Cortical control of saccades in Parkinson disease and essential tremor

Abstract

A number of studies suggest that some features of essential tremor (ET) and Parkinson disease (PD) overlap. Besides tremor, also some cognitive features have been implicated in ET and PD. There is recent evidence that a common genetic mutation occurs in ET and PD. Saccadic eye movements could provide an easily quantifiable procedure to help in the differential diagnosis in early PD and ET. Being able to distinguish early on the two diseases may help in tailoring therapy. Cortical control of saccades and antisaccades as they pertain to the potential discrimination of PD and ET is reviewed. Imaging and electrophysiological studies are highlighted; however, there are still few studies. Hopefully this review will stimulate further research, in particular in the direction of differences and similarities in the neural circuits involved in PD and ET.

Alterations of Eye Movement Control in Neurodegenerative Movement Disorders

“…The supplementary eye fields contribute to target selection and visual search [53], and the FEF are critical in target selection of competing stimuli mediating their information to the SC and directly to the saccadic generator in the brainstem [54]. The striatum serving as the main input gate of the basal ganglia evaluates incoming and competing information for appropriate execution; however, with the putamen being the most affected area in PD, it remains to be discovered to what extent the PD pathology targets this mechanism [55]. The striatum gains also incoming streams from the dorsolateral prefrontal cortex which contributes to voluntary eye movements in the sense of inhibition control to prevent unwanted reflexive saccades [35].…”

“…As a part of the limbic system, the so-called cingulate eye field, located in the anterior cingulate cortex (which is involved in motivation, behavior, and executive control), contributes to saccade generation [56]. Guiding voluntary saccades requires several neural mechanisms within the framework of preemptive perception that manifests in activation in the cingulate eye field prior to the release of a saccade [55]. …”

The association between alterations of eye movement control and cerebral intrinsic functional connectivity in Parkinson’s disease

“…In more detail, areas in the parietal cortex provide a critical interface for attention and multiple sensory integration from visual and somatosensory modalities (Ptak and Müri 2013), the supplementary eye fields contribute to visual search (Purcell et al 2012) and are critically involved in control of visual attention, together with the frontal eye fields (Bosch et al 2013). The striatum as one of the main input gates of the basal ganglia evaluates incoming and competing information, predominantly from cortical areas including the dorsolateral prefrontal cortex (Yerram et al 2013). Additionally, the cingulate eye field, located in the anterior cingulate cortex as a part of the limbic loop (which is involved in motivation, behavior, and executive control), contributes to saccade generation (Gaymard et al 1998).…”

Identification of people at the latent stage of Parkinson’s disease (the PARKINLAR study): first results and an optimization of the algorithm

“…В последние годы возобновился интерес к анализу глазодвигательных нарушений при БП, изучаются различные параметры рефлекторных и произвольных саккад, плавных следящих движений глаз. Считается, что при БП нарушается тоническое ингибирование верхних бугорков четверохолмия ретикулярной частью черной субстанции, а также изменяются корковые влияния на глазодвигательную систему ствола, опосредуемые базальными ганглиями [40,41]. Патологические изменения при БП проявляются увеличением латентных периодов саккад, их гипометрией, повышенным количеством ошибок при совершении саккад, особенно в усложненных условиях [30,42,43].…”