Visual attentional load influences plasticity in the human motor cortex

Neural plasticity plays a critical role in learning, memory, and recovery from injury to the nervous system. Although much is known about the physical and physiological determinants of plasticity, little is known about the influence of cognitive factors. In this study, we investigated whether selective attention plays a role in modifying changes in neural excitability reflecting long-term potentiation (LTP)like plasticity. We induced LTP-like effects in the hand area of the human motor cortex using transcranial magnetic stimulation (TMS). During the induction of plasticity, participants engaged in a visual detection task with either low or high attentional demands. Changes in neural excitability were assessed by measuring motor-evoked potentials in a small hand muscle before and after the TMS procedures. In separate experiments plasticity was induced either by paired associative stimulation (PAS) or intermittent theta-burst stimulation (iTBS). Because these procedures induce different forms of LTP-like effects, they allowed us to investigate the generality of any attentional influence on plasticity. In both experiments reliable changes in motor cortex excitability were evident under low-load conditions, but this effect was eliminated under high-attentional load. In a third experiment we investigated whether the attentional task was associated with ongoing changes in the excitability of motor cortex, but found no difference in evoked potentials across the levels of attentional load. Our findings indicate that in addition to their role in modifying sensory processing, mechanisms of attention can also be a potent modulator of cortical plasticity

Cultural distance, mindfulness and passive xenophobia: Using Integrated Threat Theory to explore home higher education students' perspectives on 'internationalisation at home'

This paper addresses the question of interaction between home and international students using qualitative data from 100 home students at two 'teaching intensive' universities in the southwest of England. Stephan and Stephan's Integrated Threat Theory is used to analyse the data, finding evidence for all four types of threat that they predict when outgroups interact. It is found that home students perceive threats to their academic success and group identity from the presence of international students on the campus and in the classroom. These are linked to anxieties around 'mindful' forms of interaction and a taboo around the discussion of difference, leading to a 'passive xenophobia' for the majority. The paper concludes that Integrated Threat Theory is a useful tool in critiquing the 'internationalisation at home' agenda, making suggestions for policies and practices that may alleviate perceived threats, thereby improving the quality and outcomes of intercultural interaction. © 2010 British Educational Research Association

Determining the optimal current direction of transcranial magnetic stimulation to induce motor responses in the tongue: a preliminary study of neurologically healthy individuals

Objective: To determine the optimal transcranial magnetic stimulation (TMS) coil direction for inducing motor responses in the tongue in a group of non-neurologically impaired participants. Methods: Single-pulse TMS was delivered using a figure-of-eight Magstim 200 TMS coil. Study 1 investigated the effect of eight different TMS coil directions on the motor-evoked potentials elicited in the tongue in eight adults. Study 2 examined active motor threshold levels at optimal TMS coil direction compared to a customarily-used ventral-caudal direction. Study 3 repeated the procedure of Study 1 at five different sites across the tongue motor cortex in one adult. Results: Inter-individual variability in optimal direction was observed, with an optimal range of directions determined for the group. Active motor threshold was reduced when a participant's own optimal TMS coil direction was used compared to the ventral-caudal direction. A restricted range of optimal directions was identified across the five cortical positions tested. Conclusions: There is a need to identify each individual's own optimal TMS coil direction in investigating tongue motor cortex function. A recommended procedure for determining optimal coil direction is described. Significance: Optimized TMS procedures are needed so that TMS can be utilized in determining the underlying neurophysiological basis of various motor speech disorders

Molecularly defined lubricant hydrocarbons from olefin metathesis

Hydrocarbon-based lubricants are ubiquitous in industrial applications but are typically complex mixtures of branched molecules that are challenging to characterize and to relate to their macroscopic properties. Consequently, lubricants are typically optimized empirically for specific applications by blending base oils and organic or inorganic additives. Here, we report the synthesis and characterization of molecularly defined lubricants via metathesis of branched terminal olefins followed by hydrogenation of the internal olefin products. The resulting saturated hydrocarbons are characterized by ultra-high-field (28.2 T) 1H and 13C NMR spectroscopies to establish their molecular structures and resolve different stereoisomers, showing the utility of state-of-the-art spectroscopic tools for resolving structures of branched alkanes. Furthermore, the molecular-level diffusion and bulk viscosity properties compare favorably to classical synthetic lubricants based on hydrogenated polyalphaolefin blends, establishing olefin metathesis as a selective and scalable route to high-performance lubricant oils with defined molecular structures

Analysis of Pigtail Macaque Major Histocompatibility Complex Class I Molecules Presenting Immunodominant Simian Immunodeficiency Virus Epitopes

C1 - Journal Articles Referee

Analysis of Pigtail Macaque Major Histocompatibility Complex Class I Molecules Presenting Immunodominant Simian Immunodeficiency Virus Epitopes

Successful human immunodeficiency virus (HIV) vaccines will need to induce effective T-cell immunity. We studied immunodominant simian immunodeficiency virus (SIV) Gag-specific T-cell responses and their restricting major histocompatibility complex (MHC) class I alleles in pigtail macaques ( Macaca nemestrina ), an increasingly common primate model for the study of HIV infection of humans. CD8 + T-cell responses to an SIV epitope, Gag 164 - 172 KP9, were present in at least 15 of 36 outbred pigtail macaques. The immunodominant KP9-specific response accounted for the majority (mean, 63%) of the SIV Gag response. Sequencing from six macaques identified 7 new Mane-A and 13 new Mane-B MHC class I alleles. One new allele, Mane-A*10 , was common to four macaques that responded to the KP9 epitope. We adapted reference strand-mediated conformational analysis (RSCA) to MHC class I genotype M. nemestrina. Mane-A*10 was detected in macaques presenting KP9 studied by RSCA but was absent from non-KP9-presenting macaques. Expressed on class I-deficient cells, Mane-A*10, but not other pigtail macaque MHC class I molecules, efficiently presented KP9 to responder T cells, confirming that Mane-A*10 restricts the KP9 epitope. Importantly, naïve pigtail macaques infected with SIV mac251 that respond to KP9 had significantly reduced plasma SIV viral levels (log 10 0.87 copies/ml; P = 0.025) compared to those of macaques not responding to KP9. The identification of this common M. nemestrina MHC class I allele restricting a functionally important immunodominant SIV Gag epitope establishes a basis for studying CD8 + T-cell responses against AIDS in an important, widely available nonhuman primate species

A prion protein epitope selective for the pathologically misfolded conformation

Conformational conversion of proteins in disease is likely to be accompanied by molecular surface exposure of previously sequestered amino-acid side chains. We found that induction of β-sheet structures in recombinant prion proteins is associated with increased solvent accessibility of tyrosine. Antibodies directed against the prion protein repeat motif, tyrosine-tyrosinearginine, recognize the pathological isoform of the prion protein but not the normal cellular isoform, as assessed by immunoprecipitation, plate capture immunoassay and flow cytometry. Antibody binding to the pathological epitope is saturable and specific, and can be created in vitro by partial denaturation of normal brain prion protein. Conformation-selective exposure of Tyr-Tyr-Arg provides a probe for the distribution and structure of pathologically misfolded prion protein, and may lead to new diagnostics and therapeutics for prion diseases