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)
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 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.
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
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
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
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