Long Lasting Modulation of Cortical Oscillations after Continuous Theta Burst Transcranial Magnetic Stimulation

Transcranial magnetic theta burst stimulation (TBS) differs from other high-frequency rTMS protocols because it induces plastic changes up to an hour despite lower stimulus intensity and shorter duration of stimulation. However, the effects of TBS on neuronal oscillations remain unclear. In this study, we used electroencephalography (EEG) to investigate changes of neuronal oscillations after continuous TBS (cTBS), the protocol that emulates long-term depression (LTD) form of synaptic plasticity. We randomly divided 26 healthy humans into two groups receiving either Active or Sham cTBS as control over the left primary motor cortex (M1). Post-cTBS aftereffects were assessed with behavioural measurements at rest using motor evoked potentials (MEPs) and at active state during the execution of a choice reaction time (RT) task in combination with continuous electrophysiological recordings. The cTBS-induced EEG oscillations were assessed using event-related power (ERPow), which reflected regional oscillatory activity of neural assemblies of θ (4–7.5 Hz), low α (8–9.5 Hz), µ (10–12.5 Hz), low β (13–19.5 Hz), and high β (20–30 Hz) brain rhythms. Results revealed 20-min suppression of MEPs and at least 30-min increase of ERPow modulation, suggesting that besides MEPs, EEG has the potential to provide an accurate cortical readout to assess cortical excitability and to investigate the interference of cortical oscillations in the human brain post-cTBS. We also observed a predominant modulation of β frequency band, supporting the hypothesis that cTBS acts more on cortical level. Theta oscillations were also modulated during rest implying the involvement of independent cortical theta generators over the motor network post cTBS. This work provided more insights into the underlying mechanisms of cTBS, providing a possible link between synchronised neural oscillations and LTD in humans

Divergent Cortical Generators of MEG and EEG during Human Sleep Spindles Suggested by Distributed Source Modeling

Background: Sleep spindles are,1-second bursts of 10–15 Hz activity, occurring during normal stage 2 sleep. In animals, sleep spindles can be synchronous across multiple cortical and thalamic locations, suggesting a distributed stable phaselocked generating system. The high synchrony of spindles across scalp EEG sites suggests that this may also be true in humans. However, prior MEG studies suggest multiple and varying generators. Methodology/Principal Findings: We recorded 306 channels of MEG simultaneously with 60 channels of EEG during naturally occurring spindles of stage 2 sleep in 7 healthy subjects. High-resolution structural MRI was obtained in each subject, to define the shells for a boundary element forward solution and to reconstruct the cortex providing the solution space for a noise-normalized minimum norm source estimation procedure. Integrated across the entire duration of all spindles, sources estimated from EEG and MEG are similar, diffuse and widespread, including all lobes from both hemispheres. However, the locations, phase and amplitude of sources simultaneously estimated from MEG versus EEG are highly distinct during the same spindles. Specifically, the sources estimated from EEG are highly synchronous across the cortex, whereas those from MEG rapidly shift in phase, hemisphere, and the location within the hemisphere. Conclusions/Significance: The heterogeneity of MEG sources implies that multiple generators are active during huma

Conformance of mean glandular dose from phantom and patient data in mammography

FANTOMI VRS. POTILASANNOS MAMMOGRAFIASSA (FAPOMA) Taustaa: Mammografialaitteen tarkastuksessa käytetään annosmittauksissa standardipotilasvastinetta eli fantomia (45 mm PMMA), jonka tulisi vastata noin 5 cm vertailurinnan kuvausta. Tämän hetkinen vertailutaso on määritetty näiden tarkastuksista saatujen fantomitulosten perusteella. Vertailutasolla tarkoitetaan etukäteen määriteltyä röntgentutkimuksen säteilyannostasoa, jonka ei oleteta ylittyvän normaalikokoiselle potilaalle hyvän käytännön mukaan tehdyssä toimenpiteessä. Käyttäjien vähintään kolmen vuoden välein tekemä potilaiden säteilyaltistusarviointi tehdään vähintään kymmenen potilaan joukolle. Selvitykseen valitaan tutkimuksia siten, että puristetun rinnan paksuus on keskimäärin 5 cm ja vaihteluväli on 4 – 6 cm. Tästä keskiarvona saatua tulosta verrataan STUKin antamaan vertailutasoon. Nykyisillä laitetyypeillä valotusautomatiikka valitsee usein säteilymäärän lisäksi myös käytettävän säteilylaadun esivalotuksen ja rintakudoksen koostumuksen perusteella. Saman paksuisille rinnoille käytettävä säteilylaatu saattaa vaihdella merkittävästi rintojen koostumuksesta riippuen. Fantomin avulla ei voida simuloida tätä variaatiota ja sen avulla saadaan vain yksi näyte laitteen suorituskyvystä. Tämä työ: Tässä työssä selvitettiin kuinka hyvin fantomilla saatava annosarvio vastaa potilailla mitattua tulosta. Tarkastuksista kerättyä fantomimittausdataa julkaistiin ja esitettiin perusteet STUKin käyttämälle vertailutasolle. Mitattua fantomidataa verrattiin sairaaloiden tekemiin potilasmittauksiin ja lisäksi tehtiin laajempi selvitys kahdella laitteella. Mittaustulosten perusteella arvioitiin myös kuinka hyvin paksuusrajoitetusta datasta vertailurinnalle laskettu tulos kuvaa kaikkien potilaiden keskimääräistä altistusta. Tulokset: Fantomi ja potilastulosten välillä nähdään jopa 30% eroja, kun annos määritetään 5 cm paksuiselle vertailurinnalle. Fantomimittauksen perusteella ei voida täysin todentaa laitteen toimintakykyä potilailla. Kaikkien rintojen paksuus keskiarvo on hyvin lähellä viittä senttiä ja näin ollen paksuusrajoitettu keräys kuvaa hyvin myös kaikkien potilaiden säteilyaltistuksen keskiarvoa. Toisaalta tämä pätee myös toisinpäin eli koko potilasjoukosta saatua laajempaa otosta voidaan mahdollisesti verrata vertailutasoon. Nykyään annoskeräykset voidaan enenevissä määrin toteuttaa sähköisillä keräysjärjestelmillä manuaalisen kirjoitustyön sijasta. Paksuusrajoite on usein esteenä laajemman keräyksen toteuttamiseksi ja tulevaisuudessa voitaisiin harkita myös laajemman ja paksuusrajoittamattoman otoksen sallimista potilasannosmäärityksessä. Johtopäätös: Fantomin käyttö tarkastustyyppisessä laadunvarmistuksessa on perusteltua ja sen avulla voidaan tehdä teknistä tasovertailua laitteiden välillä. Vertailutasot pitäisi kuitenkin määrittää potilaskuvauksista saatavaan dataan perustuen

