Tag: Brain

Mozart’s Brain and the Fighter Pilot

Reading Time: 6 minutes

Most of us want to be smarter but have no idea how to go about improving our mental apparatus. We intuitively think that if we raised our IQ a few points that we’d be better off intellectually. This isn’t necessarily the case. I know a lot of people with high IQs that make terribly stupid mistakes. The way around this is by improving not our IQ, but our overall cognition.

Cognition, argues Richard Restak, “refers to the ability of our brain to attend, identify, and act.” You can think of this as a melange of our moods, thoughts, decisions, inclinations and actions.

Included among the components of cognition are alertness, concentration, perceptual speed, learning, memory, problem solving, creativity, and mental endurance.

All of these components have two things in common. First, our efficacy at them depends on how well the brain is functioning relative to its capabilities. Second, this efficacy function can be improved with the right discipline and the right habits.

Restak convincingly argues that we can make our brains work better by “enhancing the components of cognition.” How we go about improving our brain performance, and thus cognition, is the subject of his book Mozart’s Brain and the Fighter Pilot.

Improving Our Cognitive Power

To improve the brain we need to exercise our cognitive powers. Most of us believe that physical exercise helps us feel better and live healthier; yet how many of us exercise our brain? As with our muscles and our bones, “the brain improves the more we challenge it.”

This is possible because the brain retains a high degree of plasticity; it changes in response to experience. If the experiences are rich and varied, the brain will develop a greater number of nerve cell connections. If the experiences are dull and infrequent, the connections will either never form or die off.

If we’re in stimulating and challenging environments, we increase the number of nerve cell connections. Our brain literally gets heavier, as the number of synapses (connections between neurons) increases. The key that many people miss here is “rich and varied.”

Memory is the most important cognitive function. Imagine if you lost your memory permanently: Would you still be you?

“We are,” Restak writes, “what we remember.” And poor memories are not limited to those who suffer from Alzheimer’s disease. While some of us are genetically endowed with superlative memories, the rest of us need not fear.

Aristotle suggested that our mind was a wax tablet in a short book on memory, arguing that the passage of time fades the image unless we take steps to preserve it. He was right in ways he never knew; memory researchers know now that, like a wax tablet, our memory changes every time we access it, due to the plasticity Restak refers to. It can also be molded and improved, at least to a degree.

Long ago, the Greeks hit upon the same idea — mostly starting with Plato — that we don’t have to accept our natural memory. We can take steps to improve it.

Learning and Knowledge Acquisition

When we learn something new, we expand the complexity of our brain. We literally increase our brainpower.

[I]ncrease your memory and you increase your basic intelligence. … An increased memory leads to easier, quicker accessing of information, as well as greater opportunities for linkages and associations. And, basically, you are what you can remember.

Too many of us can’t remember these days, because we’ve outsourced our brain. One of the most common complaints at the neurologist’s office for people over forty is poor memory. Luckily most of these people do not suffer from something neurological, but rather the cumulative effect of disuse — a graceful degradation of their memory.

Those who are not depressed (the commonest cause of subjective complaints of memory impairment) are simply experiencing the cumulative effect of decades of memory disuse. Part of this disuse is cultural. Most businesses and occupations seldom demand that their employees recite facts and figures purely from memory. In addition, in some quarters memory is even held in contempt. ‘He’s just parroting a lot of information he doesn’t really understand’ is a common put-down when people are enviously criticizing someone with a powerful memory. Of course, on some occasions, such criticisms are justified, particularly when brute recall occurs in the absence of understanding or context. But I’m not advocating brute recall. I’m suggesting that, starting now, you aim for a superpowered memory, a memory aimed at quicker, more accurate retrieval of information.

Prior to the printing press, we had to use our memories. Epics such as The Odyssey and The Iliad, were recited word-for-word. Today, however, we live in a different world, and we forget that these things were even possible. Information is everywhere. We need not remember anything thanks to technology. This helps and hinders the development of our memory.

[Y]ou should think of the technology of pens, paper, tape recorders, computers, and electronic diaries as an extension of the brain. Thanks to these aids, we can carry incredible amounts of information around with us. While this increase in readily available information is generally beneficial, there is also a downside. The storage and rapid retrieval of information from a computer also exerts a stunting effect on our brain’s memory capacities. But we can overcome this by working to improve our memory by aiming at the development and maintenance of a superpowered memory. In the process of improving our powers of recall, we will strengthen our brain circuits, starting at the hippocampus and extending to every other part of our brain.

