Microlesions in Epilepsy

June 26, 2015 by

June 26, 2015

By Medical Discovery News

Humans have been recording and diagnosing epilepsy for at least 4,000 years, but it only began to be understood a few hundred years ago. While doctors noticed some epileptic patients had brain lesions, others did not have any that were visible – until now. Using a combination of gene expression analysis, mathematical modeling, and microscopy, scientists have found microlesions in the brains of epilepsy patients, which may explain the cause of seizures in some people.

Epilepsy is characterized by unpredictable seizures that result from groups of neurons firing abnormally. Some people experience symptoms prior to a seizure that allows them to prepare. In some cases, seizures can include jerking, uncontrolled movements, and loss of consciousness. In others, the seizure may only cause confusion, muscle spasms, or a staring spell. Epilepsy patients experience repeated seizure episodes.

Epilepsy is a relatively common brain disorder affecting about 1 percent of people – 65 million worldwide, 3 million in the United States. Some causes of epilepsy are strokes, brain tumors or infections, traumatic brain injuries, lack of oxygen to the brain, genetic disorders such as Down syndrome, and neurological diseases such as Alzheimer’s. However, for two-thirds of people with epilepsy, there is no known cause. Not all seizures are related to epilepsy, as they can also be caused by low blood sugar, high fever, and withdrawal from drugs and alcohol.

Epilepsy can be treated using anti-seizure medications that control the spread of seizure in the brain, but about one-third of epileptic patients don’t respond to current medications. Some cases are treated by surgically removing or killing cells in the region of the brain that are responsible for the aberrant electrical signaling. If neither of those are options, a device can be implanted that stimulates the vagus nerve, which is part the autonomic nervous system that controls involuntary bodily functions such as heart rate and digestion.

In some people with epilepsy, the cause was traced to a visible abnormality in the brain. Now, scientists have identified millimeter-sized microlesions that could explain why a seemingly normal brain suffers seizures. Scientists compared the genes expressed in the microlesions of 15 people with epilepsy. Using mathematical modeling called cluster analysis, they discovered 11 groups of genes that were either expressed too much or too little in brain tissues experiencing the high electrical activity that causes seizures.

Based upon what these genes encoded, they predicted certain brain cells would be reduced and immune response or inflammation would increase in the microlesions. That’s exactly what they found when they stained those sections of the brain and examined them under a microscope. Brain cells lost communication with each other, limiting the brain’s communication network. This probably leads to the abnormal electrical signals that trigger seizures.

This conclusion still needs to be confirmed, but in the future it may guide the development of new treatments for epilepsy.

For a link to this story, click here.

Filed Under: Health Tagged With: , , , , , , , , , , ,

Humanizing the Mouse

April 25, 2015 by

March 20, 2015

By Medical Discovery News

Humanizing the Mouse

In the 1986 horror movie “The Fly,” a scientist’s teleportation experiment goes awry when a fly lands in one of the teleportation pods and he undergoes a transformation into a part fly, part human monster. Today, science has given us the capability to create animal-human hybrids, although so far none of them has craved human flesh like they tend to do in the movies.

Neuroscientists at the Massachusetts Institute of Technology (MIT) have been introducing human genes into mice to study the effects on mouse brain function and capabilities. They are doing this in small steps, using genetic engineering techniques to introduce a specific, single human gene into a mouse. This will allow scientists to evaluate the impact of each human gene on the brain in another species. It’s not quite a monstrous Franken-mouse, but the results have definitely been revealing.

The human version of gene Fox2p is connected with language and speech development, a trait associated with the higher order brain function unique to humans. When this gene was introduced into mice in the experiment, they developed more complex neurons and more extensive circuits in their brains. Scientists wondered if this gene is responsible for the enhanced brain and cognitive abilities displayed in humans.

In the behavioral experiments at MIT, scientists placed mice in a maze and evaluated the reactions of mice harboring the Fox2p gene versus normal mice. The maze offered two modes of navigation to the mice: visual clues in the environment that were observable from within the maze and tactile clues in the pathways of the maze consisting of smooth or textured floor.

