| 1. |
- Ahmadi, Maliheh, et al.
(författare)
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Cortical source analysis of resting state EEG data in children with attention deficit hyperactivity disorder
- 2020
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Ingår i: Clinical Neurophysiology. - : Elsevier BV. - 1388-2457 .- 1872-8952. ; 131:9, s. 2115-2130
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Tidskriftsartikel (refereegranskat)abstract
- Objective: This study investigated age-dependent and subtype-related alterations in electroencephalography (EEG) power spectra and current source densities (CSD) in children with attention deficit and hyperactivity disorder (ADHD).Methods: We performed spectral and cortical source (exact low-resolution electromagnetic tomography, eLORETA) analyses using resting state EEG recordings from 40 children (8-16 years) with combined and inattentive subtypes of ADHD and 41 age-matched healthy controls (HC). Group differences in EEG spectra and CSD were investigated at each scalp location, voxel and cortical region in delta, theta, alpha and beta bands. We also explored associations between topographic changes in EEG power and CSD and age.Results: Compared to healthy controls, combined ADHD subtype was characterized with significantly increased diffuse theta/beta power ratios (TBR) with a widespread decrease in beta CSD. Inattentive ADHD subtype presented increased TBR in all brain regions except in posterior areas with a global increase in theta source power. In both ADHD and HC, older age groups showed significantly lower delta source power and TBR and higher alpha and beta source power than younger age groups. Compared to HC, ADHD was characterized with increases in theta fronto-central and temporal source power with increasing age.Conclusions: Our results confirm that TBR can be used as a neurophysiological biomarker to differentiate ADHD from healthy children at both the source and sensor levels.Significance: Our findings emphasize the importance of performing the source imaging analysis in order to better characterize age-related changes in resting-state EEG activity in ADHD and controls.
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| 2. |
- Alix, James J. P., et al.
(författare)
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Assessment of the reliability of the motor unit size index (MUSIX) in single subject "round-robin" and multi-centre settings
- 2019
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Ingår i: Clinical Neurophysiology. - : ELSEVIER IRELAND LTD. - 1388-2457 .- 1872-8952. ; 130:5, s. 666-674
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Tidskriftsartikel (refereegranskat)abstract
- Objective: The motor unit size index (MUSIX) is incorporated into the motor unit number index (MUNIX). Our objective was to assess the intra-/inter-rater reliability of MUSIX in healthy volunteers across single subject "round robin" and multi-centre settings.Methods: Data were obtained from (i) a round-robin assessment in which 12 raters (6 with prior experience and 6 without) assessed six muscles (abductor pollicis brevis, abductor digiti minimi, biceps brachii, tibialis anterior, extensor digitorum brevis and abductor hallucis) and (ii) a multi-centre study with 6 centres studying the same muscles in 66 healthy volunteers. Intrafinter-rater data were provided by 5 centres, 1 centre provided only intra-rater data. Intrafinter-rater variability was assessed using the coefficient of variation (COV), Bland-Altman plots, bias and 95% limits of agreement.Results: In the round-robin assessment intra-rater COVs for MUSIX ranged from 7.8% to 28.4%. Inter-rater variability was between 7.8% and 16.2%. Prior experience did not impact on MUSIX values. In the multi-centre study MUSIX was more consistent than the MUNIX. Abductor hallucis was the least reliable muscle.Conclusions: The MUSIX is a reliable neurophysiological biomarker of reinnervation.Significance: MUSIX could provide insights into the pathophysiology of a range of neuromuscular disorders, providing a quantitative biomarker of reinnervation.
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| 3. |
- Awad, Amar, et al.
