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Home » Transcript: How Microbes Affect Your Psychology – Kathleen McAuliffe

Transcript: How Microbes Affect Your Psychology – Kathleen McAuliffe

Full text of Kathleen McAuliffe’s TEDx Talk titled ‘How Microbes Affect Your Psychology’ at TEDxMarshallU conference. In this talk, Kathleen explores the microbiotas in our gut and their potential influences on our brains and neurological disorders.

Listen to the audio version here:


We’ve been debating the question forever. Is there such a thing as free will? Am I captain of my ship, master of my own destiny?

I’m no philosopher. Biology is my realm, and from where I stand, there is clearly more than one of us at the helm. I’m referring to the fact that half the cells in your body do not contain your own DNA. They belong to bacteria, protozoa, fungi, and other unicellular creatures. These tiny tenants, collectively known as our microbiota, are most abundant in the gut, where they aid in digestion and carry out many other essential functions.

Most amazing, they talk to your brain. They influence your mood, your energy level, your appetite, your memory, perhaps even your personality. I can say this with confidence only to mice like this, which have no microbes. They’ve been dubbed bubble mice because they’re raised in sterile facilities.


Contrast their behavior to that of a normal mouse, which is colonized at birth with microbes, and you’ll notice striking differences. A normal mouse is a quick and eager learner. Show it a novel object like a napkin ring, and it will circle and sniff it with great interest. Place it in a maze, and it’s keen to explore new passages and remembers where it’s been.

A bubble mouse could not be more different. It lacks natural curiosity. It’s slow to learn, quick to forget, and just as inclined to favor the familiar over what’s new, exciting, or different. Indeed, they don’t even protest if separated at a young age from their mothers, a trauma that in a normal mouse would lead to lifelong skittishness.

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