end point was short-term (in-hospital or 30 days) mortality. Secondary end points included long-term mortality, cardiovascular death, reinfarction, and repeat revascularization. Safety end points were in-hospital stroke, renal failure, and major bleeding. The meta-analysis included 11 nonrandomized studies and 5850 patients (1157 MV-PCI and 4693 CO-PCI). There was no significant difference in short-term mortality with MV-PCI versus CO-PCI (odds ratio [OR], 1.08; 95% confidence interval [CI], 0.81-1.43; P=0.61). Similarly, there were no significant differences in long-term mortality (OR, 0.84; 95% CI, 0.54-1.30; P=0.43), cardiovascular death (OR, 0.72; 95% CI, 0.42-1.23; P=0.23), reinfarction (OR, 1.65; 95% CI, 0.84-3.26; P=0.15), or repeat revascularization (OR, 1.13; 95% CI, 0.76-1.69; P=0.54) between the 2 groups. There was a nonsignificant trend toward higher in-hospital stroke (OR, 1.64; 95% CI, 0.98-2.72; P=0.06) and renal failure (OR, 1.30; 95% CI, 0.98-1.72; P=0.06), with no difference in major bleeding (OR, 1.47; 95% CI, 0.39-5.63; P=0.57) with MV-PCI when compared with CO-PCI. Conclusions This meta-analysis of nonrandomized studies suggests that in patients with cardiogenic shock complicating ST-segment-elevation myocardial infarction, there may be no significant benefit with single-stage MV-PCI compared with CO-PCI. Given the limitations of observational data, randomized trials are needed to determine the role of MV-PCI in this setting.
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| 21. |
- Ljubisavljevic, M, et al.
(författare)
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Effects of cutaneous afferent input on fatigue-induced changes in fusimotor activity of decerebrate cats
- 1997
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Ingår i: Neuroscience. - 0306-4522 .- 1873-7544. ; 79:3, s. 935-942
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Tidskriftsartikel (refereegranskat)abstract
- Interaction of cutaneous and small-diameter, primarily fatigue-induced, muscle afferent inputs on fusimotor neurons has been studied in decerebrate cats. Spike discharges of fusimotor neurons to medial gastrocnemius were recorded from filaments dissected free from this muscle nerve. Non-noxious mechanical stimuli (10 Hz, 2 mm vibration) were applied to the skin area on the lateral side of the heel, innervated by sural nerve, during long-lasting (250 s) fatiguing contraction of lateral gastrocnemius and soleus muscles, elicited by electrical stimulation (40 Hz, 1.3 x motor threshold) of the muscle nerves. In 15 units (58%) the pattern of responses to muscle contraction and/or fatigue (initial transient, and late long-lasting increase in firing rate, respectively) was preserved in the presence of skin vibration which, by itself, provoked either a slight increase or no changes in fusimotor discharge rate. Pattern of the response to skin vibration prevailed in the presence of muscle contraction and fatigue only if the vibration by itself induced marked increase in fusimotor discharge rate (three units). In the remaining eight units the responses to both stimuli applied simultaneously were dissimilar in pattern to the response to either stimulus applied alone: the initial, tension-related, increase in firing rate was prolonged, while the late, fatigue-induced one was attenuated and its post-contraction part almost abolished. Possible mechanisms and functional role of interaction between cutaneous and muscle afferent inflows are discussed.
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| 22. |
- Radovanovic, Sasa, et al.
(författare)
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Effects of transcranial magnetic stimulation of the cerebellum on performance of consecutive rapid movements in patients with idiopathic sporadic cerebellar ataxia and healthy subjects
- 2006
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Ingår i: The Movement Disorder Society’s 10th International Congress of Parkinson’s Disease and Movement.
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Konferensbidrag (populärvet., debatt m.m.)abstract
- It is known that cerebellum influences the action of the motor system. The cerebellum may exert a facilitatory influence in the motor cortex, and should be involved in temporal computations in movement performance. The inability to compute time differences would affect time-related tasks. However, the cerebellar role to control precise movement performance is contradictory. Furthermore, facilitatory effect of cerebellum might be decreased in cerebellar degeneration. The aim of the study was to investigate the performance of the rapid movements in patients with “pure” cerebellar ataxia. Movement performance was compared in 13 patients and 8 healthy subjects. Movements were performed from the initial to the target position, with the movement length of 40 deg in the elbow flexion. Motor threshold (MT) of the motor cortex was determined and TMS was then applied right of the inion, in two conditions: With the strength of 5% below the MT, at the moment of command to start the flexion movement, and with the same strength 20 ms before the movement start. Two additional conditions were also tested: TM stimulus was applied with the strength of 30% above the MT at the moment of movement start, and at 20 ms before movement start. Patients perform significantly longer movements then healthy subjects, and accuracy of the movements deteriorates. Length of the movements was also prolonged in the conditions where stronger stimulus was applied. Accuracy of the movements in patients was not different when the stimulus was applied in the phase of the movement preparation, compared in moment 0 and -20 ms. Same was true for healthy subjects in both conditions - stimulus below and above MT. Results that differences in disturbance timing and strength have no clear effects might speak for preprogrammed characteristics of rapid movements in both healthy subjects and ataxia patients, where sensory input is not of primary importance. Deficits in cerebellar ataxia for the movement length may be attributable to improper processing of motor command and/or sensory information.
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| 24. |
- Dragasevic, N T, et al.
(författare)
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Cortical excitability revealed by motor evoked potential, cortical silent period and conduction time in spinocerebellar ataxias type 1, type 2 and idiopathic sporadic cerebellar ataxia : a transcranial magnetic stimulation study
- 2006
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Ingår i: The Movement Disorder Society’s 10th International Congress of Parkinson’s Disease and Movement.
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Konferensbidrag (populärvet., debatt m.m.)abstract
- Autosomal dominant cerebellar ataxias are characterized by their underlying genetic defect and are referred to as spinocerebellar ataxias (SCAs 1-23). The clinical classification of the SCA has been difficult owing to variations and overlapping of the clinical signs. The aim of this study was to compare cortical motor evoked potential (MEP), central motor conduction time (CMCT) and cortical silent period (CSP) duration in SCA patients in Serbia, namely in genetically homogenous groups of ataxia patients with type 1, type 2 and IDCA (idiopathic sporadic cerebellar ataxia). We examined 29 patients, 16 with the diagnosis of SCA 1, 6 SCA 2 and 7 IDCA patients. Eight healthy control subjects were gender and age matched. Transcranial magnetic stimulation (TMS) was used to investigate parameters of cortical excitability such as: motor threshold (MT) and MEP, CSP and CMCT. MT was established at rest, MEP was calculated as the area in the rectified EMG recording. CSP was evoked by 30% suprathreshold stimulation while subjects activated FDI muscle with contraction of 30% of their MVC. CMCT was calculated as a difference between the shortest MEP latency after cortical and after cervical stimulation (in the region of C5-C6). Results show that MT was increased in all ataxia patient groups, compared to control subjects. CMCT has significant increase in SCA 1 patients. CSP in IDCA patients is significantly longer then in SCA 1, SCA 2 and control subjects, while no difference was found between SCA 1, SCA 2 and control. MEP duration was significantly increased in all ataxia groups compared to control in relaxed muscle. Due to the cerebellar influence on the cortico-spinal system through control of inhibitory cortical interneurons, could be assumed that different categories of ataxia patients have disturbed cerebellar inhibitory influence to the various degrees. It might be possible that SCA 1 prominent abnormalities in cortical excitability originate from expansion of damage from cerebellum to some other cerebellar and brain structures.
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