Chapter 2 - 9-10-05 I) Chapter 2 Receptors and Neural...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
9.10.5 Chapter 2 – Receptors and Neural Processing I) The Visual System: a. Light goes into the eye i.Light passes through the transparent cornea and lens, which focus it on the retina ii.Light hits the cones and rods, behind the amacrine cells, bipolar cells, horizontal cells and ganglion cells, which reacts with the light-sensitive pigments iii.The axons of the ganglion cells leave the eye to form the optic nerve b. The signal then travels to the lateral geniculate nucleus in the thalamus i.Also called the striate cortex, because of the presence of white stripes (nerves) c. Then on to higher-level processing areas, which are called the extrastriate cortex i.½ brain devoted to visual processing ii.We believe what we see even when it goes against other sensory information II) The First Transformations: Light, Receptors and Electricity: a. Steps to Vision: i.Light hits retina ii.Isomerization takes place transducing light into electricity iii.Signal travels along optic nerve iv.Optic Chiasm – information is split to go to each hemisphere 1. Right halves of eyes go to right hemisphere and visa-versa v.Information travels down optic tract vi.Information goes to the lateral geniculate nucleus of the thalamus in order to get sorted and sent to the right areas of the brain vii.Information goes to the visual cortex of the occipital lobe viii.Information travels to the frontal lobe in two different ways 1. Dorsal Stream – passes through parietal lobe (where object is) 2. Ventral Stream – passes through temporal lobe (what object is) ix.All information ends up in frontal lobe (conscious perception) b. Light is Focused and Reflected in the Eye: i.Cornea – transparent covering of the front of the eye (remains static) ii.Lens – can change its shape to focus light on the retina 1. When light comes from a far away object, it comes in parallel lines, which high the eye, are bent by the cornea and lens and focus on the fovea of the retina. If object are closer then the light reflecting off of them is screwed more towards the object and the lens has to thicken to further bend the light so that the focus point can come forward to the fovea 2. Near Point – the distance at which your lens can no longer adjust to bring close objects into focus 3. Presbyopia – the near point gets farther as we age because the muscle that constricts the lens looses strength and elasticity iii.Vitreous Humor – jelly stuff that fills the eye iv.The pupil doesn’t let in light, the muscles of the iris do c. Placement of Eyes: i.Predators – eyes in front of head for binocular vision (distance perception) 1. Each eye sends 50% of information to each hemisphere so that that information that is in both creates the 3d image in the middle ii.Prey – eyes on side for better peripheral vision to detect danger 1. All information from each eye goes to opposite hemisphere d. Light Stimulus and Rod and Cone Receptors:
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
i.Rods – do not perceive color or have good acuity, but perceive well in the
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 5

Chapter 2 - 9-10-05 I) Chapter 2 Receptors and Neural...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online