Information is only as valuable as what it connects to. Echoing the latticework of mental models, Restek states:

Everything that we learn is stored in the brain within that vast, interlinking network. And everything within that network is potentially connected to everything else.

From this we can draw a reasonable conclusion: if you stop learning mental capacity declines.

That’s because of the weakening and eventual loss of brain networks. Such brain alterations don’t take place overnight, of course. But over a varying period of time, depending on your previous training and natural abilities, you’ll notice a gradual but steady decrease in your powers if you don’t nourish and enhance these networks.

The Better Network: Your Brain or the Internet

Networking is a fundamental operating principle of the human brain. All knowledge within the brain is based on networking. Thus, any one piece of information can be potentially linked with any other. Indeed, creativity can be thought of as the formation of novel and original linkages.

In his book, Weaving the Web: The Original Design and the Ultimate Destiny of the World Wide Web, Tim Berners-Lee, the creator of the Internet, distills the importance of the brain forming connections.

A piece of information is really defined only by what it’s related to, and how it’s related. There really is little else to meaning. The structure is everything. There are billions of neurons in our brains, but what are neurons? Just cells. The brain has no knowledge until connections are made between neurons. All that we know, all that we are, comes from the way our neurons are connected.

Cognitive researchers now accept that it may not be the size of the human brain which gives it such unique abilities — other animals have large brains as well. Rather its our structure; the way our neurons are structured, arranged, and linked.

The more you learn, the more you can link. The more you can link, the more you increase the brain’s capacity. And the more you increase the capacity of your brain the better able you’ll be to solve problems and make decisions quickly and correctly. This is real brainpower.

Multidisciplinary Learning

Restak argues that a basic insight about knowledge and intelligence is: “The existence of certain patterns, which underlie the diversity of the world around us and include our own thoughts, feelings, and behaviors.”

Intelligence enhancement therefore involves creating as many neuronal linkages as possible. But in order to do this we have to extricate ourselves from the confining and limiting idea that knowledge can be broken down into separate “disciplines” that bear little relation to one another.

This brings the entire range of ideas into play, rather than just silos of knowledge from human-created specialities. Charlie Munger and Richard Feynman would probably agree that such over-specialization can be quite limiting. As the old proverb goes, the frog in the well knows nothing of the ocean.

Charles Cameron, a game theorist, adds to this conversation:

The entire range of ideas can legitimately be brought into play: and this means not only that ideas from different disciplines can be juxtaposed, but also that ideas expressed in ‘languages’ as diverse as music, painting, sculpture, dance, mathematics and philosophy can be juxtaposed, without first being ‘translated’ into a common language.

Mozart’s Brain and the Fighter Pilot goes on to provide 28 suggestions and exercises for enhancing your brain’s performance, a few of which we’ll cover in future posts.

Tagged: , , , ,

Thinking Straight in the Age of Information Overload

Reading Time: 8 minutes

The Organized Mind

The Organized Mind: Thinking Straight in the Age of Information Overload, a book by Daniel Levitin, explores “how humans have coped with information and organization from the beginning of civilization. … It’s also the story of how the most successful members of society—from successful artists, athletes, and warriors, to business executives and highly credentialed professionals—have learned to maximize their creativity, and efficiency, by organizing their lives so that they spend less time on the mundane, and more time on the inspiring, comforting, and rewarding things in life.”

Memory

Memory is fallible. More than just remembering things wrongly, “we don’t even know we’re remembering them wrongly.”

The first humans who figured out how to write things down around 5,000 years ago were in essence trying to increase the capacity of their hippocampus, part of the brain’s memory system. They effectively extended the natural limits of human memory by preserving some of their memories on clay tablets and cave walls, and later, papyrus and parchment. Later, we developed other mechanisms —such as calendars, filing cabinets, computers, and smartphones— to help us organize and store the information we’ve written down. When our computer or smartphone starts to run slowly, we might buy a larger memory card. That memory is both a metaphor and a physical reality. We are off-loading a great deal of the processing that our neurons would normally do to an external device that then becomes an extension of our own brains, a neural enhancer.

