Download - Convolutions and Correlations
1
Convolutions and Correlations
2
3
)()()()()()()( xfxgxgxfduuxgufxh
)()()()()()()( xgxfxfxgduxugufxh
4
duuxgufxh )()()(
5
6
Neurons as Filters
7
8
9
10
Local Circuits in V1:
Selectivity is generated by specific connections
stimulus
Orientation selectivecortical simple cell
LGN
V1
Retina
11
12
),(),( 2
2
2
2
yxGx
yxGy
)cos()()( kxxGxg =
13
)()2
)(exp(21)(
20
kxtrigxxxg
trig=sin trig=cos
Note:2-dim. Gabor
function are elongated.Thus, cells responses
are orientationselective.Top view: .
trig=cos
15
0
),,(),()(),,( tdydxdttyyxxfyxgtvtyxR
16
m ore rea lis itic
17
duuxgufxh )()()(
18
duuxgufxh )()()(
Convolution and cell responsesImage on the retina
horizontal cross section
20
21
22
-
23Drifting grating stimulus
24
25
A Null-Response is indicative of inhibition
26
27
28
Detectors are so small close to the fixation point that theirresponses are similar.
29