33 research outputs found

    Multimodal characterisation of sensorimotor oscillations

    Get PDF
    The studies in this project have investigated the ongoing neuronal network oscillatory activity found in the sensorimotor cortex using two modalities: magnetoencephalography (MEG) and in vitro slice recordings. The results have established that ongoing sensorimotor oscillations span the mu and beta frequency region both in vitro and in MEG recordings, with distinct frequency profiles for each recorded laminae in vitro, while MI and SI show less difference in humans. In addition, these studies show that connections between MI and SI modulate the ongoing neuronal network activity in these areas. The stimulation studies indicate that specific frequencies of stimulation affect the ongoing activity in the sensorimotor cortex. The continuous theta burst stimulation (cTBS) study demonstrates that cTBS predominantly enhances the power of the local ongoing activity. The stimulation studies in this project show limited comparison between modalities, which is informative of the role of connectivity in these effects. However, independently these studies provide novel information on the mechanisms on sensorimotor oscillatory interaction. The pharmacological studies reveal that GABAergic modulation with zolpidem changes the neuronal oscillatory network activity in both healthy and pathological MI. Zolpidem enhances the power of ongoing oscillatory activity in both sensorimotor laminae and in healthy subjects. In contrast, zolpidem attenuates the “abnormal” beta oscillatory activity in the affected hemisphere in Parkinsonian patients, while restoring the hemispheric beta power ratio and frequency variability and thereby improving motor symptomatology. Finally we show that independent signals from MI laminae can be integrated in silico to resemble the aggregate MEG MI oscillatory signals. This highlights the usefulness of combining these two methods when elucidating neuronal network oscillations in the sensorimotor cortex and any interventions

    A multimodal perspective on the composition of cortical oscillations:frontiers in human neuroscience

    Get PDF
    An expanding corpus of research details the relationship between functional magnetic resonance imaging (fMRI) measures and neuronal network oscillations. Typically, integratedelectroencephalography(EEG) and fMRI,orparallel magnetoencephalography (MEG) and fMRI are used to draw inference about the consanguinity of BOLD and electrical measurements. However, there is a relative dearth of information about the relationship between E/MEG and the focal networks from which these signals emanate. Consequently, the genesis and composition of E/MEG oscillations requires further clarification. Here we aim to contribute to understanding through a series of parallel measurements of primary motor cortex (M1) oscillations, using human MEG and in-vitro rodent local field potentials. We compare spontaneous activity in the ~10Hz mu and 15-30Hz beta frequency ranges and compare MEG signals with independent and integrated layers III and V(LIII/LV) from in vitro recordings. We explore the mechanisms of oscillatory generation, using specific pharmacological modulation with the GABA-A alpha-1 subunit modulator zolpidem. Finally, to determine the contribution of cortico-cortical connectivity, we recorded in-vitro M1, during an incision to sever lateral connections between M1 and S1 cortices. We demonstrate that frequency distribution of MEG signals appear have closer statistically similarity with signals from integrated rather than independent LIII/LV laminae. GABAergic modulation in both modalities elicited comparable changes in the power of the beta band. Finally, cortico-cortical connectivity in sensorimotor cortex (SMC) appears to directly influence the power of the mu rhythm in LIII. These findings suggest that the MEG signal is an amalgam of outputs from LIII and LV, that multiple frequencies can arise from the same cortical area and that in vitro and MEG M1 oscillations are driven by comparable mechanisms. Finally, corticocortical connectivity is reflected in the power of the SMC mu rhythm. © 2013 Ronnqvist, Mcallister, Woodhall, Stanford and Hall

    Oscillatory beta activity mediates neuroplastic effects of motor cortex stimulation in humans

