The Three Amigos – left hemisphere, right hemisphere, senses – give us our sense of “reality”.

Your brain’s cortex is divided into two hemispheres – right and left. According to Orrin Devinsky, MD, professor of Neurology, Psychiatry and Neurosurgery and Director of the NYU Epilepsy Center at NYU Langone Medical Center, the right hemisphere of the brain dominates self recognition, emotional familiarity and ego boundaries. The job of the left hemisphere is to make sense out of sensual input and information from the right hemisphere – it is the story teller.

There is a complicated interaction between right hemisphere, left hemisphere, your senses, and the animal brain within you. Theories abound as to just how that interaction occurs. Recently, Dr. Devinsky conducted a review of many studies of hemispheric interaction in an attempt to better understand this interaction – focusing on right hemisphere lesions and left hemisphere delusions.

“…delusions result from the loss of these [right hemisphere] functions as well as the over activation of the left hemisphere and its language structures, that ‘create a story’, a story which cannot be edited and modified to account for reality. Delusions result from right hemisphere lesions, but it is the left hemisphere that is deluded.” Lesions in the right hemisphere can cause delusions as the left hemisphere goes to work making sense of distorted identity and emotional information it gets from the injured right hemisphere.

When in the dream state, where the senses close down in sleep, the left hemisphere continues on, creating stories in an attempt to make sense of the impulses received from the right side – unable to compare or test that input against sensory input – so it manufactures it – adding to the sense of reality in dreams. The strangeness of the dream state illustrates what happens when the left hemisphere creates a story based solely on the input from the right side without sensory data to corroborate it.

It occurs to me that my “reality” is made up of three legs:

1. Right Hemisphere (Who I am and how I feel about who I am)
2. Left Hemisphere (Story Teller – making sense of my experience)
3. Senses (measuring, testing, and validating the inner “story” against the environment outside the body)

Normally, we believe we experience our world through our senses and react accordingly. My theory is you experience your world within – corroborated by sensory input. You imagine your world as a flowing story [left hemisphere] based on who you believe you are and how you feel about that [right hemisphere] – and then test that story against your senses – your reaction to your sensual input can trigger right hemisphere activity further influencing your inner story of your “outer” experience. This happens in an instant so it feels as though you are reacting to your senses, when, in fact, you may instead be constantly reacting to and modifying your story.

You truly are delusional during dream sleep, which occurs during REM sleep, because you are without outside sensory verification. Interestingly, Rapid Eye Technology attempts to artificially induce REM sleep in the awake state in order to address those “delusions” – thinking distortions that have caused irrational behavior or interfered with living a happy and productive life.

Study Source:
“Delusional misidentifications and duplications: Right brain lesions, left brain delusions” in Neurology.