The visual and oculomotor systems. Peter H. Schiller, year The visual cortex

Transcription

1 The visual and oculomotor systems Peter H. Schiller, year 2006 The visual cortex

2 V1 Anatomical Layout

3 Monkey brain central sulcus Central Sulcus V1 Principalis principalis Arcuate Lunate lunate Figure by MIT OCW.

4 Monkey brain, back view Monkey brain, back view 8 o 4 o Lunate 2 o 1 o Vertical Horizontal Figure by MIT OCW.

5 V1 Receptive Field Organization

6 Receptive field plots of cat V1 cells using small spots Simple Simple Complex Figure by MIT OCW.

7 Asessing orientation and direction specificity of a V1 cell receptive field

8

9 Asessing spatial frequency selectivity of a V1 cell

10 Responses of a simple and complex cell to gratings of different spatial frequencies S CX Number of Discharges UNIT SP cy/deg UNIT ms Figure by MIT OCW.

11 Transforms in V1 Orientation Direction Spatial Frequency Binocularity ON/OFF Convergence Midget/Parasol Convergence

12 Striate Cortex Output Cell Intracortical LEFT EYE INPUT Midget ON Midget OFF Parasol ON Parasol OFF Midget ON Midget OFF Parasol ON Parasol OFF RIGHT EYE INPUT luminance color orientation spatial frequency depth motion

13 V1 Cytoarchitecture

14 Original Hubel-Wiesel "Ice-Cube" Model Orientation Columns Ocular Dominance Columns Left Eye Right Eye 4c 4c 5 6 L parasol midget R parasol midget 500

15 Cytochrome oxidase patches in monkey V1 Cytochrome oxidase patches in monkey V1 5 mm Figure by MIT OCW.

16 Radial Model Orientation Columns Ocular Dominance Columns Left Eye Right Eye 4c 4c 5 6 L parasol midget R parasol midget 500

17 Original Hubel-Wiesel "Ice-Cube" Model Cortical Left Eye Right Eye Sub-cortical Radical Model 1 mm Left Eye Right Eye Swirl Model Midget Parasol Three models of columnar organization in V1 Figure by MIT OCW.

18 Extrastriate cortex

19 Methods for delineating extrastriate areas achitectonics connections topographic mapping physiological characterization lesions and behavioral testing cerebral accidents and behavioral testing imaging

20 Visual functions studied

21 Basic visual capacities color brightness pattern texture motion depth Intermediate visual capacities constancy selection recognition transposition comparison location

22 Layout of visual areas

23 Central Sulcus LIP V2 V1 Lunate V4 Figure by MIT OCW.

24 Major cortical visual areas: Occipital V1 V2 V3 V4 MT (medial temporal) Temporal IT (inferotemporal) Parietal LIP (lateral intraparietal) VIP (ventral intraparietal) MST (medial superior temporal) Frontal FEF (frontal eye fields)

25 Connections among adjacent visual areas Receptive field locations and sizes at successive penetrations in V1 and V2. V1 V2 V

26 Area V2

27 stripes: thin inter thick V 2 V Ca 4Cb parasol midget 500

28 Functional Segregation in Area V2 Attribute Percent of cells Stripes Thin Pale Thick Orientation End stopping Color Direction Disparity Source: Peterhans, in Cerebral Cortex, Vol 12, 1997, sum of five studies

29 Area V4

30 Central Sulcus LIP V2 V1 Lunate V4 Figure by MIT OCW.

31 Area V4 attributes: 1. Large receptive fields 2. Complex receptive field properties 3. Responses are task and intent modulated 4. Response can also be modulated by eye movements 5. Not just a color area

32 Area MT and MST

33 Central Sulcus LIP STS V1 Principalis Arcuate V4 Lunate Figure by MIT OCW.

34 Direction specificity as a function of track distance in MT ALBRIGHT, DESIMONE, AND GROSS Axis of Motion (degrees) * * * * * * ,200 1,600 2,000 2,400 2,800 3,200 3,600 4,000 4,400 4,800 Track Distance Figure by MIT OCW.

35 Layout of directions in MT Direction Column Direction Column } Axis of Motion Column Figure by MIT OCW.

36 Inferotemporal cortex

37 Central Sulcus LIP STS MT MST V1 Principalis Arcuate V4 Lunate IT Figure by MIT OCW.

38 central sulcus LIP STS MT MST principalis V1 arcuate V4 lunate IT

39 Summary: 1. The contralateral visual hemifield is laid out topographically in V1 of each hemisphere. 2. V1 transforms are: orientation, direction, spatial frequency, binocularity, ON/OFF convergence and midget/parasol convergence. 3. V1 is organized in a modular fashion. Three models of the layout of the modules are the ice cube, radial and swirl models 4. There are more than 30 visual areas that make more than 300 interconnections. 5. Extrastriate areas do not specialize in any single function. 6. The receptive field size of neurons increases greatly in progressively higher visual areas. 7. Area MT is involved in the analysis of motion, depth, and flicker. 8. Area V4 engages in many aspects of analysis; neurons have dynamic properties. 9. In inferotemporal cortex high level analysis takes place that includes object recognition. 10. Single cells in cortex are multifunctional.

40 central sulcus LIP STS principalis V1 arcuate V4 lunate IT