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What is pain, and why do we even need it?

Arguably the least enjoyable sensation out of them all, pain always demands attention — and a reaction. But why would biology even give us the ability to feel such a debilitating sensation? Why can’t we just block it out by ourselves? Why even have it in the first place?

Image credits Dimitris Vetsikas.

Pain is unpleasant by design. It needs to be because it is our body’s alarm system. It warns us whenever some bit isn’t functioning correctly, of issues such as disease or infection, and of damage and injury. But, and this is a very important but, it doesn’t always do that. People can feel phantom limb pain even after having a limb amputated. Injuries can be sustained without any feelings of pain, either temporarily or permanently. Our brain can completely block it out if needed. And things such as loud or high-pitched noises can cause us pain without producing any injury (although they can cause these too).

It also “pains us to say this” sometimes. We all know that it’s a figure of speech, especially in work emails, but is there any literal truth behind that?

First off, what is pain?

From our direct experience of it, it’s easy to start seeing pain as punishment — scratch your knee through carelessness, then it starts hurting to get revenge. In actuality, however, pain is meant as a behavioral corrector. Research in the field showed that it doesn’t have to be produced by tissue damage, but rather works as a preventative as well as a protective mechanism. It is so unpleasant and hard to ignore because it was designed from the ground up to get your attention, hold it, and make you want to make it stop.

We all intimately know that pain is an unpleasant, physical sensation. But its current definition also includes its emotional component, meaning that pain can also be a feeling or a constellation of feelings associated with actual or potential harm.

Image via Pixabay.

Physical pain is handled by specialized nerve endings called nociceptors running through and across our bodies. These stay alert for any change that could pose a risk for us, including changes in temperature, chemistry, or pressure. The signals they send to our brains once dangerous thresholds are passed are interpreted or perceived by us as pain. For example, getting bitten hurts because the pressure being applied in that area is almost as great, or greater than, what our skin can safely handle. Keeping your palm on a block of ice for too long starts hurting because it prevents our tissues there from keeping their normal temperature.

Feelings of pain can also be neuropathic in nature (related to damage incurred by the nervous system) or nociplastic (produced by changes in our pain thresholds, generally without injury). The former is the kind of pain you perceive as burning, tingling, or stabbing in your fingers. Diabetes patients often develop long-lasting neuropathic pain, most commonly felt as severe burning pain at night, due to nerve damage incurred by the disease.

It is important to note that like pretty much every other one of our senses, pain doesn’t actually exist, it’s simply a product of our brains. The most concrete manifestation of pain would be the electrical impulses sent out by nociceptors when certain conditions are met. The actual unpleasant sensation you feel, however, is just something your brain creates as it deems necessary. It looks at information such as what threats are present (as informed by our senses), our cognitive state, previous experience with certain types of stimuli, social and cultural norms, and so on.

In other words, when a certain part of you is injured or just not having a good time, it doesn’t hurt; your brain makes you think it hurts. That pain is meant to encourage you to keep said area safe and protected so it can heal. You’ll know how to do so because it will hurt more whenever you don’t. It’s a pretty straightforward system like that.

How we feel it

One thing that I feel is important to note here is that the nerves in our bodies are not made equal.

The nerves in your body are meant to (and are thus specialized to) feel certain kinds of pain in certain ways. For example, the nerves running through your internal organs will readily pick up on distension (stretching), ischemia (reduction in blood flow), or inflammation, beaming these back to you as a diffuse pain. This pain is not highly localized because you don’t really need it to be — all that matters is that you understand there’s something going on inside your belly and you should manage it.

What these visceral nerves are not good at, however, is feeling stuff like cuts or burns. The ones in your skin, meanwhile, are very good at picking up on these, and they’re also very good at pinpointing exactly where the pain comes from. It’s much more important to know where you got a cut on your skin so you can keep it clean and prevent infection, so your body supplies this information.

However, at the end of the day, all nerve fibers make their way to the same spinal cord. But because both areas with a higher sensory density (skin, for example) and those with low sensory density (such as viscera) end up here, their data can get scrambled up. This can produce an effect where pain from one low-sensitivity area can be interpreted as coming from a high-sensitivity area.

