In this new episode of our series An Essential Guide to Your Body and Brain, we’re going to learn about the perceptive brain, how the senses really work and the incredible machine you and I have within our little skulls.
locked up safely within the skull, the brain experiences the outside world through the senses. Seeing, hearing, tasting, smelling, and feeling are how human beings collect information about the world. These data are related to the brain, which uses them to formulate ideas and opinions, assess situations, generate reactions, and then store what it has learned as memories. Information that enters the brain through the senses, powerfully influences thoughts, emotions, and personality. Put another way, what you see and hear and taste, smell and touch for that matter has much to do with who you are. The first responders in the sensory process our sensory receptors, specialized neurons that react to environmental changes known as stimuli when they register on the nervous system. Sensation is the awareness of the stimulus, such as the knowledge of music coming from your stereo, perception is an interpretation of what the stimulus means, such as that the music is a little bit too loud, or that the song is a favorite. Have I piqued your curiosity yet? Course I have. And today in our Essential Guide to your body and brain, we’re going to talk about the perceptive brain, I guarantee that you will be amazed by the information you’re going to learn about your own brain today, things you’ve never known existed inside your skull, or actually as who you are, it’s not just that about three pound of flesh inside your skull we’re talking about. But of course, in a way, everything we’re going to talk about is happening right there. Welcome to a new episode from our series, an essential guide to your body and brain. This is your host, Danny and this is English plus podcast.
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As you read a word or sentence no matter how small it is, the visual networks of your brain are taking in more than 100 million bits of information. Your eyes flit from place to place usually never landing longer than a split second on any one word. You may think you see the world as a seamless whole, but your retinas are segregating information into categories, a screening process that keeps the brain from getting overwhelmed by too much visual stimulation. So how does vision work in the brain vision begins with light of wavelengths between 407 100 nanometers striking the retina at the back of the eyeball. Four types of photo receptive cells in the retina react to different wavelengths and intensities of light. Other neurons relative measure brightness, distance and motion. The visual neurons send electrochemical signals via the optic tract to the visual cortex, which is located in the occipital lobes at the back of your brain. Once there, the information is redistributed to at least 30 neural networks for processing attributes, including color, shape, and texture. Each lobe in the right or left hemisphere receives half the visual information, these regions integrate the two images and finally forward a unified single image to the frontal cortex for analysis. Only then does the brain realize what it’s looking at far more complex than you thought, right. And imagine that this happens very quickly that you see things happening live in front of you, as if it were too simple, but nothing is simple in your brain, nothing happens to simply in your brain. I mean, try to build a machine like that. And you might end up with a very big building just to build a single machine that can achieve the same way our vision works. It’s interesting, isn’t it. One more thing before I move on. Remember that each eye takes in a slice of the visual world, which is processed in the opposite brain hemisphere. So your right eye takes the snapshot and sends it to the left hemisphere and your left eye takes a snapshot and sends it to the right hemisphere. And then both images integrate into a coherent image. And that is another extraordinary thing about what happens from your eyes to your brain. But that’s not everything. Next, we’re going to talk about color perception. That’s coming next, don’t go anywhere, I’ll be right back. Our sense of color one of the most mysterious of our perceptions depends on three varieties of cone cells in the retina. Cones react to wavelengths of bright light associated with green, red and blue. As the intensity of the color grows stronger, these neurons ratchet up the strength of the electrochemical signals that eventually went their way to the brain’s visual center. Neural networks create other colors by mixing the sensation of the three primary colors of light red, yellow, and blue in varying intensities, but this mixing doesn’t work in the same way as combining colors of paint. If you blend red and green paint, you get brown. However, mixing red and green wavelengths of light creates yellow. If the combs haven’t impaired or absent ability to register all hues of the visual spectrum. The result is color blindness. Incredible, isn’t it. But let’s not forget about the fourth type. The fourth type of light sensitive neurons is called rods. They registered light when its intensity is low as on a moonless night, but do not add to the mix of primary colors from the cones. So I bet you didn’t know everything about that. And I hope that you are learning something new because that’s what an Essential Guide to your body and brain is all about. It is about bringing you a new vision into your own brain and body and I hope you’re enjoying this but you’re not enjoying it enough yet, because next we’re going to talk about hearing and listening. That’s coming next don’t go anywhere, I’ll be right
