Society for Psychophysiological Research Eye Movement Physiology Frank M. Marchak, Ph.D. Veridical Research and Design Corporation www.vradc.com Society for Psychophysiological Research September 14 2011

Eye Anatomy webvision.med.utah.edu/imageswv/Sagschem.jpeg www.skybrary.aero/images/thumb/Vis_Fig2.jpg/500px-Vis_Fig2.jpg

Why do you move your eyes?

Yarbus (1967) Task influences eye movement behavior

Types of Eye Movements Gaze Stabilization Gaze shifting Vestibulo-ocular Optokinetic Gaze shifting Vergence Smooth Pursuit Saccade

Gaze Stabilization Vestibulo-Ocular Reflex commons.wikimedia.org/wiki/File:Vestibulo-ocular_reflex_lateroflexion _of_neck.svg www.youtube.com/user/mbolding#p/u/15/PeO6w_bCz8U Stabilize eyes relative to external world Compensate for head movements

Gaze Stabilization Optokinetic Nystagmus img.springerimages.com/Images/ImagesMD/ATOPH/01/66/WATER_ATOPH01-09-66-003B.jpg www.youtube.com/watch?v=KSJksSA6Q-A&feature=related Elicited by moving objects that produce illusion of head movement or slow head movements undetected by vestibular system Visual-ocular response

Gaze Shifting Vergence schorlab.berkeley.edu/vilis/vergence.htm www.youtube.com/user/mbolding#p/u/16/9kgi_Avr66I Align fovea of each eye with targets at different distances from observer Disconjugate

Gaze Shifting Smooth Pursuit www.youtube.com/watch?v=kEfz1fFjU78 Wetenbakerr,(1984). The Eye: Window on the World Keep moving stimulus on fovea Under voluntary control

Gaze Shifting Saccadic www.youtube.com/watch?v=FEJfAxJEP6E Ballistic movements that abruptly change point of fixation

How do you move your eyes?

Extraocular Muscles eyeaerobics.com/program/

emedicine.medscape.com/article/1189759-overview IO SR IO/SR SR/IO LR MR SO IR SO/IR IR/SO CONVERGENCE

Ophthalmotrope (Ruete, 1857) The ophthalmotrope (Ruete, 1857; Helmholtz, 1867) was used mechanically to model eye movements with two artificial eyeballs that can turn around their centres on a ball pivot. The cords, which are fixed at extraocular eye muscle insertions, have weights tied to them to maintain the direction of action of the muscles. Whereas Ruete's model used anatomical variables only, Wundt's model also used physiological variables as muscle forces, represented by springs and weights. Remarkable in his analysis is that the spring constants of his model muscles were directly related to the cross-sectional area of the muscle and inversely related to the length of the muscle, as determined in post-mortem studies. As a matter of fact, Donders (1848) had already measured the weights of the muscles to determine their relative force. He found for human eye muscles that were dried at 100 deg C after removal of the tendon: 0.072, 0.0725, 0.0603, 0.075, 0.032 and 0.0265 g for lateral, medial, superior and inferior rectus muscles, and superior and inferior oblique muscles, respectively. bjo.bmj.com/content/93/5.cover-expansion

Extraocular Muscle Innervation

Extraocular Muscle Innervation Origins

Extraocular Muscle Innervation Ocular Motor Neuron Nuclei Purves, et al., (2004). Neuroscience

Extraocular Muscle Innervation Ocular Motor Neuron Nuclei

Saccadic Eye Movements www.sharpsight.in/images/treatments/eye%20trackers.jpg Saccadic Eye Movements express.howstuffworks.com/gif/body-saccidic-composite.jpg

Time Course of Saccades Purves, et al., (2004). Neuroscience Two components Amplitude Lower motor neurons within oculomotor nuclei Direction Premotor neurons in gaze centers in brainstem

Neural Control of Saccades Purves, et al., (2004). Neuroscience Purves, et al., (2004). Neuroscience Discharge frequency directly proportional to position and velocity of eye

Neural Control of Saccades Pulse-Step Tonic signal – eyes hold position Height: speed of saccade Duration: duration of saccade Step Phasic signal – eyes move Height: amplitude of saccade brain.phgy.queensu.ca/pare/assets/Oculomotor%20lecture.pdf

Neural Control of Saccades Gaze Centers cueflash.com/decks/CONTROL_OF_EYE_MOVEMENTS_-_57 Horizontal Paramedian pontine reticular formation (PPRF) Vertical Rostral interstitial nucleus (rostral iMLF)

Neural Control of Saccades Horizontal Eye Movements Purves, et al., (2004). Neuroscience Excitatory pathways are shown in orange and the reciprocal inhibitory pathways are shown in blue. The particular pathway shown emanates from the frontal eye field (FEF), which projects through the anterior limb of the internal capsule, decussates to the opposite side at the midbrain-pontine junction, and then innervates the paramedian pontine reticular formation (PPRF). From there, projections directly innervate the lateral rectus (ipsilateral to the PPRF). A second decussation, back to the side of origin of FEF activation, via the MLF, innervates the medial rectus subnucleus of cranial nerve III and then neurons here project to innervate the medial rectus muscle. The right FEF command to trigger a saccade culminates in conjugate eye movements to the left. According to Herring's law, the horizontal yoke pair, the medial and lateral recti, are activated in synchrony.

Horizontal Saccades Excitatory Burst Neurons PPRF Phasic signal of abducens motor neurons brain.phgy.queensu.ca/pare/assets/Oculomotor%20lecture.pdf

Horizontal Saccades Tonic Neurons Nucleus prepositus hypoglossi Tonic signal of abducens motor neurons brain.phgy.queensu.ca/pare/assets/Oculomotor%20lecture.pdf

Horizontal Saccades Inhibitory Burst Neurons Paramedian pontine reticular formation (PPRF) Inhibit contralateral abducens internuclear and motor neurons brain.phgy.queensu.ca/pare/assets/Oculomotor%20lecture.pdf

Horizontal Saccades Omnipause Neurons Inhibit burst neurons in PPRF Prevent saccades Activate saccade burst generator brain.phgy.queensu.ca/pare/assets/Oculomotor%20lecture.pdf

Horizontal Saccades Superior Colliculus Motor command PPRF burst neurons Trigger command Omnipause neurons brain.phgy.queensu.ca/pare/assets/Oculomotor%20lecture.pdf

Superior Colliculus Topographic Motor Map Purves, et al., (2004). Neuroscience

Saccadic Eye Movements Higher Saccadic Centers cueflash.com/decks/CONTROL_OF_EYE_MOVEMENTS_-_57

Higher Saccadic Centers Frontal Eye Fields Purves, et al., (2004). Neuroscience

Higher Saccadic Centers Posterior Parietal Cortex camelot.mssm.edu/~ygyu/clip_image016_0001.jpg

Higher Saccadic Centers Basal Ganglia Purves, et al., (2004). Neuroscience

Neural Control of VOR library.med.utah.edu/kw/animations/hyperbrain/oculo_reflex/oculocephalic2.html lsda.jsc.nasa.gov/lsda_data/dil_data/msci1083.jpg

Neural Control of Smooth Pursuit cueflash.com/decks/CONTROL_OF_EYE_MOVEMENTS_-_57