The Senses
Primitive Expressions and Actions
When we see or smell something interesting or pleasant, we tend to lean in and inhale. When we see or experience things we don’t like, we have a visible look of disgust. Aversion and attraction are a push pull system.
Action in the nervous system (motor behavior) of moving toward or away things. When we taste bitter compounds, we tend to avoid them as they are associated with poison. Sweet or savory is appealing.
Eyes
Fish oil for vision: https://medicalxpress.com/news/2019-12-fish-oil-tablets-weeks-night.html
How We See
The experiencing of seeing is a brain phenomenon. When we look at the exterior world, ganglion cells are the key players in communicating from the eye to the brain.
Color Vision
Light is just electromagnetic radiation that is vibrating/oscillating. The photons move through space as a wave. Certain frequencies/wavelengths of these waves are detected and unpacked as different colors by different neurons.
In the first layer of the retina there are different kinds of sensitive cells have different proteins that absorb light with a specific frequency. The nervous system keeps track of these signals, compares, and contrasts to get the gist of the wavelength, and hence, the time of day or what’s in the environment.
“Strange” Vision
Dim light vision (rod with its own pigment), melanopsin pigment.
We have 3 cone types – red, blue, and green. Dogs have two channels.
How You Orient in Time
The ipRCGs are located at the other end of the retina (innermost), where the ganglion cells live. Some of the output neurons are making photopigment, absorbing light, and converting to neural signals. This is more similar to how a fly eye works (in the chemical cascade aspect) than mammals. In the wrong layer of the retina. Seemingly primitive element of biology that processes light differently to the other cells.
These cells are responsible for knowing how bright it is so that we can have an internal representation of what time of the day it is.
The neural clocks are all oscillating and need to be synchronized. The circadian clock is a bit off (a consequence of evolution vs. the way we think about engineering). We need confirmation of the external cues, which leaves room for adaptation.
The Senses, Vision, Seeing & What We Should All Do to See Better
We should all train and support our eyesight no matter what age we are or the quality of our eyesight.
Our Eyes: What They Really Do, & How They Work
Our eyes are responsible for vision, mood, and alertness. Vision starts with the eyes. We have no extraocular light perception.
The eyes are essentially parts of the brain that were squeezed out of the skull, so that the 3 layers of nerve cells could form the neural retina.
The lens focuses light. Eyelashes trigger the blink reflex to clear dust.
Converting Light into Electricity Language: Photoreceptors, Retinal Ganglion Cells
Eyes collect light information and send it to the brain in a form it can understand. When light gets to the neural retina we have photoreceptors, rods (lowlight conditions) and cones (daytime vision), have chemical reactions, which uses things like vitamin A, which converts light into energy (transduction). Within the eye, the retinal ganglion cells send the information onwards.
We Don’t See Anything Directly: It Is All a Comparison of Reflected Light
Light bounces off an object, that photon goes into our eye, compares the amount of either red, green, or blue around that reflection, the brain receives a compared signal of that estimation.
The brain doesn’t recognize a sound unless it has something to compare to it either.
Dogs, Cats, Snakes, Squirrels, Shrimps, Diving Birds, & You(r View of the World)
When a dog sees green it is different to the green you see, it is not because the object is invisible but because it can’t compare it to red like us. A green lawn looks more orange/brownish to them.
A pit viper senses heat emissions. A ground squirrel can see ultraviolet light and signals other squirrels by reflecting light off its stomach at a distance.
A diving bird can adjust its diving protectory to fish for food, to counter the water refractory. They have retinal cells that is both a streak to view the horizon, and a pupil on the bottom of their eye to dive.
What you experience is limited by the wavelengths you can see.
Everything You See Is a Best Guess, Blind Spots
The guesses are largely right. Most of our judgements allow us to functionally move through the world.
We have a giant blind spot where our axons exit the eye, and yet we can’t see it. The brain guesses what is there.
Depth Perception
Things that are closer tend to be larger, things that are closer move faster beside you, prior knowledge of the destination of something also is incorporated. You compare the location about where the light hits the two eyes and the brain works it out based on that angle.
Subconscious Vision: Light, Mood, Metabolism, Dopamine; Frog’s Skin in Your Eyes
The most ancient cells in our eyes are there to communicate information about time of day to the rest of the body. There is a particular type of retinal ganglion cells (melanopsin cells) have a photoreceptor in them. The opsin in them is similar to the melanopsin in the skin of color changing amphibians. These cells communicate to different parts of the brain when different types of wavelengths are present. They regulate when you get sleepy, awake, metabolism speed, blood sugar levels, dopamine levels, and pain threshold.
Blue-Yellow Light, Sunlight; & Protocol 1 For Better Biology & Psychology;
These melanopsin cells have been shown to set the circadian clock and respond best to the contrast between yellow and blue light of the sort that lands on the cells when you view the sun when it is at a low solar angle (morning or evening).
View the sun for 2-10 minutes every day in the morning and evening to prevent disruption of your circadian rhythm, mood, hormones, metabolism, pain threshold, memory, and learning ability.
The most important aspect of our biology is our ability to anchor ourselves in time. We only know time at a biological level based on where the sun is and where we are relative to it.
The blue light, and the contrast to the yellow, is essential for triggering positive biological reactions, as long as it is in the morning.
Protocol 2: Prevent & Offset Near-Sightedness (Myopia): Outdoors 2 Hours Per Day
Getting 2 hours a day of outdoor time (even if there is cloud cover) has a significant effect of reducing the probability of myopia. Not sure if it is sunlight driven or distance related.
Adults who spend two hours outside per day offset myopia. Myopia has to do with how the lens focuses light onto the retina. It brings it in front of the retina.
Probably has to do with the melanopsin ganglion cells (ipRCGs) also making connections within the retina. They connect to the ciliary body, the iris, the muscles and structures within the eye that move the lens and adjust vision. Increasing the health of the muscles within the eye. Also, possibly bring growth factors and blood supply to the muscles and neurons responsible for the focusing mechanism.
Artificial light doesn’t cut it. Staying indoors will lead to visual defects.
Improving Focus: Visual & Mental; Accommodation, Your Pupils & Your Bendy Lens
Accommodation: The eye dynamically adjusting where light lands by changing the shape of the lens. Improving your accommodation will allow you to focus and concentrate better for longer. Mental focus is grounded in our ability to hold visual focus. It is tiring to control movement of the lens.
When you see things far away, the lens relaxes and flattens out. If we look up closely, it takes effort and it contracts to bring light to the retina.
There are dedicated areas of our brain that are responsible for recognizing faces, eyes, and their positioning of irises and pupils. It is important for how we interpret the status of others.