(författare)
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Preserved somatosensory conduction in complete spinal cord injury : Discomplete SCI
- 2020
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Ingår i: Clinical Neurophysiology. - : Elsevier. - 1388-2457 .- 1872-8952. ; 131:5, s. 1059-1067
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Spinal cord injury (SCI) disrupts the communication between brain and body parts innervated from below-injury spinal segments, but rarely results in complete anatomical transection of the spinal cord. The aim of this study was to investigate residual somatosensory conduction in clinically complete SCI, to corroborate the concept of sensory discomplete SCI.Methods: We used fMRI with a somatosensory protocol in which blinded and randomized tactile and nociceptive stimulation was applied on both legs (below-injury level) and one arm (above-injury level) in eleven participants with chronic complete SCI. The experimental design accounts for possible confounding mechanical (e.g. vibration) and cortico-cortical top-down mechanisms (e.g. attention/expectation).Results: Somatosensory stimulation on below-level insensate body regions activated the somatotopically corresponding part of the contralateral primary somatosensory cortex in six out of eleven participants.Conclusions: Our results represent afferent-driven cortical activation through preserved somatosensory connections to the brain in a subgroup of participants with clinically complete SCI, i.e. sensory discomplete SCI.Significance: Identifying patients with residual somatosensory connections might open the door for new rehabilitative and restorative strategies as well as inform research on SCI-related conditions such as neuropathic pain and spasticity.
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| 4. |
- Bengtsson Lindberg, Marie, et al.
(författare)
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Multifocal visual evoked potentials-a method study of responses from small sectors of the visual field.
- 2005
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Ingår i: Clinical Neurophysiology. - : Elsevier BV. - 1872-8952 .- 1388-2457. ; 116:8, s. 1975-1983
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Tidskriftsartikel (refereegranskat)abstract
- Objective: A method study of the mfVEP technique to establish a standardised way to identify stable response components from small areas in all parts of the visual field and a test-retest reliability study. Methods: MfVEP was recorded from 26 healthy volunteers. Results: Two response components could be clearly identified. The latencies corresponded to those of the traditional VEP response (N75 and P100). The visual field was divided into 12 sectors. A characteristic pattern was obtained. Component I was mainly negative in the upper sectors and positive in the lower sectors. Component II was positive in the upper sectors and negative in the lower ones. Most of the sectors with missing responses were the ones adjacent to the horizontal meridian, corresponding to the phase reversals. In a test-retest reliability study, the amplitude and latency measurements of the second test were plotted against those of the first test. Correlation coefficients between 0.84 and 0.93 were obtained. Conclusions: The mfVEP allows a reliable quantification of two response components from small parts of the visual field. Significance: This paper suggests that mfVEP could be a valuable supplement to the traditional VEP for exploring restricted parts of the visual pathways.
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| 5. |
- Boenitz, Hanna, et al.
(författare)
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Event-related neuronal responses to acoustic novelty in single-sided deaf cochlear implant users: Initial findings
- 2018
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Ingår i: Clinical Neurophysiology. - : ELSEVIER IRELAND LTD. - 1388-2457 .- 1872-8952. ; 129:1, s. 133-142
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Tidskriftsartikel (refereegranskat)abstract
- Objective: A cochlear implant (CI) is an auditory prosthesis restoring profound hearing loss. However, CItransmitted sounds are degraded compared to normal acoustic hearing. We investigated cortical responses related to CI-degraded against acoustic listening. Methods: Event-related potentials (ERPs) were recorded from eight single-sided deaf CI users who performed a three-stimulus oddball task, separatelywith their normal hearing ear and CI ear. The oddball tones were occasionally intermitted by novel sounds. ERP responses were compared between electric and acoustic listening for the auditory (N1) and auditory-cognitive (Novelty P3, Target-P3) ERP components. Results: CI-degraded listening was associated with attenuated sensory processing (N1) and with attenuated early cortical responses to acoustic novelty whereas the late cortical responses to acoustic novelty and the target-P3 did not differ between NH and CI ears. Conclusion: The present study replicates the CI-attenuation of Novelty-P3 amplitudes in a within-subject comparison. Further, we show that the CI-attenuation of Novelty-P3 amplitudes extends to early cortical responses to acoustic novelty, but not to late novelty responses. Significance: The dissociation into CI-attenuated P3 early Novelty-P3 amplitudes and CI-unaffected late Novelty-P3 amplitudes represents a cortical fingerprint of CI-degraded listening. It further contributes to general claims of distinct auditory Novelty-P3 sub-components. (C) 2017 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.
