Search Our Scientific Publications & Authors

J Anat 2021 Apr 31;238(4):917-941. Epub 2020 Oct 31.

Department of Anatomy, College of Medicine, Howard University, Washington, DC, USA.

The oblique extraocular muscles (EOMs) were dissected in 19 cetacean species and 10 non-cetacean mammalian species. Both superior oblique (SO) and inferior oblique (IO) muscles in cetaceans are well developed in comparison to out-groups and have unique anatomical features likely related to cetacean orbital configurations, swimming mechanics, and visual behaviors. Cetacean oblique muscles originate at skeletal locations typical for mammals: SO, from a common tendinous cone surrounding the optic nerve and from the medially adjacent bone surface at the orbital apex; IO, from the maxilla adjacent to lacrimal and frontal bones. Read More

Int J Mol Sci 2020 Sep 20;21(18). Epub 2020 Sep 20.

Faculty of Information Technology, Tokyo City University, Tokyo 158-8557, Japan.

The terminology of cerebellar dysmetria embraces a ubiquitous symptom in motor deficits, oculomotor symptoms, and cognitive/emotional symptoms occurring in cerebellar ataxias. Patients with episodic ataxia exhibit recurrent episodes of ataxia, including motor dysmetria. Despite the consensus that cerebellar dysmetria is a cardinal symptom, there is still no agreement on its pathophysiological mechanisms to date since its first clinical description by Babinski. Read More

J Neurophysiol 2020 07 3;124(1):115-133. Epub 2020 Jun 3.

Institut für Neuroinformatik, Ruhr-Universität Bochum, Bochum, Germany.

Conventional explanations of the vestibulo-ocular reflex (VOR) and eye and head movements are revisited by considering two alternative frameworks addressing the question of how the brain controls motor actions. Traditionally, biomechanical and/or computational frameworks reflect the views of several prominent scholars of the past, including Helmholtz and von Holst, who assumed that the brain directly specifies the desired motor outcome and uses efference copy to influence perception. However, empirical studies resulting in the theory of referent control of action and perception (an extension of the equilibrium-point hypothesis) revealed that direct specification of motor outcome is inconsistent with nonlinear properties of motoneurons and with the physical principle that the brain can control motor actions only indirectly, by changing or maintaining the values of neurophysiological parameters that influence, but can remain independent of, biomechanical variables. Read More

J Binocul Vis Ocul Motil 2020 Jul-Sep;70(3):86-88. Epub 2020 May 15.

Division of Ophthalmology, Hadassah-Hebrew University Medical Center , Jerusalem, Israel.

Introduction: Understanding the primary, secondary and tertiary actions of the vertical recti and oblique muscles is important in the diagnosis of various types of strabismus (superior oblique palsy, A- and V-patterns). Unfortunately, learning these actions can be very challenging. We designed a visual memory tool, and assessed its usefulness for medical students. Read More

Invest Ophthalmol Vis Sci 2019 12;60(15):5052-5058

Eidactics and The Strabismus Research Foundation, San Francisco, California, United States.

Purpose: The discovery of extraocular muscle (EOM) pulleys resolved long-standing issues in oculomotor physiology, revived interest in EOM function generally, and led to several new theories. We describe the pulley concept of Miller and Demer (M-D Pulleys) and briefly review evidence, distinguishing this well-supported notion from the Active Pulley Hypothesis (APH) and the EOM Compartments hypothesis, and critically reviewing the methodologies and evidence on which the latter are based.

Methods: We analyze evidence on mechanical independence of individual EOM fibers, implications of nerve tracing for functional independence of EOM layers and compartments, validity of image-based methods of assessing EOM contraction, and data analysis issues. Read More

PLoS One 2018 7;13(2):e0192214. Epub 2018 Feb 7.

Department of Ophthalmology and Visual Sciences, Kellogg Eye Center, University of Michigan, Ann Arbor, Michigan, United States of America.

Insulin-like growth factors (Igfs) are key regulators of key biological processes such as embryonic development, growth, and tissue repair and regeneration. The role of Igf in myogenesis is well documented and, in zebrafish, promotes fin and heart regeneration. However, the mechanism of action of Igf in muscle repair and regeneration is not well understood. Read More

Int Ophthalmol 2018 Dec 26;38(6):2451-2462. Epub 2017 Oct 26.

Optometry Research Group (GIO), Optics, Optometry and Vision Sciences Department, University of Valencia, C/Dr. Moliner, 50, 46100, Burjassot, Spain.