When you shine a light at the eye, the pupil constricts to limit the amount of light that comes in to prevent damage to the eye. The consensual pupil reflex from deep within the brain stem causes both eyes to constrict instead of just one. This not occurring is a good sign of brainstem damage.
Healthy pupils dilate when you look far away. When you see something that excites you or stresses you out, they also dilate. If you look closely, they should shrink.
If you’re young and you spend too much time looking up close at computers or phones, you are training your eyes to be good at looking up closely.
Protocol 3: Distance Viewing For 20min For Every 90 Minutes of “Close Viewing”
We need to go out into a vast area and view the horizon. The relaxation of the lens is one of the best things you can do for the health of your eyes.
Every 30 minutes or so of focused work, look up and let your eyes go into panoramic vision, while letting your face muscles relax too.
Every 90 minutes of close-up vision get to a window or balcony and just let your eyes relax. This should reduce headaches and fatigue.
Protocol 4: Self-Generated Optic Flow; Move Yourself Through Space Daily
Optic flow is good for destressing the system. When you move through space you can self-generate optic flow. Self-generated motion of the body (not a car) and let the system acknowledge visual images to pass by your eyes.
Protocol 5: Be More Alert; Eyelids, Eye Size, Chin Position, Looking Up Versus Down
Neurons in your brain will make it easier or harder to keep your eyelids open. When we get tired our eyelids close and our chin goes down. When awake our eyes are open and chin is up. That system of alertness is linked to the position of our eyes. Creating a wakefulness signal in our brain.
Raise your eyes to the ceiling for 10-15s to trigger areas of your brain that are involved in wakefulness.
People looking down at their phone or down at a laptop can make them feel sleepy too.
Locus coeruleus releases norepinephrine to wake up the brain when looking up.
Protocol 6: Sleep in a Very Dark Room to Prevent Myopia (Nearsightedness)
Children with a nightlight are more likely to develop myopia. Wavelengths of light can often get through the eyelids. Especially in those that have thin eyelids.
Sleep in a completely black environment. Even low intensity light between the hours of 10pm-4am can be detrimental to the dopamine (suppression) and other mood systems in the brain. It can negatively impact learning, immunity, blood sugar, and may make people prone to type two diabetes, by way of the communication from the melanopsin cells to the habenula. That blue light is likely distortion the lens accommodation in the eye and leading to myopia.
Color Vision, Colorblindness, Use Magentas Not Reds
RG colorblind people can see the contrast between magenta and green better. Use them for slides.
Protocol 7: Keeping Your Vision Sharp with Distance Viewing Every Day
Spend 10 minutes per day looking far away to relax the lens and eye muscles. This also sends signals to the brainstem, releasing some of the centers involved in alertness and stress.
Protocol 8: Smooth Pursuit
Smooth pursuit is our ability to track objects through space. Take a few minutes each day and track a ball or move your pen in space, as an infinity symbol or saw tooth, to keep the extra ocular muscles healthy and strong. Watch kids play, tennis match, sports, etc.
5-10 minutes, 3 x per week.
Protocol 9: Near-Far Visual Training 2-3 Minutes 3-4 Times a Week
Looking at something up close (pen or hand) and then moving it at arm’s length while following it for 5-10s each way. Adjusting at different lengths to challenge the eye muscles with your accommodation mechanisms. Try not to get so close that you go cross-eyed. Your brain might start to lose information and the ability to see binocular depth.
Similar to post-concussion training for vision and make sense of the environment.
Also, doing the smooth pursuit exercise.
Protocol 10: Red Light, Emerging Protocol to Improve Photoreceptors & Vision
Flashing red light into the eyes early on in the day can help offset some age-related macular degeneration. Presumably by enhancing the mitochondrial function in the photoreceptors. Never just shine bright light in your eyes though. Especially if it’s painful. Just a couple minutes per day of red light flashing into one eye and then the other (studies were done in those 40 years or older).
Your photoreceptors are actually most active in the dark. When light comes on, they shut off their activity.
Dry Eyes; Blinking, Protocol 11
The lubrication of the cornea is supported by blinking. Sometimes if we focus too much we don’t blink much. Just blink more.
Lazy Eye, Binocular Vision, Amblyopia; Triggering Rapid Brain Plasticity; Protocol 12
The young brain is extremely vulnerable to ocular input differences between the two eyes (critical periods). Even a few hours of occluding one eye can have permanent brain imbalance effects into adulthood. Messing with binocular vision.
If you’ve had an occlusion, you’ll need to cover up the other eye to create an imbalance to make the lazy one work harder. If you cover both, you extend the period of critical plasticity. The eyes compete for space.
Protocol 12: Determine Your Dominant Eye; Near-Far Training
Cover an eye up and see if one is fuzzy or less blurry. Wearing glasses will possibly make the problem worse, as it is like putting an arm in a sling.
Cover the good eye and do near far exercises with the bad eye to strengthen it.
Visual Hallucinations: The Consequence of An Under-Active Visual Brain
Portions of your brain become under-active. Like being in a sensory deprivation chamber. A compensatory response.
Protocol 13: Snellen Chart: A Simple, Cost-Free Way to Test & Maintain Vision
Put a Snellen chart in your home. Practice at different distances.
Your performance will vary during the day, depending on your fatigue level.
Corrective lenses at the supermarket or discount stores are usually wrong by a fair amount.
Vitamin A, Lutein, Idebenone, Zeaxanthine, Astaxanthin, Blood Flow
The metabolic cascade, that uses vitamin A is essential for vision. Eating vegetables in their raw form can help to support vision. Eating huge amounts won’t make much difference though.
Increase macular pigment optical density and visual acuity following lutein rich egg yolk drinks. Lutein is in the pathway that relates to vitamin A and the formation of the opsin in the photopigment that captures light and converts it into electrical signals. Lutein supplementation can help mitigate age-related macular degeneration in those with severe macular degeneration. People with regular vision don’t see much benefit.
Idebenone can be beneficial for Leber’s optic neuropathy.
Zeaxanthines and astaxanthins (the red/pink pigment in seafood) have been shown to offset some of the disruption of vision shown with aging. Structurally similar to betacarotene, so it’s very pro vitamin A, but has some chemical differences that may make it safer. Notably increases the antioxidant enzyme profile, increases ocular blood flow, notable effect on male fertility, positive effects on skin elasticity, moisture, quality, etc.
Hearing and Balance
How We Perceive Sounds
Ears are technically called oracles or pinna. The shape of ears amplifies high frequencies sounds. Sound waves are just fluctuations or shifts in the way air is approaching your ears.