back. Hearing is often ranked as the most important sense after sight. The brain registers sound when air pressure stimulates the auditory region of the temporal lobe of the cerebral cortex. To get to that region pressure waves must transfer their energy through the air to membranes fluids and bones in the ear and onto receptor cells of the so called spiral organ or organ of Corti in the inner ear. When these signals reach the brain stem neural networks sort them by tone and by quality. The brain stem eliminates those echoes that are commonly created by vibrations bouncing off walls, ceilings and floors. If a sound is new or strange, though, maybe a potential threat for example, the brainstem lets it through the brainstem also begins the processing of phonemes to start the comprehension of speech, as if what’s happening so far is not incredible enough. But the next thing is even more incredible And that is synthesizing sound. How does that happen? Auditory impulses are then routed to the midbrain superior colliculus. Once they’re the sensations of sound are synthesized with those of other senses to begin creating a unified experience of the world, such as hearing a boom and smelling gunpowder. When witnessing the flash of a musket at a pioneer celebration, for example, all of that creates a unified experience and your brain remembers that auditory sensations then rise through the thalamus to reach the primary auditory complex, where they interact with other neural networks that link sound to memory, other senses and awareness processing sound is not evenly divided between the brains hemispheres, the left hemisphere decodes musical rhythms better than the right while the right specializes in the quality or tambor of sound? Incredible. I mean, you might think that why would I want to know about these things? Well, I mean, these things are working, and we take it for granted. First of all, the information itself is very important. But that’s not all. When you understand what’s happening inside your brain, you have your own ways to improve these processes. And as I usually say, I’m not going to tell you everything because there’s no time in the world that I can tell you everything. But if I can pique your curiosity enough, so after you finish listening to this episode, first, you go to my website, of course, but after you visit my website and explore everything, you go and look up information based on what you learned in this episode, then for me, it’s mission accomplished. All I’m trying to do is to pique your curiosity, because curiosity is the basis of knowledge. And I hope I can help you revitalize that. But anyway, we talked about hearing and listening, and I hope you learned some new things when it comes to hearing and listening. And next we’re going to talk about smell and taste that’s coming next. Don’t go anywhere, stick around, I’ll be right back.
Smell and taste are separate senses, but they have much in common. They analyze molecules entering the body from the outside world, they screen out harmful threats, and together maximize appreciation of food and drink. Now we know that they both have a lot to do with our appreciation of food. But let’s start with smell. And then we will talk about taste. So smell. How does that work? Well, first smell is the most ancient of the senses. It takes a direct path to the brain, it sensations going straight into the amygdala and olfactory cortex, which are both parts of the limbic system. And they do that without stopping at the thalamus along the way. Smell is also hardwired to the brain’s emotional centers. When you smell something the sensation brushes, particularly unfiltered into the frontal lobes, as the amygdala directly influences the sympathetic branch of the nervous system smells can trigger a rise in heartbeat and blood pressure, or bring the feeling of calm and well being direct wiring into the brains, emotional and memory centers empowers odors to trigger past events. It’s not just about smelling good things or bad things. It’s much more than that. It’s hard wired to your emotions, memories. It’s very important. But that’s only half of it. Right? We said we will talk about smell and taste. So what about taste? Now, of course, when we talk about taste, you think that yeah, this is about food and stuff. But mind you that about three quarters of what the brain perceives as stasis also enters our perception through the nose. Maybe some of you have heard about that before. But that’s why you almost can’t taste anything when you have the flu. Not because the problems is with your taste buds when you have the flu, but it is in your smell sense. And that’s why you can’t really taste the food because remember about three quarters of what the brain perceives his taste also enters our perception through the nose. And when we talk about the tastes, we’re talking about our tongue and our taste buds, but only a fraction of a flavor enters through the taste buds of the tongue along with the perception of the foods texture and temperature. Now when you sip orange juice, the chemicals that give it its flavor mix with saliva, contact the taste pores of the taste buds, and touch the gustatory cells of the tongue, nerve fibers forward taste sensations to the medulla, and from there to the thalamus and gustatory cortex. gustatory fibers also connect to the hypothalamus and limbic system. They’re in regions associated with emotions, the brain forms its appreciation of the orangey flavor. So again, it’s not that simple. A lot is happening and you take everything for granted like we all do, of course, you say I can taste I can see I can hear, etc. But a lot is happening in your brain. A lot of miracles are happening in your brain right now while you’re listening to me Maybe you’re eating something, maybe you’re looking at something, maybe you’re jogging or something. And a lot is happening in your brain. I mean, not even the best supercomputer in the world can catch up to the amount of processing that is happening in your brain. But it is happening right now. And we do it almost effortlessly, which is on its own incredible. But now we talked about seeing talked about smelling and tasting. Let’s talk about the sense of touch, which is also a very important sense, and that’s coming next don’t go anywhere. I’ll be right back.