These external memory mechanisms are generally of two types, either following the brain’s own organizational system or reinventing it, sometimes overcoming its limitations. Knowing which is which can enhance the way we use these systems, and so improve our ability to cope with information overload.

And once memory became external (written down and stored) our attention systems “were freed up to focus on something else.”

But we need a place (and a system) to organize all of this information.

The indexing problem is that there are several possibilities about where you store this report, based on your needs: It could be stored with other writings about plants, or with writings about family history, or with writings about cooking, or with writings about how to poison an enemy.

This brings us to two aspects of the human brain that are not given their due: richness and associative access.

Richness refers to the theory that a large number of the things you’ve ever thought or experienced are still in there, somewhere. Associative access means that your thoughts can be accessed in a number of different ways by semantic or perceptual associations— memories can be triggered by related words , by category names, by a smell, an old song or photograph, or even seemingly random neural firings that bring them up to consciousness.

Being able to access any memory regardless of where it is stored is what computer scientists call random access. DVDs and hard drives work this way; videotapes do not. You can jump to any spot in a movie on a DVD or hard drive by “pointing” at it. But to get to a particular point in a videotape, you need to go through every previous point first (sequential access). Our ability to randomly access our memory from multiple cues is especially powerful. Computer scientists call it relational memory. You may have heard of relational databases— that’s effectively what human memory is.

[…]

Having relational memory means that if I want to get you to think of a fire truck, I can induce the memory in many different ways. I might make the sound of a siren, or give you a verbal description (“ a large red truck with ladders on the side that typically responds to a certain kind of emergency”).

We categorize objects in a seemingly infinite number of ways. Each of those ways “has its own route to the neural node that represents fire truck in your brain.” Take a look at one way we can think of a firetruck.

Firetruck

Thinking about one memory or association activates more. This can be both a strength and a weakness.

If you are trying to retrieve a particular memory, the flood of activations can cause competition among different nodes, leaving you with a traffic jam of neural nodes trying to get through to consciousness, and you end up with nothing.

Organizing our Lives

The ancients Greeks came up with memory palaces and the method of loci to improve memory. The Egyptians became experts at externalizing information, inventing perhaps the biggest pre-google repository of knowledge, the library.

We don’t know why these simultaneous explosions of intellectual activity occurred when they did (perhaps daily human experience had hit a certain level of complexity). But the human need to organize our lives, our environment, even our thoughts, remains strong. This need isn’t simply learned, it is a biological imperative— animals organize their environments instinctively.

But the odd thing about the mind is that it doesn’t, on its own, organize things the way you might want it to. It’s largely an unconscious process.

It comes preconfigured, and although it has enormous flexibility, it is built on a system that evolved over hundreds of thousands of years to deal with different kinds and different amounts of information than we have today. To be more specific: The brain isn’t organized the way you might set up your home office or bathroom medicine cabinet. You can’t just put things anywhere you want to. The evolved architecture of the brain is haphazard and disjointed, and incorporates multiple systems, each of which has a mind of its own (so to speak). Evolution doesn’t design things and it doesn’t build systems— it settles on systems that, historically, conveyed a survival benefit (and if a better way comes along, it will adopt that). There is no overarching, grand planner engineering the systems so that they work harmoniously together. The brain is more like a big, old house with piecemeal renovations done on every floor, and less like new construction.

Consider this, then, as an analogy: You have an old house and everything is a bit outdated, but you’re satisfied. You add a room air conditioner during one particularly hot summer. A few years later, when you have more money, you decide to add a central air-conditioning system. But you don’t remove that room unit in the bedroom— why would you ? It might come in handy and it’s already there, bolted to the wall. Then a few years later, you have a catastrophic plumbing problem—pipes burst in the walls. The plumbers need to break open the walls and run new pipes, but your central air-conditioning system is now in the way, where some of their pipes would ideally go. So they run the pipes through the attic, the long way around. This works fine until one particularly cold winter when your uninsulated attic causes your pipes to freeze. These pipes wouldn’t have frozen if you had run them through the walls, which you couldn’t do because of the central air-conditioning. If you had planned all this from the start, you would have done things differently, but you didn’t— you added things one thing at a time, as and when you needed them.

Or you can use Sherlock Holmes’ analogy of a memory attic. As Holmes tells Watson, “I consider that a man’s brain originally is like a little empty attic, and you have to stock it with such furniture as your choose.”

