Cortical recruitment and functional dynamics in postural control adaptation and habituation during vibratory proprioceptive stimulation.

OBJECTIVE: Maintaining upright posture is a complex task governed by the integration of afferent sensorimotor and visual information with compensatory neuromuscular reactions. The objective of the present work was to characterize the visual dependency and functional dynamics of cortical activation during postural control. APPROACH: Proprioceptic vibratory stimulation of calf muscles at 85 Hz was performed to evoke postural perturbation in open-eye (OE) and closed-eye (CE) experimental trials, with pseudorandom binary stimulation phases divided into four segments of 16 stimuli. 64-channel EEG was recorded at 512 Hz, with perturbation epochs defined using bipolar electrodes placed proximal to each vibrator. Power spectra variation and linearity analysis was performed via fast Fourier transformation into six frequency bands (Δ, 0.5-3.5 Hz; θ, 3.5-7.5 Hz; α, 7.5-12.5 Hz; ß, 12.5-30 Hz; [Formula: see text], 30-50 Hz; and [Formula: see text], 50-80 Hz). Finally, functional connectivity assessment was explored via network segregation and integration analyses. MAIN RESULTS: Spectra variation showed waveform and vision-dependent activation within cortical regions specific to both postural adaptation and habituation. Generalized spectral variation yielded significant shifts from low to high frequencies in CE adaptation trials, with overall activity suppressed in habituation; OE trials showed the opposite phenomenon, with both adaptation and habituation yielding increases in spectral power. Finally, our analysis of functional dynamics reveals novel cortical networks implicated in postural control using EEG source-space brain networks. In particular, our reported significant increase in local θ connectivity may signify the planning of corrective steps and/or the analysis of falling consequences, while α band network integration results reflect an inhibition of error detection within the cingulate cortex, likely due to habituation. SIGNIFICANCE: Our findings principally suggest that specific cortical waveforms are dependent upon the availability of visual feedback, and we furthermore present the first evidence that local and global brain networks undergo characteristic modification during postural control.

Treatment as Prevention for Hepatitis C (TraP Hep C) - a nationwide elimination programme in Iceland using direct-acting antiviral agents.

A nationwide programme for the treatment of all patients infected with hepatitis C virus (HCV) was launched in Iceland in January 2016. By providing universal access to direct-acting antiviral agents to the entire patient population, the two key aims of the project were to (i) offer a cure to patients and thus reduce the long-term sequelae of chronic hepatitis C, and (ii) to reduce domestic incidence of HCV in the population by 80% prior to the WHO goal of HCV elimination by the year 2030. An important part of the programme is that vast majority of cases will be treated within 36 months from the launch of the project, during 2016-2018. Emphasis is placed on early case finding and treatment of patients at high risk for transmitting HCV, that is people who inject drugs (PWID), as well as patients with advanced liver disease. In addition to treatment scale-up, the project also entails intensification of harm reduction efforts, improved access to diagnostic tests, as well as educational campaigns to curtail spread, facilitate early detection and improve linkage to care. With these efforts, Iceland is anticipated to achieve the WHO hepatitis C elimination goals well before 2030. This article describes the background and organization of this project. Clinical trial number: NCT02647879.