Types of pain

A pain management chart, meant to help patients more accurately describe the levels of pain they’re feeling. Image credits LPWaterhouse / Flickr.

The first one we’ll talk about today is ‘referred‘ or ‘reflected’ pain, that’s felt in one part of the body but produced by injuries in another. For example, a kidney stone will make your back hurt, and a stroke can make your jaw sore. Referred pain is produced because the nerve pathways serving the injured areas also connect to others, which may mess up where our brains perceive the pain (although we don’t yet have a good grasp on why it happens). There is also ‘radiating‘ pain, similar to the referred one, with the slight difference that the sensation is also felt in the area that has sustained an injury, not just away from it.

Acute pain is diagnosed mostly based on duration and re-emergence. If the pain can be resolved quickly it is considered to be acute. The exact definitions are still a bit blurry, and the time window used to determine acute pain has varied from 30 days to 6 months, even up to 12 months. One simple way to describe acute pain is that it doesn’t extend beyond the expected period of healing, or that it is short-lived.

On the other hand, we have chronic pain. This can last for years, even your whole lifetime, if you’re particularly unlucky. This can be produced by a variety of conditions, although doctors sometimes make a distinction between cancer-related and benign chronic pain. One easier way of describing it is as pain that extends past the expected period of healing, or that it is long-lasting.

Phantom pain sounds spooky, and it is. This is the type of pain individuals sometimes feel in a limb they lost through accident or amputation. Although a part of their body is gone, these individuals still feel (sometimes very significant) levels of pain in that limb. This is a type of neuropathic pain. It’s a very common symptom, occurring in over 80% of upper-limb amputees and over 50% of lower-limb amputees.

Breakthrough pain is often associated with cancer patients, but they’re not the only ones to experience it. Breakthrough pain is a ‘background’ pain that’s usually controlled by medication but sometimes ‘breaks through’ these in bouts of acute pain.

Finally, to your brain, emotional pain is almost the same as the physical kind; which is why breakups are so enjoyable.

How do pain blockers work?

Image credits Arek Socha.

Pain pathways form a very intricate system in our bodies. This is also by design: our ability to feel pain has to be reliable, because it’s meant to keep us alive.

However, our brains can block out pain when needed. If we find ourselves in a dangerous situation where tending to our wounds is not possible — when we’re facing a predator, for example — pain can become counterproductive. The sensation could limit our range of motion or willingness to move and fight in this scenario. As such, our brains temporarily block painful sensations to allow us to escape or prevail. You’ve probably also experienced getting injured during a tense or dangerous situation and only later noticing it. Adrenaline or states of shock can also block out the sensation of pain.

This process takes place without our input and isn’t reproducible at will. Still, having the ability to stop pain is very handy, so we’ve developed ways of doing so. Anesthetics or pain blockers work by either preventing nerve endings from transmitting pain signals to the brain, or in one way or another stopping the brain from producing a painful sensation.

General anesthesia, for example (the kind you’d get before surgery) disrupts nerve activity throughout your whole body. This prevents us from feeling pain while under anesthesia, and blocks our recollection of it afterwards. All the extra bits that come with general anesthesia — the specialized doctor who administers the drugs and monitors you, tubes to feed oxygen into your lungs, monitoring devices — are all there because anesthesia basically shuts down your nervous system. If not done properly, this can and will kill you, most commonly by breaking the communication lines between your brain, heart, and lungs.

There are four stages to general anesthesia — induction, delirium, surgery anesthesia, and overdose.

  • Induction starts when the drugs are administered, and lasts until you fall asleep. During this stage, you’ll still be able to talk and focus to some extent. However, your breathing will slow down, and you’ll slowly lose the ability to feel pain.
  • The delirium phase is quite dangerous, and an anesthesiologist will do their best to make it last for as brief a time as possible. This step takes place as the nerves connecting your body to your brain stop working properly, making bits of you act weird. The delirium phase can produce uncontrolled movements, irregular breathing, and can lead to an increase in your heart rate. It’s also possible to see patients vomit during this stage, which can be quite deadly (there is a significant risk of choking).
  • In the surgical anesthesia phase, things calm down a little. A patient’s eyes stop moving and their muscles relax completely. It’s very possible that a patient in this state is unable to breathe unassisted. This is the ideal state for surgery and the one an anesthesiologist will try to keep you in as it is the least dangerous stage apart from induction.
  • The overdose stage takes place if too much anesthesia is administered to a patient. It’s rarer nowadays, but it’s still a very dangerous event with a high risk of being fatal. The risks are related to the communication lines between your brain, heart, and lungs going completely silent. If a patient is not brought up fast enough, or his breathing and heartbeat not maintained artificially, he will die.

