Your Sweet Memory

Emily Johnson Sugar Learning

Esmeralda Morales-Gonzalez presents her poster “Does chronic sweetener intake affect learning?” at the Experimental Biology 2016 meeting in San Diego. Credit: Emily Johnson

Most of us know it’s not healthy to eat a lot of sugar. Overeating sweets for a long time can cause weight gain, cavities, type 2 diabetes and other health problems. But what if sweets also had effects on your brain and memory? Researchers at the Universidad Autónoma del Estado de México reported at the Experimental Biology 2016 meeting in San Diego that consuming too much sugar may have negative effects on memory.

Esmeralda Morales-González and her colleagues in the neuroscience research group gave mice either water, sucralose (an artificial sugar) in water or sucrose (real sugar) in water for five weeks. They tested how well the mice learned to solve a water maze. For five days, mice were allowed to learn the location of a hidden platform in a mouse swimming pool. (The platform allows mice to stand and rest so they want to find the platform as quickly as possible.) On the sixth day, the research group measured how long it took the mice to get to the platform.

Mice in the sugar group took longer to find the platform, suggesting they had not learned as well as the mice in the other two groups. The fact that sugar impaired learning in mice is still an early finding, and Morales-Gonzalez stresses that more tests need to be done to confirm their data could apply to humans. For now, the data suggest that sugary treats may have not-so-sweet effects on memory.

Emily JohnsonEmily Johnson, PhD, is an APS member and a former volunteer editor for the I Spy Physiology blog.

Is Fat the Sixth Taste?

Chocolate Cake

Credit: Getty Images

Restaurant menus for Valentine’s Day can be described in one word: decadent. From molten chocolate cake to marbled steaks, fat makes these foods so palatable. For a long time, scientists thought that we find heavy foods more appealing because of their mouth feel and aroma. However, recent studies suggest that the tongue might be able to taste fat, along with the five basic tastes—sweet, sour, salty, bitter and umami. This could explain why we are extra perceptive to richness in foods.

As we chew and savor, chemicals released from the food stimulate proteins called taste receptors on the tongue’s taste buds. Each basic taste has dedicated taste receptors, and the basic tastes blend together to give food the flavor we perceive. Contrary to popular belief, the tongue does not have specific regions for each basic taste. Every taste bud has all the taste receptors. How do scientists judge if a flavor is really a basic taste? Many define a basic taste as having all of the following:

  • a source,
  • taste receptors that respond to it,
  • a signaling pathway between the taste receptors and the brain so that we perceive the taste,
  • sensitivity to it that’s controlled by the body, and
  • subsequent effects on the body’s physiology.

So far, the prospect of fat becoming the sixth taste is looking good. Researchers identified the taste source: molecules in fat called fatty acids. They have a few ideas on which receptors fatty acids from fat stimulate, with the strongest evidence supporting a protein called CD36. Along with studies showing that stimulating CD36 sends signals to the brain, other studies have reported that people can tell fattiness without knowing appearance, smell and texture. Certain hormones also appear to control the craving for fat, at least in mice, and there’s evidence that fatty acids on the tongue have physiological effects—they signal to the intestines to get ready to digest fat.

Researchers are also exploring if obesity is related to fat as a taste. Obese mice seem less sensitive to fat and prefer the high-fat chow as a result. People who underwent gastric bypass surgery to treat obesity have said that fatty meals became less appealing after the procedure. More work needs to be done to say conclusively that fat is a basic taste, but imagine eating molten chocolate cake with a dash of “taste of fat” powder. Too decadent?

Maggie KuoMaggie Kuo, PhD, is the former Communications and Social Media Coordinator for APS. Catch more of her writing in the Careers Section of Science Magazine.

Football Safety Tips from Birds? How Woodpeckers Avoid Concussions after Head Impact


Credit: Getty Images

The NFL has been under a lot of heat over concussion injuries in its players and the long-term brain injury and health impacts. With the size of the player and the speed he runs, it’s not hard to imagine the sheer force and damage that can occur from even a single collision. Woodpeckers, though, bang their head about 12,000 times a day at 10 times the impact of the average football hit. Why don’t woodpeckers get concussions?

The human brain floats in the skull in what is known as cerebrospinal fluid. This fluid acts as a cushion between the brain and the skull and helps lessen the impact of a blow to the head. Sudden, violent motions, such has from helmet-to-helmet contact, twist the brain or slam it against the skull. The movement stretches and damages the brain cells, causing problems in how the brain processes information.

Woodpeckers avoid brain injury because of the way their heads are designed. The bird’s brain fits snugly in the skull, so the brain doesn’t slosh around after a head impact. The brain is also oriented differently. Brains are shaped like a walnut: an oval-shaped dome. In humans, the dome faces the top of the head. In woodpeckers, the dome faces forward so the force of an impact is spread over a larger area. Size helps, too. Similar to how a cellphone stays intact after falling off the table while a laptop may not, a smaller brain has a better chance of getting away unharmed after a head injury.

The NFL recently found that more concussions were diagnosed in the 2015 season than in 2014. Officials and team physicians are not sure if the increase is due to more self-reporting by players and active identification of injury by trainers. Let’s root for Super Bowl 50 this Sunday to be full of drama on the field and 100 percent concussion free.

Maggie KuoMaggie Kuo, PhD, is the former Communications and Social Media Coordinator for APS. Catch more of her writing in the Careers Section of Science Magazine.