Levitin argues that we should learn “how our brain organizes information so that we can use what we have, rather than fight against it.” We do this primarily through the key processes of encoding and retrieval.

(Our brains are) built as a hodgepodge of different systems, each one solving a particular adaptive problem. Occasionally they work together, occasionally they’re in conflict, and occasionally they aren’t even talking to one another. Two of the key ways that we can control and improve the process are to pay special attention to the way we enter information into our memory— encoding—and the way we pull it out— retrieval.

We’re busier than ever. That’s not to say that it’s information overload, as there are arguments to why that doesn’t exist. Our internal to-do list is never satisfied. We’re overwhelmed with things disguised as wisdom or even information and we’re forced to sort through the nonsense. Levitin implies that one consequence to this approach is that we’re losing things. Our keys. Our driver’s licenses. Our iPhone. And it’s not just physical things. “we also forget things we were supposed to remember, important things like the password to our e-mail or a website, the PIN for our cash cards— the cognitive equivalent of losing our keys.”

These are important and hard to replace things.

We don’t tend to have general memory failures; we have specific, temporary memory failures for one or two things. During those frantic few minutes when you’re searching for your lost keys, you (probably) still remember your name and address, where your television set is, and what you had for breakfast —it’s just this one memory that has been aggravatingly lost. There is evidence that some things are typically lost far more often than others: We tend to lose our car keys but not our car, we lose our wallet or cell phone more often than the stapler on our desk or soup spoons in the kitchen, we lose track of coats and sweaters and shoes more often than pants. Understanding how the brain’s attentional and memory systems interact can go a long way toward minimizing memory lapses.

These simple facts about the kinds of things we tend to lose and those that we don’t can tell us a lot about how our brains work, and a lot about why things go wrong.

The way this works is fascinating. Levitin also hits on a topic that has long interested me. “Companies,” he writes, “are like expanded brains, with individual workers functioning something like neurons.”

Companies tend to be collections of individuals united to a common set of goals, with each worker performing a specialized function. Businesses typically do better than individuals at day-to-day tasks because of distributed processing. In a large business, there is a department for paying bills on time (accounts payable), and another for keeping track of keys (physical plant or security). Although the individual workers are fallible, systems and redundancies are usually in place, or should be, to ensure that no one person’s momentary distraction or lack of organization brings everything to a grinding halt. Of course, business organizations are not always prefectly organized, and occasionally, through the same cognitive blocks that cause us to lose our car keys, businesses lose things, too— profits, clients, competitive positions in the marketplace.

In today’s world it’s hard to keep up. We have pin numbers, phone numbers, email addresses, multiple to-do lists, small physical objects to keep track of, kids to pick up, books to read, videos to watch, nearly infinite websites to browse, and so on. Most of us, however, are still largely using the systems to organize and maintain this knowledge that were put into place in a less informatic time.

The Organized Mind: Thinking Straight in the Age of Information Overload shows us how to organize our time better, “not just so we can be more efficient but so we can find more time for fun, for play, for meaningful relationships, and for creativity.”

Tagged: , , , , , ,

The Divided Brain and the Making of the Western World

Reading Time: 2 minutes

The defining features of the human condition can all be traced to our ability to stand back from the world, from our selves and from the immediacy of experience. This enables us to plan, to think flexibly and inventively, and, in brief, to take control of the world around us rather than simply respond to it passively. This distance, this ability to rise above the world in which we live, has been made possible by the evolution of the frontal lobes.

For centuries we’ve wondered about the left hemisphere and right hemisphere divide.

The “left hemisphere is detail oriented, prefers mechanisms to living things, and is inclined to self-interest, where the right hemisphere has greater breadth, flexibility, and generosity.”

This division, psychiatrist Iain McGilchrist explains in The Master and His Emissary: The Divided Brain and the Making of the Western World, “helps explain the origins of music and language, and casts new light on the history of philosophy, as well as on some mental illnesses.”

“My thesis,” McGilchrist writes, “is that for us as human beings there are two fundamentally opposed realities:”

two different modes of experience; that each is of ultimate importance in bringing about the recognizably human world; and that their difference is rooted in the bihemispheric structure of the brain. It follows that the hemispheres need to co-operate, but I believe they are in fact involved in a sort of power struggle, and that this explains many aspects of contemporary Western culture.

