Summary of Huberman Lab Podcast Episode: Decoding Your Brains Logic & Function with Dr. David Berson | Huberman Lab

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Introduction

• Dr. David Berson is Professor & Chairman of Neuroscience at Brown University. Dr. Berson discovered the neurons in your eye that set your circadian rhythms for sleep, wakefulness, mood, and appetite. He is also a world-renowned professor with many of his students becoming leaders in neuroscience.
• Andrew Huberman and Dr. Berson break down the science behind how we learn and perceive the world, our internal landscape, how we process information, see, balance, and much more.
• Host: Andrew Huberman (@hubermanlab)

How We See & Process Color

• Your brain associates input from the periphery
• The experience of seeing is a brain phenomenon – what the retina is telling the brain is what matters
• Ganglion cells (in the retina) are the key cells between the eye and the brain
• The eye is like the camera, the photoreceptors are like the film of the camera
• Perception of color: light hits the eye, goes in, photoreceptors convert that to an electrical signal
• Cones are the cells that absorb light at different wavelengths
• Wavelengths give us the different sensations of color based on the sensitivity of the neurons to that wavelength processing the light
• Biological mechanisms for seeing color are physiologically similar across people
• Most humans have three cone types we can see color from, others animals like dogs and cats have two cone types

Circadian Rhythm, Sensory Processing & Mood

• Circadian system: we have an internal sense for rotation of the earth in our brain keeping time
• The circadian system works with natural light processing to adjust our body clock
• Most of the cell types in the body operate on a clock
• Coordinating center of the body: pathways from the retina and cells that encode light intensity send signals to a processing center in the hypothalamus which is also responsible for the autonomic nervous system
• Light directly impacts hormones: the autonomic nervous system is the major source of melatonin in the body
• People with retinal blindness often complain about insomnia because their clock is there but the synchronization signal doesn’t work as well
• Sensory information comes from peripheral sensors (i.e., eyes, skin, nose, fingertips, etc.) taking information in and processing
• Some sensory information passes through the thalamus and sends signals through a different pathway to the front of the brain, providing feedback on how you feel internally – mood, self-confidence, etc.

General Rules Of Light Viewing

• Don’t wear blue light blockers during the day – daytime is when you want max light exposure for circadian effects & mood
• Avoid all bright light exposure at night, it will slam melatonin levels and disrupt sleep
• Get as much light as you can anytime you want to be alert, and avoid light when you want to sleep

Link Between Visual System, Balance, & Motion Sickness

• The vestibular system (deep in the inner ear) is designed to detect how you are moving through the world
• The hearing system and vestibular system are collocated
• The brain unpacks information about how your head is moving and confirming movement
• Internal image stabilization: if you suddenly rotate your head to the right, your eyes will rotate to the left to compensate for the vestibular system to stabilize
• Motion sickness: brain senses motion and asks itself whether it came from an internal or external source and tries to find context for what is happening
• If you look at your phone (or book) while in forward motion, you are uncoupling the motion from what is happening in your body and the brain doesn’t like that so tries to induce behavior change – that’s when you feel nausea
• Remedies for motion sickness: stay off devices, look forward
• If ears feel bad because of pressure change when taking off & landing on plane: plug nose and blow out or suck in – it doesn’t matter either way

Cerebellum AKA “Mini Brain”

• The cerebellum is a key place where visual and balance information is combines
• Think of the cerebellum like air traffic control – it takes in information from everywhere and coordinates and shapes movement
• Without the cerebellum, you’d still be able to move but the timing between input and output would be off
• The cerebellum is responsible for motor learning and precision
• People with damage to the cerebellum may have tremors and be unsteady on feet

Other Parts Of The Brain Involved In Movement & Processing

• The mid-brain is one of the earliest evolutionary traits in animals to provide critical information about location in space
• The mid-brain houses an important visual center that reorients attention from the external world and prompts you to avoid or go towards something
• Basal ganglia: region of “go/no go” – from sitting still to activating behavior depending on what is appropriate based on context
• The basal ganglia sits in the forebrain and grows as the cortex grows – plans are made in the cortex and executed in basal ganglia (but the circuits work closely throughout processing)
• To build a skill you want to have, exercise “no go”: withhold something minor from yourself to practice restraint – e.g., don’t reach for your phone a few times per day when you really want it
• Cortex: map(s) in the brain of things going on in the visual world
• The paradox of the brain: areas of the brain are multi-functioning and interactive – but also highly specialized in arrangement and processing
• In people blind from birth, the visual cortex is repurposed as the center to process tactile information (i.e., braille)
• Neurotransmitters are the chemical messengers, released at one end of the nerve and diffuse across synapses to another region
• Interested in learning more about neuroscience? Check out Eyewire – or read – We Know It When We See It by Richard Masland