Purpose: The aim of this pilot study was to evaluate a new semiautomatic procedure to assess in vivo changes in the crystalline lens and ciliary muscle during accommodation.

Methods: A total of 14 subjects were divided into two groups, young (aged between 20 and 25 years) and adult (aged between 35 and 40 years), and measured with an anterior segment optical coherence tomography. A semiautomatic procedure was implemented to measure the central lens thickness (CLT), anterior lens radius (ALR) and the ciliary muscle area (CMA) for the unaccommodated eye and for a vergence of - 3. Read More

Acta Psychol (Amst) 2017 Oct 21;180:130-136. Epub 2017 Sep 21.

Würzburg University, Germany.

While there is ample evidence that actions are guided by anticipating their effects (ideomotor control) in the manual domain, much less is known about the underlying characteristics and dynamics of effect-based oculomotor control. Here, we address three open issues. 1) Is action-effect anticipation in oculomotor control reflected in corresponding spatial saccade characteristics in inanimate environments? 2) Does the previously reported dependency of action latency on the temporal effect delay (action-effect interval) also occur in the oculomotor domain? 3) Which temporal effect delay is optimally suited to develop strong action-effect associations over time in the oculomotor domain? Participants executed left or right free-choice saccades to peripheral traffic lights, causing an (immediate or delayed) action-contingent light switch in the upper vs. Read More

J Neurophysiol 2017 12 13;118(6):3175-3193. Epub 2017 Sep 13.

Washington National Primate Research Center, University of Washington, Seattle, Washington.

In pattern strabismus the horizontal and vertical misalignments vary with eye position along the orthogonal axis. The disorder is typically described in terms of overaction or underaction of oblique muscles. Recent behavioral studies in humans and monkeys, however, have reported that such actions are insufficient to fully explain the patterns of directional and amplitude disconjugacy of saccades. Read More

J Electromyogr Kinesiol 2016 Jun 8;28:23-30. Epub 2016 Mar 8.

Department of Biology Science and Technology, National Chiao Tung University, Hsinchu, Taiwan; Institute of Physics, Academia Sinica, Taipei, Taiwan. Electronic address:

Upper eyelid movement depends on the antagonistic actions of orbicularis oculi muscle and levator aponeurosis. Blepharoptosis is an abnormal drooping of upper eyelid margin with the eye in primary position of gaze. Transconjunctival incisions for upper eyelid ptosis correction have been a well-developed technique. Read More

J Neurophysiol 2016 Jan 4;115(1):370-8. Epub 2015 Nov 4.

Stein Eye Institute and Department of Ophthalmology, David Geffen Medical School, University of California, Los Angeles, California; and Department of Neurology, David Geffen Medical School, University of California, Los Angeles, California

Anatomical studies demonstrate selective compartmental innervation of most human extraocular muscles (EOMs), suggesting the potential for differential compartmental control. This was supported by magnetic resonance imaging (MRI) demonstrating differential lateral rectus (LR) compartmental contraction during ocular counterrolling, differential medial rectus (MR) compartmental contraction during asymmetric convergence, and differential LR, inferior rectus (IR), and superior oblique (SO) compartmental contraction during vertical vergence. To ascertain possible differential compartmental EOM contraction during vertical ductions, surface coil MRI was performed over a range of target-controlled vertical gaze positions in 25 orbits of 13 normal volunteers. Read More

J Neurophysiol 2015 Apr 14;113(7):2150-63. Epub 2015 Jan 14.

Department of Ophthalmology, David Geffen Medical School, University of California, Los Angeles, California; and.

Vertical fusional vergence (VFV) normally compensates for slight vertical heterophorias. We employed magnetic resonance imaging to clarify extraocular muscle contributions to VFV induced by monocular two-prism diopter (1.15°) base-up prism in 14 normal adults. Read More

Brain Behav Evol 2014 24;83(2):162-75. Epub 2014 Apr 24.

Department of Biology II, Ludwig Maximilians University Munich, Planegg, Germany.

Developmental and evolutionary data from vertebrates are beginning to elucidate the origin of the sensorimotor pathway that links gravity and motion detection to image-stabilizing eye movements--the vestibulo-ocular reflex (VOR). Conserved transcription factors coordinate the development of the vertebrate ear into three functional sensory compartments (graviception/translational linear acceleration, angular acceleration and sound perception). These sensory components connect to specific populations of vestibular and auditory projection neurons in the dorsal hindbrain through undetermined molecular mechanisms. Read More

Exp Brain Res 2013 Oct 14;230(3):291-300. Epub 2013 Aug 14.