These two hemispheres “coexist together on a daily basis, but have fundamentally different sets of values, and therefore priorities, which means that over the long term they are likely to come into conflict. Although each is crucially important, and delivers valuable aspects of the human condition, and though each needs the other for different purposes, they seem destined to pull apart.”

Both of these hemispheres are “hugely valuable,” but they stand in opposition to one another and “need to be kept apart—hence the bihemispheric structure of the brain.”

McGilchrist explores the differences between our two hemispheres and argues that modern society, and its formal structures, favors the left brain:

An increasingly mechanistic, fragmented, decontextualised world, marked by unwarranted optimism mixed with paranoia and a feeling of emptiness, has come about, reflecting, I believe, the unopposed action of a dysfunctional left hemisphere.

Yet we require both sides of our brain … (much like our Apollonian desire for control and order balances our natural Dionysian wildness).

It might then be that the division of the human brain is also the result of the need to bring to bear two incompatible types of attention on the world at the same time, one narrow, focused, and directed by our needs, and the other broad, open, and directed towards whatever else is going on in the world apart from ourselves.

Below is a fascinating video from RS Animate of McGilchrist explaining how our ‘divided brain’ has profoundly altered human behaviour, culture and society.

Still curious? Read The Master and His Emissary.

Tagged: , , , ,

Brain Rules: 12 Ways to Supercharge Brain Power

Reading Time: 6 minutes

If workplaces had nap rooms, multitasking was frowned upon, and meetings were held during walks, we’d be vastly more productive. These are just some of the things we know about how to optimize our brain use.

Below find 12 rules we know about how the brain works from Brain Rules.

#1 Exercise Boosts Brain Power

Wondering whether there is a relationship between exercise and mental alertness? The answer is yes.

Just about every mental test possible was tried. No matter how it was measured, the answer was consistently yes: A lifetime of exercise can result in a sometimes astonishing elevation in cognitive performance, compared with those who are sedentary. Exercisers outperform couch potatoes in tests that measure long-term memory, reasoning, attention, problem-solving, even so-called fluid-intelligence tasks. These tasks test the ability to reason quickly and think abstractly, improvising off previously learned material in order to solve a new problem. Essentially, exercise improves a whole host of abilities prized in the classroom and at work.

#2 Survival

The human brain evolved, too.

The brain is a survival organ. It is designed to solve problems related to surviving in an unstable outdoor environment and to do so in nearly constant motion (to keep you alive long enough to pass your genes on). We were not the strongest on the planet but we developed the strongest brains, the key to our survival. … The strongest brains survive, not the strongest bodies. … Our ability to understand each other is our chief survival tool. Relationships helped us survive in the jungle and are critical to surviving at work and school today. … If someone does not feel safe with a teacher or boss, he or she may not perform as well. … There is no greater anti-brain environment than the classroom and cubicle.

#3: Every Brain is Wired Differently

What you do and learn in life physically changes what your brain looks like – it literally rewires it. … Regions of the brain develop at different rates in different people. The brains of school children are just as unevenly developed as their bodies. Our school system ignores the fact that every brain is wired differently. We wrongly assume every brain is the same.

#4: We Don’t Pay Attention to Boring Things

The brain is not capable of multi-tasking. We can talk and breathe, but when it comes to higher level tasks, we just can’t do it. … Workplaces and schools actually encourage this type of multi-tasking. Walk into any office and you’ll see people sending e-mail, answering their phones, Instant Messaging, and perusing Facebook — all at the same time. Research shows your error rate goes up 50% and it takes you twice as long to do things. When you’re always online you’re always distracted. So the always online organization is the always unproductive organization.

We must do something emotionally relevant every 10 minutes to reset our attention.

10-minute-rule

#5: Repeat to Remember

Improve your memory by elaborately encoding it during its initial moments. Many of us have trouble remembering names. If at a party you need help remembering Mary, it helps to repeat internally more information about her. “Mary is wearing a blue dress and my favorite color is blue.” It may seem counterintuitive at first but study after study shows it improves your memory.