Researchers believe human contact plays a crucial role in development. In a famous set of experiments in the 1960s, psychologist Henry Harlow tested infant rhesus monkeys, the monkeys had the choice of accepting one of two mothers. The first was draped in terry cloth, but had no food. The second had a body of bare wire and a baby bottle filled with milk. The monkeys prefer to cling to the terrycloth mothers whose reassuring contact was apparently more important than food. Babies begin experiencing the sense in the uterus and are born with their neural wiring for touch significantly further develop the networks for vision and hearing. As a newborn reaches out to touch its environment, it develops its cerebral cortex. So what are the receptors for touch there, the pressure, the heat, the vibration, pain, and other sensations of touch register on specialized receptors in the skin and Oregon’s receptors are unevenly scattered all over your skin. And the brain allocates space for analysis based on how many receptors the body part contains. Thus, the number of neurons devoted to sensations from the face, a relatively small area is larger than the number allocated for several other body parts combined. And here, let’s stop for a moment and focus on something that is very important. What are the benefits of touch? Now of course, we all know the benefits of seeing, hearing and smelling but what about touch of course, it’s important you can sense heat, you can sense pressure, but beyond that, what are the benefits of touch, maybe the emotional benefits of touch. Given the importance of touch and the abundance of receptors in the skin, it is not surprising that touch can have therapeutic value for people of any age. full body massage has been shown to ease the symptoms of diabetes and hyperactivity, and improve the immunity of HIV positive patients. Massage can relieve the pain of migraines help people with asthma breathe and increase the mental focus of children with attention deficit disorder. The rubbing action of massage stimulates neural networks that cause the brain to lower the levels of stress related hormones, cortisol and epinephrine. Touch also communicates at a basic level more profoundly than words. So a gentle caress says I love you better than the words. And I reckon most of you agree with me on that. But anyway, that was about the touch. We talked about the senses. But now let’s talk about the integration of the senses. That’s coming next, don’t go anywhere, I’ll be right back.
