Shaul Hochstein

1. ניורוביולוגיה ומדעי המחחלק 2 – מערכת הראייהIntroduction to NeurobiologyPart 2 – The Visual System Shaul Hochstein

2. ניורוביולוגיה ומדעי המחIntroduction to Neurobiology Introduction to Sensory Systems The retina “From Neuron to Brain” Chapter 19: 379-405 Transduction and signaling in the retina

3. ניורוביולוגיה ומדעי המחIntroduction to Neurobiology Introduction to Sensory Systems The retina 1- Structure of the eye 2- Muscles of the eye – fixation; convergence; accommodation; 3- Structure of the retina 4- The blind spot 5- Rods and Cones 6- Visual Pigments 7- Color vision: Young & Helmholtz 8- Photoreceptor sensitivity and signal amplification 9- Structure-Function relationships 10- Ribbon synapses 11- The fovea: Comparing central and peripheral vision

4. ניורוביולוגיה ומדעי המחIntroduction to Neurobiology Introduction to Sensory Systems Is the eye like a camera? Yes and No: lens, focus, pupil, inverted image, film=layer of photorceptors But: information processing

6. ניורוביולוגיה ומדעי המחIntroduction to Neurobiology Introduction to Sensory Systems To where are retinal signals transmitted? Right sides of both retinas to right brain. Left sides of both retinas to left brain. BUT: image was inverted (up-down and right-left) by optical pin-hole (lens) effect.

8. ניורוביולוגיה ומדעי המחIntroduction to Neurobiology Introduction to Sensory Systems layers of neurons & connections in the retina. Note 3 types of neurons at middle cell-body layer.

9. The Retina and its layers

10. The Retina and its layers Cell bodies connections Cell bodies connections Cell bodies

11. ניורוביולוגיה ומדעי המחIntroduction to Neurobiology Introduction to Sensory Systems Rods and cones - sensitivity vs. acuity & color; - located in central vs. peripheral retina - night vs. day

14. ניורוביולוגיה ומדעי המחIntroduction to Neurobiology Introduction to Sensory Systems Pros and Cons for an inside-out retina.

17. ניורוביולוגיה ומדעי המחIntroduction to Neurobiology Introduction to Sensory Systems Depolarizing and Hyperpolarizing receptor, generator, and action potential signals - still only one trick: change in conductance to specific ion(s).

18. The photoreceptor response: Receptor potential & generator potential Graded potentials vs. Action potentials

19. In the dark, Na channels are open, causing depolarization and allowing Na influx and K efflux, counteracted by pump. In light, Rhodopsin ultimately closes these channels stopping the flow.

20. ניורוביולוגיה ומדעי המחIntroduction to Neurobiology Introduction to Sensory Systems The source of color vision: How many cone types do we need? 1 type: no color (confuse color and intensity) 2 types: full color spectrum but no combinations 3 types: color spectrum plus white (& other unsaturated colors) plus purple (red & blue) …

22. ניורוביולוגיה ומדעי המחIntroduction to Neurobiology Introduction to Sensory Systems Transmission: Photoreceptor to Bipolar

24. ניורוביולוגיה ומדעי המחIntroduction to Neurobiology Introduction to Sensory Systems The receptive field Definition – area in the world (or on retina) where change in stimulus induces change in response in recorded neuron. Extension – area in multi-dimensional stimulus space where … Physiological research – aids in guessing connectivity from area to area

25. Limulus

26. Mapping a receptive field

27. ניורוביולוגיה ומדעי המחIntroduction to Neurobiology Introduction to Sensory Systems A first computation: Lateral Inhibition: mechanism, consequences and function

36. Supplementary material