Local anesthesia is far less powerful, affects a much smaller, more controlled area, but it’s also less risky. The most reliable way to differentiate local from general anesthesia is that the former involves loss of pain sensation but not loss of consciousness — general anesthesia leads to a temporary loss of both.

Local anesthetics typically work by blocking certain biochemical pathways inside nerve cells in a certain area. Most commonly, they target sodium ion pumps on the membranes of cells. This effectively prevents those cells from sending signals to the brain, as the electrical signals our bodies rely on are mediated by ions zipping here and there over nerve cells.

Psychological pain

Image via Pixabay.

The muddier and arguably worse type of pain, psychological pain can be summarized as ‘suffering’. It’s also referred to as emotional or mental pain, and is usually described as a deeply unpleasant but hard to delineate feeling.

Since people are complex creatures, psychological pain is hard to define in concrete terms. It encompasses a wide range of feelings and subjective experiences produced by the awareness of negative events or changes in one’s life, abilities, bodily functions, social standing, and so forth. Perceived shortcomings or deficiencies in the self can also lead to psychological pain. Losing a loved one is a major cause of psychological pain and, for better or for worse, an inescapable part of being human.

Being a deeply subjective experience, psychological pain is much harder to discuss in concrete terms. One of the most commonly used definitions of psychological pain today is that it is caused by our unmet psychological needs (making it the opposite of happiness). Unlike physical pain, it is most often described as being a diffuse sensation without necessarily having a known cause, is seen as generally long-lasting, and as having an adverse effect on the self and our ability to function.

Art has long grappled with themes of suffering, emotional distress, how these impact us, and it may be, in many ways, one of our most efficient tools in learning how to deal with psychological pain on a personal level. Therapy also works wonders. You can mix and match them if you need to.

To wrap things up

Pain, to hold to the definition we started this journey with, is meant to help correct our poor behavior — i.e. do things that hurt your body then feel pain, so, hopefully, you’ll stop doing the bad thing. Psychological pain, then, can also be seen as a way to correct our poor behavior in the social or cognitive realm.

This gives pain, and especially suffering, a strange double nature. They both are supremely unpleasant to us, but they are also great teachers. People will go to great lengths to avoid pain, which shows just how great this feeling is at correcting behavior. In fact, Freudian psychology considers the ability to endure pain now for a worthy outcome (delayed gratification) as the hallmark of maturity, as we don’t really have free will until we can face the fear of pain and overcome it (the pleasure principle vs reality principle).

People have recognized this nature for millenia now. The oldest stories we know of, such as the Epic of Gilgamesh, the Iliad, or creation myths around the world, delve deeply into experiences such as loss of a loved one and/or rebirth, loss of social standing and power, of being far away from home unable to return. Characters, be they mortals or gods, are shown to pass through suffering and emerge anew on the other side — sometimes stronger, sometimes weaker for it. Others, like Darth Vader for example, try and fail to overcome their suffering, and become defined by it until they succeed. Those are the kinds of stories that still captivate us because we can all understand and have experienced psychological pain, and desire to see our heroes and villains overcome it and get their due.

I’ll end with a quote from Fyodor Dostoevsky, a titan of the Russian novel, that I feel perfectly encapsulates humanity’s unique relationship to pain. Dostoyevsky started his adult life as an idealistic, passionate political reformist. A religious awakening after a mock execution and a real sentence in a Siberian labor camp (he was a very interesting guy) led him to a captivation with how the human ‘soul’ (in his words) or psychology (in modern parlance) works. His writing is very good, if at times disjointed (he was suffering from a particularly debilitating form of epilepsy), so go read them if you like exploring new depths of despair. But until then I leave you with this quote from his 1864 book Notes from the Underground:

“And why are you so firmly, so triumphantly, convinced that only the normal and the positive — in other words, only what is conducive to welfare — is for the advantage of man? Does not man, perhaps, love something besides well-being? Perhaps he is just as fond of suffering? Perhaps suffering is just as great a benefit to him as well-being?”

