Saccadous' history dates back nearly 15 years, to the Visual Neuroscience Lab at the Barrow Neurological Institute in Phoenix, Arizona. While investigating the connections between the eyes and brain, researchers at Barrow discovered, using ultra high-speed cameras, that the way the eyes drift and correct themselves differs among patients with different known neurological disorders.
During visual fixation, the eyes are never completely still, but produce small involuntary movements, called “fixational eye movements,” including microsaccades, drift, and tremor. In certain neurological disorders, attempted fixation results in abnormal fixational eye movements with distinctive characteristics. Thus, determining how normal fixation differs from pathological fixation has the potential to aid early and differential noninvasive diagnosis of neurological disease as well as the quantification of its progression and response to treatment. These scientists we recorded the eye movements produced by patients with Alzheimer’s disease, patients with mild cognitive impairment, and healthy age-matched individuals during attempted fixation. They found that microsaccade magnitudes, velocities, durations, and intersaccadic intervals were comparable in the three subject groups, but microsaccade direction differed in patients versus healthy subjects. The results indicate that microsaccades are more prevalently oblique in patients with Alzheimer’s disease or mild cognitive impairment than in healthy subjects. These findings extended to those microsaccades paired in squarewave jerks, supporting the hypothesis that microsaccades and square-wave jerks form a continuum, both in healthy subjects and in neurological patients.
Saccadous recently launched a new IRB-approved proof-of-concept study to validate the methodology using our commercial-grade VR headset. If you would like more information about this study, Contact Us.
Z. Kapoula, Q. Yang, J. Otero-Millan, S. Xiao, S. L. Macknik, A. Lang, M. Verny, and S. Martinez-Conde, “Distinctive features of microsaccades in Alzheimer’s disease and in mild cognitive impairment.,” Age (Dordr). , vol. 36, no. 2, pp. 535–43, 2014.
S. Martinez-Conde, J. Otero-Millan, and S. L. Macknik, “The impact of microsaccades on vision: towards a unified theory of saccadic function,” Nat. Rev. Neurosci. , vol. 14, no. 2, pp. 83–96, 2013.
J. Otero-Millan, X. G. Troncoso, S. L. Macknik, I. Serrano-Pedraza, and S. Martinez-Conde, “Saccades and microsaccades during visual fixation, exploration, and search: foundations for a common saccadic generator.,” J. Vis. , vol. 8, no. 14, p. 21.1-18, 2008.
H. Rieiro, S. Martinez-Conde, A. P. Danielson, J. L. Pardo-Vazquez, N. Srivastava, and S. L. Macknik, “Optimizing the temporal dynamics of light to human perception,” Proc. Natl. Acad. Sci. , vol. 109, no. 48, pp. 19828–19833, Nov. 2012.