Transduction of Light

In my Sensation and Perception class, I am learning about the transduction of light. As practice for a essay on my exam, I am going to tell you all how transduction works. I could be wrong. Last night I studied with my intelligent roommate who is also t!aking the class and discovered that I was learning it wrong! You don't have to read this unless you want to. 

We first must understand how the photo receptors work in the dark. In the dark, the retinal in the opsin is bent. Because the retinal is bent, the g protein is not activated. The emzyme is producing cGMP which allows the sodium channel to be open. It is disinhibited, which means that it is allowing the nuerotransmitters to send inhibitory signals to the bipolar cell. The light enters into the retinal and isomerization will occur when the retinal straightens out. It will straighten out because the two chlorides on the retina don't want to be near each other when the light touches it. The straightening of the retinal causes the g protein to become activated which will in turn tell the enzyme to change the cGMP to GMP. This change will close the sodium channel. It will then be inhibited as neurotransmitters are no longer being sent to the bipolar cell. The bipolar cell will then be able to fire because it is not receiving any inhibitory signals from the photoreceptors. It will excitatory signals to the ganglion cell, which will send it to the LGN. In the LGN, there are 6 layers. Each layer will receive information from different eyes. Layers 1, 4, and 6 will recieve from the opposite eye and layers 2, 3, and 5 will receive from the other eye. From the LGN, it will go to the Striate Cortex where everything will be processed. It will head back to the LGN, where it can be transferred all over the brain. More information will be transferred to the LGN after going to the Straite Cortex. Yep, so this is the fascinating yet complicated process of transduction!