“Man is sometimes extraordinarily, passionately, in love with suffering, and that is a fact.”

The extracellular matrix, and how it keeps you in tip top shape

Would you live in a city without streets? Or in a flat with no walls? Probably not — and the cells in our bodies expect the same level of comfort. Today, we’re taking a look at the tissues that create and maintain an ideal working environment for our tissues: the extracellular matrix.

A mammalian trachea cross-section, magnified 200 times.
Image credits Berkshire Community College Bioscience Image Library / Flickr.

We’ve had a look at the differences between animal and plant cells before (here’s a refresher). One of the key differences between them is that plants reinforce their cells with thick, sturdy walls. These walls are why plant tissues such as wood can get so resilient. However, the reverse of the coin is that it also limits plant cells somewhat: a muscle made out of wood wouldn’t be very effective.

Animals need cells that can perform a wide variety of activities, but these cells also need biological and mechanical support to perform their tasks. That’s where the extracellular matrix, or “ECM”, comes in.

So what is it?

The ECM is a complex mix of proteins and carbohydrates that fills the spaces between cells; it is comprised of the basement membrane and interstitial matrix. Going forward, I’ll use the term ECM quite loosely to mean both ‘the extracellular matrix’ and ‘the interstitial matrix’. If I don’t mention the basement membrane specifically, I’m probably talking about the interstitial matrix (as it’s the more dynamic and frankly more interesting half of the topic).

Think of the basement membrane as a sheet of plastic wrap the body stretches over every individual tissue or organ to keep everything tidy and in place. This membrane is made up of two layers of cells and it’s quite fibrous and hard to rip.

X-ray of an elbow. The ECM in our joints (the empty volume between the bones) uses more collagen to become tough and resistant to wear.
Image via Wikimedia.

The interstitial matrix is, for lack of a better term, the goo that our cells live in. Most of the time, it looks and feels a bit like a clear gel. It’s produced by the cells themselves, which secrete and release certain compounds around them.

The simplest definition of the extracellular matrix is that it represents the sum of non-cellular components present within all tissues and organs. As we go forward, keep in mind that the ECM isn’t the same everywhere.

What’s it made of?

“Although, fundamentally, the ECM is composed of water, proteins, and polysaccharides, each tissue has an ECM with a unique composition and topology that is generated during tissue development,” Christian Frantz, Kathleen M. Stewart, Valerie M. Weaver, 2010.

Collagen, the most abundant protein in mammals, is the main component of the ECM. Outside the cell, collagen binds with carbohydrate molecules and assembles into long molecules called collagen fibrils. These fibrils extend through the ECM and lend flexibility and strength to the material, acting similarly to the role of rebar in reinforcing concrete (which is tough but inflexible). Collagen fibrils are flexible and tough to break, so they’re used to ‘bind together’ the rest of the ECM. In humans, genetic disorders that affect collagen (such as Ehlers-Danlos syndrome) cause tissues to become fragile and tear easily.

While the ECM contains a wide range of proteins and carbohydrates, another important set of compounds alongside collagen are proteoglycans (groups of proteins tied to simple sugars). Proteoglycans come with many shapes and functions, depending on which proteins and sugars they’re made of, and perform a wide range of tasks in the ECM. They can also bind to each other, to collagen (forming cartilage), or to hyaluronic acid, making them even more versatile. As a rule of thumb, proteoglycans act as fillers and regulate the movement of molecules through the ECM among other functions.

Collagen fibers in rabbit skin.
Image via Wikimedia.

Their overall structure looks like a tree: the ‘sugar’ part of the polyglycans are twigs set on a branch (the protein), which ties to a trunk made out of polysaccharide (‘many-sugar’) molecules. A class of proteins in the membranes of cells, called integrins, serve as connection ports between the membrane and material in the ECM (such as collagen fibers and proteoglycan-polysaccharide bundles). Beneath the membrane, integrins tie into the cell’s support ‘girders’ (the cytoskeleton).