UCL Institute of Cognitive Neuroscience, 17 Queen Square, London, WC1N 3AR, UK,

The desire to increase rewards and minimize punishing events is a powerful driver in behaviour. Here, we assess how the value of a location affects subsequent deployment of goal-directed attention as well as involuntary capture of attention on a trial-to-trial basis. By tracking eye position, we investigated whether the ability of an irrelevant, salient visual stimulus to capture gaze (stimulus-driven attention) is modulated by that location's previous value. Read More

Can J Ophthalmol 2013 Aug;48(4):292-9

Department of Ophthalmology, Ivey Eye Institute, University of Western Ontario, London, Ont., Canada.

Objective: To determine whether surgery to correct decompensated exotropia in adulthood had an impact on common visually guided manual tasks in the postoperative period.

Design: Case report.

Participants: Three adult patients with long-standing strabismus. Read More

Radiographics 2013 Jan-Feb;33(1):47-59

Department of Radiology, Seoul National University Bundang Hospital, 166 Gumi-ro, Bundang-gu, Seongnam-si, Gyeonggi-do 436-707, Korea.

Horizontal eye movements are conducted by the medial rectus and the lateral rectus muscles, which are innervated by the oculomotor nerve (cranial nerve III) and the abducens nerve (cranial nerve VI), respectively. The oculomotor and the abducens nuclei are interconnected by a tract in the brainstem named the medial longitudinal fasciculus (MLF). Through the MLF, the actions of the oculomotor and the abducens nuclei are coordinated, generating conjugate horizontal eye movements. Read More

Invest Ophthalmol Vis Sci 2012 Dec 19;53(13):8414-23. Epub 2012 Dec 19.

Department of Ophthalmology, Jules Stein Eye Institute, Los Angeles, California 90095-7002, USA.

Purpose: Intramuscular innervation of horizontal rectus extraocular muscles (EOMs) is segregated into superior and inferior (transverse) compartments, while all EOMs are also divided into global (GL) and orbital (OL) layers with scleral and pulley insertions, respectively. We sought evidence of potential independent action by examining passive mechanical coupling between EOM compartments.

Methods: Putative compartments of each of the six whole bovine anatomical EOMs were separately clamped to a physiologically controlled, dual channel microtensile load cell (5-mN force resolution) driven by independent, high-speed, linear motors having 20-nm position resolution. Read More

PLoS Comput Biol 2012 17;8(5):e1002508. Epub 2012 May 17.

Radboud University Nijmegen Medical Centre, Donders Institute for Brain, Cognition, and Behaviour, Department of Cognitive Neuroscience, Section Biophysics, Nijmegen, The Netherlands.

A major challenge in computational neurobiology is to understand how populations of noisy, broadly-tuned neurons produce accurate goal-directed actions such as saccades. Saccades are high-velocity eye movements that have stereotyped, nonlinear kinematics; their duration increases with amplitude, while peak eye-velocity saturates for large saccades. Recent theories suggest that these characteristics reflect a deliberate strategy that optimizes a speed-accuracy tradeoff in the presence of signal-dependent noise in the neural control signals. Read More

Acta Ophthalmol 2012 Jun 23;90(4):e310-3. Epub 2012 Jan 23.

Hôpital Ophtalmique Jules Gonin, Lausanne University Ophthalmology Department, Lausanne, Switzerland.

Purpose: To elucidate the aetiology of congenital Brown syndrome.

Methods: Four consecutive patients diagnosed with unilateral congenital Brown syndrome had a comprehensive standardized ocular motility examination. Any compensatory head posture was measured. Read More

Neuropsychologia 2011 May 18;49(6):1605-10. Epub 2011 Feb 18.

Department of Cognitive Psychology, Vrije Universiteit, Van der Boechorststraat 1, 1081 BT Amsterdam, The Netherlands.

Humans tend to create and maintain internal representations of the environment that help guiding actions during the everyday activities. Previous studies have shown that the oculomotor system is involved in coding and maintenance of locations in visual-spatial working memory. In these studies selection of the relevant location for maintenance in working memory took place on the screen (selecting the location of a dot presented on the screen). Read More

Rev Laryngol Otol Rhinol (Bord) 2010 ;131(2):145-52

Clinique Tourny, 68 rue du Palais Gallien, 33000 Bordeaux, France.

