Neural multimodal integration underlying synchronization with a co-performer in music: influences of motor expertise and visual information

Sensorimotor synchronization is a general skill that musicians have developed to the highest levels of performance, including synchronization in timing and articulation. This study investigated neurocognitive processes that enable such high levels of performance, specifically testing the relevance of 1) motor resonance and sharing high levels of motor expertise with the co-performer, and 2) the role of visual information in addition to auditory information. Musicians with varying levels of piano expertise (including non-pianists) performed on a single piano key with their right hand along with recordings of a pianist who performed simple melodies with the left hand, synchronizing timing and articulation. The prerecorded performances were presented as audio-only, audio-video, or audio-animation stimuli. Double pulse Transcranial Magnetic Stimulation (dTMS) was applied to test the contribution of the right dorsal premotor cortex (dPMC), an area implicated in motor resonance with observed (left-hand) actions, and the contribution of the right intraparietal sulcus (IPS), an area known for multisensory binding. Results showed effects of dTMS in the conditions that included visual information. IPS stimulation improved synchronization ability, although this effect was found to reverse for the video condition with higher levels of relevant motor expertise. dPMC stimulation improved or worsened synchronization ability. Level of relevant motor expertise was found to influence this direction in the video condition. These results indicate that high levels of relevant motor expertise are required to beneficially employ visual and motor information of a co-performer for sensorimotor synchronization, which may qualify the effects of dPMC and IPS involvement

Do sensorimotor cortex activity, an individual's capacity for neuroplasticity, and psychological features during an episode of acute low back pain predict outcome at 6 months: a protocol for an Australian, multisite prospective, longitudinal cohort study

INTRODUCTION:Low back pain (LBP) is the leading cause of disability worldwide, with prevalence doubling in the past 14 years. To date, prognostic screening tools display poor discrimination and offer no net benefit of screening over and above a 'treat all' approach. Characteristics of the primary sensory (S1) and motor (M1) cortices may predict the development of chronic LBP, yet the prognostic potential of these variables remains unknown. The Understanding persistent Pain Where it ResiDes (UPWaRD) study aims to determine whether sensorimotor cortex activity, an individual's capacity for plasticity and psychosocial factors in the acute stage of pain, predict LBP outcome at 6 months. This paper describes the methods and analysis plan for the development of the prediction model. METHODS AND ANALYSIS:The study uses a multicentre prospective longitudinal cohort design with 6-month follow-up. 120 participants, aged 18 years or older, experiencing an acute episode of LBP (less than 6 weeks duration) will be included. Primary outcomes are pain and disability. ETHICS AND DISSEMINATION:Ethical approval has been obtained from Western Sydney University Human Research Ethics Committee (H10465) and from Neuroscience Research Australia (SSA: 16/002). Dissemination will occur through presentations at national and international conferences and publications in international peer-reviewed journals. TRIAL REGISTRATION NUMBER:ACTRN12619000002189; Pre-results.Luke C Jenkins, Wei-Ju Chang, Valentina Buscemi, Matthew Liston, Barbara Toson, Michael Nicholas, Thomas Graven-Nielsen, Michael Ridding, Paul W Hodges, James H McAuley, Siobhan M Schabru

Intramuscular injection of nerve growth factor as a model of temporomandibular disorder: nature, time-course, and sex differences characterising the pain experience

Background: Temporomandibular disorder (TMD) is a common condition that frequently transitions to chronic symptoms. Experimental pain models that mimic the symptoms of clinical TMD may be useful in understanding the mechanisms, and sex differences, present in this disorder. Here we aimed to comprehensively characterise the nature and time-course of pain, functional impairment and hyperalgesia induced by repeated intramuscular injection of nerve growth factor (NGF) into the masseter muscle, and to investigate sex differences in the NGF-induced pain experience. Methods: 94 healthy individuals participated in a longitudinal study with 30-day follow-up. NGF was injected into the right masseter muscle on Day 0 and Day 2. Participants attended laboratory sessions to assess pain (Numerical Rating Scale; NRS), functional limitation (mouth opening distance, Jaw Functional Limitation Scale; JFLS) and mechanical sensitization (pressure pain thresholds; PPTs) on Days 0, 2 and 5 and completed twice daily electronic pain dairies from Day 0 to day 30. Results: Peak pain averaged 2.0/10 (95 % CI: 1.6–2.4) at rest and 4.3/10 (95 % CI: 3.9–4.8) on chewing. Pain-free mouth opening distance reduced from 5.0 cm (95 % CI: 4.8–5.1 cm) on Day 0 to 3.7 cm (95 % CI: 3.5–3.9 cm) on Day 5. The greatest reduction in PPTs was observed over the masseter muscle. Females experienced higher pain, greater functional impairment, and greater sensitivity to mechanical stimuli than males. Conclusion: Intramuscular injection of NGF is a useful model with which to explore the mechanisms, and sex differences, present in clinical TMD