    Get PDF
    Continuous theta burst stimulation (cTBS) is a repetitive transcranial magnetic stimulation protocol that can inhibithumanmotor cortex (M1) excitability and impair movement for ≀1 h. While offering valuable insights into brain function and potential therapeutic benefits, these neuroplastic effects are highly variable between individuals. The source of this variability, and the electrophysiological mechanisms underlying the inhibitory after-effects, are largely unknown. In this regard, oscillatory activity at beta frequency (15-35 Hz) is of particular interest as it is elevated in motor disorders such as Parkinson's disease and modulated during the generation of movements. Here, we used a source-level magnetoencephalography approach to investigate the hypothesis that the presence of neuroplastic effects following cTBS is associated with concurrent changes in oscillatory M1 beta activity. M1 cortices were localized with a synthetic aperture magnetometry beamforming analysis of visually cued index finger movements. Virtual electrode analysis was used to reconstruct the spontaneous and movement-related oscillatory activity in bilateral M1 cortices, before and from 10 to 45 min after cTBS. We demonstrate that 40 s of cTBS applied over left M1 reduced corticospinal excitability in the right index finger of 8/16 participants. In these responder participants only, cTBS increased the power of the spontaneous beta oscillations in stimulated M1 and delayed reaction times in the contralateral index finger. No further changes were observed in the latency or power of movement-related beta oscillations. These data provide insights into the electrophysiological mechanisms underlying cTBS-mediated impairment of motor function and demonstrate the association between spontaneous oscillatory beta activity in M1 and the inhibition of motor function. © 2013 the authors

    Quantitative assessment based on kinematic measures of functional impairments during upper extremity movements: a review

    Full text link
    Quantitative measures of human movement quality are important for discriminating healthy and pathological conditions and for expressing the outcomes and clinically important changes in subjects' functional state. However the most frequently used instruments for the upper extremity functional assessment are clinical scales, that previously have been standardized and validated, but have a high subjective component depending on the observer who scores the test. But they are not enough to assess motor strategies used during movements, and their use in combination with other more objective measures is necessary. The objective of the present review is to provide an overview on objective metrics found in literature with the aim of quantifying the upper extremity performance during functional tasks, regardless of the equipment or system used for registering kinematic data

    Obemannade system, ett hot mot marinen?

    No full text
    I en komplex miljö som skĂ€rgĂ„rdar vĂ€ntar en del utmaningar. Detta tillsammans med den teknik som finns idag inom UAV omrĂ„det skapar nya hotbilder. Ett av fartygen som den svenska flottan anvĂ€nder Ă€r Visbykorvetten, som Ă€r ett komplext system med kompetent förmĂ„ga som ska kunna lösa mĂ„nga uppgifter. Rapporten avser att analysera vilket hot som drönare kan utgöra mot Visbykorvetten.   NĂ„gra UAV som anvĂ€nds i kriget i Ukraina Ă€r Switchblade 300, 600 och Shahed-136. Arbetet syftar till att undersöka dessa UAV och vilket hot de kan utgöra mot en Visbykorvett, i syfte för att se om korvettens skydd Ă€r tillrĂ€ckligt.  Fartyget har ett bra egenskydd mot ankommande hot frĂ„n luften, dock pĂ„ grund av vapensystemens placering pĂ„ fartyget uppstĂ„r en begrĂ€nsning i möjligheterna att erhĂ„lla ett eget skydd runt hela fartyget. Detta kan Ă€ven försvĂ„ras av den komplexa miljö som skĂ€rgĂ„rden medför. BegrĂ€nsningen i egenskyddet bedöms en UAV kunna nyttja och pĂ„ sĂ„ sĂ€tt fĂ„ möjligheten att skada fartygets sensorer som sitter relativt oskyddade. Vilket medför att fartyget inte fullt ut kan lösa tilldelade uppgifter utan Ă€r behov av att repareras. För att undvika detta kan fyra olika Ă„tgĂ€rder vidtas. Undvika trĂ„nga sund om det Ă€r möjligt, frĂ„ga externa marina förband om eskortmöjligheter, eller installera vapenstation pĂ„ akterdĂ€ck för att öka egenskyddet, och ge fartyget signalstörningsförmĂ„ga.The complex environments that the archipelago provides, alongside the technical developments of drones, create a new form of threat. The Visby class corvette is a complex platform that can fulfil many different tasks both above and below the surface. This thesis will look closer at its surface-to-air defense system, and capability to defend against drones. Some of the drones that are used in the Russo-Ukrainian war, are Switchblade 300, 600 and Shahed-136. The thesis aims to investigate these drones and what threat they may pose against a Visby Corvette, to see if the ship’s protection is sufficient.  The ship has good self-protection against incoming threats from the air, but due to the location of the weapon systems on the ship, there is a limitation in obtaining full protection. The protection can also be hampered by the complex environment that the archipelago entails. A drone can exploit this limitation of self-protection and obtain the possibility of damaging the sensors of the ship that are relatively unprotected. This means that the ship cannot fully solve the assigned tasks due to its need for repairs.  In conclusion, to prevent this, four different actions can be taken. Avoid narrow straits, if possible. Ask external units for escort. Install a weapon station in the stern to increase self-protection and provide the vessel with signal interference technology

