The primate visual systemHelmuth Radrich, The primate visual system 1.Structure of the eye 2.Neural responses to light 3.Brightness perception & visual acuity 4.Spatial frequency analysis & spatial context 5.Form perception (psychological) 6.Visual pathways & visual cortex (humans) 7.Visual System & form perception (macaque)

The primate visual systemHelmuth Radrich, Visible spectrum

The primate visual systemHelmuth Radrich,

The primate visual systemHelmuth Radrich, The crystalline lens

The primate visual systemHelmuth Radrich,

The primate visual systemHelmuth Radrich, The fovea

The primate visual systemHelmuth Radrich, Rods and cones distribution

The primate visual systemHelmuth Radrich,

The primate visual systemHelmuth Radrich, 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 systemHelmuth Radrich, The primate visual system 1.Structure of the eye 2.Neural responses to light 3.Brightness perception & visual acuity 4.Spatial frequency analysis & spatial context 5.Form perception (psychological) 6.Visual pathways & visual cortex (humans) 7.Visual System & form perception (macaque)

The primate visual systemHelmuth Radrich, Neural response types

The primate visual systemHelmuth Radrich, Receptive fields

The primate visual systemHelmuth Radrich, Parvo and magno cells

The primate visual systemHelmuth Radrich, Parvo and magno cells

The primate visual systemHelmuth Radrich, The primate visual system 1.Structure of the eye 2.Neural responses to light 3.Brightness perception & visual acuity 4.Spatial frequency analysis & spatial context 5.Form perception (psychological) 6.Visual pathways & visual cortex (humans) 7.Visual System & form perception (macaque)

The primate visual systemHelmuth Radrich, Intensity & perceived brightness

The primate visual systemHelmuth Radrich, Dark adaptation

The primate visual systemHelmuth Radrich, Relative sensitivity (wavelength)

The primate visual systemHelmuth Radrich, Visual angle

The primate visual systemHelmuth Radrich, Visual acuity

The primate visual systemHelmuth Radrich, The primate visual system 1.Structure of the eye 2.Neural responses to light 3.Brightness perception & visual acuity 4.Spatial frequency analysis&spatial context 5.Form perception (psychological) 6.Visual pathways & visual cortex (humans) 7.Visual System & form perception (macaque)

The primate visual systemHelmuth Radrich, Light distributions

The primate visual systemHelmuth Radrich, Approximation of square waves

The primate visual systemHelmuth Radrich,

The primate visual systemHelmuth Radrich, Apparent brightness

The primate visual systemHelmuth Radrich, Modulation transfer function

The primate visual systemHelmuth Radrich, Frequency analysis (biological)

The primate visual systemHelmuth Radrich,

The primate visual systemHelmuth Radrich, Spatial context (lat. inhibition)

The primate visual systemHelmuth Radrich,

The primate visual systemHelmuth Radrich, Temporal context effects

The primate visual systemHelmuth Radrich, The primate visual system 1.Structure of the eye 2.Neural responses to light 3.Brightness perception & visual acuity 4.Spatial frequency analysis & spatial context 5.Form perception (psychological) 6.Visual pathways & visual cortex (humans) 7.Visual System & form perception (macaque)

The primate visual systemHelmuth Radrich, Properties of visual environment

The primate visual systemHelmuth Radrich, Masking

The primate visual systemHelmuth Radrich, Feature extraction

The primate visual systemHelmuth Radrich, Emergent features

The primate visual systemHelmuth Radrich, Figure and ground

The primate visual systemHelmuth Radrich,

The primate visual systemHelmuth Radrich, Subjective contours

The primate visual systemHelmuth Radrich, Figural grouping

The primate visual systemHelmuth Radrich,

The primate visual systemHelmuth Radrich, Texture defined grouping

The primate visual systemHelmuth Radrich, Spatial frequency grouping

The primate visual systemHelmuth Radrich, Good figures

The primate visual systemHelmuth Radrich, Good figures

The primate visual systemHelmuth Radrich, Good figures

The primate visual systemHelmuth Radrich, What is this???

The primate visual systemHelmuth Radrich, Conceptually driven processing

The primate visual systemHelmuth Radrich, Global vs. local processing

The primate visual systemHelmuth Radrich, Context and identification

The primate visual systemHelmuth Radrich,

The primate visual systemHelmuth Radrich,

The primate visual systemHelmuth Radrich, The primate visual system 1.Structure of the eye 2.Neural responses to light 3.Brightness perception & visual acuity 4.Spatial frequency analysis & spatial context 5.Form perception (psychological) 6.Visual pathways & visual cortex (humans) 7.Visual System & form perception (macaque)

The primate visual systemHelmuth Radrich,

The primate visual systemHelmuth Radrich,

The primate visual systemHelmuth Radrich,

The primate visual systemHelmuth Radrich, Receptive fields (simple cortical)

The primate visual systemHelmuth Radrich,

The primate visual systemHelmuth Radrich, Layer of V1

The primate visual systemHelmuth Radrich,

The primate visual systemHelmuth Radrich, Visual pathways (human)

The primate visual systemHelmuth Radrich,

The primate visual systemHelmuth Radrich, The primate visual system 1.Structure of the eye 2.Neural responses to light 3.Brightness perception & visual acuity 4.Spatial frequency analysis & spatial context 5.Form perception (psychological) 6.Visual pathways & visual cortex (humans) 7.Visual System & form perception (macaque monkey)

The primate visual systemHelmuth Radrich, Oram&Prett proposal Neurobiological data form macaque monkeys Analogies to human visual system  Object recognition as series of 4 computational stages in 7 major hierarchically arranged processing areas  Simple feed-forward network sufficient for computer simulation

The primate visual systemHelmuth Radrich,

The primate visual systemHelmuth Radrich, 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????  Combinatorial explosion if object is to be recognized from simple features (only edges, etc.)  Basic edges etc. information not helpful in complex feature recognition at higher level

The primate visual systemHelmuth Radrich,

The primate visual systemHelmuth Radrich,

The primate visual systemHelmuth Radrich,

The primate visual systemHelmuth Radrich, 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):  Only 7 interneuron connections can lay on the way of the signal (correspond to biological layers of the visual cortex)  No time for lateral inhibition or feedback processes to interact with the information processing  Feed-forward only model is plausible, but only half of the story in higher perception

The primate visual systemHelmuth Radrich,

The primate visual systemHelmuth Radrich, 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),

The primate visual systemHelmuth Radrich, The END Thank you for your attention!