| 1. |
- Söderlund, Göran, 1955-
(författare)
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Noise improves cognitive performance in children with dysfunctional neurotransmission
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Research on children with Attention Deficit Hyperactivity Disorder (ADHD) has shown that they are extremely sensitive to distraction from external stimuli that lead to poor cognitive performance. This thesis shows that cognitive performance can be improved if this external stimulus is smooth and continuous (e.g. auditory white noise). Control children attenuate their performance under such conditions. The first Study proposes the moderate brain arousal model (MBA). This neurocomputational model predicts selective improvement from noise in ADHD children. Noise through a phenomenon called stochastic resonance (SR), can be beneficial in dopamine deprived neural systems. The statistical phenomenon of SR explains how the signal-to-noise ratio can be improved by noise in neural systems where the passing a threshold is required. The second Study provides experimental support for the MBA-model by showing that ADHD children improve performance in a free recall task while exposed to auditive noise. Control children declines in the same condition. The third Study generalizes this finding among low achieving children, which it is argued have low dopamine levels. Noise exposure improves performance in low achievers, but inhibits performance in high achievers. The conclusion is that external auditory noise can restore low dopamine levels and thus improve cognitive performance. It is also proposed that dopamine levels modulate the SR effect; this means that low dopamine persons require more noise to obtain an SR effect. Both excessive and insufficient dopamine is detrimental for cognitive performance. The MBA model can be used to explain several shortcomings where changes in the dopamine system have been identified. The MBA model can also help create appropriate and adaptive environments, especially in schools, for persons with a deficient dopamine function, such as ADHD children.
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| 2. |
- Wikgren, Mikael, 1981-, et al.
(författare)
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Shorter telomere length is linked to brain atrophy and white matter hyperintensities
- 2014
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Ingår i: Age and Ageing. - : Oxford University Press (OUP). - 0002-0729 .- 1468-2834. ; 43:2, s. 212-217
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Tidskriftsartikel (refereegranskat)abstract
- Background: leukocyte telomere length (TL) is considered a marker of biological aging. Several studies have investigated the link between leukocyte TL and aging-associated functional attributes of the brain, but no prior study has investigated whether TL can be linked to brain atrophy and white matter hyperintensities (WMHs); two prominent structural manifestations of brain aging. Methods: we investigated whether leukocyte TL was related to brain atrophy and WMHs in a sample of 102 non-demented individuals aged 64-75 years. Results: shorter TL was related to greater degree of subcortical atrophy (beta = -0.217, P = 0.034), but not to cortical atrophy. Furthermore, TL was 371 bp shorter (P = 0.041) in participants exhibiting subcortical WMHs, and 552 bp shorter (P = 0.009) in older participants exhibiting periventricular WMHs. Conclusion: this study provides the first evidence of leukocyte TL being associated with cerebral subcortical atrophy and WMHs, lending further support to the concept of TL as a marker of biological aging, and in particular that of the aging brain.
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| 3. |
- Berggren Söderlund, Maria, et al.
(författare)
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Concentrations of retinoids in early pregnancy and in newborns and their mothers.
- 2005
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Ingår i: American Journal of Clinical Nutrition. - 1938-3207. ; 81:3, s. 633-636
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Tidskriftsartikel (refereegranskat)abstract
- Background: Retinoids are vital for embryonic development; both excesses and deficiencies of vitamin A are known to give similar patterns of birth defects. Concentrations of retinol in newborns and in pregnant women have been investigated, but concentrations of the biologically active metabolite all-trans retinoic acid and its isomer 13-cis retinoic acid have not. Objective: We measured serum concentrations of these retinoid derivatives in newborns and their mothers and in women in the first trimester of pregnancy, when embryonic differentiation (organogenesis) takes place. Design: In this descriptive study, 10 newborns from normal deliveries and their mothers and 16 healthy women in their first trimester of pregnancy were studied. Seventeen healthy women served as control subjects. all-trans and 13-cis Retinoic acid and retinol concentrations were measured by HPLC. Results: The newborns had significantly lower retinol concentrations (1.0 mu mol/L) than did their mothers (1.7 mu mol/L; P = 0.013). Serum all-trans retinoic acid was also significantly lower in the newborns (3.4 nmol/L) than in their mothers (5.8 nmol/L; P = 0.008). In addition, serum concentrations of 13-cis retinoic acid were significantly lower in the newborns (2.0 nmol/L) than in their mothers (2.6 nmol/L; P = 0.005). The serum concentrations of all-trans retinoic acid and retinol did not correlate in any group. Conclusion: Retinol concentrations do not accurately reflect the concentrations of the biologically active derivative all-trans retinoic acid.
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| 6. |
- Brinkfeldt, Klas, et al.
(författare)
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Feasibility of PCB-integrated vibration sensors for condition monitoring of electronic systems
- 2018
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Ingår i: ASME 2018 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems, InterPACK 2018. - 9780791851920
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Konferensbidrag (refereegranskat)abstract
- The increasing complexity of electronics in systems used in safety critical applications, such as for example self-driving vehicles requires new methods to assure the hardware reliability of the electronic assemblies. Prognostics and Health Management (PHM) that uses a combination of data-driven and Physics-of-Failure models is a promising approach to avoid unexpected failures in the field. However, to enable PHM based partly on Physics-of-Failure models, sensor data that measures the relevant environment loads to which the electronics is subjected during its mission life are required. In this work, the feasibility to manufacture and use integrated sensors in the inner layers of a printed circuit board (PCB) as mission load indicators measuring impacts and vibrations has been investigated. A four-layered PCB was designed in which piezoelectric sensors based on polyvinylidenefluoride-co-trifluoroethylene (PVDF-TrFE) were printed on one of the laminate layers before the lamination process. Manufacturing of the PCB was followed by the assembly of components consisting of BGAs and QFN packages in a standard production reflow soldering process. Tests to ensure that the functionality of the sensor material was unaffected by the soldering process were performed. Results showed a yield of approximately 30 % of the sensors after the reflow soldering process. The yield was also dependent on sensor placement and possibly shape. Optimization of the sensor design and placement is expected to bring the yield to 50 % or better. The sensors responded as expected to impact tests. Delamination areas were present in the test PCBs, which requires further investigation. The delamination does not seem to be due to the presence of embedded sensors alone but rather the result of a combination of several factors. The conclusion of this work is that it is feasible to embed piezoelectric sensors in the layers of a PCB.
