Damage to the visual cortex doesn"t equal blindness. Visual agnosia (they may be fine with seeing objection but they have trouble perieving it and recognizing it) Inability for the information for visual world to make contact with his knowledge (can recognizes face) Uses memories before the accident to imagine what is in front of him. Imput brain receives from world is action potentials. In all cases, sesnsory stimulation is the same but the perception is different. Vergence: example holding a finger infront of you and focusing on it as you move it closer. Photreceptors are at the back of the eye. We have 1 fovea, birds have 2 fovea"s. Nocturnal animals are dicromats (don"t see the color don"t respond to all wavelengths ex: rats are sesntive to some wavelengths) Depolarisation of bipolar cell leads to increased glutamate release causing it to increase rate of firing in the ganglion cells.