Eye Movement Research in the Twenty-First Century—a Window to the Brain, Mind, and More

Abstract

The study of eye movements not only addresses debilitating neuro-ophthalmological problems but has become an essential tool of basic neuroscience research. Eye movements are a classic way to evaluate brain function-traditionally in disorders affecting the brainstem and cerebellum. Abnormalities of eye movements have localizing value and help narrow the differential diagnosis of complex neurological problems. More recently, using sophisticated behavioral paradigms, measurement of eye movements has also been applied to disorders of the thalamus, basal ganglia, and cerebral cortex. Moreover, in contemporary neuroscience, eye movements play a key role in understanding cognition, behavior, and disorders of the mind. Examples include applications to higher-level decision-making processes as in neuroeconomics and psychiatric and cognitive disorders such as schizophrenia and autism. Eye movements have become valued as objective biomarkers to monitor the natural progression of disease and the effects of therapies. As specific genetic defects are identified for many neurological disorders, ocular motor function often becomes the cornerstone of phenotypic classification and differential diagnosis. Here, we introduce other important applications of eye movement research, including understanding movement disorders affecting the head and limbs. We also emphasize the need to develop standardized test batteries for eye movements of all types including the vestibulo-ocular responses. The evaluation and treatment of patients with cerebellar ataxia are particularly amenable to such an approach.Keywords Saccade . Vestibulo-ocular reflex . Pursuit Eye movements are critical for the survival of any animal that sees. Promptly bringing an image to the fovea of an object that suddenly intrudes into one's periphery, and then keeping the image stable on the fovea, allows the cognitive brain to analyze the visual scene in a tenth of a second. In this way, it can generate an immediate, and sometimes life or death, decision whether to flee, fight, embrace, or just do nothing. Neural correlates of eye movements are found in almost every corner of the brain, helping to provide the most reliable information from our visual systems for all aspects of behavior.Using eye movements to understand human disease extends back to at least the mid-nineteenth century when early reports of strabismus [1][2][3][4][5] and nystagmus [4,[6][7][8][9][10][11][12][13] appeared. Nevertheless, in the years following, for almost another century, the literature on eye movements was meager. In the mid1940s, however, the number of publications on nystagmus and strabismus began to grow (https://www.ncbi.nlm.nih. gov/pubmed/?term = nystagmus, https://www.ncbi.nlm.nih. gov/pubmed/?term = strabismus), and in the mid-1960s, there was another growth spurt with more studies reporting various types of dysfunction of eye movements in conditions affecting the brainstem or cerebellum. Topics such as adaptive control of eye movements and the central role of normal and

Measures of possible allostatic load in comorbid cocaine and alcohol use disorder: Brain white matter integrity, telomere length, and anti-saccade performance

“…The eye-tracking data were analyzed as (1) overall error rates on all anti-saccade trials (global inhibitory control), (2) the ratio of anti-saccade errors on cocaine-stimulus trials to total anti-saccade errors over all trials (cocaine/total: attentional bias towards cocaine cues). Anti-saccade errors provide an index of inhibitory control circuitry, both with regard to neural pathways subserving the control of eye movements and to markers of pathology in psychiatric and neurological disease [49,50]. Attentional bias provides an index of asymmetrical attentional control by the salience of specific stimuli (in this case cocaine cues) relative to neutral stimuli, with clinical relevance to SUD [15,51,52].…”

Application of eye trackers for understanding mental disorders: Cases for schizophrenia and autism spectrum disorder

“…As has been postulated, eyes are windows to the brain as well as to the mind . Studies of eye movement have become an essential tool of basic neuroscience research.…”

“…Studies of eye movement have become an essential tool of basic neuroscience research. Almost every area of the brain plays some role in relation to ocular motor control . Eye movements are used to evaluate brain function in disorders affecting mostly the brain stem and cerebellum.…”

“…Eye movements are used to evaluate brain function in disorders affecting mostly the brain stem and cerebellum. Recently, measures of eye movements have been applied to higher brain functions such as cognition, social behavior, and higher‐level decision . Four noticeable features regarding the utility of eye movements have been observed.…”

“…First, in many reports on schizophrenia and autism spectrum disorder (ASD), eye movement components are altered in the patient groups. Second, measures of eye movements may contribute to the early diagnosis of mental disorders . Third, eye movements may help group current diagnoses into new categories with or without certain types of eye control problems.…”