The type of ECM I’ve described so far is your run of the mill variety that you’ll find in skin, around muscle fibers, in adipose tissue (fat), and so on. But each tissue has an ECM that fully supports its function — blood plasma is the interstitial matrix of blood. Unlike the ECM of muscles, for example, which is meant to reduce friction and wear in the tissue, blood plasma primarily works as a medium to carry blood cells around. Blood vessels are coated with a basement membrane, and together, they form the ECM of blood. Each type of animal connective tissue has its own type of ECM, even bone.

What does it do?

Cross-section of compact human bone, magnified 100 times.
Image credits Berkshire Community College Bioscience Image Library / Flickr.

Seeing as there are many types of ECM out there, it stands to reason that there are many functions they perform. However, by and large, there are a few functions that all ECMs fulfill.

The first and perhaps most important function is that they provide support to tissues, segregate (separate) them, and that they mediate intercellular communication. The ECM is also what regulates a cell’s ‘dynamic behavior’ — i.e. whether a cell moves around, and how. The ECM keeps cells in place so we don’t simply unravel. The connections formed between the ECM and integrins on a cell’s membrane also function as signaling pathways.

It is also essential for the good functioning of tissues at large. The ECM creates and maintains the proper environmental conditions for cells to develop, multiply, and form functioning tissues. While the exact details are still unknown, the ECM has been found to cause tissue regrowth and healing after injury. In human fetuses, for example, the extracellular matrix works with stem cells to grow and regrow all parts of the human body. Fetuses can regrow anything that gets damaged in the womb, but since babies can’t, we suspect that the matrix loses this function after full development. Researchers are looking into applying it for tissue regeneration in adults.

The ECM can also act as a storage space for various compounds. In joints, it contains more hyaluronic acid which in turn absorbs water and acts as a mechanical cushion. ECMs can also store a wide range of cellular growth factors and release them as needed. This allows our bodies to activate cell growth on a dime when needed without having to produce and ship these factors to a certain area.

It also seems to impact cell differentiation and gene expression. Cells can switch genes on or off depending on the elasticity of the ECM around them. Cells also seem to want to migrate towards stiffer areas of the ECM generally (durotaxis) from less-firm ones.

The ECM isn’t very well known today, and it definitely goes unsung. But no matter how you cut it, it is a key part of biology as we know it today. Without it, both animals and plants would be formless, messy blobs — quite literally. And I don’t know about you but I love it when my tissues stay where they’re supposed to, the way they’re supposed to.


Some people have extra bones, teeth, and even nipples. Here are some examples


The red arrow points to the fabella. Jmarchn and Mikael Häggström/Wikimedia CommonsCC BY-SA

Scientists in the UK recently reported that a bone that was thought to be lost to evolution is making a comeback. The little bone, known as the fabella (little bean), is found at the back of the knee – if it is found at all. The scientists discovered that people were nearly three-and-a-half times more likely to have the bone in 2000 than in 1900. Its exact purpose, however, remains a mystery.

The fabella is not the only variation in human anatomy. Variants occur as a result of genetics, environmental factors, mistimings in embryological development, or simply a failure of structures to disappear as part of normal development. Most variations are benign and don’t cause disease. Here are some of those that are well known to us anatomists…

Teeth


X-ray of person with supernumerary teeth.Albert/Wikimedia Commons

People have 20 primary teeth (“milk teeth”), which are lost and replaced by 32 permanent teeth. But up to 2% of people have extra teeth. Most of these people have one or two extra (supernumerary) teeth, but there are medical reports of people with many more extra teeth, with one female having 19 supernumerary teeth.

Nipples

Males and females have nipples because, early on in development, before the sex of the foetus has been determined, two ridges of tissue form, running from the front of the armpits to the groin. These ridges are known as mammary ridges.

Over time, both disappear to leave a single area where the mammary gland and nipple develop. It is possible for people to have supernumerary nipples, known as polythelia, along these lines, not in the middle of the chest between the existing nipples, as depicted in some TV and film shows. There are reports of people with seven nipples.

Digits

Most people have ten fingers and ten toes, but many people are born with extra digits. They are most commonly seen on the hands and are usually associated with disorders, such as Down syndrome.

