08a vision processing intorduction
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Visual receptor
Neuronal architecture of mammalian visual system
Retina
Photoreceptors Rod and Cone
Anatomical Distribution of Rods and Cones
Phototransduction
Phototransduction
LightDark
Retina Functional organization
1. Retinal cell types
2. Neural Circuitry of Retina
3. Hyperpolarization
4. Neurotransmitters
5. Electrical synapse with graded conduction
6. Lateral inhibition
7. Bipolar cell depolarization/ hyperpolarization
Receptive Field
An experimental plan for recording from the visual pathway. The animal, usually a macaque monkey, faces a screen onto which we project a stimulus. We record by inserting a microlectrode into some part of the pathway, in this case, the primary visual cortex. (The brain in this diagram is from a human, but a monkey brain is very similar.)
Receptive field of Retina
Receptive Field
Receptive fields of photoreceptors and their connections. (A) The receptive field center provides a direct input from the photoreceptors to the bipolar cell, and the receptive field surround provides indirect input from the photoreceptor to the bipolar cells via horizontal cells. (B) 1: Photoreceptor cell; 2: on-center bipolar cell; 3: off-center bipolar cell; 4: on-center ganglion cell; 5: off-center ganglion cell.
Receptive field of two ganglion cells overlap
Two neighboring retinal ganglion cells receive input over the direct path from two overlapping groups of receptors. The areas of retina occupied by these receptors make up their receptive-field centers, shown face on by the large overlapping circles.
Dimension of Receptive field
One millimeter on the retina corresponds to 3.5 degrees of visual angle. On a screen1.5 meters away, 1 millimeter on the retina thus corresponds to about 3.5 inches, or 89 millimeters.
Receptive field
Responses of retinal bipolar and ganglion cells to darkness and illumination in the receptive field center.A) Changes in the electrical activity of the photoreceptor and on- and off-center bipolar and ganglion cells when the photoreceptor receptive field center is in the dark. (B) Changes in the electrical activity of the photoreceptor and on- and off-center bipolar and ganglion cells when the photoreceptor receptive field center is illuminated
Lateral inhibition mechanism
Responses of retinal bipolar and ganglion cells to darkness and illumination in the receptive field surround. (A) Changes in the electrical activity of the photoreceptor and on- and off-center bipolar and ganglion cells when the photoreceptor receptive field surround is in the dark. (B) Changes in the electrical activity of the photoreceptor and on- and off-center bipolar and ganglion cells when the photoreceptor receptive field surround is illuminated.
Receptive Field: Ganglion Cells
Stimulus M Cells P Cells
Color No Yes
Contrast High Low
Spatial Low High
Temporal High Low
Ganglion Cell : Contrast discrimination
Central Projections of Retinal Ganglion Cells
Lateral Geniculate Nucleus
Lateral Geniculate Ganglia
Pupillary reflex
Organization of Visual Cortex
Extrastriate Visual Areas Macaque Monkey
Human Visual Cortex fMRI
Visual Cortex Architecture
Visual Cortex Architecture
Recording from Visual Cortex
Simple cell of visual cortex
Simple Cell
Complex cell
Complex Cell
Complex Cells
Hypercomplex Cells
Significance of Movement Cells
Orientation Column
Orientation column of visual cortex
Illusion of Edges: V2 in Monkey
Inferior Temporal neuron response to Form
Illusion of Edges: V2 in Monkey
Face and Complex Form Recognition ITC
Blobs
40μm thick layer of upper cortex that has been processed histochemically to reveal the density of cytochrome oxidase, a mitochondrial enzyme involved in energy production
Ocular dominance column
Visual Cortex Architecture
AIT = anterior inferior temporal area; CIT = central inferior temporal area; LIP = lateral intraparietal area; Magno = magnocellular layers of the lateral geniculate nucleus; MST = medial superior temporal area; MT = middle temporal area; Parvo = parvocellular layers of the lateral geniculate nucleus; PIT = posterior inferior temporal area; VIP = ventral intraparietal area.) (Based on Merigan and Maunsell 1993.)
Motion in the visual field
PET scan of MT area for Motion Processing
Depth of vision
Neuronal basis of stereoscopic vision
AIT = anterior inferior temporal area; CIT = central inferior temporal area; LIP = lateral intraparietal area; Magno = magnocellular layers of the lateral geniculate nucleus; MST = medial superior temporal area; MT = middle temporal area; Parvo = parvocellular layers of the lateral geniculate nucleus; PIT = posterior inferior temporal area; VIP = ventral intraparietal area.) (Based on Merigan and Maunsell 1993.)
MT lesions in Monkey and Man with altered Motion Perception
Inferior Temporal neuron response to Color & Form
Color Vision
Cones and Color Vision
Surface reflectance
Surface reflected from blue vase in sunlight and skylight
The reflectance function of a natural surface
L+M
L-M
L+M-S
Receptive field of Primate Ganglion Cells for Color
The Importance of Context in Color Perception
Color blindness
Normal Protanope
Deuteranope Tritanope
Ishihara Chart for Color blindness testing
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