Your eardrum has a hammer (malleus, incus, and stapes), which hits the cochlea. Sound gets converted into electrical signals from here. The base of the cochlea is more rigid – high freq, flexible at the apex – low freq, which is important for decoding the frequency of the sounds. Within the cochlea are hair cells that move to send that transduced signal.
A prism splits light wavelengths into different colors. The cochlea essentially acts as a prism for sound. Splitting the sound into different frequencies.
Your Hearing Brain (Areas)
The hair cells convey the signals to the spiral ganglion, where it then travels to the cochlea nuclei (in the brain stem), then up to the superior olive, then up to the inferior colliculus, then to the medial geniculate nucleus, and finally to the neocortex where we make sense of it all.
Localizing Sounds
Our auditory and visual system collaborate to locate the position of things in space. Disruptions are the basis of the ventriloquism effect.
Interaural time differences: sound landing in one ear at a different time than the other, providing a gauge on where the source of the sound is in space.
Elevation is determined by frequencies. The shape of the ear modifies the sound depending on where it is on the x plane.
Ear Movement: What It Means
Humans are not great at moving their ears. About 60% of people can consciously. Usually no more than 2-3mm.
Try look all the way to the left or right and you should feel a contraction in the ear. People who can move their ears can also usually move their eyebrows. It is controlled by the same motor pathway. Typically, men can do it more than women.
Your Ears (Likely) Make Sounds: Role of Hormones, Sexual Orientation
Otoacoustic emissions are sounds that your ears make. 70% of people make these noises. Females that report themselves as heterosexual have a higher frequency (quantity not soundwaves) of otoacoustic emissions. Women who report as homosexual or bisexual make fewer sounds.
Exposure to certain combinations of hormones in development may be shaping the way our hearing apparati develop.
https://asa.scitation.org/doi/10.1121/1.426845
Binaural Beats: Do They Work?
One frequency to one ear and another to the other one. The brain is apparently supposed to average that information and make an intermediate frequency that is better for learning.
Been thought to increase focus, relaxation, creativity, etc., depending on the soundwave frequencies.
Delta waves (1-4Hz) can help in the transition of sleep. Theta waves (4-8Hz) can bring the brain into a state of subtle sleep or meditation. Alpha (8-13Hz) can increase alertness to a moderate level, which is good for recall of existing information. Beta waves (15-20Hz), good for focus states for sustained thoughts or new information. Gamma waves (32-100Hz) learning and problem solving.
They are effective but not uniquely special for learning. Good evidence for anxiety reduction when bringing the brain waves into delta and alpha waves. Evidence for treating pain, cognition, creative, etc. Pain reduction and anxiety have the greatest benefits/application.
White Noise Can Enhance Learning & Dopamine
To enhance brain states for learning in certain adults but can be detrimental for auditory learning in infants.
White noise, provided it is at a low enough intensity, has been shown to enhance learning and brain function. By modulating activity in the dopaminergic mid-brain regions and right superior temporal sulcus. Enhancing neurons in the substantia nigra VTA, which is a rich source of dopamine neurons (the dopamine neurons produce something that makes it dark). White noise seems to be able to raise the basal levels of dopamine that is being released from this area.
However, people have different levels of auditory sensitivity. Adjust the white noise to a level where you are able to focus.
Headphones
When you put headphones in your ears it makes it seem like sounds are coming from inside your head instead of outside. If using headphones for white noise practice, keep it low. The dopamine neurons fire when we are exposed to something exciting, so you only really want to “tickle” them a little bit to raise that basal level.
You can trigger hearing loss quite rapidly by listening to music loud with headphones. Hair cells do not regenerate. Avoid big inflections of sounds.
White Noise During Development: Possibly Harmful
If young animals were exposed to white noise during development, it disrupted their auditory maps (tonotopic) of the world. Frequencies are organized in a systematic way in the tonotopic map. The developing brain takes these separated frequencies to learn about the outside world. White noise contains no tonotopic information as the frequencies are all intermixed. White noise is analogous to white light.
During sleep the child’s brain is still learning so you don’t want to degrade that map with white noise.
The visual system is a retinotopic map.
Remembering Information, The Cocktail Party Effect
You are in an environment that is rich with sound. Somehow you need to attend to specific frequencies by creating a cone of attention. Your brain uses up a lot of energy trying to do this.
We can expand and contract our auditory view by tuning out noise to a background chatter. We can do this by paying attention to the onset and offset of words.
When meeting a new person at a party, we often forget their name immediately, partially because of the presence of other auditory information interferes. The signal to noise isn’t high enough.
If somebody is giving you directions and you want to remember what they are telling you, pay attention the onset and offset of those words to remember better.
How to Learn Information You Hear
By listening to certain frequencies or cues in speech, you can remap tonotopic maps. Even in the adult brain.
If you are trying to learn music or information you’re going to recite, decide to highlight certain words, frequencies, scales, etc., and only focus on them for certain bouts. You will already be passively learning and listening to the content, but the act of listening for something in particular makes you focus better. Resulting in a greater extraction of information overall.
Doppler
When the thing that makes a sound is moving. We experience sounds that are closer to us at higher frequencies at lower ones further away. We can use this to measure speeds and trajectories.
Bats navigate with the Doppler effect, sending out clicks, pinging the environment, and experiencing the sounds that come back.
Tinnitus: What Has Been Found to Help?
Can be caused by disruption to the hair cells. You could listen to loud music and then go to a loud concert, effectively making it worse as the hair cells are still vulnerable.
Melatonin, ginkgo bilboa, zinc, and magnesium. 3mg for 30 days to 6 months of taking melatonin to reduce symptoms. Ginkgo bilboa may help age-related tinnitus. Decrease in severity with 50mg of zinc. 532 mg of elemental magnesium for lessening of symptoms.
Aging: How Big Are Your Ears?
Ears grow our entire life, growing quicker in older age. If you know your ear circumferences in mm, find the average between your ears, subtract 88.1, and then whatever that value is multiply by 1.96 and that will tell you your biological age.
Balance: Semi-Circular Canals
The 3 semicircular canals have marbles at the base of them. Vertical, 90-degree angle, and tilted at 45 degrees for the different planes (pitch, yaw, and roll). They cause the marbles to move in the respective planes, deflecting little hair cells, sending information to the brain. Every animal that has a jaw has this balance system.
A Vestibular Experiment
Sit, move head to the left very slowly, then do it quickly, slowly again. You may notice it is very uncomfortable doing it slowly. This is because the marbles don’t get much of a signal and uncouple with the visual information. It is really hard trying to keep your eye movements smooth too. If you move quickly, your eyes can jump to the spot you move too.