Some ethnic groups are more likely to have extra digits than others. African-Americans have a much higher presence of an ulnar polydactyly – a digit on the little finger side of the hand. Caucasians have a higher presence of an additional digit on the radial (thumb) side of the hand, known as radial polydactyly. But this is less common.

While most people with extra digits have one or two, there are reports of people with 31 and even 34 digits.

Muscles

Muscles can also vary from one person to another. One of the easiest to observe (or observe its absence) is a muscle called palmaris longus. The best way to see if you have this muscle is to put your thumb and ring finger together and then bend your hand towards you. If you have this muscle, you should see a tendon pop up out of the wrist, running from the forearm and into the hand.

Testing for the palmaris longus muscle.

This muscle can be in one or both arms. In some people, it is absent in both. It is absent in both arms in about 10% of Caucasians and absent in one arm in 16%.

There are suggestions of an evolutionary loss of this muscle, with mammals such as orangutans, who use their arms for walking, having this muscle, but higher apes, such as gorillas and chimpanzees, showing an absence.

The good news for those of us who don’t have it is that it doesn’t make our grip strength weaker compared with those who have it. Although those who do have it may find it useful if surgeons ever need to repair a tendon, as the palmaris tendon is easily accessible and can be harvested for grafting.

There is a similar muscle in the lower leg called plantaris. It is believed to be absent in 7-20% of limbs. This muscle cannot be seen without using imaging, such as ultrasound, as it lies deep in the calf region of the leg. But like its variably present compatriot in the arm, it can be used for tendon grafting if needed.

Uterus

Some variations only come to light as people age, such as men born with a uterus. This developmental anomaly may only become manifest during puberty, with blood appearing in the urine. This is actually the menstrual cycle exiting through the urinary system.

All of this goes to show that human anatomy is not as clear-cut as school textbooks might suggest. We’re as variable as snowflakes. Something to be celebrated, surely.

Adam Taylor, Director of the Clinical Anatomy Learning Centre and Senior Lecturer, Lancaster University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

The Conversation

Women undoubtedly prefer strong, muscular men, study shows

Psychologists have confirmed something most women deep down know regarding male physical attractiveness: strong men are, by far, preferred to weaker looking men.

The study was based on interviews with 160 women. The female participants had to rate the physical individual attractiveness of men from two categories: a group composed of 130 psychology students and one composed of 60 gym-going university students who worked out a few times per week.

Aaron Sell, a psychology lecturer at School of Criminology and Criminal Justice, Griffith University, Australia and his co-author, Aaron Lukaszewski, an evolutionary psychologist at California State University at Fullerton measured the males’ strength via weightlifting machines, grip strength tests and other methods.

Source: Pexels/Pixabay

The male recruits all came from the University of California at Santa Barbara. The assessors, students from Oklahoma State University and Australia’s Griffith University, rated both strength and physical attractiveness on a scale from 1 to 7. Interestingly, the scores the women gave for strength were fairly accurate compared to the actual physical performances of the students.

“The rated strength of a male body accounts for a full 70 percent of the variance in attractiveness,” Sell said.

None of the surveyed women showed a statistically important preference for weaker looking guys.

“No one will be surprised by the idea that strong men are more attractive,” said one of the study authors, Aaron Lukaszewski, told The Washington Post. “It’s no secret that women like strong, muscular guys.”

“That is so obvious, people are going to wonder why scientists needed to study it,” said Holly Dunsworth, an anthropologist at the University of Rhode Island, also to The Post. “And the answer would be because they want to know how these preferences evolved.”

Dunsworth also raised questions about the reliability of the paper, because the study involved only 20-year-olds, who she adds, may not have very much experience with the meaning of attractiveness.

Source: Geralt/Pixabay

Lisa Wade, a sociologist at Occidental College in Los Angeles, also criticizes the study’s interpretation: “It’s my opinion that the authors are too quick to ascribe a causal role to evolution,“ she told The Post.

According to Wade, culture has a bigger impact on male torso aesthetics.

