Brain Development

Summary:

Prenatal Period

The formation of neurons begins in the prenatal period. A few weeks after conception, the neurons begin dividing and migrating to their specific area of the brain. In this stage, the neurons will also begin myelination which is the forming of the myelin sheath around the axon of the neurons.

Newborn Period

At birth, the newborn brain has about 100 billion neurons and weights 2/3 to 3/4 pounds. The areas in charge of basic survival and reflexes are almost fully developed and the neurons controlling vision and hearing are quickly developing at this stage. The connections of neurons in the brain begin to rapidly develop in the newborn period.

Childhood

During early childhood the brain goes through rapid change. The brain forms and refines neuron networks through the processes of synaptogenesis, pruning, and myelination.

Synaptogenesis is the process of forming connections in the brain. This process, although it is biologically driven, is affected by experiences. During early childhood the brain will go through a process called synaptic overproduction which is when the brain forms more synapses than it will use. That’s when pruning comes into the picture. Pruning is the process that refines the synapses, which were created during synaptogenesis, based on experience. The connections that are used regularly are strengthened, and the connections that are not are pruned by the brain.

Adolescence

The brain of an adolescent reaches its adult weight at about fourteen.  Myelination in the frontal lobes enables the adolescent to become more capable of insight, judgment, inhibition, reasoning, and social conscience.  This front lobe development continues until age 25-30. The regions responsible for judgment, planning, assessing risks, and decision-making are the last areas to finish developing.

In this stage, the connections that are used regularly become stronger and more complex. Pruning also continues through adolescence. Also, new synapses form in response to new experiences.

Adulthood

In adulthood the brain is still changing but at a much slower rate than in childhood. The brain continues to develop connections but they are formed based only on specific experiences.

Keeping the mind active is important in order to prevent brain atrophy. Activities such as reading, crossword puzzles, talking to others, and maintaining relationships can help maintain healthy brain growth.

Analysis:

The fact that neurons form in the prenatal period and that the areas in charge of basic survival and reflexes are highly developed at birth shows that everyone starts with pretty much the same abilities. Synaptogenesis is also a biologically driven process. All of this is then shaped by experience. If an infant is not exposed to new information and experiences during early childhood, many of their synaptic connections will be lost. Early childhood is a critical period during a person’s life that can definitely affect that person’s intelligence levels later on. If the connections are used regularly and the brain is kept active these connections will become stronger and more complex which will lead to higher intelligence levels. Exposure to new experiences is important, not only during childhood, but all throughout that person’s life in order to keep the brain active.

Questions:

·         What could be the consequences of lack of exposure to experiences during early childhood?

·         What plays a bigger role, genes or exposure to experiences?

Link:

http://www.fcs.uga.edu/ext/bbb/brainTimeNewBorn.php

·         Brain development timeline. (2012). Retrieved from http://www.fcs.uga.edu/ext/bbb/brainTimeNewBorn.php

Epigenetics


Summary:

          Epigenetics is the study of all modifications to genes other than actual changes in the DNA sequence itself. Although we can’t change genes that are already in our DNA, it is possible to control the switching on and off of these genes. This is what epigenetics strives to understand and achieve. Being able to accomplish these genetic alterations comes with great advantages such as the treatment of inherited diseases and cancer.

          What we know as “good genes” or “bad genes” is not as important as the actual activation of these genes. Genes are in charge of providing cells with instructions to make proteins. In the cell, DNA sequences are transcribed into RNA, which is then translated into the sequence of a protein. Epigenetic modifications, by turning genes on or off, allow or prevent the gene information from being transcribed into a protein.

          For example, in cancer, tumor-suppressor genes are mistakenly turned off, which prevents the growth-limiting protein from being made. Also, there are many growth-promoting genes for which a single dose is enough for normal cell proliferation. But if another copy of this growth-promoting gene is mistakenly turned on, uncontrolled cell growth can occur.

          Epigenetic changes can be caused by environmental factors such as diet, exercise and drugs. But what’s even more surprising is that these alterations can also be caused by exposure to other people in whom the genes are already active. This supports the idea that “You become more like whatever you are surrounded by.” It also explains familial traits, which are the characteristics shared within a family but that are not genetically inherited.

          Epigenetics alterations are not concrete. Instead, they are present throughout the lifetime of a person and are generally accumulated over time. For example, identical twins, although they have the same DNA, may have different epigenetic material due to difference in their environments.