Big oscillations, like on a boat, can make you sick because of this mechanism.
The inner mechanisms of your ear usually tell your eyes where to go, as well as your eyes telling your balance/vestibular system how to function.
Improve Your Sense of Balance
Stand up, look forward (10-12 feet), stand on one leg, close your eyes. You’ll suddenly feel postural sway.
How to: Raise on leg, look at a shirt distance (about arm’s length), step your vision out further, further again, and then step it back. This sends robust information about the world and helping you to map your visual surface and adjust postural muscles during that visual change.
Unilateral movements and tilting seem to be important for this training. As well as acceleration.
Accelerating Balance
Head position, visual position, direction you are moving, and how fast. Linear acceleration plus tilting with respect to gravity.
Self-Generated Forward Motion
If you aren’t tilting while accelerating, you aren’t really getting the most out of your nervous system and cerebellar activation. This kind of activity can cause the cerebellum to release neuromodulators like dopamine to improve learning speed and make us feel good. Surfing, roller coasters, drifting, skiing, cycling, etc. Amazing effects on our mobility, balance, and mood.
Dizzy versus Light-Headed
Are you dizzy or lightheaded? If you feel your world is spinning and you can still focus on looking at your thumb, that is dizziness. If you feel like you are falling or need to get down to the ground, that is light headed.
Lightheaded could be low blood sugar or low in salt or other electrolytes.
Motion Sickness Solution
For dizziness or seasickness get fresh air and allow your visual system to track with your vestibular system, instead of just looking at the horizon.
Sense of Balance
Vestibular system is designed to detect how you’re moving through the world, interoceptively. Deep in the ear and served by the same nerve for the hearing system. Little hair cells are bent by moving fluid within the 3 tubes of different axis, which transduce a signal about head orientation.
If we sit in a car and the driver hits the accelerator, we can sense it even if our eyes are closed.
Visual information needs to combine with these vestibular signals so that the eyes can stabilize the what the vestibular system expects. The brain works hard to stabilize everything.
Why Pigeons Bob Their Heads, Motion Sickness
Pigeons and chickens keep their vision static on their retina for as long as they can by maintaining head position in one place. Pigeons know to keep their head back while they move forward.
Visual vestibular conflict tends to cause motion sickness. If you are looking at a stable cellphone while your vestibular system is being tested, it makes you feel nauseas.
Visual and vestibular input is combined in the cerebellum (the flocculus). The cerebellum requires input from signals all over to coordinate movements. If your vestibular apparatus is damaged, your cerebellum can learn by taking in new information so it can readjust.
Popping Ears
Pressure builds up in the inner ear. Ascending, ears plugged (higher pressure inside vs. lower outside). You should probably suck in rather than blow out to correct it, but opening the passageway will probably fix the pressure differential regardless.
Midbrain & Blindsight
The midbrain controls a lot of unconscious reflexes. As you enter the skull the spinal cord spreads out into the midbrain before the thalamus. The superior colliculus lives in the midbrain, which visual input may be interpreted reflexively to regions of space (like predators). These areas emerged early in evolution. Taking sensory information from the external world and reacting reflexively.
If you have a weak signal from one sensor in one direction and a weak one from another, it is much more likely that those sensors are picking up something useful as they communicate and sum.
Why Tilted Motion Feels Good
Might be dopaminergic influence. There is a sense of agency moving through the world.
Taste
Neural Basis of Food Preference, Yum, Yuck, Meh; Taste, Guts, & Beliefs
Taste on the mouth. The sensation that we have of the foods that we eat (somatosensory), palatability, and consistency.
Chemical sensors on the tongue (bitter, sweet, umami/savory, salty, and sour). Chemicals bind to the receptors, this gets transduced into an electrical signal that travels from the tongue along the gustatory nerve, then synapses to the brain stem (nucleus of the solitary tract), then it sends information up to the insula.
The insula cortex is mainly concerned with interoception. This could be gut pressure, acidity in the gut, neurons in the gut may pay attention to psychological stress, alertness, etc. The signal from the tongue gives us the impression of whether what we’ve eaten tastes good or not.
An internal representation of an external sense. Relative activation traveling to the brain as essentially the same electrical signals.
Braising meat is done to activate the umami taste.
Taste is 100% In your Head
You can silence or activate the neurons that respond to tongue senses, such as sweet. You can eliminate the preference for the sweet taste by doing this. You could also activate the sweet neurons while drinking plain water and the subject will begin to actively prefer it.
Taste is a representation of the external environment that is specific to your current wants and needs.
Gut Neurons Controlling Food Preference: Neuropod Cells; (Tool 7: Fermented Foods)
Your digestive tract has neurons all the way down. They can detect how full your gut it, if food is spicy, etc. (Size and chemistry of the food and gut contents/mechanics).
Neuropod cells reside within the gut and have dendrites and axons in the mucosal lining that respond to amino acids, sugars, and fatty acids. They essentially survey the contents rather than doing anything with them. This signal gets sent via the nodose ganglion to trigger the release of dopamine. A subconscious signal about the quality of food you’re eating and triggering dopamine to get you to seek more.
Hidden sugars, which you can’t taste in processed foods, can lead you to want to eat more subconsciously. The combination of the tongue sensors and gut lining ones will contribute to cravings. Which is why we don’t crave fatty acids, even though these neuronal processes are looking for fatty acids too.
A healthy gut microbiome will allow these neurons to function in more positive ways. Eat 2-4 servings of low-sugar fermented foods (natto, kimchi, sauerkraut) per day to enhance the quality of the mucosal lining.
Learning to Like Specific Tastes: Sweetness & Brain Metabolism
Subjects will pursue more of a sweet food item/drink whether they are consumed or put into the gut. Meaning we will develop preference based on glucose increase rather than purely taste. When neutralizing blood sugar uptake into neurons you can also decrease preference and response. Meaning, it is not enough to have taste, increased dopamine, or blood glucose levels increase. You also need it to be taken up and utilized by neurons. We seek things that allow our neurons to be metabolically active.
Artificial & Non-Caloric Sweeteners: Safe or Harmful Depends on (Glucose) Context
Initially we don’t like artificial sweeteners that much since blood glucose and dopamine levels don’t go up, but it is preferred over not having them. Over time the dopamine levels go up without the glucose levels or neuron utilization, reinforcing the desire for artificial sweeteners. Meaning people can eventually get “addicted” to these.