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| 8. |
- Brantberg, Krister, et al.
(författare)
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Skull tap induced vestibular evoked myogenic potentials : an ipsilateral vibration response and a bilateral head acceleration response?
- 2008
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Ingår i: Clinical Neurophysiology. - : Elsevier BV. - 1388-2457 .- 1872-8952. ; 119:10, s. 2363-2369
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To explore the mechanisms for skull tap induced vestibular evoked myogenic potentials (VEMP). METHODS: An electro-mechanical "skull tapper" (that provided a constant stimulus intensity) was used to test the effects of different midline stimulus sites/directions in healthy subjects (n=10) and in patients with severe unilateral loss of vestibular function (n=8). RESULTS: The standardized midline skull taps caused highly reproducible VEMP. There were highly significant differences in amplitude and latency in both normals and patients depending on site/direction of tapping (suggesting a stimulus direction dependency). Occiput skull taps caused, in comparisons to forehead and vertex taps, larger amplitude VEMP with more pronounced differences between the lesioned and the healthy side in the patients. CONCLUSIONS: The present data, in conjunction with earlier findings, support a theory that skull tap VEMP are mediated by two different mechanisms. It is suggested that skull tapping causes both skull vibration and head acceleration. Further, the VEMP would be the sum of the direction-independent vibration-induced response (from the sound-sensitive part of the saccule) and the direction-dependent head acceleration response (from other parts of the labyrinth). SIGNIFICANCE: Skull tap VEMP, as a diagnostic test, is not equivalent to sound-induced VEMP.
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| 9. |
- Brantberg, Krister, et al.
(författare)
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Vestibular evoked myogenic potentials in response to lateral skull taps are dependent on two different mechanisms
- 2009
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Ingår i: Clinical Neurophysiology. - : Elsevier BV. - 1388-2457 .- 1872-8952. ; 120:5, s. 974-979
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To explore the mechanisms for skull tap induced vestibular evoked myogenic potentials (VEMP). METHODS: The muscular responses were recorded over both sternocleidomastoid (SCM) muscles using skin electrodes. A skull tapper which provided a constant stimulus intensity was used to test cervical vestibular evoked myogenic potentials (VEMP) in response to lateral skull taps in healthy subjects (n=10) and in patients with severe unilateral loss of vestibular function (n=10). RESULTS: Skull taps applied approximately 2 cm above the outer ear canal caused highly reproducible VEMP. There were differences in VEMP in both normals and patients depending on side of tapping. In normals, there was a positive-negative ("normal") VEMP on the side contra-lateral to the skull tapping, but no significant VEMP ipsi-laterally. In patients, skull taps above the lesioned ear caused a contra-lateral positive-negative VEMP (as it did in the normals), in addition there was an ipsi-lateral negative-positive ("inverted") VEMP. When skull taps were presented above the healthy ear there was only a small contra-lateral positive-negative VEMP but, similar to the normals, no VEMP ipsi-laterally. CONCLUSIONS: The present data, in conjunction with earlier findings, support a theory that skull-tap VEMP responses are mediated by two different mechanisms. It is suggested that skull tapping causes both a purely ipsi-lateral stimulus side independent SCM response and a bilateral and of opposite polarity SCM response that is stimulus side dependent. Possibly, the skull tap induced VEMP responses are the sum of a stimulation of two species of vestibular receptors, one excited by vibration (which is rather stimulus site independent) and one excited by translation (which is more stimulus site dependent). SIGNIFICANCE: Skull-tap VEMP probably have two different mechanisms. Separation of the two components might reveal the status of different labyrinthine functions.
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