          Epigenetics also explains brain plasticity, not only in the neurons themselves, but also in the genes that enable or disable their function. Certain environmental cues are necessary for turning on certain genes in charge of network development. However, if these cues aren’t present, these genes may not be activated. Also, wrong environmental cues can cause dysfunction. Environment plays a huge role in manipulating the structure and function of neurons. This proves that intelligence enhancement is possible and epigenetics shows how this alteration works. Epigenetics will also all
ow us to determine the factors that affect intelligence growth and decline.

Analysis:

          Epigenetics shows how nature and nurture interact. Although most of our characteristics are genetically predisposed, our environment determines to what extent we will be affected by them. This applies to the genes responsible for intelligence. We could have them or not, but that wouldn’t be as important as knowing how to activate and use them to their full potential. In a previous source, it was mentioned that every human is born being a genius, but not all of us take advantage of that privilege. If certain environment cues are not present or if we are influenced by the wrong ones, our level of intelligence could be altered. What we eat, how often we exercise, and whether or not we take certain drugs are all factors that could affect our intellectual power. Even the people we spend a lot of time with could influence the development of some genes that may or may not be responsible for intelligence. Although there is still not a specific way to control the activation of these genes, thanks to epigenetics we are closer and closer to finding this answer.

Questions:

• Is it possible that spending time with people with higher intelligence levels affect our own intellectual power?
• If scientists developed a drug that could activate these "intelligence" genes, what could be the advantages and disadvantages?

Source:
Plasticity & epigenetics: The basics. (2009, April 29). Retrieved from http://neurohackers.com/index.php/en/menu-top-nhalib-neurohacking/37-cat-nh-basics/69-plasticity-epigenetics-basics

Link:
http://neurohackers.com/index.php/en/menu-top-nhalib-neurohacking/37-cat-nh-basics/69-plasticity-epigenetics-basics

Part 2
Part 3
Part 4

Intelligence

Summary:

                Today we live in a creative world in which our productivity depends on how efficient we are at using our minds.

 Every human being is born being a genius. In a study, children that were two to four years old were tested and 95% of them resulted to be highly creative, imaginative, and innovative. Also, they showed a high capacity for abstract thinking. The same test was done on the same children when they were about seven years of age and only four percent tested out as highly creative. This is because, according to the video, being creative and thinking abstractly is discouraged in children.

Intelligence follows the law of use. This law says that with any human faculty, if we don’t use it we lose it. This higher, “superconscious” intelligence seen on children and on great minds like Mozart and Edison is never totally lost. Instead, it becomes a latent capability that is always available for us. In order to take full advantage of this intelligence, we have to trust and have faith in the value of our insights and thoughts. Also, we have to set clear goals, be positive and have a relaxed state of mind. Concentration is also essential when trying to formulate answers to our problems.

Creativity and abstract thinking is described as a muscle; the more we use it, the more of it we have. And if we exercise it often it, the easier it will become to see things from different perspectives, therefore allowing us to solve problems more efficiently.

Analysis:

                This video describes intelligence as being both nature and nurture. From the nature point of view, it says that everybody is born with the same capability and that this “superconscious” intelligence is innate in human beings. On the other hand, it is also affected by the way we are brought up and the way we ourselves use our mental abilities in daily life. Our motivations and environment also make a difference, which shows that the nurture idea is very important when it comes to intelligence.

Questions:

Why is creativity said to be discouraged in today’s world?

If intelligence is indeed innate, does everyone have the same level of intelligence or does it vary?

GeniusBrainPower. (2010). Doubling your brain power [Web].

The Human Genome Project: Ethical Implications

Summary:

Genetic Engineering

The first ethical problem that The Human Genome project deals with is the issue of genetic engineering, which is the manipulation of genes. The purpose of the project is to map the human genetic blueprint. This would allow scientists to link diseases to the genes that cause them and therefore develop treatments. Although the main goal of the project is to find these “faulty” genes, it also involves finding the specific genes linked to physical and psychological traits. As a result, scientists would be able to use this information to manipulate these traits by using genetic engineering.

There are two types of genetic intervention: somatic cell and germline intervention.

Changes made through somatic cell manipulation are limited to one individual while changes made through germline manipulation are passed on to the genome of future generations. Germline interventions involve more ethical concerns than somatic cell interventions. This is because, unlike risks involving somatic cell manipulation which only influence one single person, risks involving germline interventions can be passed on to future generations.  However, germline manipulations can be way more efficient at permanently getting rid of certain diseases.

