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How does anesthesia work, and how does it affect the brain? 

Asked by: Phoebe Macaulay
School: Central Baptist Christian Academy
Grade: 10

Hobbies/Interests: Violin, piano, textile arts and family.
Career Interest: Biomedical Engineer

Answer from Justine Landin

Research Assistant at the Center for Development and Behavioral Neuroscience and PhD Candidate

Research area: Molecular Neurobiology
Interests/hobbies: Reading and writing, movies, kickboxing, running, being outdoors, cooking and baking and spending time with family and friends.

Although the first primitive anesthetics were used hundreds of years ago, scientists are still trying to figure out exactly how anesthesia works. Modern-day anesthetics are much more sophisticated than those used in the 15th century, and scientists are getting closer to understanding the exact effects that anesthesia has on the brain. Anesthetics are now classified as general, local, regional, or dissociative. They can be inhaled, injected, or applied directly to the skin. We will focus on general anesthesia for this question, because it is the type that you are probably thinking of and the kind of anesthesia that you would get if you needed to undergo an operation.

Let’s pretend that you are going to have surgery to have your appendix removed. How would the doctors know when you are ready to be operated on? Well, general anesthesia results in three main effects that can be observed and tested. First, there is memory loss.  When you wake up from your surgery, you have no recollection of what happened while they operated on you. After memory loss occurs, you lose consciousness. Surprisingly, memory loss and consciousness are actually considered to be two different things. You can experience memory loss without loss of consciousness. For example, if a person got a concussion from a hit on the head, they might walk and talk right afterward, but may not remember anything that they say or do during this time period. All general anesthetics cause you to be unconscious and to forget. The third and last effect is immobility, or loss of response to an outward stimulus. This may seem like the most important one, especially for surgeries. This effect can easily be tested. The nurse can simply pinch your skin to make sure that you don’t flinch. So to sum up, after anesthesia, you will lose: 1) memory, 2) consciousness, and 3) response to outward stimuli.

So, how does anesthesia do this?  What is going on in our brains to allow this kind of response to a drug? These questions have very complex and detailed answers.  Our brains are composed of cells called neurons, which communicate with one another by transmitting electrical chemicals and signals. When a drug enters the brain, it can have different effects on these neurons. It can excite neuron, and make it easier for the neurons to communicate with one another, or inhibit them, making it harder for the "communication" to occur. Anesthesia is no exception. It inhibits the neurons that are associated with memory, consciousness and mobility. Exactly how they do this is not completely understood, and is still being examined today!

Last Updated: 9/18/13