    Obemannade system, ett hot mot marinen?

    No full text
    I en komplex miljö som skĂ€rgĂ„rdar vĂ€ntar en del utmaningar. Detta tillsammans med den teknik som finns idag inom UAV omrĂ„det skapar nya hotbilder. Ett av fartygen som den svenska flottan anvĂ€nder Ă€r Visbykorvetten, som Ă€r ett komplext system med kompetent förmĂ„ga som ska kunna lösa mĂ„nga uppgifter. Rapporten avser att analysera vilket hot som drönare kan utgöra mot Visbykorvetten.   NĂ„gra UAV som anvĂ€nds i kriget i Ukraina Ă€r Switchblade 300, 600 och Shahed-136. Arbetet syftar till att undersöka dessa UAV och vilket hot de kan utgöra mot en Visbykorvett, i syfte för att se om korvettens skydd Ă€r tillrĂ€ckligt.  Fartyget har ett bra egenskydd mot ankommande hot frĂ„n luften, dock pĂ„ grund av vapensystemens placering pĂ„ fartyget uppstĂ„r en begrĂ€nsning i möjligheterna att erhĂ„lla ett eget skydd runt hela fartyget. Detta kan Ă€ven försvĂ„ras av den komplexa miljö som skĂ€rgĂ„rden medför. BegrĂ€nsningen i egenskyddet bedöms en UAV kunna nyttja och pĂ„ sĂ„ sĂ€tt fĂ„ möjligheten att skada fartygets sensorer som sitter relativt oskyddade. Vilket medför att fartyget inte fullt ut kan lösa tilldelade uppgifter utan Ă€r behov av att repareras. För att undvika detta kan fyra olika Ă„tgĂ€rder vidtas. Undvika trĂ„nga sund om det Ă€r möjligt, frĂ„ga externa marina förband om eskortmöjligheter, eller installera vapenstation pĂ„ akterdĂ€ck för att öka egenskyddet, och ge fartyget signalstörningsförmĂ„ga.The complex environments that the archipelago provides, alongside the technical developments of drones, create a new form of threat. The Visby class corvette is a complex platform that can fulfil many different tasks both above and below the surface. This thesis will look closer at its surface-to-air defense system, and capability to defend against drones. Some of the drones that are used in the Russo-Ukrainian war, are Switchblade 300, 600 and Shahed-136. The thesis aims to investigate these drones and what threat they may pose against a Visby Corvette, to see if the ship’s protection is sufficient.  The ship has good self-protection against incoming threats from the air, but due to the location of the weapon systems on the ship, there is a limitation in obtaining full protection. The protection can also be hampered by the complex environment that the archipelago entails. A drone can exploit this limitation of self-protection and obtain the possibility of damaging the sensors of the ship that are relatively unprotected. This means that the ship cannot fully solve the assigned tasks due to its need for repairs.  In conclusion, to prevent this, four different actions can be taken. Avoid narrow straits, if possible. Ask external units for escort. Install a weapon station in the stern to increase self-protection and provide the vessel with signal interference technology

