The primate visual system 1 2 3 4
- Slides: 73
The primate visual system 1. 2. 3. 4. 5. 6. 7. The primate visual system Structure of the eye Neural responses to light Brightness perception & visual acuity Spatial frequency analysis & spatial context Form perception (psychological) Visual pathways & visual cortex (humans) Visual System & form perception (macaque) Helmuth Radrich, 24. 06. 2004
Visible spectrum The primate visual system Helmuth Radrich, 24. 06. 2004
The primate visual system Helmuth Radrich, 24. 06. 2004
The crystalline lens The primate visual system Helmuth Radrich, 24. 06. 2004
The primate visual system Helmuth Radrich, 24. 06. 2004
The fovea The primate visual system Helmuth Radrich, 24. 06. 2004
Rods and cones distribution The primate visual system Helmuth Radrich, 24. 06. 2004
The primate visual system Helmuth Radrich, 24. 06. 2004
Information flow from eye to brain • Via optic nerve • Data is not “raw”… preprocessed by retina • Human eye: – 120 million rods – 5 million cones – Another few millions of bipolar/amacrine/horizontal cells – Optic nerver: 1 million axons => A single ganglion cell axon receives information from many receptors in a region of the retina defining the cells receptive field The primate visual system Helmuth Radrich, 24. 06. 2004
The primate visual system 1. 2. 3. 4. 5. 6. 7. The primate visual system Structure of the eye Neural responses to light Brightness perception & visual acuity Spatial frequency analysis & spatial context Form perception (psychological) Visual pathways & visual cortex (humans) Visual System & form perception (macaque) Helmuth Radrich, 24. 06. 2004
Neural response types The primate visual system Helmuth Radrich, 24. 06. 2004
Receptive fields The primate visual system Helmuth Radrich, 24. 06. 2004
Parvo and magno cells The primate visual system Helmuth Radrich, 24. 06. 2004
Parvo and magno cells The primate visual system Helmuth Radrich, 24. 06. 2004
The primate visual system 1. 2. 3. 4. 5. 6. 7. The primate visual system Structure of the eye Neural responses to light Brightness perception & visual acuity Spatial frequency analysis & spatial context Form perception (psychological) Visual pathways & visual cortex (humans) Visual System & form perception (macaque) Helmuth Radrich, 24. 06. 2004
Intensity & perceived brightness The primate visual system Helmuth Radrich, 24. 06. 2004
Dark adaptation The primate visual system Helmuth Radrich, 24. 06. 2004
Relative sensitivity (wavelength) The primate visual system Helmuth Radrich, 24. 06. 2004
Visual angle The primate visual system Helmuth Radrich, 24. 06. 2004
Visual acuity The primate visual system Helmuth Radrich, 24. 06. 2004
The primate visual system 1. 2. 3. 4. 5. 6. 7. The primate visual system Structure of the eye Neural responses to light Brightness perception & visual acuity Spatial frequency analysis&spatial context Form perception (psychological) Visual pathways & visual cortex (humans) Visual System & form perception (macaque) Helmuth Radrich, 24. 06. 2004
Light distributions The primate visual system Helmuth Radrich, 24. 06. 2004
Approximation of square waves The primate visual system Helmuth Radrich, 24. 06. 2004
The primate visual system Helmuth Radrich, 24. 06. 2004
Apparent brightness The primate visual system Helmuth Radrich, 24. 06. 2004
Modulation transfer function The primate visual system Helmuth Radrich, 24. 06. 2004
Frequency analysis (biological) The primate visual system Helmuth Radrich, 24. 06. 2004
The primate visual system Helmuth Radrich, 24. 06. 2004
Spatial context (lat. inhibition) The primate visual system Helmuth Radrich, 24. 06. 2004
The primate visual system Helmuth Radrich, 24. 06. 2004
Temporal context effects The primate visual system Helmuth Radrich, 24. 06. 2004
The primate visual system 1. 2. 3. 4. 5. 6. 7. The primate visual system Structure of the eye Neural responses to light Brightness perception & visual acuity Spatial frequency analysis & spatial context Form perception (psychological) Visual pathways & visual cortex (humans) Visual System & form perception (macaque) Helmuth Radrich, 24. 06. 2004
Properties of visual environment The primate visual system Helmuth Radrich, 24. 06. 2004
Masking The primate visual system Helmuth Radrich, 24. 06. 2004
Feature extraction The primate visual system Helmuth Radrich, 24. 06. 2004
Emergent features The primate visual system Helmuth Radrich, 24. 06. 2004
