2020
Perception & Motor Control
Summary Lecture 7-14, English
BakedToast
EINDHOVEN UNIVERSITY OF TECHNOLOGY
, ~ Lecture 7 ~
Spatial vision:
Contrast:
L − Lmin luminance difference
C = max = abs
Lmax + Lmin total luminance
C = (1 - 0.5)/(1 + 0.5) = 1/3
C = (0.5 - 0.5)/(0.5 + 0.5) = 0
C =|(0 - 0.5)/(0.5 + 0) | = |-1| = 1
Spatial frequency:
The retina: Receptive fields
Receptive fields: Neurons in the somatosensory
cortex (touch).
- Stimulus space: Fires for a certain
region on the skin
- Stimulation in centre → excitatory
- Stimulation in surround → inhibitory
o Centre-surround structure
o Lateral inhibition of nearby
neurons
o Receptive fields vary in size.
Visual neurons typically respond to a certain patch of light. It is often interesting to know which
(external) stimuli trigger a neuron to fire.
Definition: The stimulus space that causes a neuron to fire is called a receptive field.
- A receptive field is a property of a neuron
- The stimulus space can have many dimensions
- (Sensory) Neurons typically fire for a range of events
,Receptive fields: Ganglion cells in the retina
The stimulus space
• Location (on a screen) (spatial opponency)
• Colour content (spectral opponency)
The receptive field has a centre-surround structure
• Excitatory centre & inhibitory surround (or vice versa)
• Varying sizes
• Lateral inhibition
Lateral inhibition of Cones
• Spatial opponency
• Neighbouring cones inhibit each other
• Spectral opponency
• Different cone types inhibit each other
Receptive fields: Spatial opponency
On-cells
• Excitatory centre
• Inhibitory surround
Off-Cells
• Inhibitory centre
• Excitatory surround
• Functionally equivalent -> always explain using ON-cells
, Receptive field response:
Ricco’s law
Intensity * Area = Constant Treshold Value
Valid up to 10 arc min (1 mm at arms length)
Contrast & Receptive fields:
Mach Band Illusion
Receptive fields: Ganglion cells in the retina
Perception & Motor Control
Summary Lecture 7-14, English
BakedToast
EINDHOVEN UNIVERSITY OF TECHNOLOGY
, ~ Lecture 7 ~
Spatial vision:
Contrast:
L − Lmin luminance difference
C = max = abs
Lmax + Lmin total luminance
C = (1 - 0.5)/(1 + 0.5) = 1/3
C = (0.5 - 0.5)/(0.5 + 0.5) = 0
C =|(0 - 0.5)/(0.5 + 0) | = |-1| = 1
Spatial frequency:
The retina: Receptive fields
Receptive fields: Neurons in the somatosensory
cortex (touch).
- Stimulus space: Fires for a certain
region on the skin
- Stimulation in centre → excitatory
- Stimulation in surround → inhibitory
o Centre-surround structure
o Lateral inhibition of nearby
neurons
o Receptive fields vary in size.
Visual neurons typically respond to a certain patch of light. It is often interesting to know which
(external) stimuli trigger a neuron to fire.
Definition: The stimulus space that causes a neuron to fire is called a receptive field.
- A receptive field is a property of a neuron
- The stimulus space can have many dimensions
- (Sensory) Neurons typically fire for a range of events
,Receptive fields: Ganglion cells in the retina
The stimulus space
• Location (on a screen) (spatial opponency)
• Colour content (spectral opponency)
The receptive field has a centre-surround structure
• Excitatory centre & inhibitory surround (or vice versa)
• Varying sizes
• Lateral inhibition
Lateral inhibition of Cones
• Spatial opponency
• Neighbouring cones inhibit each other
• Spectral opponency
• Different cone types inhibit each other
Receptive fields: Spatial opponency
On-cells
• Excitatory centre
• Inhibitory surround
Off-Cells
• Inhibitory centre
• Excitatory surround
• Functionally equivalent -> always explain using ON-cells
, Receptive field response:
Ricco’s law
Intensity * Area = Constant Treshold Value
Valid up to 10 arc min (1 mm at arms length)
Contrast & Receptive fields:
Mach Band Illusion
Receptive fields: Ganglion cells in the retina