Graves disease orbitopathy is a complex progressive inflammatory disease. Medical treatment remains in all cases the proposed treatment of choice. Surgical treatment by bone decompression can be considered as an emergency mainly in cases of optic neuropathy or ocular hypertension not being controlled medically or in post-traumatic exophthalmos stage. Read More

Graefes Arch Clin Exp Ophthalmol 2011 Jun 18;249(6):909-19. Epub 2011 Jan 18.

Directorate of Orthoptics and Vision Science, University of Liverpool, Thompson Yates Building, Liverpool, L69 3GB, UK.

Purpose: To compare the range of ocular rotations measured by Octopus versus Goldmann perimetry.

Methods: Forty subjects (20 controls and 20 patients with impaired ocular movements) were prospectively recruited, age range 21-83 years. Range of uniocular rotations was measured in six vectors corresponding to extraocular muscle actions: 0°, 67°, 141°, 180°, 216°, 293°. Read More

Invest Ophthalmol Vis Sci 2011 Apr 27;52(5):2830-6. Epub 2011 Apr 27.

Department of Ophthalmology, University ofCalifornia, Los Angeles, California, USA.

Purpose: It has been proposed that the lateral rectus (LR), like many skeletal and craniofacial muscles, comprises multiple neuromuscular compartments subserving different physiological functions. To explore the anatomic potential of compartmentalization in all four rectus extraocular muscles (EOMs), evidence was sought of possible regional selectivity in intramuscular innervation of all rectus EOMs.

Methods: Whole orbits of two humans and one macaque monkey were serially sectioned at 10 μm thickness and stained with Masson's trichrome. Read More

Invest Ophthalmol Vis Sci 2010 Sep 30;51(9):4612-7. Epub 2010 Apr 30.

Department of Ophthalmology, University of California, Los Angeles, Los Angeles, CA 90095-7002, USA.

Purpose: Skeletal and craniofacial muscles are frequently composed of multiple neuromuscular compartments that serve different physiological functions. Evidence of possible regional selectivity in LR intramuscular innervation was sought in a study of the anatomic potential of lateral rectus (LR) muscle compartmentalization.

Methods: Whole orbits of two humans and five macaque monkeys were serially sectioned at 10-microm thickness and stained with Masson trichrome. Read More

J Anat 2010 Apr 22;216(4):496-509. Epub 2010 Feb 22.

Division of Human Anatomy and Cell Biology, School of Biomedical Sciences, University of Liverpool, Liverpool, UK.

The spatial arrangement of the semicircular canals and extraocular muscles of the eye has been of considerable interest, particularly to researchers working on adaptations of the vestibulo-ocular reflex. Here we offer the first, extensive comparative analysis of the spatial relationships between each extraocular muscle and the canal providing its primary excitatory stimulus. The sample consisted of 113 specimens, representing 51 extant mammalian species. Read More

Alcohol Clin Exp Res 2009 Nov 10;33(11):1956-65. Epub 2009 Aug 10.

Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, Oregon, USA.

Introduction: Urocortin 1 (Ucn 1) is an endogenous peptide related to the corticotropin-releasing factor (CRF). Ucn 1 is mainly expressed in the perioculomotor area (pIII), and its involvement in alcohol self-administration is well confirmed in mice. In other species, the relationship between the perioculomotor Ucn 1-containing population of neurons (pIIIu) and alcohol consumption needs further investigation. Read More

Int Rev Neurobiol 2009 ;86:3-21

University of Pisa, Interdepartmental Research Centre E. Piaggio, School of Engineering, 56100 Pisa, Italy.

A great demand for brain-machine and, more generally, man-machine interfaces is arising nowadays, pushed by several promising scientific and technological results, which are encouraging the concentration of efforts in this field. The possibility of measuring, processing and decoding brain activity, so as to interpret neural signals, is often looked at as a possibility to bypass lost or damaged neural and/or motor structures. Beyond that, such interfaces currently show a potential for applications in other fields, space science being certainly one of them. Read More

J Neurosci 2009 Feb;29(7):2136-50

Department of Neuroscience, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6074, USA.

In subjects trained extensively to indicate a perceptual decision with an action, neural commands that generate the action can represent the process of forming the decision. However, it is unknown whether this representation requires overtraining or reflects a more general link between perceptual and motor processing. We examined how perceptual processing is represented in motor commands in naive monkeys being trained on a demanding perceptual task, as they first establish the sensory-motor association and then learn to form more accurate perceptual judgments. Read More