Investigating TMS–EEG indices of long-interval intracortical inhibition at different interstimulus intervals

Available online 8 August 2016Abstract not availableGeorge M. Opie, Nigel C. Rogasch, Mitchell R. Goldsworthy, Michael C. Ridding, John G. Semmle

Priming theta burst stimulation enhances motor cortex plasticity in young but not old adults

Abstract not availableGeorge M. Opie, Eleni Vosnakis, Michael C. Ridding, Ulf Ziemann, John G. Semmle

Short-term immobilization influences use-dependent cortical plasticity and fine motor performance

Short-term immobilization that reduces muscle use for 8-10h is known to influence cortical excitability and motor performance. However, the mechanisms through which this is achieved, and whether these changes can be used to modify cortical plasticity and motor skill learning, are not known. The purpose of this study was to investigate the influence of short-term immobilization on use-dependent cortical plasticity, motor learning and retention. Twenty-one adults were divided into control and immobilized groups, both of which underwent two experimental sessions on consecutive days. Within each session, transcranial magnetic stimulation (TMS) was used to assess motor-evoked potential (MEP) amplitudes, short- (SICI) and long-interval intracortical inhibition (LICI), and intracortical facilitation (ICF) before and after a grooved pegboard task. Prior to the second training session, the immobilized group underwent 8h of left hand immobilization targeting the index finger, while control subjects were allowed normal limb use. Immobilization produced a reduction in MEP amplitudes, but no change in SICI, LICI or ICF. While motor performance improved for both groups in each session, the level of performance was greater 24-h later in control, but not immobilized subjects. Furthermore, training-related MEP facilitation was greater after, compared with before, immobilization. These results indicate that immobilization can modulate use-dependent plasticity and the retention of motor skills. They also suggest that changes in intracortical excitability are unlikely to contribute to the immobilization-induced modification of cortical excitability.George M. Opie, Alexandra Evans, Michael C. Ridding and John G. Semmle

An analytic model for a cooperative ballistic deposition in one dimension

We formulate a model for a cooperative ballistic deposition (CBD) process whereby the incoming particles are correlated with the ones already adsorbed via attractive force. The strength of the correlation is controlled by a tunable parameter $a$ that interpolates the classical car parking problem at $a=0$, the ballistic deposition at $a=1$ and the CBD model at $a>1$. The effects of the correlation in the CBD model are as follows. The jamming coverage $q(a)$ increases with the strength of attraction $a$ due to an ever increasing tendency of cluster formation. The system almost reaches the closest packing structure as $a\to\infty$ but never forms a percolating cluster which is typical to 1D system. In the large $a$ regime, the mean cluster size $k$ increases as $a^{1/2}$. Furthermore, the asymptotic approach towards the closest packing is purely algebraic both with $a$ as $q(\infty)-q(a) \sim a^{-1/2}$ and with $k$ as $q(\infty)-q(k) \sim k^{-1}$ where $q(\infty)\simeq 1$.Comment: 9 pages (in Revtex4), 9 eps figures; Submitted to publicatio

Determinants of the essential one-carbon metabolism metabolites, homocysteine, S-adenosylmethionine, S-adenosylhomocysteine and folate, in cerebrospinal fluid

Background: Disturbances in the levels of one-carbon (1C) metabolism metabolites have been associated with a wide variety of neuropsychiatric diseases. Cerebrospinal fluid (CSF) levels of homocysteine (Hcy) and the other 1C metabolites, nor their interrelatedness and putative determinants, have been studied extensively in a healthy population. Methods: Plasma and CSF samples from 100 individuals free from neuropsychiatric diseases were analyzed (55 male, 45 female; age 50±17 years). In blood, we measured plasma Hcy, serum folate and serum vitamin B12. In CSF, we measured total Hcy, S-adenosylmethionine (SAM), S-adenosylhomocysteine (SAH) and 5-methyltetrahydrofolate (5-methylTHF). Highly selective analytical methods like liquid chromatography combined with either mass spectrometry or fluorescence detection were used. Results: CSF Hcy was inversely correlated with CSF 5-methylTHF and positively with plasma Hcy, independent of serum folate status. CSF SAH correlated with age, lower CSF 5-methylTHF and higher CSF Hcy. CSF 5-methylTHF showed independent negative correlations with age and positive correlations with serum folate. CSF SAM did not correlate with any of the 1C metabolites. Conclusions: Aging is characterized by a reduction in CSF 5-methylTHF levels and increased CSF levels of the potentially neurotoxic transmethylation inhibitor SAH. CSF 5-methylTHF, which is itself determined in part by systemic folate status, is a powerful independent determinant of CSF levels of Hcy and SA

