Development of a Tool to Measure the Dyadic Process of Shared Decision Making in Young Children: The Making Decisions for Kids (MADE for Kids) Survey.

Parkinson's disease (PD) is a progressive motor disorder caused by the degeneration of dopaminergic neurons in the substantia nigra pars compacta region of the midbrain. It is primarily characterized by motor dysfunctions such as resting tremor, rigidity, and bradykinesia, which manifest after significant dopaminergic neuronal loss. However, the problematic remains that a diagnosis of PD is mainly reached after the appearance of motor symptoms and supportive criteria, with the diagnosis being confirmed postmortem. At this point, there is already substantial and irreversible neurodegeneration. Existing treatments may only ameliorate symptoms, but there is a limitation on their efficacy with such a late diagnostic time point. Nevertheless, patients with PD often complain of visual disturbances, such as blurry vision, in earlier stages of the disease. With progression, a large proportion of Parkinsonian patients also suffer from visual system deficits that manifest as significant errors in chromatic discrimination and reduced contrast sensitivity. Although motor symptoms of PD can be attributed to the prominent dopaminergic dysfunction seen in the midbrain, it seems that pathological non-motor disturbances of the retinal tissue arise earlier via a less clearly understood mechanism. As these visual disturbances present themselves in the early stages of pathology, retinal anomalies have been proposed as an early biomarker of disease in PD. During the embryonic development, the retina and optic nerve extend from the diencephalon and are therefore considered part of the central nervous system. However, unlike other parts of the central nervous system, it remains relatively accessible for functional assessment in live subjects. The retina is also a well-studied tissue so that alterations to the healthy structure are easily detectable. Moreover, due to its well-defined neuronal compartment, the retina is a prime candidate for studying mechanisms of pathology and reactions to pharmacological agents in their intact form. These properties have been leveraged using the non-invasive technique known as electroretinography (ERG), which is used in both clinical and research settings to assess retinal function. This technique directly measures the overall change in the electrical potential of the retina in response to light stimulation. Physiologically, the light-induced retinal field potential is generated by circulating ion currents of rods and cone photoreceptors and can be sectioned into ERG components called waves. In a single ERG reading, light stimulus first results in the hyperpolarization of the outer segments of photoreceptors in the outer retina, creating the negatively deflected a-wave component. Next, the depolarization of bipolar cells and Müller cells in the inner retina generates the positively deflected b-wave component. Additionally, oscillatory potentials are found along the ascending part of the b-wave, most likely generated by the interaction between amacrine and bipolar cells. Recording such traces in both scotopic (dark-adapted) and photopic (light-adapted) conditions further assesses the rod or mixed rod-cone and cone system contribution to each of the ERG components, respectively. Ultimately, analysis of an ERG trace is accomplished via amplitude and latency characterization of each ERG component (). Representative human ERG wave trace. This photopic trace demonstrates the two main ERG wave components commonly used in ERG studies, i.e., a-wave and b-wave. Following flash-light stimulus, the former is negatively deflected, and the latter follows with a positive deflection. Each ERG component is characterized via latency (ms) or the speed of the response, and the amplitude (µV) or the strength of the response.