    Korsningspunkter mellan fotgÀngare och cyklister

    No full text
    Rapporten Ă€r framtagen med ekonomiska bidrag frĂ„n Trafikverket, Skyltfonden. StĂ„ndpunkter och slutsatser i rapporten reflekterar författaren och överensstĂ€mmer inte med nödvĂ€ndighet med Trafikverkets stĂ„ndpunkter och slutsatser inom rapportens Ă€mnesomrĂ„den.Resor till fots och med cykel Ă€r viktiga delar i arbetet mot de transportpolitiska mĂ„len. För att fĂ„ fler att anvĂ€nda dessa transportmedel Ă€r det av stor vikt att utformningen av infrastrukturen Ă€r vĂ€l genomtĂ€nkt och utformad pĂ„ ett sĂ€tt som frĂ€mjar sĂ„vĂ€l hög trafiksĂ€kerhet som upplevd trygghet och framkomlighet för dessa trafikslag. Korsningspunkter Ă€r sĂ€rskilt utsatta platser eftersom flera olika typer av trafikanter korsar varandras vĂ€gar vilket leder till en ökad risk för konflikter. För att göra utformningen tydligare anvĂ€nds ibland övergĂ„ngsstĂ€lle pĂ„ cykelbanan men dess effekt Ă€r oklar och det finns inga tydliga riktlinjer för nĂ€r denna Ă„tgĂ€rd bör anvĂ€ndas. Syftet med studien Ă€r att undersöka hur cyklister och gĂ„ende samspelar i korsningspunkter med övergĂ„ngsstĂ€lle pĂ„ cykelbanan. Syftet Ă€r ocksĂ„ att skapa bĂ€ttre förstĂ„else för vad som leder till konflikter vid korsningspunkter mellan gĂ„ende och cyklister. Studien syftar Ă€ven till att leda till ny kunskap som kan anvĂ€ndas som stöd vid utformning av korsningspunkter för cyklister och fotgĂ€ngare, med fokus pĂ„ övergĂ„ngsstĂ€llets lĂ€mplighet. Resultatet frĂ„n observationerna visar att de allra flesta som passerar korsningspunkterna kan göra det utan att synligt interagera med andra trafikanter. De interaktioner som sker Ă€r i de allra flesta fall lugna, utan risk för olyckor. Det Ă€r vĂ€ldigt fĂ„ cyklister som vĂ€jer, trots att det Ă€r övergĂ„ngsstĂ€lle pĂ„ cykelbanan. PĂ„ samtliga platser Ă€r fotgĂ€ngarna i tydlig majoritet bland de som vĂ€jer. Det Ă€r ingen tydlig skillnad mellan platser med och utan övergĂ„ngsstĂ€lle. Slutsatsen Ă€r att övergĂ„ngsstĂ€llen inte har nĂ„gon pĂ„visad effekt i sig sjĂ€lv. IstĂ€llet krĂ€vs det att man arbetar med fler element i korsningspunkter för att sĂ€kerstĂ€lla hög trafiksĂ€kerhet. För att kunna skapa korsningspunkter som Ă€r attraktiva och som gör att trafikanter kan kĂ€nna sig trygga Ă€r det till exempel viktigt med god sikt och Ă„tgĂ€rder som generösa ytor för fotgĂ€ngare.ÖvergĂ„ngsstĂ€llen kan vara ett hjĂ€lpmedel i utformningen av korsningspunkter men i sĂ„ fall mĂ„ste det utvecklas metoder och strategier som gör att fler respekterar regleringen.(Trafikverkets beteckning: TRV 2018/105634 ”En förbĂ€ttrad utformning av befintliga cykel-gĂ„ende, cykel-cykel och cykel-fordonkorsningar”)Projektet har utförts under 2019 och 2020. Projektet slutrapporterades i maj 2020
    corecore