Non-Caloric Sweetener & Insulin; (Tool 8: Don’t Have w/Glucose Elevating Foods)
If you pair them with glucose, you can condition yourself to want it as well as messing with your body’s anticipation for glucose. Insulin levels go up in response to the diet soda. Don’t have diet soda with food unless you want to end up with type 2 diabetes from drinking the diet drinks later on without food.
Only consume a diet soda without food so you don’t mess up your blood sugar management.
Particular artificial sweeteners can have a deleterious effect on the microbiome.
TASTE: Sweet, Salty, Bitter, Umami, Sour; Your Tongue, Gustatory Nerve, NST, Cortex
Umami is the name for a receptor that tastes savory tastes. Each taste sense has a particular function in response to chemicals. There are not certain areas on the tongue that are dedicated to senses.
You have neurons in your tongue that respond to things like sugars. Taking the electrical signal via the gustatory nerve, to the nucleus of the solitary tract, then to the thalamus, and the insular cortex. This is where we sort out and distinguish the different tastes.
Energy, Electrolytes, Poisons, Gagging, Amino Acid & Fatty Acid Sensing, Fermentation
Sweet stuff senses the presence of energy/sugars. The ability to sense rapid energy source is essential.
Salty senses are there to detect electrolytes. Just not too much salt.
Bitter receptors are there to detect poisonous compounds. They travel to an area in the brainstem that control the gag reflex. Putrid smells will also evoke the same neurons.
The umami receptors sense amino acids.
The sour receptor is there to detect spoiled or fermented fruit, which can be poisonous. Evoking the pucker response.
Our 6th Sense of Taste: FAT Sensing
We also have receptors for fat. The texture and flavor of fat can be sensed and would have been critical for our survival.
Gut-Brain: Your Mouth as an Extension of Your Gut; Burned Mouth & Regeneration
In the mucosal lining of the gut, we have neurons that can sense amino acids, sugar, and fatty acids. A signal gets sent by the vagus nerve to the nodose ganglion into the brain to squirt dopamine, so we can pursue more of that food, independent of the taste. The first stop is the tongue and nose to detect whether we want to bring foods in.
If you burn your tongue with heat, you’ll burn the receptors, reducing your sense of taste until they heal.
Protocol 3: Learn to Be a Super-Taster by Top-Down Behavioral Plasticity
You can train your sense of taste, so you can detect the nuance of certain foods, using top-down mechanisms. Just by paying attention to what you’re trying to taste. It is very amenable to behavioral plasticity.
The Umami-Sweet Distinction: Tigers Versus Pandas
Taste receptors like T1R1 and T1R2, which were identified as sweet and umami receptors. Carnivorous animals have no ability to detect sweet, but their ability to detect umami is 5000 that of humans.
Herbivores have no umami receptors but have a much higher degree of sweet receptors.
Eating More Plants Versus Eating More Meat, Cravings & Desire
People that eat pure carnivore or more meat will develop a more sensitive palate to more savory foods and those that eat plant based will develop a heightened sensitivity to sugars and plant-based foods. The systems are plastic.
Food That Makes You Feel Good or Bad: Taste Receptors on Our Testes or Ovaries
We have taste receptors on our testes and ovaries. Some foods make us feel so good or bad that we have a visceral response. Ho the molecules would get there is not known, but it evokes a cellular response in the gonads. The sensual nature of foods (sweet and savory usually) and sex. No data to support the stimulation of the gonads yet, but interesting nonetheless.
https://pubmed.ncbi.nlm.nih.gov/23423265/
Appetitive & Aversive Sensing: Touching Certain Surfaces, Tasting Certain Foods
Some people who touch nice velvety surfaces feel good elsewhere. Some people who hear nails on a chalkboard can feel aversive signals all over too.
Amino Acids Are Key to Life, The Maillard Reaction, Smell-Taste Merge, Food Texture
A reaction that is the non-enzymatic browning (caramelization), a sugar-sugar interaction that leads to a nicely toasted sweet taste. The Maillard reaction is a sugar amino acid reaction. This involves a free aldehyde. The use of heat and braising you create a ketone group. A ketone smells like alcohol but has a savory taste.
The combination of odor receptors being activated as well as taste receptors triggers the activation of multiple brain regions that may lead to aversion or desire.
How Processed Food Make You Crave More Processed Foods
Processed foods have taken advantage of novel texture, as well as sweet, and savory tastes. They are activating neurons in your gut so you desire more. Triggering the release of dopamine.
Protocol 4: Invert Your Sense of Sweet & Sour: Miracle Fruit; Swapping Bitter & Sweet
Miracle fruit causes a change in configuration of your sense of taste for several hours.
Smell
How We Sense Chemicals: Enter Our Nose, Mouth, Eyes, Skin
There are photons that land on the retina and get converted into electrical energy; there are sound waves – particles moving through the air that create sound for hearing; mechanical stimuli – pressure, light touch, vibration, scratch, tickle on our skin sensing mechanical sensation; then there are volatile chemicals that are inhaled into the nose to be detected by the brain; there is also taste where chemicals bind to receptors on our tongue; chemicals can also enter mucosal linings, like our nose, eyes, and mouth.
People can also actively make chemicals that they release from our mouth, tears, possibly pheromones too, that enter our systems and change our biology.
The Chemicals from Other People’s Tears Lower Testosterone & Libido
Humans have a strong biological and hormonal response to the tears of women. Men smelt these tears that were evoked by sadness, which lowered testosterone levels and sexual arousal. The tears were released from people who cried during movies, which is the prerequisite for being recruited for the study.
There are chemicals in tears that can change the biology of others. Powerfully modulating our internal state.
https://www.science.org/doi/10.1126/science.1198331
SMELL: Sniffing, A Piece of Your Brain in Your Nose, 3 Responses to Smells
Volatile chemicals can get into the nose by sniffing. The nose has a mucosal lining that helps them to get stuck there.
The olfactory neurons extend into nose mucosal lining. They respond to different odorant compounds. The olfactory neurons also send a branch deeper into the brain which splits into 3 different paths. One is for innate odor responses. Hardwired smells like smoke that call for action, sending a message to the amygdala. Triggering you to wake up or to react defensively.
You also have neurons that respond to odorants that evoke a sense of desire (appetitive behaviors), approach behaviors, making you want to move towards something like food.
Some pathways are involved with learned associations, like your grandmother’s house. Typically, of a nurturing sort, related to safety and protection.
Smells & Memory: Why They Are So Powerfully Associated
Chemical sensing is one of the most ancient senses. Certain smells evoke a memory, pathway, or context. Reminding you of a place.
