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2002/02/05PSYC202-005, Term 2, Copyright Jason Harrison, 20021 Visual pathways from here to there to everywhere.

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Presentation on theme: "2002/02/05PSYC202-005, Term 2, Copyright Jason Harrison, 20021 Visual pathways from here to there to everywhere."— Presentation transcript:

1 2002/02/05PSYC , Term 2, Copyright Jason Harrison, Visual pathways from here to there to everywhere

2 2002/02/05PSYC , Term 2, Copyright Jason Harrison, Pathways are between maps maps maintain neighborhoodness and local features (corners, lines, etc) First map: retina a slightly distorted map

3 2002/02/05PSYC , Term 2, Copyright Jason Harrison, Each ganglion cell fires according to what is at its location Area that each cell responds to is a receptive field

4 2002/02/05PSYC , Term 2, Copyright Jason Harrison, neighbouring cells in retina respond to neighbouring locations in image visual map

5 2002/02/05PSYC , Term 2, Copyright Jason Harrison, Visual pathways path of visual information through brain starts with ganglion cells ends at cortical area maps at LGN, V1, etc (LGN) Striate Cortex

6 2002/02/05PSYC , Term 2, Copyright Jason Harrison, What not to worry about images in visual maps are distorted images in visual maps are upside-down this does not matter as long as neighbours in image are also neighbours in visual map

7 2002/02/05PSYC , Term 2, Copyright Jason Harrison, What can you do with a distorted upside down map? determine edge orientations determine line intersections (which and angle) number of lines, motions of lines regions, holes, patterns Visual system determines structure of world measurements from maps some knowledge (experience/evolution) of world

8 2002/02/05PSYC , Term 2, Copyright Jason Harrison, How, What and Watch Out How: parietal lobe –LGN…V5/MT, action, spatial vision, visually guided behaviour What: temporal lobe –LGN…V3/4/8, object recognition, complex object recognition –if damaged can produce action, but not perceive location or orientation (Rama, pp. 63-) Watch out: superior colliculus –optic nerve…midbrain, orientation, “snake on your left?”, illumination changes –processes auditory and tactile sensations too

9 2002/02/05PSYC , Term 2, Copyright Jason Harrison, How: parietal lobe -dorsal path LGN…V5/MT, action, spatial vision, visually guided behaviour and action global movement (LGN) Striate Cortex V5/MT Parietal Lobe

10 2002/02/05PSYC , Term 2, Copyright Jason Harrison, What: temporal lobe - ventral path LGN…V3 object recognition through form and local movement (LGN) Striate Cortex V3 Temporal Lobe

11 2002/02/05PSYC , Term 2, Copyright Jason Harrison, What: temporal lobe LGN…V4…V8 object recognition through colour (LGN) Striate Cortex V4 Temporal Lobe V8

12 2002/02/05PSYC , Term 2, Copyright Jason Harrison, Watch out: superior colliculus optic nerve…midbrain: Tecto-fugal receives ~20% of optic nerve fibers more concerned with where a stimulus is than what controls eye movements, detects objects located away from fixation and guides eyes towards objects (LGN) Superior Colliculus

13 2002/02/05PSYC , Term 2, Copyright Jason Harrison, Watch out: superior colliculus orientation of gaze and attention “snake on your left?”, illumination changes processes auditory and tactile sensations too (LGN) Superior Colliculus

14 2002/02/05PSYC , Term 2, Copyright Jason Harrison, Watch out: superior colliculus passes on some information to parietal lobe when V1 is destroyed –“blindsight” - unconscious sight (LGN) Superior Colliculus

15 2002/02/05PSYC , Term 2, Copyright Jason Harrison, Summary of pathways 1.Object structure (“what I am seeing?”) located in temporal lobe; conscious? form perception colour perception 2.Movement (“how do I get this there?”) located in parietal lobe; unconscious? motion perception and planning 3.Preconscious reactions (“Aieee! Snake!?”) Located in midbrain Reacts to sound, touch: which direction is danger?

16 2002/02/05PSYC , Term 2, Copyright Jason Harrison, Summary of pathways All pathways operate separately, in parallel Question: how do we experience a unified world?


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