The hybrid mice learned to navigate the maze quickly, finishing it three times faster than normal mice. This cognitive enhancement or flexibility reflects the human capability of handling and processing information. The tactile information is handled by something called procedural or unconscious learning. However, the sight-derived clues represent declarative learning. It is the addition of the Fox2p gene that gave mice the ability to integrate both forms of learning.

Interestingly, if the visual clues or the tactile clues were removed, the hybrid mice did no better than the normal mice at navigating the maze. This might mean that the hybrid mice only performed better when they could utilize both forms of information. This ability to switch between and consider different forms of memory (procedural and declarative) is important and may explain in part why it is so important in human speech and language development.

Humanized animals are being used in a number of scientific fields to help us understand different elements of human physiology. Expect to see more of the humanization of animals in the future, but alas for you Sci-Fi fans – a Frankenmouse is not yet on the horizon.

For a link to this story, click here.

Filed Under: Uncategorized Tagged With: , , , , , , , , , , , ,

Does Grey Matter?

August 9, 2014 by

Aug. 8, 2014

By Medical Discovery News

The brain

What do brain scientists and fans of E. L. James have in common? They are both passionate about shades of grey. Results from a recent study in the scientific journal “Molecular Psychiatry” indicate that grey matter really does, well, matter. This study shows that the thickness of grey matter in the brain may be linked to intelligence and may also explain why some people have learning difficulties.

Grey matter is the outermost region of the brain, a layer of tissue two to four millimeters thick covering the brain on both sides with a wrinkled surface. Underneath the grey matter, also called the cerebral cortex, is the white matter of the brain, the cerebrum.

Grey matter is responsible for some major human functions including awareness, attention, consciousness, language, thought, and memory. Previous studies have shown that animals with bigger brains generally have thicker cortexes, but there has not been a strict link between intelligence and the thickness of the grey matter until now. 

For this new study, researchers at King’s College London’s Institute of Psychiatry obtained brain scans and DNA samples from 1,583 14-year-olds. They also tested the verbal and nonverbal intelligence of these subjects. Using DNA analysis, scientists looked for gene variants that could be responsible for the intelligence differences of this group. This proved to be a daunting task as they discovered more than 50,000 gene variants associated with brain development. However, with the help of computation biology, researchers uncovered some astounding results. Those with one particular gene variant caused by a single nucleotide polymorphism (or change) had thinner grey matter on the left side of their brains. And, these same individuals tested lower on the intelligence tests. 

Called NPTN, this gene encodes a protein that works in brain cells called neurons. The variant of NPTN affects communication between neurons in the brain, thereby explaining its impact on important functions of grey matter. Additional experiments suggest the NPTN variant may have more of an effect in the left side of the brain than the right side. This may correlate to lower intelligence due to the function of this important gene and its encoded protein in the left brain. 

While important, NPTN is not the only thing that determines intelligence – a multitude of other genes and environmental influences are clearly involved as well. However, this gene may provide new clues as to how intelligence is built in humans. Also, it will be interesting to see if this gene variant is associated with cognitive diseases like autism or psychological disorders like schizophrenia. 

Thanks to the new B.R.A.I.N. initiative that funds basic and translational research, we look forward to better understanding the human brain, arguably one of the most important human organs we know the least about. 

For a link to this story, click here.

Filed Under: Health Tagged With: , , , , , , , , , , , , , , , , , , , , , , ,

Do We Smell the Same Thing?

February 10, 2014 by

Feb. 7, 2014

By Medical Discovery News

Do We Smell the Same Thing?

Have you ever wondered if we all sense the world in the same way? Evidence suggests that the sense of smell is highly individualized, based on genetic differences. This could revolutionize scents and food flavors into custom-designed creations for individuals.

Humans have specialized neuronal cells within the lining the nasal cavities, part of what’s called the olfactory epithelium. The surface of these cells, like much of the nasal cavity, is covered with mucus. Odor molecules dissolve into this layer and are detected when they bind to receptors on the neurons. This sets off a string of biochemical events that produces a signal, which travels along the olfactory nerve to the olfactory bulb of the brain. Then that signal is transferred to different regions of the brain’s cerebrum. Here odors can be distinguished and characterized. These signals are stored in long-term memory, which is linked to emotional memory. That’s why particular smells can evoke memories. This process is quite complex due to the highly evolved sense of smell in humans.

