Electrical activity in ganglion cells of the retina and in neurons of the lateral geniculate nucleus and cerebral cortex is evoked in response to light on the retina.The way in which each type of neuron responds to light at a particular point on the retina provides information about how the brain interprets visual information.
Light cast on the retina directly affects the activity of pho-toreceptors and indirectly affects the neural activity in bipolar and ganglion cells. The part of the visual field that affects the activity of a particular ganglion cell can be considered its receptive field. As previously mentioned, each cone in the fovea has a private line to a ganglion cell, and thus the receptive fields of these ganglion cells are equal to the width of one cone (about 2 |im). By contrast, ganglion cells in more peripheral parts of the retina receive input from hundreds of photoreceptors, and are therefore influenced by a larger area of the retina (about 1 mm in diameter).
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This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.