Over 50 Percent of School-Age Children in the U.S. Are Dehydrated: Why Should We Be Alarmed?

Pascale Lane, MD

Pascale Lane, MD

The fluid in our body is water mixed with minerals and nutrient particles. Balancing the amount of mineral and nutrients to water level ensures that our body works properly. A recent study found that more than half of U.S. children between six and 19 are not drinking enough water. What are the health consequences if children don’t get enough?

First, let’s consider the brain. Water balance is especially critical because the brain sits in a bath of fluid in the skull. Swings in water balance can cause the brain to swell or shrivel; either can be a big problem for its function. Moreover, the pathways that the brain uses to keep from shriveling may impair learning. Many studies have observed cognitive function problems in adults and children when dehydrated and better performance on cognitive tests with water intake.

Urinating regularly also protects from urinary tract infections (UTIs). Only colds cause more illnesses in children than UTIs do. Drinking enough to flush the bladder every few hours can help prevent these disorders.

As a pediatric nephrologist, my bigger concern is kidney stone disease. The prevalence of this disorder has increased in the U.S. in recent years. Kidney stones produce significant pain and suffering, as well as increase the risk of chronic kidney disease. The first line of treatment for any stone-forming disorder is drinking a lot of fluids.

Many school-age children don’t drink water because they don’t have easy access to bathrooms during the school day. Classroom rules limit bathroom use during class to avoid the disruption of students leaving. In large high schools, moving from class to class in the allotted time makes bathroom trips a challenge. Many students also find their school bathrooms unpleasant or even dangerous.

Our stock letter for kidney patients starts with the statement “Hydration is important for health.” We need to push our schools to let students drink water and urinate when necessary. It would improve their health and their scholastic performance.

Pascale Lane, MD, is a pediatric nephrologist and professor at the Oklahoma University Health Sciences Center.

Can You Work Off Depression with a Workout?

Jessica C. Taylor, PhD

Jessica C. Taylor, PhD

Stress is a part of all of our lives. From work, to family, to waiting in rush hour traffic, stress comes at us from all directions and in many shapes and sizes. Stress and other physical and mental health problems have been linked to increases in depression, which is a globally recognized public health problem.

To understand how stress leads to depression, it’s important to look at how the brain communicates with the rest of the body. Chemicals in the brain, known as neurotransmitters, send messages to help regulate brain activity, emotions, memory and health. The brain has receptors that help decode these messages so the body can act on them. One neurotransmitter, serotonin, has been linked to feelings of happiness and general well-being. Decreases in the level of serotonin and its receptors have been associated with feelings of sadness, fatigue and depression.

Luckily, there is a powerful tool that we can use to pump up serotonin levels and increase health and happiness: exercise. It is well known that exercise improves heart health and can leave a person feeling invigorated after a workout. But can it also decrease depression and improve mental health? Researchers say yes.

A recent mouse study in the International Neurology Journal supports exercise as an important part in the treatment of stress-related depression. The study demonstrated that stress decreased serotonin levels and quantities of the serotonin receptor. Serotonin and serotonin receptor levels could be elevated toward normal when the subjects participated in low-intensity exercise. The subjects also demonstrated anti-depressive behaviors after exercise, despite being exposed to stress.

So the next time you need to lift your spirits, get moving. Your body and your brain will be glad you did. For more information on depression and when to see a doctor, visit the Anxiety and Depression Association of America website.

Jessica C. Taylor, PhD, is an assistant professor of physiology in the College of Osteopathic Medicine at William Carey University in Hattiesburg, Miss.

A Bug Steps into a Hole…

walking stick 3

New study describes how the brain controls movement in walking stick insects. Credit: Trista Rada/Flickr

What happens when you accidentally step into a hole? You were expecting a solid landing, but all of a sudden, it’s not there. One leg is left hanging, and you are caught off-guard. How the body reacts in this situation says a lot about how the brain controls the muscles used to walk. A new study in the Journal of Neurophysiology from researchers at the University of Cologne in Germany used this idea on walking stick insects to understand how the brain times the activation of the leg muscles to contract when walking.

The brain controls and receives information about the body through an intricate network of cells called the nervous system. Walking reflects how the brain coordinates the muscles, and understanding this interaction can provide insight into how the nervous system works. The researchers study walking in insects because their nervous systems have fewer cells and are less complicated.

Taking a step can be divided into two phases: swing, when the foot is in the air, and stance, when it’s on the ground. Each phase requires the activation of different sets of muscles in the legs. When the foot touches the ground is the transitioning point between the two phases. The researchers wanted to know how the brain knows to activate the leg muscles used in stance. Does it wait for the leg to feel the pressure of the foot hitting the ground? Or does it do it automatically because it dictates the walking pace?

To answer this question, the researchers developed a new apparatus that instantaneously generates a hole beneath the insect’s foot as the insect moves across it. The researchers looked at five leg muscles used in stance and found that only the activation of one muscle, the flexor tibiae, a muscle in the thigh-equivalent in an insect, depended on the foot making contact with the ground. The other four muscles activated whether or not the foot touched the ground. However, the intensity of the activation of all five muscles, which corresponds to the strength of the muscle’s contraction, depended on how hard the foot hit the surface.

So next time you’re walking on uneven ground, know that you’ll be thinking twice.

Maggie KuoMaggie Kuo, PhD, is the former Communications and Social Media Coordinator for APS. Catch more of her writing in the Careers Section of Science Magazine.

Reviewed by Matthias Gruhn, PhD