Medical neuroscience

1. Domina Petric, MD
Eye movements

2. adjust fixation when visual target moves
adjust fixation during head movements
adjust fixation when acquiring a new target
Eye movements

3. Abducens nucleus,
abducens nerve
Ipsilateral rectus
lateralis muscle
ABduction
Trochlearis
nucleus, trochlearis
nerve
CONTRALATERAL
superior oblique
muscle
Downward gaze,
intorsion
Occulomotor
nucleus,
occulomotor nerve
Ipsilateral inferior,
superior and medial
rectus muscle; inferior
oblique muscle
Upward gaze,
ADuction, downward
gaze without
intorsion
Eye muscles

4. Vergence
(convergence,
divergence):
visually guided
near and far
fixations
Disconjugate eye movements: eyes
move in opposite direction
Saccades: quick, ballistic
Smooth pursuit: slow, visually guided
Optokinetic: smooth pursuit and
saccades combination, visually guided
Vestibulo-ocular: slow, vestibular
guided
Conjugate eye movements: eyes move in
the same direction
Eye movements

5. Saccade is a quick, ballistic eye movement
that allows us to change fixation point from
one target to another.
200 ms is necessary interval between the
onset of the target and the onset of the eye
movement for target fixation.
Saccades

6. Visually guided eye movements.
After catch-up saccade, eyes can
track the target smoothly.
Smooth pursuit eye movements

7. • Optokinetic nystagmus has two components: saccade
component and smooth pursuit component.
Optokinetic nystagmus
Saccade
Saccade

8. Both eyes are in
adduction.
Near objects fixation.
Convergence

9. Both eyes are in
abduction.
Far objects fixation.
Divergence

10. • PPRF is Paramedian Pontine Reticular Formation and it is
horizontal gaze center.
• PPRF controls horizontal movements of the eyes.
• When we look at the right, right PPRF sends excitatory
signals to the right abducens nucleus so the right lateral
rectus muscle is activated.
• Internuclear neuron that crosses the midline, sends
excitatory impulse to the contralateral (in this case left)
oculomotor nucleus: activation of the left medial rectus
muscle.
PPRF

11. Vertical gaze center is
located in the
mesencephalon.
Vertical gaze

12. Frontal eye field
Superior colliculus in the
midbrain
Upper motor neuronal control of eye
movements

13. Sensory map represents locations in the contralateral
visual hemifield.
Sensory map is present in both frontal eye field and
superior colliculus.
There is also a motor map for saccadic eye
movements located in frontal eye field and superior
colliculus.
Upper motor neuronal control of eye
movements

14. • Frontal eye field is connected with ipsilateral superior colliculus
and with contralateral gaze centers of the reticular formation
(horizontal and vertical gaze centers).
• Lesion in the frontal eye field or in the superior colliculus
causes deficit in saccadic eye movements.
• Frontal eye fields are concerned with intentional saccades to
the opposite (contralateral) direction.
• If the patient has a stroke involving the anterior parts of the
premotor cortex, that patient can not intentionally look at the
opposite side: if the left frontal eye field is damaged, patient
can not look to the right side if asked.
Frontal eye field (Brodmann´s area 8)

15. Superior colliculus generate express saccades
that are not associated with planned
movements of the eyes.
If we hear a noise, we will automatically look
towards the source of that noise.
Superior colliculus

16. https://www.coursera.org/learn/medical-
neuroscience/lecture: Leonard E. White,
PhD, Duke University
Literature