Rapid translocation of nanoparticles from the lung airspaces to the body

Nano-size particles show promise for pulmonary drug delivery, yet their behavior after deposition in the lung remains poorly understood. In this study, a series of near-infrared (NIR) fluorescent nanoparticles were systematically varied in chemical composition, shape, size and surface charge, and their biodistribution and elimination were quantified in rat models after lung instillation. We demonstrate that nanoparticles with hydrodynamic diameter (HD) less than ≈34 nm and a noncationic surface charge translocate rapidly from the lung to mediastinal lymph nodes. Nanoparticles of HD < 6 nm can traffic rapidly from the lungs to lymph nodes and the bloodstream, and then be subsequently cleared by the kidneys. We discuss the importance of these findings for drug delivery, air pollution and carcinogenesis

Study of B^0 -> rho^0 rho^0 decays, implications for the CKM angle phi_2 and search for other B^0 decay modes with a four-pion final state

We present a study of the branching fraction of the decay B^0->rho0rho0 and the fraction of longitudinally polarized rho0 mesons in this decay. The results are obtained from the final data sample containing 772 million BBbar pairs collected at the Y(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider. We find 166 +- 59 B^0 -> rho0 rho0 events (including systematic uncertainties), corresponding to a branching fraction of B(B^0->rho0rho0) = (1.02 +- 0.30 (stat) +- 0.15 (syst)) x 10^{-6} with a significance of 3.4 standard deviations and a longitudinal polarization fraction fL = 0.21^{+0.18}_{-0.22} (stat) +- 0.15 (syst). We use the longitudinal polarization fraction to determine the Cabibbo-Kobayashi-Maskawa matrix angle phi_2 = (84.9 +- 13.5) degrees through an isospin analysis in the B->rhorho system. We furthermore find 149 +- 49 B^0->f0rho0 events, corresponding to B(B^0->f0rho0) x B(f0->pi+pi-) = (0.78 +- 0.22 (stat) +- 0.11 (syst)) x 10^{-6}, with a significance of 3.1 standard deviations. We find no other significant contribution with the same final state, and set upper limits at 90% confidence level on the (product) branching fractions, B(B^0->pi+pi-pi+pi-)rho0pi+pi-)<12.0 x 10^{-6}, B(B^0->f0pi+pi-) x B(f0->pi+pi-) f0f0) x B(f0->pi+pi-)^{2} < 0.2 x 10^{-6}.Comment: 21 pages, 20 figures, conference paper for the 2012th CKM workshop, submitted to PR

Measurement of the branching ratio of Bˉ→D(∗)τ−νˉτ\bar{B} \to D^{(\ast)} \tau^- \bar{\nu}_\tau relative to Bˉ→D(∗)ℓ−νˉℓ\bar{B} \to D^{(\ast)} \ell^- \bar{\nu}_\ell decays with hadronic tagging at Belle

We report a measurement of the branching fraction ratios R(D(*)) of Bbar -> D(*) tau- nubar_tau relative to Bbar -> D()* l- nubar_l (where l = e or mu) using the full Belle data sample of 772 x 10^6 BBbar pairs collected at the Y(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider. The measured values are R(D)= 0.375 +- 0.064(stat.) +- 0.026(syst.) and R(D*) = 0.293 +- 0.038(stat.) +- 0.015(syst.). The analysis uses hadronic reconstruction of the tag-side B meson and purely leptonic tau decays. The results are consistent with earlier measurements and do not show a significant deviation from the standard model prediction.Comment: Accepted for publication in Phys.Rev.