When an object changes position on the retinal image, it can be because A) the object moved or B) the eye moved
To know which object moved in the physical world, the movement of the eyes needs to be taken into account.
"Real Motion" Cells
Motion-responsive neurons in visual cortex (discovered in area V3A) Respond differently based on whether the movement of the retinal image was caused by the movement of the eyes or movement of the object
Anticipating Eye Movements
The brain sends information about an upcoming eye movement before the movement is actually executed, Allows the perceptual system to plan accordingly
Deriving Direction & Speed
To represent the direction and speed of motion, neurons need to do more than monitor from 2 receptive fields
By building in delays in transmission time, the direction and speed of motion can be represented
Population Code for Motion
Receptive fields in motion-responsive neurons exhibit tuning curves/functions
Note the suppression relative to baseline for directions opposite the preferred
The direction & position of motion is represented as a population code
Motion aftereffect
Motion Aftereffect
happens when a stationary object appears to be moving in the opposite direction to a moving object shown just beforehand
Sometimes called the waterfall effect because, if you stare at a waterfall awhile, and then look at a rock, the rock will appear to be moving
Motion Aftereffect
happens when a stationary object appears to be moving in the opposite direction to a moving object shown just beforehand
This video is designed to create a natural hallucination based on the motion aftereffect
Motion Aftereffect
WHY IT HAPPENS:
Motion Aftereffect
Why it happens:
Neurons representing a particular direction of motion in a particular area of space can become fatigued
This gives rise to the perceptiion of the opposite direction of motion
THE MT (V5) CORTEX
A MOTION-SENSITIVE BRAIN AREA
MT cortex is selectively responsive to motion
Note that the MT shows little response to object features
However, the MT appears to be involved in motion perception
MT cortex is selectively responsive to motion
The receptive field of neurons in early stages of visual processing (e.g., V1) are often too small to know the movement of a whole object
To represent the movement of larger objects, it is necessary to pool over multiple neurons
17- Motion Perception Part III (10.1.25)
Morgan Paladino
Created on October 1, 2025
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Transcript
motion perception
part III
10.1.25
START
cont'd, again
Motion & Changes in the Retinal Image
When an object changes position on the retinal image, it can be because A) the object moved or B) the eye moved
To know which object moved in the physical world, the movement of the eyes needs to be taken into account.
"Real Motion" Cells
Motion-responsive neurons in visual cortex (discovered in area V3A) Respond differently based on whether the movement of the retinal image was caused by the movement of the eyes or movement of the object
Anticipating Eye Movements
The brain sends information about an upcoming eye movement before the movement is actually executed, Allows the perceptual system to plan accordingly
Deriving Direction & Speed
To represent the direction and speed of motion, neurons need to do more than monitor from 2 receptive fields By building in delays in transmission time, the direction and speed of motion can be represented
Population Code for Motion
Motion aftereffect
Motion Aftereffect
happens when a stationary object appears to be moving in the opposite direction to a moving object shown just beforehand
Sometimes called the waterfall effect because, if you stare at a waterfall awhile, and then look at a rock, the rock will appear to be moving
Motion Aftereffect
happens when a stationary object appears to be moving in the opposite direction to a moving object shown just beforehand
This video is designed to create a natural hallucination based on the motion aftereffect
Motion Aftereffect
WHY IT HAPPENS:
Motion Aftereffect
Why it happens:
Neurons representing a particular direction of motion in a particular area of space can become fatigued
This gives rise to the perceptiion of the opposite direction of motion
THE MT (V5) CORTEX
A MOTION-SENSITIVE BRAIN AREA
MT cortex is selectively responsive to motion
Note that the MT shows little response to object features However, the MT appears to be involved in motion perception
MT cortex is selectively responsive to motion
The receptive field of neurons in early stages of visual processing (e.g., V1) are often too small to know the movement of a whole object To represent the movement of larger objects, it is necessary to pool over multiple neurons