The complexities of the nervous system will undoubtedly be a mystery for generations to come. In fact, often in the pursuit of an answer more questions are provoked. One example of this is when researchers at John Hopkins School of Medicine were conducting experiments with the optical nerve in mice. These researchers found that despite severing the connection to the brain, the cornea of the eye continued to dilate and contract depending on the light conditions of the environment. This came as a surprise since it had been previously believed that the complex system of muscles required in the sensory and response of this process was controlled by the brain. These discoveries imply that the majority of sight could be controlled by a photosensitive reflex arc. Ph.D King-Wai Yau, a neuroscientist at the Johns Hopkins said, "The traditional view of this reflex is that light triggers nerve signals traveling from the eye's retina to the brain, thereby activating returning nerve signals, relayed by the neurotransmitter acetylcholine, that make the sphincter muscle contract and constrict the pupil." This opinion was disproven by Yau research and experiments with the optical system. Yau has proven that the optical nerve does not affect the contraction of the sphincter, but the muscle itself has light sensitive components. John Hopkins conducted experiments by severing the optic nerve and blocking acetylcholine. If the muscle contracted under light then there is indisputable evidence that the sphincter is responsive.
The results showed that the melanopsin in the mice's eyes allowed them to be able to contract and dilate their eyes without a signal from the brain and optic nerve. While this result is revolutionary in the study of primitive vertebrates, it is believed that the optic nerve and brain became much more involved in the process. Humans and other primates rely much more heavily on the external signals rather than those from the sphincter.
Work Cited:
Johns Hopkins Medicine. "A no-brainer? Mouse eyes constrict to light without direct link to the brain." ScienceDaily. ScienceDaily, 19 June 2017<www.sciencedaily.com/releases/2017/06/170619092201.htm>.
King-Wai Yau, Ph.D." John Hopkins Medicine. John Hopkins Medicine, n.d. Web. 19 June 2017. <http://www.hopkinsmedicine.org/profiles/results/directory/profile/7456451/king-wai-yau>.
The results showed that the melanopsin in the mice's eyes allowed them to be able to contract and dilate their eyes without a signal from the brain and optic nerve. While this result is revolutionary in the study of primitive vertebrates, it is believed that the optic nerve and brain became much more involved in the process. Humans and other primates rely much more heavily on the external signals rather than those from the sphincter.
Very education and cute Mr.Duncan! I never knew people would be conducting experiments with the optical nerve in mice
ReplyDeleteGreat summary josh! I thought it was super interesting that the mices eyes work without the brain
ReplyDeleteGreat writing, and a very interesting topic that could potentially be relevant to many other species. This discovery is important in disproving a previous theory, and updating our knowledge of how the nervous system works and communicates within the body of all sorts of animals.
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