Pheromone Effects: Spontaneous Miscarriage, Males & Timing Female Puberty
The accessory olfactory pathway. This is what is responsible in animals for true pheromone effects.
Female mandrills can spontaneously go into puberty earlier with the pheromones/urine scent of a sexually competent post-pubertal male. They can also spontaneously miscarry if you take away the father of a fetus and introduce the scent of another post-pubertal male.
Sniffing Creates Alertness & If Done Properly Can Help You Focus & Learn Better
The act of smelling powerfully impacts how your brain functions. The act of inhaling increases brain arousal and alertness. It is a cue to the rest of the brain to pay attention and may help you to retain information. When you exhale you have a drop in arousal.
If human subjects are restricted to breathing through their nose, they learn better.
https://pubmed.ncbi.nlm.nih.gov/31089297/
Protocol 1: Sniffing (Nothing) 10-15X Enhances Your Ability to Smell & Taste
If you don’t have a sense of smell, you can practice sniffing to improve it. Do 10-15 inhales, then sniff something like an orange to increase your ability to perceive those odors. The waking up of the brain and olfactory system heightens the sensitivity of the sense of smell.
Smell an orange, gauge how it smells, put it away, do 10-15 inhales, smell it again and the richness of the smell should be greater after priming the nerves as well as heightening the brain arousal.
Smelling Salts, Ammonia & Adrenaline
If you use ammonia smelling salts, you can heighten your sense of arousal and alertness by triggering the fear and arousal systems. Resulting in a huge boost of adrenaline.
How You Can Become a Human Scent Hound, Detecting Cancer, & Tasting Better
Wear goggles to block out sight (or close eyes) and interact with some sort of food item by smelling it mindfully. It will have long term effects on your ability to discriminate between certain odors.
Take 10-15 sniffs of nothing to improve your olfactory sense. You can end up improving your palate and better guide your eating preferences in line with your biology.
Smell As a Readout of Brain Health & Longevity; Regaining Lost Sense of Smell
Our olfactory neurons get replenished throughout life. The cells are constantly turning over throughout life. Every 3-4 weeks they die and get replaced by neurons from the subventricular zone. If you are exercising regularly and your dopamine levels are high enough, they spit out neuroblasts that migrate to the front of your brain and then shimmy down into the into the rostral migratory stream to replace the neurons in the olfactory nerve.
Exercise and blood flow, social interactions, and interacting with odorants can increase this neurogenesis. Dopamine modulates this process as a powerful trigger. Some people who take certain medications that increase dopamine levels may find a sudden ability to smell more odors.
Dopamine, Sense of Smell, New Neurons & New Relationships
Some people who are in a new relationship, because of dopamine, testosterone, and estrogen being associated with novelty, find they are obsessed with the scent of that person.
As well age, we lose our sense of smell. Likely correlated with the loss of other neurons.
Why Brain Injury Causes Loss of Smell; Using Smell to Gauge & Speed Recovery
Olfactory dysfunction is a common theme in traumatic brain injury. The olfactory neurons extend wires into the mucosa of the nose and also a wire up into the skull through the cribriform plate, which might get sheared during an injury. Recovery may be evaluated by the return of the sense of smell.
Post-injury olfactory training can help to create new neurons.
Using Smell to Immediately Becoming Physically Stronger
https://pubmed.ncbi.nlm.nih.gov/28922211/
Smelling In Our Dreams, Active Sniffing in Sleep, Sniffing as a Sign of Consciousness
When we are in REM sleep our ability to wake up to odors are diminished. Less likely to sniff. They may recall the smell of something though.
The ability to sniff is a way to see if somebody has become brain dead after an injury. A sniffing reflex to a lemon is often used.
Mint Scents Create Alertness by Activating Broad Wake-Up Pathways
Peppermint scents will increase attention. They trigger specific olfactory neurons that communicate with the amygdala and associated neurocircuitry that trigger alertness that a cold shower or stressful text message would elicit. Like a less intense version of smelling salts.
Protocol 2 Pleasant or Putrid: The Microwave Popcorn Test, Cilantro, Asparagus, Musk
Some people hate the smell of popcorn (the molecule: 2-acetyl-1-pyrroline). They have a gene that makes the smell seem like vomit. Some hate the smell of cilantro. Some people can’t smell asparagus pee. If you don’t have these specific genes you won’t respond to the odors. The musky scent can be found pleasant by some, whereas others can find it noxious.
Skunks, Costello, All Quiet on the Western Front
The smell of skunk is not that bad to some unless it is in high concentration.
Pheromones, Desire to Continue Mating: Coolidge Effect Occurs in Males & Females
Male of a given species mating and reaching exhaustion. If you swap out the old mate for a new one, they suddenly get the vigor to carry on. You can also do this the other way around and get a new male to get the female to lordose again. It is pheromonal as you can just give them the odor to evoke it. Requiring Jakobson’s organ.
Humans seem to have responses that suggest we can detect pheromones.
Do Women Influence Each Other’s Menstrual Cycles?
There is chemical signaling but it is depending on the phase, either lengthening or shortening the other woman’s phase. Not necessarily synchronizing, just shifted.
Recognizing the Smell of Your Romantic Partner
People can recognize the t-shirt of a mate. Women in a stable relationship can detect the shirt of the partner even if it is diluted. They may not know why but they can tell.
Differences In Odor Detection Ability, Effects of Hormones
Women seem better at detecting odors than men.
We Rub the Chemicals of Others on Our Eyes and Skin, Blunting Behavior
Chemical-chemical signaling exists, we just having identified what the molecules are that do it. When shaking hands with a new person we tend to touch our face without realizing it. Placing the chemicals on our mucosal membranes subconsciously. Evaluating the molecules on people’s breath, sweat, hands, etc. Wiping ourselves with other’s chemicals.
Touch
Huberman
Skin, Pain, Pleasure
Our skin acts as a barrier to the outside world and harbors nerves to detect pressure, light touch, temperature, etc. As well as the capacity for experiencing pleasure.
Protocol 1: Maximizing Motivation (with Dopamine & Pleasure)
Changes in motivation reflect changes/fluctuations in dopamine. Reward prediction variance.
Dopamine is released into the brain and body in anticipation of a reward to make us feel activated and motivated to pursue a goal. When the reward arrives, dopamine goes back down to baseline.
By not delivering the reward at the expected schedule (randomized/intermittently) the amount of dopamine doubles or triples. This is why gambling is so addictive. You can use this schedule to stay motivated in your pursuits. Don’t reward every action or goal.