Although neural networks are attuned towards registering perceptions of light, sound, and so on, they often work together. Perception functions particularly well when objects are appreciated by a variety of senses. A person’s walk, for example, registers in the brain as visual stimulation, as you watch the moving body, as well as auditory stimulation from the clacking of a Walker’s heels, an examination of a handful of coins is perceived not only as the site of the images of heads and tails, but also as the tactile stimulation of the hard round and smooth or rigid edge. And here, I will tell you about something that is mind blowing, and might change a lot or solve a lot of problems in the future. It’s still not there. But it is very interesting. And that is about rerouting vision. Since we’re talking about integration and the different parts of the brain that do different things and how they work together to create a single experience. How about rerouting these regions to work in different ones, maybe you still don’t understand what I’m saying. But just bear with me, sensory stimuli are associated with specific regions of the brain, but these areas apparently are not predetermined genetically. This was demonstrated by a series of classic experiments on plasticity between 1990 and 2000 neurophysiologist Braganca suit of the Massachusetts Institute of Technology took newborn ferrets and surgically rewired their brains, right out in the ferrets visual impulses to the regions normally associated with auditory processing, the ferrets soon began seeing the world with brain tissue normally used for hearing. The new wiring wasn’t a perfect substitution the ferrets lost some of their visual acuity having perhaps maybe 20 out of 60 vision instead of 20 out of 20. Nevertheless, the experiment raises the intriguing idea that blindness at birth could one day be corrected by surgery to reroute visual signals to healthy neural networks in other regions, creating detours around damaged neurons will also open new avenues for treating strokes and other injuries. Amazing, isn’t it? And one more thing before we move on to the last part of today’s episode, in which we’re going to talk about motion, we’re going to talk about the Gestalt perceptions. What what is that about? Well, I’ll tell you in the brain neural networks act together to integrate sensations many networks actually do double duty reacting with a primary response to one sense and a secondary response to another among cats for example, cells in the superior colliculus respond to both sights and sounds. And in the human brain, an old idea of common threads among the senses is gaining new adherence. Ale University psychologist Lawrence Marx argues that all senses evolved from the tactile function of the skin and still retain connections to it. He suggests that stimuli such as brightness exist across all the senses. Now, of course, that’s not final yet, but it kind of makes sense. Of course, we need a lot more studies. And you might want to look it up and read more about it. Because by the time you listen to this episode, of course, a lot has happened in the world of neuroscience and the study of the brain. But anyway, that’s it for integration. For our episode. Today, we still have one more thing to talk about, that has to do with the perceptive brain. And that has to do with motion that’s coming next, don’t
go anywhere, I’ll be right back. On the surface, the study of motion seems so simple, the brain sends out the appropriate stimulus through its network of nerves, and voila, muscles move. It sounds simple, isn’t it, but it’s not that simple. Motion has proved to be far more complicated than that. It may be voluntary or involuntary, or some mix of the two, it may involve skeletal muscles activated by the central nervous system, or in the case of peristalsis, which is the rhythmic contractions that push food through the digestive tract, it may automatically call into play the smooth muscles of internal organs, it may occur consciously take place at a level below awareness, or even in the case of a reflex not involve the brain at all. It may be executed through a hardwired set of instructions available at birth, or learned and refined After much practice. And here’s something mind blowing for you. That has to do with imagining movement. Now all motion requires events in sequence. What may be surprising, however, is that when the brain simply bonders action, it neural firing patterns appear similar to ones for execution of actual movements. Think about the layout of your house, in your imagination, take a walk through its rooms, as you performed this mental task, you probably didn’t move any muscles. But you know what your brain moved, merely thinking about moving from room to room activated both cognitive and motor regions in your brain synapses fired in your occipital parietal and frontal lobes as well as in the cerebellum, just as they would have if you had actually gotten up to make the trip. It’s amazing, isn’t it. And by the way, that’s part of the training of some athletes, they are told to imagine the moves they’re going to perform, and just close their eyes. And imagine just go through the whole motion of moving every single muscle in their body in their head, because actually, that’s part of the training, your brain is training, even if you’re not moving. And that has proven to be very effective with athletes. It’s just mind blowing, isn’t it, but it’s not mind blowing enough. I know. This is the last thing we’re going to talk about in today’s episode, but next time we’re going to talk about the body. That’s right. But when we come back to talk about the brain, we’re going to talk about the unconscious brain and that’s going to be mind blowing on its own. So don’t miss that. Stay tuned for next week’s episode from our series, an essential guide to your body and brain. And of course, come back everyday to listen to our daily episodes. We have different series. We have word power on Monday, and very soon, we’re going to have our fiction series on Friday. Now with that being said, all I have to do is to remind you that you can find the transcript on our website English plus podcast.com. And while you’re there, just take a look and explore the websites see the audio series, the brand new video series, the English plus bytes, the daily short reads the online courses, the books that you can buy from the website. All of that you can find on the website and much more is coming. And if you want to unlock all the good stuff on the website, you can simply do that by becoming a patron on Patreon. All the links you need are in the show notes of this episode. And with that, we come to the end of today’s episode. Thank you very much for listening. This is your host Danny, I will see you next time.
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