17860024
Description
Flashcards by Holly Goodenough, updated more than 1 year ago
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Created by Holly Goodenough
over 5 years ago
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| Question | Answer |
| The anatomy of the eye | |
| The retina | transduction and to brain; lines the back of our eye. Light rays are focused onto the retina through cornea, pupil and lens.. It converts the rays into impulses that travel through the optic nerve to our brain, where they are interpreted as the images we see. |
| What are the 2 important parts of the retina (central vision)? | 1. Macula (2mm), 2. Fovea (reading, detail) |
| Macular degeneration | |
| The optic disk | “Blind spot”; start of optic nerve. Circular; slightly off-centre, nasal |
| Optic nerve | Assembly / exit point from retina Information to visual cortex |
| Cells in the retina | |
| Types of cells in the retina | Bottom layer of retina: Photopigment cells (rods, cones) sensitive to light Two layers of neurons Middle layer: Bipolar cells – first neuron Layer closest to inner eyeball: Ganglion cells |
| photopigment cells: rods | Rods: Sensitive to light only in black & white, higher level of convergence (pooling) |
| photopigment cells: cones | Cones: Sensitive to light in specific colour. Three types: Blue, Green, Red. |
| What is the difference between rods and cones? | Light-sensitivity and distribution Cones: more in centre of retina, good for bright light, good for detail / colour Rods: more in periphery of retina, colour-blind, good for dim light (pooling), not good for detail When dark: cannot see colours! |
| Transduction - step 1 - photopigment release | Light -> photoreceptors These contain photopigment Opsin (cones) / rhodopsin (rods) + retinal, synthesised from vitamin A) Photopigment released Then complex chemical cascade |
| Transduction - step 2 and 3 | Photopigment release sends signals to bipolar cells The bipolar cells pass the signal on to ganglion cells They pass it up the optic nerve. *NEURAL PROCESSING IN THE RETINA* |
| Which lobe contains the visual cortex? | Occipital lobe |
| The visual pathway | |
| Visual fields and the optic chiasm | Left visual field -> right hemisphere Right visual field -> left hemisphere |
| Organisation of cortical tissue | laminar (horizontal layers) |
| What and where pathways | |
| Bottom up vs. top down | Bottom up processing: mental processing of external stimuli Top down modulation: mental control affecting lower levels of processing |
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