contrast sensitivity
Receptive field�The region of retina over �
which a stimulus affects the� electrical activity of a neuron
-- -
--
---
-+ ++ +
--
-
bipolar cellin vivo
+ ++ +
-- -
--
---
-+ ++ +
--
-
ganglion cellin vivo
receptorin vitro
Receptive field of a ganglion cell
1°-10° Light stimulus Light in
RF centre
RF periphery Centre and periphery On-centre neuron
Off-centre neuron 1s
RF centre
RF periphery Centre and periphery
Orientation tuning
A cortical binocular cell
Ocular dominance
Ocular dominance columns
Orientation columns
A sinusoidal grating
contrast
Spatial frequency
A neuron as a spatial filter
Filtering along the pathway
A spatial analysis
Contrast responses
1.0
0.5
Contrast %0.1 0.3 1.0
Sens
itivi
ty
P-cells
threshold saturation
Contrast vs spatial frequency
SPATIAL FREQUENCY (cycles/degree)
CON
TRA
ST S
ENSI
TIV
ITY
Window of visibility
SPATIAL FREQUENCY (cycles/degree)
CON
TRA
ST S
ENSI
TIV
ITY
Spatially-tuned channels
SPATIAL FREQUENCY (cycles/degree)
CON
TRA
ST S
ENSI
TIV
ITY
Temporal response of a neuron
1.0
0.5
Temporal Frequency (hz)1 10 100
Sens
itivi
ty
Human temporal sensitivity
Peripheral sensitivity
Types of retinal ganglion cell
Magno & parvo layers
An isoluminant grating
Colour vs luminance CSF
Robert F Hess
Amblyopia: a new view
McGill Vision Research Unit Dept. of Ophthalmology, McGill University, Canada
The Stimuli
Visual Development
Eileen Birch
Days of recovery
G
ratin
g ac
uity
(c/d
egre
e)
Gaussian size (sd min)
Alig
nmen
t acc
urac
y (m
in)
Monocular deprived cats
Strabismic cats
Gaussian size (sd min) Alig
nmen
t acc
urac
y (m
in)
Unrelated to visibility loss
Positional loss
Acu
ity lo
ss
Cont
rast
sens
itivi
ty lo
ss
Stimuli: positional sensitivity
Amblyopes
Contrast sensitivity ratio (dB)
Alig
nmen
t acc
urac
y ra
tio