Phototransduction & Visual Pathway Mmp March 10

Phototransduction & Image perception Dr. Nisreen Abo-elmaaty Physiology Department

Perception of a Visible Object ,[object Object],[object Object],[object Object],[object Object],[object Object]

1 st , u have to know what is the retina & its major elements; ,[object Object],[object Object],[object Object],[object Object]

Special Parts of the Retina ,[object Object],[object Object],[object Object],[object Object]

Fovea Centralis (yellow spot) ,[object Object],[object Object],[object Object]

10 Histological Layers of the Retina

4 retinal layers of physiological significance

Why Fovea is the most sensitive spot in retina? ,[object Object],[object Object],[object Object],[object Object],[object Object]

Why Fovea is the most sensitive spot in retina?

What is the Role of the 4 retinal layers of physiological significance?

1)- Retinal Pigmented Epithelium ,[object Object],[object Object],[object Object],[object Object]

2- Photoreceptors; Rods & Cones The 1 st order neuron in visual pathway

Convergence vs. No Convergence

[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Function No convergence (1:1; direct private line) Convergence (300:1 connection) Connection 3 types (iodopsin) Rhodopsin Photosensitive pigment ~ 6 millions in each retina More in centre Present ~ 120 millions in each retina More in periphery Non in Fovea Number Distribution Cones Rods

[object Object],[object Object]

3)- Bipolar Cells ,[object Object],[object Object],[object Object],[object Object],[object Object]

4)- Ganglion cells ,[object Object],[object Object],[object Object],[object Object],[object Object]

[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],4- Ganglion cells

♥ The Receptive Field (RF) of Ganglion Cells ,[object Object],[object Object],[object Object],[object Object]

♥ The Receptive Field (RF) of Ganglion Cells

[object Object],[object Object],[object Object],[object Object]

[object Object],[object Object],[object Object]

The Receptive Field (RF) of Ganglion Cells Response of ON-centre Ganglion cell to Light

What is the role of Lateral Cells? ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Phototransduction = Ionic Basis of photoreceptor Potential = Genesis of electric responses in retina

Phototransduction ,[object Object],[object Object],[object Object],[object Object]

Effect of Light on Retinal Neurons

[object Object],[object Object],[object Object],[object Object],[object Object],Ionic Basis for Phototransduction

[object Object],[object Object],Ionic Basis for Phototransduction

Ionic Basis of Light-evoked Hyperpolarization in Photoreceptors

Neural Processing of Visual Information ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Lateral Geniculate Body; LGB ,[object Object],[object Object],[object Object],[object Object]

LGB ,[object Object],[object Object],[object Object],[object Object],[object Object]

Primary Visual area (Area 17, V1) ,[object Object],[object Object],[object Object],[object Object],[object Object]

Role of Area 17 (V1) ,[object Object],[object Object],[object Object],[object Object],[object Object]

Secondary Visual Processing: Association Areas (18 &19; V2,3 & V4,5) ,[object Object],[object Object],[object Object],[object Object]

Retinotopic Organization & Processing of visual information

COLOUR VISION ,[object Object],[object Object],[object Object]

[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],COLOUR VISION

[object Object],[object Object],[object Object],[object Object],COLOUR VISION

Colour Blindness ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Phototransduction & Visual Pathway Mmp March 10

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Phototransduction & Visual Pathway Mmp March 10