Pleasure & Pain, & Skin Sensors
Pleasure is generally a sensation in the mind that leads us to pursue more of whatever is bring the sensation. Pain, in general, is the desire to move away from a signal. Appetitive behaviors and aversive behaviors.
The nerve cells in the skin have their cell bodies just outside the spinal cord (dorsal root ganglia), which send one branch to the skin and the other to the brain. Huge cells that sense stimuli in the skin. Different neurons responding to different sorts of stimuli, such as mechanical forces (light touch, hard pressure, temperature) and chemical forces (hot peppers).
Sensing Touch with Your Brain: Magnification of Feet, Hands, Lips, Face, Genitals
The brain takes the electrical signals and interprets them. Some things require prior experience, such as spicy foods.
The somatosensory cortex you have a map of your entire bodily surface (homunculus). Some areas with more sensation than others. Your representation of touch. Highly organized for areas with the highest density of receptors.
Lips, face, tips of the fingers, genitals, and feet have the highest density.
Two-Point Discrimination, Dermatomes
Your ability to know if two points of pressure are near or far with your eyes closed. The middle of your back may feel two close points of pressure as one point.
The dermatome is the way the body surface is carved up into different territories. The way neurons connect to the different areas of the body. You will feel cold, pain or heat in a boundary, rather than a refined point.
The herpes virus lives in the trigeminal nerve, which sends branches to the lips, eyes, and certain portions of the face. When the virus flares up, it inflames their dermatome areas. A rash or bodily pattern with a stark boundary is probably affecting the nerves of a dermatome.
Thoughts & Genes That Make Physical Pain Worse
Expectations of pain, anxiety (autonomic arousal), how well you slept, where you are on your circadian cycle (daylight waking is better), etc., can all affect your tolerance to pain and ability to sense pleasure. Pain threshold and how long it lasts can also be affected by genes.
If we know a painful stimulus is coming, we can better prepare for it and buffer the pain. However, the timing is important for not making it worse. If subjects are warned 2s before, things are worse because they aren’t ready, if they are warned 2 minutes before, the anxiety ramps up autonomic arousal.
20s-40s is a good advanced warning for pain.
Expectations, Anxiety, & Pain Threshold
Pain threshold – the amount of chemical, mechanical, or thermal stimulus it takes to decide it is too much. Also, how long the pain persists.
Some experience a very painful but brief experience (such as cold), whereas others will have a lower pain experience but for longer. This important for the treatment of pain, because pain is not an event in the skin, it is a subjective and emotional experience.
Nociceptors carry information about stimuli that affects the skin. The brain determines if it is painful.
If a doctor has a high threshold for pain, their interpretation of another’s pain will be inaccurate and the treatment will be inappropriate. Unfortunately, there is no way of measuring objective pain.
Protocol 2: Cold Sensing Is Relative; Getting into Cold Water
Getting into cold is much harder if you do it slowly. One of the best tests to see how somebody responds to pain is to get them into an ice bath. Some start quaking and complaining and just can’t jump in.
The neurons that sense cold respond to relative drops in temperature. You can bypass these relative changes in temperature by just jumping in. Get your shoulders submerged. If you sit in water that is not circulating, you’ll begin to feel an envelope of heated water around you.
Just be smart about not jumping into freezing water too quickly, as it can cause a heart attack.
Protocol 3: Heat Is Absolute
Hits you all at once but then stays at that level. Neurons measure heat as an absolute. You don’t really adapt like you do with the cold. Gradually moving into heat makes more sense in terms of reducing discomfort.
Injury & Pain
The experience of pain and the damage done to the body are not always correlated. We don’t feel the damage from repeated x-rays. We can also feel extreme pain with no damage. An example of a guy who had pain when he saw a nail go through his shoe. Upon taking it off, it missed his foot.
We don’t know how other people are feeling pain. We barely understand how we feel, let alone others.
Protocol 4: Plasticity of Pain: Key Role of Vision
People that have missing limbs or digits may have phantom limb pain. When you remove a part, the dorsal root ganglion no longer has the wire out to the part. However, the somatosensory area is still there. The homunculus just doesn’t reorganize the missing limb space even though there is a lack of sensation.
Areas of the map that are adjacent to each other can invade each other.
By using vision, in the case of the mirror box experiment, you can retrain the brain to relax by showing an intact and undamaged limb.
Sensing Disparate Body Parts as Merged
Certain areas that we usually don’t consider related start to connect. In the story mentioned, a person was having orgasms in their phantom foot, during sex, because the foot and genitalia areas were interdigitated in the homunculus.
We experience pain and pleasure due to local phenomena and body-wide.
Pain “Syndromes”, Psychogenic Fever, “Psychosomatics”
Fibromyalgia is an example of whole-body pain. Any time you see or hear the word syndrome, that is a sign the medical establishment doesn’t understand what is going on.
Everything is neural, so the body/brain/psychosomatic argument is irrelevant.
Psychogenic fevers – areas of the thalamus (integrates and filters sensory information) and the brainstem (DMH) that show a true neurological basis for psychogenic fever. Our thinking generating the fever.
Fibromyalgia, Naltrexone, Protocol 5: Acetyl-L-Carnitine
For a long time, written off as one of these “syndromes.” There is a receptor on glia called the toll 4 receptor, which is related to the whole-body pain of fibromyalgia.
Naltrexone is used for the treatment of various opioid addictions and a low dose has shown to have success of treating some forms of fibromyalgia by blocking the toll 4 receptors on glia.
Acetyl-l-carnitine (1-4g per day) can reduce the symptoms of chronic whole-body pain. Some use it for diabetic neuropathy. Improves peripheral health generally, sperm motility and health, and women’s fertility. Has its effects on reduced inflammation through its impact on inflammatory cytokines (IL-1-beta, CRP, IL-6). Matrix metalloproteinases are used to break down elements around wounds and scarring to let glial cells in to clean. L-carnitine seems to be able to assist this.
Protocol 6: Agmatine, S-adenosyl-L-methionine (SAMe), L-5-Methyltetrahydrofolate*
Agmatine and SAMe, some impact on pain. SAMe shown head-to-head with Naproxen, seen to work as well but slower. Sometimes up to a month to work. Some companies have stopped making SAMe and are now making 5-MTHF instead, which is necessary for converting homocysteine to methionine, which is then converted into SAMe.
It pays to research compounds before attempting to try them.
Acupuncture: Mechanism, Non-Responders, Itch & Inflammation
Some people respond well to acupuncture and others will not. Itch and pain are often associated. Mosquito venom creates packets of histamine, mast cells go to the area, making us want to scratch, histamine gets released, and it gets worse. The experience of pain and itch is considered a pyrogenic experience. Itch brings inflammation, which can bring pain.