Figure and ground The primate visual system Helmuth Radrich, 24. 06. 2004
The primate visual system Helmuth Radrich, 24. 06. 2004
Subjective contours The primate visual system Helmuth Radrich, 24. 06. 2004
Figural grouping The primate visual system Helmuth Radrich, 24. 06. 2004
The primate visual system Helmuth Radrich, 24. 06. 2004
Texture defined grouping The primate visual system Helmuth Radrich, 24. 06. 2004
Spatial frequency grouping The primate visual system Helmuth Radrich, 24. 06. 2004
Good figures The primate visual system Helmuth Radrich, 24. 06. 2004
Good figures The primate visual system Helmuth Radrich, 24. 06. 2004
Good figures The primate visual system Helmuth Radrich, 24. 06. 2004
What is this? ? ? The primate visual system Helmuth Radrich, 24. 06. 2004
Conceptually driven processing The primate visual system Helmuth Radrich, 24. 06. 2004
Global vs. local processing The primate visual system Helmuth Radrich, 24. 06. 2004
Context and identification The primate visual system Helmuth Radrich, 24. 06. 2004
The primate visual system Helmuth Radrich, 24. 06. 2004
The primate visual system Helmuth Radrich, 24. 06. 2004
The primate visual system 1. 2. 3. 4. 5. 6. 7. The primate visual system Structure of the eye Neural responses to light Brightness perception & visual acuity Spatial frequency analysis & spatial context Form perception (psychological) Visual pathways & visual cortex (humans) Visual System & form perception (macaque) Helmuth Radrich, 24. 06. 2004
The primate visual system Helmuth Radrich, 24. 06. 2004
The primate visual system Helmuth Radrich, 24. 06. 2004
The primate visual system Helmuth Radrich, 24. 06. 2004
Receptive fields (simple cortical) The primate visual system Helmuth Radrich, 24. 06. 2004
The primate visual system Helmuth Radrich, 24. 06. 2004
Layer of V 1 The primate visual system Helmuth Radrich, 24. 06. 2004
The primate visual system Helmuth Radrich, 24. 06. 2004
Visual pathways (human) The primate visual system Helmuth Radrich, 24. 06. 2004
The primate visual system Helmuth Radrich, 24. 06. 2004
The primate visual system 1. 2. 3. 4. 5. 6. 7. The primate visual system Structure of the eye Neural responses to light Brightness perception & visual acuity Spatial frequency analysis & spatial context Form perception (psychological) Visual pathways & visual cortex (humans) Visual System & form perception (macaque monkey) Helmuth Radrich, 24. 06. 2004
Oram&Prett proposal • Neurobiological data form macaque monkeys • Analogies to human visual system à Object recognition as series of 4 computational stages in 7 major hierarchically arranged processing areas à Simple feed-forward network sufficient for computer simulation The primate visual system Helmuth Radrich, 24. 06. 2004
The primate visual system Helmuth Radrich, 24. 06. 2004
• like in humans two major processing streams (only form perception is discussed) • strong similarities to human brain • Interconnection not as complete as it could be Why? ? àCombinatorial explosion if object is to be recognized from simple features (only edges, etc. ) àBasic edges etc. information not helpful in complex feature recognition at higher level The primate visual system Helmuth Radrich, 24. 06. 2004
The primate visual system Helmuth Radrich, 24. 06. 2004
The primate visual system Helmuth Radrich, 24. 06. 2004
The primate visual system Helmuth Radrich, 24. 06. 2004
Min. -timings in information-stream Assumptions (biologically plausible): • about 5 ms to trigger firing in the next neuron + some ms for signal transmission inside neurons (minimum) With the experimentally measured timings for the arrival of the first reactions in STPa after stimulus presentation (above): àOnly 7 interneuron connections can lay on the way of the signal (correspond to biological layers of the visual cortex) àNo time for lateral inhibition or feedback processes to interact with the information processing àFeed-forward only model is plausible, but only half of the story in higher perception The primate visual system Helmuth Radrich, 24. 06. 2004
The primate visual system Helmuth Radrich, 24. 06. 2004
Reference • Coren, S. , Ward, L. M. and Enns, J. T. (1993). Sensation and perception • Oram M. W. and Prrett, D. I. (1994), Modeling visual cognition from neurobiological constraints. Neural Networks 7 (6/7), 945 -972 The primate visual system Helmuth Radrich, 24. 06. 2004
The END Thank you for your attention! The primate visual system Helmuth Radrich, 24. 06. 2004