Connectivity of human brain measured with TMS and EEG

this paper, we will describe how transcallosal conduction times are determined utilizing activation maps, derived from EEG recorded during TMS experiments. We use the electrophysiological reasoning that the rate of the current-density chance in any cortical area is largest during the onset of neuronal firing. When the maximal activation is reached, the rate of the current-density change slows down to zero. We also trace the activation spread post-stimulus and discuss the physiological explanation of the observed spatial activation pattern

Understanding the Effects of Practices on KDE Ecosystem Health

Part 3: Licensing, Strategies, and PracticesInternational audienceOpen source software ecosystems have adjusted and evolved a set of practices over the years to support the delivery of sustainable software. However, few studies have investigated the impacts of such practices on the health of these ecosystems. In this paper, we present the results of an ethnographic-based study conducted during the Latin-American KDE users and contributors meeting (LaKademy 2015) with the goal of collecting practices used within the KDE ecosystem and understanding how they affect ecosystem health. The analysis was based on softgoal interdependency graphs adapted to represent practices and relate them to non-functional requirements and goals. Our results provide a preliminary insight to understand how KDE ecosystem community interacts, which working practices have been adopted and how they affect ecosystem health

Ipsi- and contralateral EEG reactions to transcranial magnetic stimulation

Objectives: Transcranial magnetic stimulation (TMS) and high-resolution electroencephalography (EEG) were used to study the spreading of cortical activation in 6 healthy volunteers. Methods: Five locations in the left sensorimotor cortex (within 3 cm2) were stimulated magnetically, while EEG was recorded with 60 scalp electrodes. A frameless stereotactic method was applied to determine the anatomic locus of stimulation and to superimpose the results on magnetic resonance images. Scalp potential and cortical current-density distributions were derived from averaged electroencephalographic (EEG) data. Results: The maxima of the ipsilateral activation were detected at the gyrus precentralis, gyrus supramarginalis, and lobulus parietalis superior, depending on the subject. Activation over the contralateral cortex was observed in all subjects, appearing at 22±2 ms (range 17–28); the maxima were located at the gyrus precentralis, gyrus frontalis superior, and the lobulus parietalis inferior. Contralateral EEG waveforms showed consistent changes when different sites were stimulated: stimulation of the two most medial points evoked the smallest responses fronto-parietally. Conclusions: With the combination of TMS, EEG, and magnetic resonance imaging, an adequate spatiotemporal resolution may be achieved for tracing the intra- and interhemispheric spread of activation in the cortex caused by a magnetic pulse

Agile’TRIZ Framework: Towards the Integration of TRIZ Within the Agile Innovation Methodology

Part 3: Managing with TRIZInternational audienceApplying TRIZ is difficult, time-consuming and therefore requires implies important development costs: designers spend a lot of time to analyze the problem, to identify the contradictions, and then to develop innovative concepts and propose technical solutions. The efficiency of TRIZ strongly depends on the level of completeness of the problem and the experience of the designer with TRIZ tools. Agile methodologies are commonly used to efficiently develop new products toward an iterative, incremental and adaptive development cycle. They allow to rapidly provide a first technical solution and break the product development work into small increments for minimizing the amount of up-front planning and design. Agile’TRIZ is an Agile-based framework for TRIZ intended for enhancing the innovative skills and the efficiency of the designers, and to provide an efficient approach for quickly analyzing a problem and rapidly developing new innovative solutions using TRIZ tools through an iterative development cycle