The Visual System: Feature Detection Model
description
Transcript of The Visual System: Feature Detection Model
![Page 1: The Visual System: Feature Detection Model](https://reader036.fdocuments.us/reader036/viewer/2022082712/56813bd9550346895da5021d/html5/thumbnails/1.jpg)
The Visual System:Feature Detection
ModelLesson 17
![Page 2: The Visual System: Feature Detection Model](https://reader036.fdocuments.us/reader036/viewer/2022082712/56813bd9550346895da5021d/html5/thumbnails/2.jpg)
Cortical Mechanisms
Primary Visual Cortex - V1 Striate or calcarine cortex
Hubel and Wiesel - Nobel Prize Single cell recording
Feature detection model simple stimuli complex perceptions ~
![Page 3: The Visual System: Feature Detection Model](https://reader036.fdocuments.us/reader036/viewer/2022082712/56813bd9550346895da5021d/html5/thumbnails/3.jpg)
Feature Detection Model
Visual perception of objects detection of simple features points, lines, corners, curves
Convergence of information retina LGN V1
Primary Visual Cortex (V1) Simple cells complex cells hypercomplex cells ~
![Page 4: The Visual System: Feature Detection Model](https://reader036.fdocuments.us/reader036/viewer/2022082712/56813bd9550346895da5021d/html5/thumbnails/4.jpg)
Simple Cells Detect lines & edges
not center-surround Best stimulus
bar of light or line particular orientation particular location ~
![Page 5: The Visual System: Feature Detection Model](https://reader036.fdocuments.us/reader036/viewer/2022082712/56813bd9550346895da5021d/html5/thumbnails/5.jpg)
Simple Cells
LGN neurons RF center-surround converge onto simple cells (V1)
Bar of light APs in simple cell ~
![Page 6: The Visual System: Feature Detection Model](https://reader036.fdocuments.us/reader036/viewer/2022082712/56813bd9550346895da5021d/html5/thumbnails/6.jpg)
Simple Cell
Simple Cells
wrong location or angle doesn’t affect simple cell ~
LGN
V1
Wronglocation
Wrongangle
![Page 7: The Visual System: Feature Detection Model](https://reader036.fdocuments.us/reader036/viewer/2022082712/56813bd9550346895da5021d/html5/thumbnails/7.jpg)
Complex Cells
In V1 & V2 (secondary visual cortex) Convergence
of LGN & simple cells responds to movement
Best stimulus line or bar Fixed angular orientation Location not as important preferred direction of movement ~
![Page 8: The Visual System: Feature Detection Model](https://reader036.fdocuments.us/reader036/viewer/2022082712/56813bd9550346895da5021d/html5/thumbnails/8.jpg)
S1 S2 S3
Complex Cell
Complex Cells
V1
V1/V2
![Page 9: The Visual System: Feature Detection Model](https://reader036.fdocuments.us/reader036/viewer/2022082712/56813bd9550346895da5021d/html5/thumbnails/9.jpg)
Hypercomplex Cells
V1 & V2 Complex cells converge Hypercomplex cells
Best stimulus lines of specific length Detect Corners ~
![Page 10: The Visual System: Feature Detection Model](https://reader036.fdocuments.us/reader036/viewer/2022082712/56813bd9550346895da5021d/html5/thumbnails/10.jpg)
Feature Detection Theory Features = lines & corners
Can it represent a curve?