Levodopa alters resting-state functional connectivity more selectively in Parkinson's disease with freezing of gait.

Freezing of gait (FOG) is a debilitating motor symptom of Parkinson's disease (PD). Although PD dopaminergic medication (L-DOPA) seems to generally reduce FOG severity, its effect on neural mechanisms of FOG remains to be determined. The purpose of this study was to quantify the effect of L-DOPA on brain resting-state functional connectivity in individuals with FOG. Functional magnetic resonance imaging was acquired at rest in 30 individuals living with PD (15 freezers) in the ON- and OFF- medication state. A seed-to-voxel analysis was performed with seeds in the bilateral basal ganglia nuclei, the thalamus and the mesencephalic locomotor region. In freezers, medication-state contrasts revealed numerous changes in resting-state functional connectivity, not modulated by L-DOPA in non-freezers. In freezers, L-DOPA increased the functional connectivity between the seeds and regions including the posterior parietal, the posterior cingulate, the motor and the medial prefrontal cortices. Comparisons with non-freezers revealed that L-DOPA generally normalizes brain functional connectivity to non-freezers levels but can also increase functional connectivity, possibly compensating for dysfunctional networks in freezers. Our findings suggest that L-DOPA could contribute to a better sensorimotor, attentional, response inhibition and limbic processing to prevent FOG when triggers are encountered but could also contribute to FOG by interfering with the processing capacity of the striatum. This study shows that levodopa taken to control PD symptoms induces changes in functional connectivity at rest, in freezers only. Increases (green) in functional connectivity of GPe, GPi, putamen and thalamus with cognitive, sensorimotor and limbic cortical regions of the Interference model (blue) was observed. Our results suggest that levodopa can normalize connections similar to non-freezers or increases connectivity to compensate for dysfunctional networks.

Resting-state Functional Connectivity of the Motor and Cognitive Areas is Preserved in Masters Athletes.

Aging is characterized by a decline in physical and cognitive functions, often resulting in decreased quality of life. Physical activity has been suggested to potentially slow down various aspects of the aging process, a theory that has been supported by studies of Masters Athletes (MA). For example, MA usually have better cognitive and physical functions than age-matched sedentary and healthy older adults (OA), making them a valuable model to gain insights into mechanisms that promote physical and cognitive function with aging. The purpose of this study was to identify differences in resting-state functional connectivity (rs-FC) of motor and cognitive regions between MA and OA and determine if these differences in the resting brain are associated with differences in cognitive and physical performance between groups. Fifteen MA (9 males) and 12 age-matched OA (six males) were included. rs-FC images were compared to identify significant between-groups differences in brain connectivity. There was higher connectivity between the cognitive and motor networks for the OA group, whereas the MA group had stronger connectivity between different regions within the same network, both for the cognitive and the motor networks. These results are in line with the literature suggesting that aging reduces the segregation between functional networks and causes regions within the same network to be less strongly connected. High-level physical activity practiced by the MA most likely contributes to attenuating aging-related changes in brain functional connectivity, preserving clearer boundaries between different functional networks, which may ultimately favor maintenance of efficient cognitive and sensorimotor processing.

Long-Term Impact of Thyroid Biopsy Specialists on Efficiency and Quality of Thyroid Biopsy.

OBJECTIVE: To assess consistency and long-term progress in thyroid biopsy performed by trained sonographers under supervision of a radiologist. METHODS: Trained sonographers started performing thyroid biopsy at our institute in August 2011. The data for this study were extracted from a prospectively maintained database for ultrasound guided thyroid biopsy and included the number of thyroid fine needle aspiration biopsy procedures performed between August 2011 and 2016 and the final cytopathology report as per the Bethesda Classification. For the analysis, the study was divided into two time periods: initial postimplementation period (August 2011 to 2013) and late postimplementation period (2014-2016). RESULTS: In all, 5,538 thyroid biopsies were performed by trained sonographers in the period, 2,561 in the initial implementation period and 2,977 between 2014 and 2016. The unsatisfactory rates dropped from 21% to 10% in the two periods (P < .001), and the proportion of malignant nodules on cytopathology increased from 6% to 7% in the two periods (P = .010). Wait times for thyroid biopsies remained low during the period. CONCLUSION: Sonographers trained to perform ultrasound guided thyroid biopsies provide persistent improved patient care over a long-term period. This reinforces the role of physician extenders in targeted scopes of practice.