#6: Remember to Repeat

How do you remember better? Repeated exposure to information / in specifically timed intervals / provides the most powerful way to fix memory into the brain. … Deliberately re-expose yourself to the information more elaborately if you want the retrieval to be of higher quality. Deliberately re-expose yourself to the information more elaborately, and in fixed, spaced intervals, if you want the retrieval to be the most vivid it can be. Learning occurs best when new information is incorporated gradually into the memory store rather than when it is jammed in all at once. … Memory is enhanced by creating associations between concepts. This experiment has been done hundreds of times, always achieving the same result: Words presented in a logically organized, hierarchical structure are much better remembered than words placed randomly—typically 40 percent better.

#7: Sleep Well, Think Well

The bottom line is that sleep loss means mind loss. Sleep loss cripples thinking, in just about every way you can measure thinking. Sleep loss hurts attention, executive function, immediate memory, working memory, mood, quantitative skills, logical reasoning ability, general math knowledge.

Should we nap or is that just being lazy?

Napping is normal. Ever feel tired in the afternoon? That’s because your brain really wants to take a nap. There’s a battle raging in your head between two armies. Each army is made of legions of brain cells and biochemicals –- one desperately trying to keep you awake, the other desperately trying to force you to sleep. Around 3 p.m., 12 hours after the midpoint of your sleep, all your brain wants to do is nap.

When is the ideal time to nap?

nap zone

One more tip, “[d]on’t schedule important meetings at 3 p.m. It just doesn’t make sense.”

#8: Stressed Brains Don’t Learn The Same Way

Your brain is built to deal with stress that lasts about 30 seconds. The brain is not designed for long term stress when you feel like you have no control. The saber-toothed tiger ate you or you ran away but it was all over in less than a minute. If you have a bad boss, the saber-toothed tiger can be at your door for years, and you begin to deregulate. If you are in a bad marriage, the saber-toothed tiger can be in your bed for years, and the same thing occurs. You can actually watch the brain shrink.

What causes stress?

Business professionals have spent a long time studying what types of stress make people less productive and, not surprisingly, have arrived at the same conclusion that Marty Seligman’s German shepherds did: Control is critical. The perfect storm of occupational stress appears to be a combination of two malignant facts: a) a great deal is expected of you and b) you have no control over whether you will perform well.

What effect does stress have on the brain?

Stress damages virtually every kind of cognition that exists. It damages memory and executive function. It can hurt your motor skills. When you are stressed out over a long period of time it disrupts your immune response. You get sicker more often. It disrupts your ability to sleep. You get depressed.

Stress not only lowers performance but also heightens emotional memory so that the poor performances are very easy for us to remember.

stress

#9: Stimulate More of the Senses

Our senses work together so it is important to stimulate them! Your head crackles with the perceptions of the whole world, sight, sound, taste, smell, touch, energetic as a frat party. … Smell is unusually effective at evoking memory. If you’re tested on the details of a movie while the smell of popcorn is wafted into the air, you’ll remember 10-50% more. … Those in multisensory environments always do better than those in unisensory environments. They have more recall with better resolution that lasts longer, evident even 20 years later.

learning

#10: Vision Trumps All Other Senses

We are incredible at remembering pictures. Hear a piece of information, and three days later you’ll remember 10% of it. Add a picture and you’ll remember 65%. … Pictures beat text as well, in part because reading is so inefficient for us. Our brain sees words as lots of tiny pictures, and we have to identify certain features in the letters to be able to read them. That takes time. … Why is vision such a big deal to us? Perhaps because it’s how we’ve always apprehended major threats, food supplies and reproductive opportunity.

pics

#11: Male and Female Brains are Different

What’s different? Mental health professionals have known for years about sex-based differences in the type and severity of psychiatric disorders. Males are more severely afflicted by schizophrenia than females. By more than 2 to 1, women are more likely to get depressed than men, a figure that shows up just after puberty and remains stable for the next 50 years. Males exhibit more antisocial behavior. Females have more anxiety. Most alcoholics and drug addicts are male. Most anorexics are female. … Men and women process certain emotions differently. Emotions are useful. They make the brain pay attention. These differences are a product of complex interactions between nature and nurture.

#12: We are Powerful and Natural Explorers

The desire to explore never leaves us despite the classrooms and cubicles we are stuffed into. Babies are the model of how we learn—not by passive reaction to the environment but by active testing through observation, hypothesis, experiment, and conclusion. Babies methodically do experiments on objects, for example, to see what they will do.

Still curious? Read the entire book.

Tagged: , , , , , ,

Explore

Browse