39 - NeuroScience - Vestibular & Occulomotor Systems

Question 1

2 Components of the vestibular system in the inner ear

Answer 1

Saccule & Utricle

Semicircular Canals

Question 2

Saccule & Utricle

Answer 2

Linear Acceleration

Question 3

Semicircular Canals

Answer 3

Angular Acceleration (3D)
Activated by specific movements of the head with respect to the rest of the  body.

Question 4

Saccule, Utricle & Semicircular Canals

Answer 4

Activate peripheral projections of the vestibular ganglia

Question 5

Hair Cells synapse on

Answer 5

Peripheral Dendrites of ganglion cells

Question 6

Central projection of ganglion cells project to

Answer 6

Vestibular nuclei in Medulla & Pons (via CN VIII)

Question 7

Afferents in CN VIII project to

Answer 7

Vestibular Nuclei

Cerebellum (Flocculus/Nodulus)

Question 8

What makes the Trochlear Nerve so unique?!

Answer 8

Exits brainstem on dorsal surface

Crossed, Right CN IV controls Left Superior Oblique

Question 9

Vestibular Nucleus

Answer 9

Complex
Collection of 4 nuclei:

Each is indistinguishable from a standard view of the brainstem, but connectivity is different.

Located in rostral medulla through middle-pons

Question 10

Location of Occulomotor Nuclei

Answer 10

Midbrain (Occulomotor & Trochlear)

Pons (Abducens)

Question 11

Vestibular System - 2 Descending Components

Answer 11

Lateral Vestibulospinal Tract (LVST)

Medial Vestibulospinal Tract (MVST)

Question 12

Descending Vestibular System - Lateral Vestibulospinal Tract (ACTUALLY ONE OF THE MEDIAL DESCENDING SYSTEMS)

Answer 12

Emerges from projection neurons in Lateral Vestibular Nucleus (LVN)

Regulates activity of motor neurons to ipsilateral antigravity muscles

In spinal cord, its projections are in the Ventral Medial aspects of the white matter.

Question 13

Descending Vestibular System - Medial Vestibulospinal Tract

Answer 13

Originates in Medial Vestibular Nucleus (MVN)

Only goes to cervical portion of the spinal cord

Stabliizes head position & coordinates head/eye movements

Question 14

Vestibular System - 3 Ascending Components

Answer 14

Medial Longitudinal Fasciculus (MLF)
Projection to VPN of Thalamus
Projection to Cerebellum

Question 15

Ascending Vestibular System - Medial Longitudinal Fasciculus (MLF)

Answer 15

Arises from Medial Superior & Inferior Nuclei

Coordinates eye movements via inputs to CN III, CN IV, CN VI

Question 16

Ascending Vestibular System - Projection to Ventral Posterior Nucleus (VPN) of the Thalamus

Answer 16

At the level of the VPL and VPM

Allows conscious perception of head position, orientation & balance. (Proprioception)

Question 17

Ascending Vestibular System - Projection to the Cerebellum

Answer 17

Projects to Vermis, Floculus/Nodulus through juxtarestiform body (medial portion of cerebellar peduncle)

Balance & control of eye movements

Question 18

Broca’s Area 3a

Answer 18

Head Position

Question 19

Broca’s Area 2v (posterior postcentral gyrus)

Posterior Insular Cortex

Answer 19

Balance and body orientation

Question 20

Posterior Parietal Cortex

Answer 20

Eye Position

Question 21

Areas that receive information about position from VPN in the thalamus and provide cortex with perceptions of these behaviors

Answer 21

Broca’s Areas:

3a (Head position
2v (Balance & Body Orientation)
Posterior IC (Balance & Body Orientation)
PPC (Eye Position)

Question 22

Brainstem Structures Controlling Eye Movement

Answer 22

Motor Nuclei:
III
IV
VI

Mesencephalic Gaze Center
Paramedian Pontine Reticular Formation
Pontine Nuclei
Superior Colliculus
Cerebellum
Vestibular Nuclei

Question 23

Conjugate Vertical Eye Movements are regulated by

Answer 23

Mesencephalic Gaze Center

Must integrate its connectivity with III and IV

Question 24

Location of the Mesencephalic Gaze Center

Answer 24

Midbrain

Question 25

Location of the Paramedian Pontine Reticular Formation (PPRF)

Answer 25

Medial Pons

Question 26

Horizontal Gaze is regulated by

Answer 26

Paramedian Pontine Reticular Formation

Question 27

Smooth pursuit is regulated by

Answer 27

Pontine Nuclei Superior Colliculus Cerebellum

Question 28

Superior Colliculus is important for

Answer 28

Saccadic Movement | Smooth Pursuit

Question 29

Cerebellum is good for

Answer 29

Maintaining Eye Position | Smooth Pursuit

Question 30

Vestibular Nuclei & Nucleus Prepositus Hypoglossi - Location

Answer 30

Medial portion of the Medulla, just rostral to the hypoglossal nucleus

Question 31

Vestibular Nuclei & Nucleus Prepositus Hypoglossi - Function

Answer 31

Eye position & movement

Question 32

Vestibulo-Ocular Reflex - Pathway

Answer 32

Head moves to the right Vestibular Complex on the right is activated by inputs from CN VII Vestibular Complex projects to the contralateral (left) side to the Abducens Nucleus. Left lateral rectus is activated. The internuncial cells of that abducens nucleus project through the MLF to the contralateral Nucleus of III. Right medial rectus is activated. 1:21:34