Vision No.12

Imagine wearing a virtual reality headset that could also track your eye movements. The experimenter asks you to first look at an object in the centre of an image, and then to saccade off to the side. As you make your saccade the image is shifted to precisely match your eye movement, i.e. the original image remains stationary on your retina. Do you perceive the object as moving, and why?

Motion cells respond strongly to high contrast stimuli. They also respond strongly to faster motion. How can this cell signal the difference between a high contrast target moving at low speed, and a low contrast target moving at high speed?

What is the Enigma illusion an example of?

What is a common impairment associated with a cerebellar stroke/lesion?

Early-stage Huntingdon's disease is associated with loss of D2 receptors in the Striatum. Based on your knowledge of basal ganglia function, what is the most likely motor symptom that you would expect to see?

Which basal ganglia nucleus is implicated in suppressing (but not facilitating) actions/movements?

The size of the hippocampus

Which of the following is not represented in posterior parietal cortex?

One muscle fibre has one NMJ which is intervened by one motor nerve terminal.

Virtual Reality and Eye Movement

In a virtual reality experiment, if an image is shifted to match eye movement during a saccade, the object is not perceived as moving because the original image remains stationary on the retina.

Motion Cells

Motion cells respond strongly to high contrast stimuli and faster motion.
To signal the difference between a high contrast target moving at low speed and a low contrast target moving at high speed, motion cells would need to integrate contrast and speed information.

Visual Illusions

The Enigma illusion is an example of a visual illusion.

Cerebellar Stroke/Lesion

A common impairment associated with a cerebellar stroke or lesion is ataxia.

Basal Ganglia Function

Early-stage Huntingdon's disease is associated with loss of D2 receptors in the Striatum, which would likely lead to motor symptoms such as chorea (involuntary movements).
The Globus Pallidus Internus (GPi) is the basal ganglia nucleus implicated in suppressing (but not facilitating) actions/movements.

Hippocampus and Posterior Parietal Cortex

The size of the hippocampus is an important consideration in certain neurological conditions.
The posterior parietal cortex does not represent somatosensory information.

Eye Movements

Saccades are rapid movements of the eyes between fixation points.

Motor Neuron Function

One muscle fibre has one neuromuscular junction (NMJ) innervated by one motor nerve terminal.

In a virtual reality experiment, an object's position is manipulated to match the user's eye movement. Does the user perceive the object as moving, and why? Explore the relationship between eye movement, visual perception, and virtual reality.