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| 7. |
- Brinkfeldt, Klas, et al.
(författare)
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Feasibility of Printed Circuit Board-Integrated Vibration Sensors for Condition Monitoring of Electronic Systems
- 2019
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Ingår i: Journal of Electronic Packaging. - : American Society of Mechanical Engineers (ASME). - 1043-7398 .- 1528-9044. ; 141:3
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Tidskriftsartikel (refereegranskat)abstract
- The increasing complexity of electronics in systems used in safety critical applications, such as self-driving vehicles, requires new methods to assure the hardware reliability of the electronic assemblies. Prognostics and health management (PHM) that uses a combination of data-driven and physics-of-failure models is a promising approach to avoid unexpected failures in the field. However, to enable PHM based partly on physics-of-failure models, sensor data that measure the relevant environment loads to which the electronics are subjected during its mission life are required. In this work, the feasibility to manufacture and use integrated sensors in the inner layers of a printed circuit board (PCB) as mission load indicators measuring impacts and vibrations has been investigated. A four-layered PCB was designed in which piezoelectric sensors based on polyvinylidenefluoride-co-trifluoroethylene (PVDF-TrFE) were printed on one of the laminate layers before the lamination process. Manufacturing of the PCB was followed by the assembly of components consisting of ball grid arrays (BGAs) and quad flat no-leads (QFN) packages in a standard production reflow soldering process. Tests to ensure that the functionality of the sensor material was unaffected by the soldering process were performed. Results showed a yield of approximately 30% of the sensors after the reflow soldering process. The yield was also dependent on sensor placement and possibly shape. Optimization of the sensor design and placement is expected to bring the yield to 50% or better. The sensors responded as expected to impact tests. Delamination areas were present in the test PCBs, which requires further investigation. The delamination does not seem to be due to the presence of embedded sensors alone but rather the result of a combination of several factors. The conclusion of this work is that it is feasible to embed piezoelectric sensors in the layers of a PCB.
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| 8. |
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| 9. |
- Egeland, Jens, et al.
(författare)
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Effects of auditory white noise stimulation on sustained attention and response time variability
- 2023
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Ingår i: Frontiers in Psychology. - 1664-1078. ; 14
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: “The moderate brain arousal model” claims that white noise improves attention by optimizing brain arousal. We analyze Conners’ Continuous Performance Test-3 (CCPT-3) performance, expecting to find reduced reaction time variability with noise mediated by decrease under long event-rates and in later parts of the test, indicating that noise reverse fall in phasic and tonic arousal. Methods: Sixty-five children with high or lower ADHD-symptoms from a child psychiatric unit, succeeded to complete the CCPT-3 with and without white noise. Results: Noise reduced overall variability, improved performance in later parts of the test, and reduced response variability under the longest event rate particularly in the high symptoms group. No overall change in omissions and commissions, but the high symptoms group made fewer omissions during noise compared the low symptom group. Discussion: The study indicates an arousal effect of noise but should be replicated with other noise variants and amplitudes to improve effect and compliance.
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| 10. |
- Göran, Söderlund, et al.
(författare)
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Listen to the Noise: Noise is Beneficial for Cognitive Performance in ADHD
- 2007
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Ingår i: Journal of Child Psychology and Psychiatry and Allied Disciplines. - : Wiley. - 0021-9630 .- 1469-7610. ; 48:8, s. 840-847
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Tidskriftsartikel (refereegranskat)abstract
- Background: Noise is typically conceived of as being detrimental to cognitive performance. However, given the mechanism of stochastic resonance, a certain amount of noise can benefit performance. We investigate cognitive performance in noisy environments in relation to a neurocomputational model of attention deficit hyperactivity disorder (ADHD) and dopamine. The Moderate Brain Arousal model (MBA; Sikstro¨m & So¨derlund, 2007) suggests that dopamine levels modulate how much noise is required for optimal cognitive performance. We experimentally examine how ADHD and control children respond to different encoding conditions, providing different levels of environmental stimulation. Methods: Participants carried out self-performed mini tasks (SPT), as a high memory performance task, and a verbal task (VT), as a low memory task. These tasks were performed in the presence, or absence, of auditory white noise. Results: Noise exerted a positive effect on cognitive performance for the ADHD group and deteriorated performance for the control group, indicating that ADHD subjects need more noise than controls for optimal cognitive performance. Conclusions: The positive effect of white noise is explained by the phenomenon of stochastic resonance (SR), i.e., the phenomenon that moderate noise facilitates cognitive performance. The MBA model suggests that noise in the environment, introduces internal noise into the neural system through the perceptual system. This noise induces SR in the neurotransmitter systems and makes this noise beneficial for cognitive performance. In particular, the peak of the SR curve depends on the dopamine level, so that participants with low dopamine levels (ADHD) require more noise for optimal cognitive performance compared to controls. Keywords: ADHD, stochastic resonance, dopamine, episodic memory, SPT, noise. Abbreviations: MBA: moderate brain arousal; SR: stochastic resonance; SPT: subject-performed task; VT: verbal task (VT).
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