appearance of the room Morris Water Maze –designed to study the spatial abilities of rats xPlaced in a circular, featureless pool of cool milky water, in which they must swim until they discover the escape platform –which is invisible just beneath the surface of the water xAllowed to rest on the platform before retuned to the water for another trial xDespite the fact that the starting point is varied from trial to trail –learn after only a few trials to swim directly to the platform, presumably by suing spatial cues from the room as a reference xThis is useful for assessing the navigational skills of brain lesioned or drugged animals Conditioned Defensive Burying –rats receive a single aversive stimulus from an object mounted on the wall of the chamber just above the floor, which is littered with bedding material xAfter a single trial, almost every rat learns that the test object is a threat and responds by flinging bedding material at the test object with its head and forepaws xAntianxiety drugs reduce the amount of conditioned defensive burying, and thus the paradigm is used to study the neurochemistry of anxiety Distributing prohibited | Downloaded by School Work ([email protected])
Chapter 6 The Visual System 6.1 Light enters the Eye and Reaches the Retina xSome animals have special adaptations that allow them to see under very dim illuminations, but no anima can see in complete darkness xLight can be seen in two different ways: as discrete particles of energy, called photons, traveling through space at about 300 000 kilometers per second; or as waves of energy xLight is sometimes defined as waves of electromagnetic energy that are between 380 and 760 nanometers in length xThere is nothing special about these wavelengths except that the human visual system responds to them xWavelength and intensity are two properties of light that are of particular interst oWavelength because it plays an important role in the perception of colour, and intensity because it plays an important role in the perception of brightness xThe concepts of wavelength and color are often used interchangeably, so are intensity and brightness The Pupil and the Lens xThe amount of light reaching the retinas is regulated by the donut shaped bands of contractile tissue, the irises, which give out eyes their characteristic colour xLight enters the eye through the pupil, the hole in the iris xThe adjustment of pupil size in response to changes in illumination represents a compromise between sensitivity (the ability to detect the presence of dimly lit objects) and acuity (the ability to see the details of objects) xWhen the level of illumination is high and sensitivity is thus not important, the visual system takes advantage of the situation by constricting the pupils xWhen the pupils are constricted, the image falling on each retina is shaper and there is a greater depth of
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- Fall '16
- Psychology, brain damage, Electroencephalography