The Chemistry of Synesthesia


Synesthesia is a brain condition that can range anywhere from 1 in 200 to 1 in 100,000. This condition is the mixing between senses. Where in a situation a person may experience only one sense, but a synesthete will experience two completely different senses.

I chose to research this condition because it sounds very interesting, after researching it I think that this condition would be a cool experience to have. I personally do not have this condition, but I do know of a person who does and their form of synesthesia is where they can hear a note being played and they will see a color.

My life is not being affected by this condition because I do not have it, but if I did it may make it easier to remember people’s names, numbers or words. Composition of ...

    • Brain
    • Senses
    • Serotonin
  • Neurons

Main Chemicals, Compounds, Components

    • Serotonin
      • Brain chemical
      • Occurs naturally
        • There are cases of lack of serotonin in brain so it has to be taken
      • Responsible for neurotransmitting
        • Produces happy feelings
        • Can affect learning and memory
    • Neurons
      • Cells in brain
      • Parts of Neurons
        • dendrites - inputs
        • cell body
        • axons - outputs
    • Transfer information through synapses to other neurons

Chemistry's Role

The two main components of Synesthesia, which are serotonin and neurons, are naturally occurring in the brain. In some cases serotonin can be man made and taken by a person to get more of that certain chemical in their brain, but in this case of this phenomenon it is naturally occurring. Neurons are also naturally made inside the brain which is also naturally made. The neurons that can be affected in this condition have been like this since the person was born. One of the only non-naturally occurring things that is involved with this condition may be the smells or the sights or sounds that can make a person have their senses affected.

Background Research

This is a brain condition that cross-wires two senses together. It is a connection that is made early on in life will stay the same connection for the rest of the person’s life. Doctors do not know for sure how exactly this condition occurs and there is no certain test to see if a person has synesthesia. The connections will be made from different parts of the brain and those parts are where each different sense is processed. Those places are: the Parietal lobe where taste and touch are processed, the visual cortex where vision is processed, the frontal lobe where smell is processed, and the temporal lobe where hearing is processed. The Synesthesia condition is usually passed down through families and is a gene, and the condition is more common in women and in left handed people. This condition will be in effect since birth, the person will not acquire synaesthesia over their life. Only if a person takes hallucinogenic drugs will they possibly acquired synesthesia later in life, if they do not already have the condition. There are over 35 different forms of synesthesia, usually a person will only have one form. Many people with the condition say that they do not mind it, they said that they actually like it. The condition works with the Neurons in the brain, the connections of the neurons can be interrupted by the Synesthesia gene or excess of serotonin.


    • Description of condition
    • What the condition will usually be like
    • Who has it

    • Description of condition
    • Many synesthetes (people who have condition) enjoy the condition that they have
    • How long people will have lived with the condition (usually born with condition)
    • How many different forms of synesthesia (at least 35)

    • Tells how some people will turn days or months into colors
      • John Fullwood
    • Synesthesia can vary for each person who has it
    • If synesthesia is linked between vision the parts of the brain affected by this condition will be in the more visual areas of the brain

Synesthesia: The Smell of a Sound, The Taste of a Color

    • Four Conditions
      • consistent - always the same throughout your life
      • conscious - always aware that you are having the experience
      • automatic - happens automatically
      • induced with concurrent experience
    • Researchers do not know for sure what is happening in the brain, but there are two theories:
      • one theory - everyone has the same paths, but to synesthete, some of the path connections are unmasked - they can take a path a normal person can’t
      • another theory - synesthetes have extra paths that connect different parts of the brain

    • Areas of the brain that analyse senses are close and when they are cross-wired they are considered to be linked by a genetic trait
    • There are a few tests to see if someone is a Synesthete
    • The process after birth that happens in a brain to keep all the needed brain cells may be interrupted by a synesthesia gene and that results in cross-wiring of the senses

    • Some areas of the brain that can be affected by a certain synesthesia could be
      • Parietal lobe
        • where touch and taste occur
      • Visual cortex
        • where vision occurs
      • temporal lobe
        • where hearing occurs
      • frontal lobe
        • where smell occurs

    • Description of condition
      • What is synesthesia? A condition where two or more unrelated senses are stimulated by one event,
    • People who have it:
      • People who have it . . .
        • Some say they have had it for as long as they can remember.
        • Some people say they experienced it after taking drugs or having a seizure
    • It can possibly be inherited because studies have shown various forms existing within one family
    • Why does it occur? It may happen because of extra neuron connections in the sensing areas of the brain

    • Neurons:
      • The brain has 10 billion nerve cells - also called neurons. Neurons have
      • dendrites - inputs
      • cell body
      • axons - outputs
    • Neurons connect to other neurons through synapses

    • Study by Berit Brogaard from the center of Neurodynamics of the University of Missouri concludes that at least sometimes synesthesia is triggered by excessive serotonin in the brain. It happens through excitatory neurotransmitter action.
    • “I conclude on these grounds that one commonality among at least some cases of acquired, developmental and drug-induced synesthesia may be the presence of excessive levels of serotonin, which increases the excitability and connectedness of sensory brain regions.” [Berit Brogaard - Serotonergic Hyperactivity as a Potential Factor in Developmental, Acquired and Drug-Induced Synesthesia - Published online 2013, October 21

    • Serotonin:
      • Formula: C₁₀H₁₂N₂O
      • 90% of body’s serotonin is located in intestinal track
      • Other 10% of serotonin is synthesized in serotonergic neurons which
      • It is a neurotransmitter
      • It is thought to be a chemical that produces feelings of well-being and happiness
    • Serotonin can affect learning and memory
    • Can stop the production of dopamine in the brain especially while eating food and can make a person lose their appetite

  • Brain Diagram

About the Author

The author, Caroline Dimich, is a Junior at Billings Senior High School. She is on the varsity soccer team, and on the track team. She is also part of the STEM club (Science Technology Engineering and Math) at Senior High. Caroline is in the Platinum Program at Senior, and participates in both band and orchestra. She chose to research this condition, because she wanted to learn more about how a person’s senses can be overlapped. She first heard about someone who could hear colors and that sounded very interesting to her.