Metastability and Eye Movements: A Dynamical‑Systems Interpretation

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  1. Why metastability is a natural language for gaze behavior The idea that perception, attention, and neural activity evolve through transiently stable states has deep roots in cognitive science and neuroscience. Concepts such as attractors , basins , noise‑induced transitions , and escape times appear in work on perceptual switching, decision‑making, and neural population dynamics (Kelso, 1995; Rabinovich et al., 2008; Deco & Jirsa, 2012). Eye movements, especially the alternation between fixations and saccades ,   fit remarkably well into this metastable picture. The Freidlin–Wentzell theory of rare events (Freidlin & Wentzell, 2012) provides a rigorous mathematical language for these intuitions. 2. Fixations as metastable states  Consider the gaze position X t as the state of a stochastic dynamical system. During a fixation the  gaze remains confined to a small region, microsaccades and noise generate small fluctuations, and the gaze tends to return...
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MRI Helps Depict Clinically Undetectable Risk Factors in Advanced Stage Retinoblastomas

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If diagnosed early, retinoblastoma is a highly curable cancer. Conservative treatment options have significantly improved in the last decades. The main aims in the management of retinoblastoma are maintaining the eye and reducing the systemic toxicity. A combination of local treatments, systemic and/or peri-ocular chemotherapy, external beam radiation, and enucleation have been used to successfully treat the tumour.
Our data [http://neu.sagepub.com/content/28/1/53.full] confirm the usefulness of high-resolution brain and orbit MRI in combination with clinical examinations in detecting possible risk factors for metastasis in advanced stages retinoblastomas leading to correct “customized” treatments. In particular, pre-laminar optic nerve and scleral infiltration suspected at MRI were strongly associated with the histology findings, and overall choroid provided good performances in sensitivity, NPV and accuracy. LEICR sign could be included in optic nerve evaluation at MRI, and AASE has been confirmed as a valuable additional sign alerting an increasing risk of metastasis.

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