User:Mpicon1212/sandbox

Discovery
Inhibition in single sensory neurons was discovered and investigated starting in 1949 by Haldan K. Hartline when he used logarithms to express the effect of Ganglion receptive fields. His algorithms also help explain the experiment conducted by David H. Hubel and Torsten Wiesel that expressed a variation of sensory processing, including lateral inhibition, within different species.

In 1956, Hartline revisited this concept of lateral inhibition in Limulus amebocyte lysate, horseshoe crab, during an experiment conducted with the aid of Henry G Wagner and Floyd Ratliff. Hartline explored the anatomy of ommatidium, in the horseshoe crab because of their similar function and physiological anatomy to photoreceptors in the human eye. Also, they are much larger than photoreceptors in humans which would make them much easier to observe and record. Hartline contrasted the response signal of the ommatidium when a single concentrated beam of light was directed at one receptor unit as opposed to three surrounding units. He further supported his theory of lateral inhibition as the response signal of one unit was stronger when the surrounding units were not exposed to light.

Visual Inhibition
Visual Lateral Inhibition is the process in which photoreceptor cells aid the brain in perceiving contrast within an image. Electromagnetic light enters the eye by passing through the cornea, pupil, and the lens (optics). It then bypasses the ganglion cells, amacrine cells, bipolar cells, and horizontal cells in order to reach the photoreceptors rod cells which absorb light. The rods become stimulated by the energy from the light and release an excitatory neural signal to the horizontal cells.

This excitatory signal, however, will only be transmitted by the rod cells in the center of the Ganglion cell receptive field to ganglion cells because horizontal cells respond by sending an inhibitory signal to the neighboring rods to create a balance that allows mammals to perceive more vivid images. The retinal ganglion cells will still receive an excitatory neural response but only from the center rod. The central rod will send its excitatory neural response directly to bipolar cells which in turn will relay the signal to the ganglion cells. This inhibition produced by horizontal cells creates a more concentrated and balanced signal for the retinal ganglion cells to send to the cerebral cortex through the optic nerve, which accounts for an individuals' blind spot.

Embryology
In embryology, the concept of lateral inhibition has been adapted to describe processes in the development of cell types. Lateral inhibition is described as a part of the Notch signaling pathway, a type of cell–cell interaction. Specifically, during asymmetric cell division one daughter cell adopts a particular fate that causes it to be copy of the original cell and the other daughter cell is inhibited from becoming a copy. Lateral inhibition is well documented in flies, worms and vertebrates. In all of these organisms, the transmembrane proteins Notch and Delta (or their homologues) have been identified as mediators of the interaction. Research has been more commonly associated with Drosophila, the fruit fly.


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