“We value tall, lean men with strong upper bodies in American society. We’re too quick to assume that it requires an evolutionary explanation,” she said. “We know what kind of bodies are valorized and idealized,” Wade added. “It tends to be the bodies that are the most difficult to obtain.”

In her opinion, a few centuries ago, women would have preferred larger torsos, due to the scarcity of hyper-caloric food and the requirements of heavy physical labour. The preference for leaner upper masculine bodies was not universally valued at that time.

The paper published in Proceedings of the Royal Society B surely has many scientists arguing over it, but the team led by Sell and Lukaszewski plans to examine physical attractiveness on a larger scale, with a cross-cultural study on the way.

Scientists image organs at microscopic scales

In a new study published in Nature, researchers have demonstrated a technique that allows the mapping of organs at microscopic scales; they detail its use and produced images of the microvessels in the brain of a live rat.

Image of the whole brain vasculature at microscopic resolution in the live rat using ultrafast Ultrasound Localization Microscopy: Local density of intravascular microbubbles in the right hemisphere, quantitative estimation of blood flow speed in the left hemisphere. Credit: ESPCI/INSERM/CNRS

Image of the whole brain vasculature at microscopic resolution in the live rat using ultrafast Ultrasound Localization Microscopy: Local density of intravascular microbubbles in the right hemisphere, quantitative estimation of blood flow speed in the left hemisphere.
Credit: ESPCI/INSERM/CNRS

Current techniques of microscopic imaging are not ideal. Just like in geological imaging techniques, there’s a tradeoff between penetration depth, resolution, and time of acquisition. In other words, if you want to see all the way through the human body, you won’t have good enough resolution – or you will but it will take a very long time. Until now, conventional imaging techniques have worked at milimetre and sub-milimetre scale at best, being limited by one of the fundamental laws of physics: features smaller than the wavelength of the radiation used for imaging cannot be resolved. But Mickael Tanter, a professor at the Langevin Institute and his colleagues have come up with a new approach, and report a new super-resolution.

Like a few other recent studies, they used microbubbles, with diameters of 1–3 micrometres, which were injected into the bloodstream of live rats. They then combined deep penetration and super-resolution imaging in a technique they call ‘ultrafast ultrasound localization microscopy’. With this, they obtained ultra fast frame rates (500 / second), and achieved a resolution equal to the rat brain microvasculature – less than 10 micrometers in diameter (0.01 milimetres).

While this is still a work in progress, authors believe it can help doctors make better diagnostics and better understand how some diseases affect the body.

 

Mapping our bodily emotions

Researchers from the Aalto University in Finland have revealed how the most common emotions are experienced in the body.

Different emotions are associated with discernible patterns of bodily sensations. (Credit: Image courtesy of Aalto University). Red areas represent an increase in activity/sensation, and blue ones represent a decrease.

Emotions are a very good way of preparing us for environmental challenges. It has been known for quite some time that our emotions trigger physical reactions in our body, and the bodily maps of these sensations were topographically different for different emotions. For example, anxiety may be associated with chest pain, while being excited or in love can develop a general feeling of being warm.

“Emotions adjust not only our mental, but also our bodily states. This way the prepare us to react swiftly to the dangers, but also to the opportunities such as pleasurable social interactions present in the environment. Awareness of the corresponding bodily changes may subsequently trigger the conscious emotional sensations, such as the feeling of happiness,” tells assistant professor Lauri Nummenmaa from Aalto University.

The research was carried online, and it relied on subjects responding to certain stimuli. Over 700 individuals from Finland, Sweden and Taiwan took part in the study, with the researchers inducing certain emotional states to the subjects. They were then asked to colour human body images with red where they felt increased activity and with blue where they felt reduced activity.

“The findings have major implications for our understanding of the functions of emotions and their bodily basis. On the other hand, the results help us to understand different emotional disorders and provide novel tools for their diagnosis.”

The emotional patterns were consistent throughout the different cultures, which goes to show that emotions are experienced in pretty much the same way by all people, regardless of age, sex, and culture – the bodily sensations are biological functions.

Journal Reference:

  1. L. Nummenmaa, E. Glerean, R. Hari, J. K. Hietanen. Bodily maps of emotions. Proceedings of the National Academy of Sciences, 2013; DOI: 10.1073/pnas.1321664111