Humanizing the Mouse

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.

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Where’s the Beat?

Jan. 9, 2015

By Medical Discovery News

Where's the Beat

Have you ever noticed when someone in the audience can’t clap along with a beat at a concert? Well, it turns out that beat deafness actually exists. The first case was documented nearly five years ago, identified in a 26-year-old man who could not follow the beat at all when listening to music. Chances are, you don’t have it, though. Beat deafness is a form of musical brain disorder that is extremely rare.

Sometimes, audience members get so off beat that performers stop in an effort to get back on track. That in part inspired a group of neuroscientists in Montreal to look for people who felt they had no sense of the beat. After screening dozens of people, only one, Mathieu, was found to have true beat deafness.

Mathieu loves music, studies guitar, and once had a job as an amusement park mascot that involved dancing, which by his own admission did not go so well. “I just can’t figure out what’s rhythm, in fact,” Mathieu said. “I just can’t hear it, or I just can’t feel it.” However, he can follow the beat if he watches someone else. He could also follow the beat of a metronome, indicating that he did not have a movement disorder. In one test, Mathieu was asked to bounce or bend his knees to the beat of different kinds of music while holding a Wii controller that logged his movements. His results were compared to normal people who could identify the beat. After being tested with merengue, pop, rock, belly dancing, and techno music, he was only able to follow the distinct and obvious beats of techno music.

Rhythm appears to be sensed by a widespread network in the brain, not in a defined region like speech. Rhythm itself consists of several temporal elements such as pattern, meter, and tempo. Meter is the repeating cycles of strong and weak beats, pattern is the intervals at each point in time, and tempo is the frequency of underlying pulses. Each of these appears to be sensed differently and has been mapped to neural systems within the brain through positron emission tomography (PET) scans. It also appears that only humans can process meter, whereas other species may be able to process pattern and perhaps tempo. Distinct and distributed neural systems are also involved in sensing and processing other elements of music such as melody, harmony, and timbre.

When it comes to dancing to music, though, neural processing of rhythm is only the beginning. Orchestrated or planned movements start in the motor cortex, which is divided into sections that each govern a different part of the body. Signals from the motor cortex travel down 20 million nerve fibers in the spinal cord to an arm or finger, telling it to respond in a particular way.

To achieve a rhythmic, well-coordinated style of dance, the brain must coordinate all these efforts for joints to act in proper order and muscles to contract to the perfect degree. So as complex as all this is, perhaps it is not all that surprising that some people are better dancers than others.

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Love or Lust?

By Medical Discovery News

Nov. 3, 2012

Love

People seem to talk, sing, and write about love and lust more than any other emotions. Feelings behind love and sex give rise to intense emotions, and scientists have asked for years whether the feelings originate from one or separate structures in the brain. Most people can relate to relationships that made them wonder whether they’re in love or just in lust. Now evidence suggests love and sexual desire stimulate different but related parts of the brain.

Researchers in the U.S. and Switzerland pooled their brain imaging data from 20 studies to map areas of the brain that lit up as people viewed erotic images or pictures of their romantic partners.  Regardless of gender, two areas of the brain were triggered: the insula and striatum. The structures play a role in both sex and love, and provide evidence that first comes lust before love can follow.

For a person to realize they are feeling desire, the insula brings it to consciousness. Located inside the cerebral cortex, the insula connects the limbic system, which is a primitive emotion area of the brain, to the cortex, where the brain’s higher thinking takes place. By doing this, the insula creates awareness of feelings and attributes meaning to them.

The brain images also reveal that the back portion the insula is triggered by desire, the front by romantic feelings, and the middle portion is activated when people are with someone they both love and desire. As this is happening, the striatum is also triggered. The striatum, not far from the insula in the cortex of the brain, coordinates cognitive processes that include planning and executing pathways so that when a person is motivated to do something, they act. In this way, they can act on the object of their love and desire.

The striatum furthers this process with two other functions. It has reward pathways that are activated by sex and food, allowing a person to feel pleasure from these stimuli. Over time, as sexual pleasure continues with a person, the striatum’s other function of conditioning rewards this action and paves the way for sexual desire to progress to love.

Drug addictions trigger the same pathways, offering the first evidence to prove what people have always felt – that love is addictive. Put simply, love may be a habit that evolves from lust, as the desire is rewarded.

Love’s a good habit when it comes to partners, children or parents. Addiction to love is not as healthy, when a person is perpetually in new relationships and can’t sustain lasting bonds. While the new study suggests desire may be the precursor to love, it also shows love is more complex and abstract. It’s less dependent than lust on the physical presence of another person.

Love involves pathways of the brain responsible for monogamy and pair bonding, characteristics that many societies base their values on. More studies on understanding these emotions will lay the groundwork for further social neuroscience research.

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