The genes that are involved in olfactory or smell sensations are not well understood. People do perceive odors differently, but researchers have only identified genes for certain odors. For example, human perception of cilantro has been linked to the olfactory receptor OR6A2 and grassy odors have been linked to receptor OR2J3.

New Zealand scientist Dr. Richard Newcomb tested the ability of almost 200 people to smell 10 different chemicals associated with the key odors of things like apples and blue cheese. Then these individuals’ genomes were completely sequenced, and genetic variances that could account for these olfactory differences were determined. For four of the chemicals tested, clusters of genes were identified as being able to detect these odors. Interestingly, these genes were located on different chromosomes. Newcomb’s work almost doubled the number of genes known to be connected with the sense of smell. For beta-ionone, a chemical associated with the smell of violets, a single gene was shown to allow people to sense that fragrant flower’s scent. Overall, the result of this study was that people are capable of experiencing chemical smells in different ways.

This opens the door for scientists to define an individual’s olfactory profile. If it’s understood how an individual perceives smells, a chef could personalize food just for their senses. Imagine walking into a restaurant and handing your server a card with your olfactory profile based on your genes. And violá! A dinner prepared with the seasonings and flavors you find most pleasing. With continued research, our sense of smell may be able to experience this scenario and more. 

For a link to this story, click here.

Filed Under: Uncategorized Tagged With: , , , , , , ,

Thinking with your Stomach

May 31, 2013 by

May 31, 2013

By Medical Discovery News

“The way to a man’s heart is through his stomach.” New research might amend this common proverb to “the way to a man’s brain is through his stomach.” An article in the “New Scientist” argues that the enteric nervous system (ENS), found in the tissues of the gastrointestinal (GI) tract, functions as a second brain of sorts.

Spanning the mouth to anus, the GI system is approximately 30 feet long and can be divided into the upper (esophagus, stomach, and duodenum) and lower (large and small intestine) tracts. This is where digestion occurs, providing metabolic functions and energy to the body. With this complex role, it is not hard to imagine why it needs its own nervous system.

Like the brain, the ENS consists of different types of neurons as well as glial cells, which provide support and protection for the neurons. The human ENS contains upward of 500 million neurons and an equal number of glial cells, more than all of those in a rodent’s brain. However, the human brain contains 90 billion neurons. The ENS communicates with the brain to control unconscious or autonomic processes, like peristalsis, the wave-like motions that push food through the GI tract. 

To accomplish this, the ENS produces hormones and neurotransmitters much like the brain. In fact, the ENS produces as much dopamine (which triggers feelings of reward and pleasure) as the brain and most of the serotonin (which controls mood, appetite, and sleep) within the body.

So, if the ENS truly acts as a second brain, then the GI system can affect a person’s moods and sense of wellbeing. The ENS causes this by transmitting signals to the brain through the vagus nerve. This makes sense, since people typically feel good after enjoying a meal. For example, when rich foods are digested they release fatty acids. The gut detects this, prompting the ENS to send certain signals to the brain. According to brain imaging studies, the brain then releases pleasurable sensations, altering a person’s mood. So it’s no wonder that people crave rich, fatty foods!

On the other hand, people usually eat differently when stressed. Stress can lead to the production of a GI hormone called ghrelin, which causes feelings of hunger and leads to a reduction of anxiety and depression. In experiments, mice subjected to stress sought out fatty foods, which elevated the production of ghrelin. The link between chronic stress and obesity is then a no-brainer.

The main function of the ENS is to monitor the digestion of food and identify threats in what is eaten, such as toxins or infections. So, perhaps listening to the stomach when it comes to choosing meals isn’t all bad. After all, that’s the second brain at work.

Filed Under: Uncategorized Tagged With: , , , , , , , , , , , ,