Non-invasive induction of plasticity in the human cortex: uses and limitations

The last couple of decades have seen the development of a number of non-invasive brain stimulation (NIBS) techniques that are capable of inducing short-lasting plasticity in the human cortex. Importantly, the induction of lasting plastic changes can, under some conditions, reversibly modify behaviour and interact with learning. These techniques have provided novel opportunities to study human cortical plasticity and examine the role of cortical regions in behaviour. In this review we briefly summarise current NIBS techniques, outline approaches to characterise and quantify cortical plastic change, and describe mechanisms that are implicated in the induced plastic changes. We then outline the areas in which these techniques might be useful, namely, investigating the mechanisms of human cortical plasticity, the characterisation of influences on plasticity, and the investigation of the role of cortical regions in behaviour. Finally, we conclude by highlighting some current limitations of the techniques and suggest that further development of the current NIBS paradigms and more focussed targeting should further enhance the utility of these powerful non-invasive techniques for the investigation of the cortical plasticity and pathophysiology

Non-invasive induction of plasticity in the human cortex: uses and limitations

The last couple of decades have seen the development of a number of non-invasive brain stimulation (NIBS) techniques that are capable of inducing short-lasting plasticity in the human cortex. Importantly, the induction of lasting plastic changes can, under some conditions, reversibly modify behaviour and interact with learning. These techniques have provided novel opportunities to study human cortical plasticity and examine the role of cortical regions in behaviour. In this review we briefly summarise current NIBS techniques, outline approaches to characterise and quantify cortical plastic change, and describe mechanisms that are implicated in the induced plastic changes. We then outline the areas in which these techniques might be useful, namely, investigating the mechanisms of human cortical plasticity, the characterisation of influences on plasticity, and the investigation of the role of cortical regions in behaviour. Finally, we conclude by highlighting some current limitations of the techniques and suggest that further development of the current NIBS paradigms and more focussed targeting should further enhance the utility of these powerful non-invasive techniques for the investigation of the cortical plasticity and pathophysiology

A Case of Henoch-Schonlein Purpura Associated with Rotavirus Infection in an Elderly Asian Male and Review of the Literature.

BACKGROUND Henoch-Schönlein purpura (HSP), a small vessel vasculitis mediated by deposition of immune-complexes containing IgA in the skin, gut, and glomeruli, often presents with abdominal pain, purpuric rash in the lower extremities and buttocks, joint pain, and hematuria. The disease most commonly targets children but can affect adults who tend to have a worse prognosis. CASE REPORT We discuss a case of HSP in an elderly Chinese male who presented with severe proximal bowel inflammation, vasculitic rash, and proteinuria; he was found to have positive stool rotavirus and giardia. He improved significantly with high dose steroids. We believe rotavirus may have been a triggering event in this patient. A brief review of the literature is also presented. CONCLUSIONS This is the first case report describing a classic presentation of HSP in an adult following a rotavirus infection. HSP can cause significant morbidity and mortality in adult patients predominantly from progressive renal failure; therefore careful management and monitoring is important. GI infections seem to be a common trigger for HSP and this case report suggests that rotavirus may be part of the spectrum

Age-related differences in pre- and post-synaptic motor cortex inhibition are task dependent

Abstract not availableGeorge M. Opie, Michael C. Ridding, John G. Semmle

A comparison of neuroplastic responses to non-invasive brain stimulation protocols and motor learning in healthy adults

Non-invasive brain stimulation (NBS) techniques can induce neuroplastic changes similar to those associated with motor learning and there is evidence for the involvement of common mechanisms. Whether there are correlations between the changes induced by NBS and those associated with motor learning remains unclear. We investigated whether there was any relationship between an individual's neuroplastic responses to several different NBS protocols (continuous theta-burst stimulation (cTBS); intermittent theta-burst stimulation (iTBS); facilitatory paired associative stimulation (PAS: inter-stimulus interval 25ms)) and whether these responses correlated with the neuroplastic response associated with a motor training (MT) task involving repeated fast-as-possible thumb abductions. Changes in motor evoked potential (MEP) amplitude were used to assess the neuroplastic response to each protocol. MEP amplitude decreased significantly following cTBS, however there was no significant change in MEP amplitude following iTBS, PAS or MT. There were no significant correlations between individuals' neuroplastic responses to any of the NBS protocols tested or between individuals' neuroplastic responses to the NBS protocols and motor learning. These results provide no support for an association between individuals' neuroplastic responses to several plasticity-inducing protocols. Although there is evidence for involvement of common mechanisms in the neuroplastic changes induced by NBS and motor learning, the results of this study suggest (1) the mechanisms mediating TBS-, PAS-, and MT-induced plasticity may only partially overlap, and (2) additional factors, including large intra and inter-subject response variability, may make the demonstration of associations between neuroplastic responses to the various protocols difficult

The influence of cortical alpha oscillatory activity on motor cortical excitability and plasticity induction

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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

Fate of semi-natural grassland in England between 1960 and 2013: a test of national conservation policy

It is well documented that significant losses in semi-natural grassland occurred across Europe during the second half of the twentieth century. However, comparatively few studies have investigated and quantified the fate of large numbers of individual grassland areas. This is important for understanding the causes of decline, and consequently establishing new policies to conserve and restore lost habitats. This study addresses this problem; GIS was used to compare historic survey data collected between 1960 and 1981 with two contemporary spatial datasets of habitats in England. The datasets included the Priority Habitats Inventory 2013 and the Land Cover Map 2007 and this was undertaken for different types of semi-natural grassland across England. Considerable decreases occurred across the different grassland types, with a loss of 47% of studied semi-natural grasslands sites in England over 32–53 years. Of this, the majority of grassland was lost to conversion to agriculturally-improved grassland or arable cultivation, 45% and 43% respectively. Changes to woodland and urban areas were also evident, but on a much smaller scale. Sites receiving statutory protection as a Site of Special Scientific Interest were found to have retained more grassland (91%), compared with non-protected sites (27%), thus highlighting the effectiveness of this aspect of current conservation policy in England, and the need for this to continue in the future

Investigating the impact of feedback update interval on the efficacy of restorative brain–computer interfaces

Restorative brain-computer interfaces (BCIs) have been proposed to enhance stroke rehabilitation. Restorative BCIs are able to close the sensorimotor loop by rewarding motor imagery (MI) with sensory feedback. Despite the promising results from early studies, reaching clinically significant outcomes in a timely fashion is yet to be achieved. This lack of efficacy may be due to suboptimal feedback provision. To the best of our knowledge, the optimal feedback update interval (FUI) during MI remains unexplored. There is evidence that sensory feedback disinhibits the motor cortex. Thus, in this study, we explore how shorter than usual FUIs affect behavioural and neurophysiological measures following BCI training for stroke patients using a single-case proof-of-principle study design. The action research arm test was used as the primary behavioural measure and showed a clinically significant increase (36%) over the course of training. The neurophysiological measures including motor evoked potentials and maximum voluntary contraction showed distinctive changes in early and late phases of BCI training. Thus, this preliminary study may pave the way for running larger studies to further investigate the effect of FUI magnitude on the efficacy of restorative BCIs. It may also elucidate the role of early and late phases of motor learning along the course of BCI training

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