Acupuncture can cause relief from and also exacerbate pain. The activation of sympathetic ganglia in the abdomen can release noradrenaline and neuropeptide Y. Electroacupuncture can be anti-inflammatory or inflammatory depending on if it was at high or low intensity.
Low-stimulation of the legs caused a neural circuit that goes to the DMV in the brain, activating the adrenal glands, causing the release of catecholamines, which were strongly anti-inflammatory. Possibly accelerating wound healing too.
Because of Western studies, insurance coverage is beginning to cover acupuncture.
Mucuna pruriens is 99% L-DOPA on the inside. The outside of the bean makes people itch.
Laser Photobiomodulation, Protocol 7: Hypnosis (reveri.com)
For the treatment of chronic and acute pain. Use hypnosis – reveri.com. Modulating the PFC.
Protocol 8: Pressure-Based Pain Relief, “Gate Theory of Pain (Relief)”
Hypnosis takes advantage of how we interpret events to experience what would be painful as less painful overall.
Even brief self-hypnosis can achieve significant pain relief.
Gate Theory of Pain: Putting pressure above or below a painful area to impact the perception of pain. We have c-fibers, that bring about nociceptor information, making us rub something painful, activating a-fibers that respond to mechanical pressure, inhibiting the pain carrying c-fibers.
Redheads & Pain Thresholds, Endogenous Opioids
MC1R gene encodes for proteins related to the production of melanin, which is what causes fair skin and red hair in some. This gene is associated with a pathway – POMC – which is cleaved into different hormones. Including one that enhances pain perception (melanocyte stimulating hormone) and one that blocks it (beta-endorphin). Red heads make more of these endogenous endorphins and have a higher pain threshold on average.
Protocol 8: Love & Pain, Dopamine
Love, and in particular obsessive love, can counter the pain response. Correlated with the ability to handle/buffer sustained pain. Dopamine is coursing throughout the body when we fall in love, and can have powerful effects on the inflammation system. It does this by interaction through the brain stem and to trigger killer cells from the spleen to battle infection. Dopamine tells the body/brain that conditions are good. Allowing us to lean into challenge.
Pleasure & Reproduction, Dopamine & Serotonin, Oxytocin
The process of reproduction is associated with pleasure. The currency of pleasure is the dopamine system (anticipation and motivation) and serotonin system (immediate experience). Oxytocin (pair bonding), is more closely associated with serotonin biochemically and circuitry. Dopamine is more related to testosterone and other molecules involved in pursuit.
Protocol 9: PEA, L-Phenylalanine (Precursor to Tyrosine)
Phenethylamine (PEA) is potent at increasing cells that relate to the pleasure system. Dark chocolate, aspartame (glutamate pathway) in some people, and supplements. A bit of a stimulant and heightens the perception of pleasure in response to a particular amount of dopamine and serotonin.
If levels of dopamine and serotonin are too low it seems almost impossible to experience pleasure (anhedonia). PEA can cause a slight increase in the “tide” of these neuromodulators, making them more available (gain control).
Contextual Control of Pleasure by Autonomic Arousal, Dopamine Baselines
Different experiences use the same currency. If you artificially increase these levels with antidepressants side effects can be loss of desire for food, sex, or other things.
PEA only lasts about 20 minutes. Although, any time you raise your baseline, it will take much more of an increase to achieve the same pleasure.
Pleasure-Pain Balance
Be wary of any experience that boosts dopamine too high. There is a mirror reward system, increasing circuits of disappointment, dropping peaks of dopamine. Habituating or attenuating.
Protocol 10: Controlling Pleasure, Dopamine & Motivation Over Time
If you can continue to achieve pleasure over time, you probably have your system well-tuned.
Engage in the intermittent reward schedule. Don’t always allow the reward every time. Keep it random. Adjust down your excitement.
In a situation of winning money or something, wait to spend it so you don’t layer on dopamine rewards.
If you reward someone (a child in particular) with an experience that exceeds the actual accomplishment (like a sports win) you are inhibiting the ability for them to perform the same sort of activities that led to it. Especially if it is given every time.
Protocol 11: Immediate, Non-Goal-Directed Pleasure, PAG
The periaqueductal gray area is associated with pain and pleasure by deploying endogenous opioids that lead to a blissed out feeling, during things like long distance exercise or childbirth.
Sexual activity can increase pain threshold because of the release of these opioids.
Direction of Touch: Pleasure Versus Pain, Arousal & Touch “Sensitivity”
Some neurons respond to direction of touch. Some hairs like to go in the direction compared to another (like some cats and stroking the opposing way). The nerves that go up from the hair bifurcate between pain and pleasure centers, resulting in enjoyment or discomfort. Areas of our skin with a high density of receptors are very sensitive to touch and whether a touch is too firm or too light. Modulated by overall levels of arousal. In a deep plane of relaxation (especially anesthesia) in it hard to feel pleasure or pain.
At heightened states of arousal our ability to achieve pleasure goes up and so does our threshold for pain.
A System of Touch (Somatosensation)
Understanding touch/physical feeling.
Nerve cells below the skin, some respond to mechanical touch, heat, cold, vibration, etc. Send to spinal cord and then the brain where it is interpreted. This determines what the stimulus is. Nociceptors are the sensors below the skin that detect particular stimuli.
Pain and Injury are Dissociable
If exposed to high radiation levels, you wouldn’t feel anything. There can still be a lot of tissue damage without physical or mental perception of pain. Pain and tissue damage are dissociable from one another.
Objective versus Subjective Control of Experience
The specific type of connection one has to a romantic partner will determine how they perceive pain.
Lack of Pain Is Self-Destructive; So Is Excessive Pain
Kids with a genetic mutation who are born without a particular sodium channel (1.7) feel no pain at all. They burn themselves, don’t make micro-adjustments, and joints get destroyed. Some people make too much of this receptor and feel extreme pain.
Homoculous, Ratonculous, Dogunculus
Map of body surface in our brain (homunculus). This representation is scaled to the sensation and density of sensory receptors.
“Sensitivity” explained
Fingers have a larger density of receptors and finer discrimination of sensation.
Inflammation
More inflammation in areas with higher receptor density. Good for healing.
Phantom Limb Pain
Sensation of missing limb is feeling pain as the representation of it is still intact.
Top-down Relief of Pain by Vision
Use the brain to control perceptions of what’s happening in the body. Ramachandran.
Using mirror boxes to eliminate phantom pain by showing a safe hand (opposing) to remap the perception of the phantom limb. Also contributes to reducing emotional pain.