The primate visual system 1 2 3 4

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