Term
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Definition
| Nucleus of the Optic Tract |
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Term
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Definition
| Ventral Paraflocculus (a part of the cerebellum & primary structure in VOR cancellation when the target moves at the same rate as your head & body) |
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Term
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Definition
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Term
| What is the latency and velocity of a pursuit? Velocity in athletes? |
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Definition
| Vel = 70°/sec and Latency = 100-130 msec (faster than saccades); Vel = Up to 130°/sec in athletes |
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Term
| Can you make a pursuit without a moving target? |
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Definition
| According to Kundart, no. "…retinal slip is critical to trigger pursuits" and "Without a moving target, you make a series of small saccades rather than a true pursuit" The caveat is that as long as the visual cortex THINKS there is motion, pursuits can be triggered. |
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Term
| Pursuits and saccades share much of the same neurological pathway. Why is critical observation of pursuits comsidered less clinically useful? |
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Definition
| Because pursuit deficits don't always have the "localizing value" that saccadic deficits do. (Can't always play "Where's the lesion?" with pursuits.) |
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Term
| Where do horizontal eye movements (pursuits and saccades) occur? |
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Definition
| Pons (specifically the pons and vestibular nucleus (CN VI and CN VIII)) |
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Term
| Where do vertical and torsional pursuits occur? |
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Definition
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Term
| What very major part of the visual pathway is used in pursuits but NOT saccades? (Hint: Think of any foveation needs.) |
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Definition
| The Primary Visual Cortex (V1) |
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Term
| Global motion = what part of the brain? |
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Definition
| V5 aka MT ("Moving Target"… but not really) |
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Term
| Loss of vision in either V1 or V5 (MT) can cause what pursuit condition? |
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Definition
| A "scotoma of motion" aka akinetopsia in the hemisphere opposite the lesion - an "MT" hemisphere (Get it?! Hah!) |
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Term
| Local motion = what part of the brain? |
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Definition
| V3 aka MST ("Do the local motion V3") |
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Term
| Loss of vision in V3 (MST) can cause what pursuit condition? |
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Definition
| A directional pursuit deficit toward the side of the lesion |
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Term
| If a pt has impaired ipsiversive horizontal pursuits, where might the lesion be? |
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Definition
| The Frontal Eye Fields in the prefrontal gyrus at the top of the head. |
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Term
| If a pt has impaired vertical pursuits, where might the lesion be? |
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Definition
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Term
| What if one side of the VPF (ventral paraflocculus) breaks? Bilateral VPF and the flocculus? Just bilateral flocculus? |
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Definition
Unilateral VPF lesion = mild pursuit deficit
Bilateral VPF & flocculus lesions = severe pursuit deficit & VOR goes nuts
Bilateral flocculus lesions = no biggie. Pursuits are just fine. |
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Term
| What do vermis lesions cause? |
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Definition
| Ipsiversive horizontal pursuit deficits |
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Term
| What do fastigial nucleus lesions cause? |
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Definition
| Contraversive horizontal pursuit deficits |
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Term
| Catch-up saccades indicate a gain that is too high/low? Backup saccades? |
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Definition
| Catch-up saccades = gain too low; Backup saccades = gain too high |
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Term
| Normal vertical pursuit asymmetry is more likely found when the patient is attempting to pursue an object up/down? |
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Definition
| Up. Vertical targets are harder to pursue looking up vs moving downward |
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Term
| Your patient is being spun in a chair and fixating on their own outstretched thumb. You see corrective saccades. What does this indicate? |
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Definition
| The corrective saccades are OKN quick phases due to deficient VOR cancellation in the direction of chair rotation |
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Term
| A cerebral hemisphere lesion will present with what effect on pursuits? …saccades? |
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Definition
| Ipsiversional pursuit dysfunction toward the lesion; Hypometric saccades away from the lesion. |
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Term
| Pursuits and VOR Cancellation are managed/affected by what structure? |
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Definition
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