 Genetic engineering can also be scientifically problematic. This is because in order to perfect the enhancement of genes there are other risks that may arise from it. For example, many diseases depend on more than one gene, and there is a high probability that one of the genes might also be responsible for other parts of the organism.

Analysis

The major concern that The Human Genome Project deals with is whether or not genetic engineering is ethical. The information being collected from the project allows scientists to locate the genes responsible for specific traits. Although they haven’t found which specific set of genes are responsible for intelligence, there is a very high possibility that they will do so in the near future. If they do so scientists could, just like they could with any other trait, alter them to make someone more or less intelligent. Although this is not the goal of the project, it is something that we have to keep in mind.

Also, there is the problem of somatic cell and germline intervention.  Germline manipulation can be more efficient at getting rid of a disease not only for one individual but also for his or her future generations. But this is also true for other physical and psychological traits. If one person decides to alter his or her physical appearance and get rid of certain characteristics, this will also affect future generations.

Questions:

·         Is it worth taking the risk of developing unexpected problems in order to develop treatments for genetic disorders?

·         How might finding the genes responsible for intelligence be helpful or problematic?

Carroll, M., & Ciaffa, J. (2003, August). actionbioscience.org. Retrieved from http://www.actionbioscience.org/genomic/carroll_ciaffa.html

http://www.actionbioscience.org/genomic/carroll_ciaffa.html

Summary:

                The Human Genome Project is a coordinated science project which started in 1990 with the purpose of mapping the human genetic blueprint.

                Humans are made up of trillions of cells each of which contains genetic material called DNA. Within these long filaments reside the genes that we inherit from our parents. Scientists have found that some (if not all) diseases are linked to abnormalities in the genes. Locating and mapping the human genetic blueprint can help scientists understand these genetic abnormalities and the interplay of several genes which cause disorders such as cystic fibrosis and Duchene muscular dystrophy.

Mapping the human genes has proved to be no easy task. The human genome is considered to be the “master library” which contains all of the genetic information which resides in twenty four different chromosomes. Each cell in the human body contains DNA filaments that can be up to six feet long within its nucleus. In each of these filaments there are six billion base pairs.

Recently, investigators found that the gene responsible for Huntington’s disease was located on chromosome four, but even after a decade of study they still don’t know which gene in particular. This shows how arduous it can be to pinpoint specific genes.  One way to map these genes is to compare the chromosomes of many people with the same disease or characteristic. By finding similarities in genes we can determine what exact gene or genes are responsible for the disease.

A method of analyzing chromosomes is flow cytometry. In flow cytometry, individual chromosomes are held in aqueous suspensions and passed in single file through one or more laser beams for analysis. This allows analyzing thousands of chromosomes per second.

The main goals of the Human Genome Project are to develop resources useful for genome research, develop DNA mapping strategies, make ordered clone maps and DNA sequences of human chromosomes, and use the sequences to study genome organization and variation. The main goal, however, is not just to determine the exact sequence of the DNA, but to find the significance of specific genes and how they interact with each other.

Analysis:

Although there is proof that intelligence is at least partly genetic, scientists still haven’t found the specific gene or genes that are responsible for a person’s intelligence. It is likely, since there seem to be different “types” of intelligences, that intellectual abilities do not rely solely on one gene but on the interaction of many genes. In order to identify these genes, scientists would have to collect a large group of people who score above-average on intelligence tests, sequence their chromosomes, and analyze them to look for similarities among the group. This is easier said than done, scientist would have to analyze the entire genome of a person and what makes it all the more difficult is that intelligence is made up of different factors and there is no clear, exact definition of what intelligence is.

Questions:

What would be the benefits of finding the genes responsible for intelligence?

What ethical problems could arise from finding these genes?

"The Human Genome Project." Energy & Technology Review. April/May 1992: 29+. SIRS Government Reporter. Web. 15 Apr 2012.

http://sks.sirs.com/cgi-bin/hst-article-display?id=SFL2086-0-4692&artno=0000079562&type=ART&shfilter=U&key=genome%20project&title=The%20Human%20Genome%20Project&res=N&ren=Y&gov=Y&lnk=Y&ic=N

Summary:

            In the fourth century B. C. E., Aristotle introduced the idea that the mind was a blank slate. On the other hand, we had Plato’s idea that the human mind was an entity that pre-existed somewhere in the heavens before it was sent down to Earth.

            In the seventeenth century, John Locke, an English philosopher, brought back the idea of the mind being a “white paper”. His idea of the tabula rasa was that humans were born with an empty mind and that knowledge is gained solely by one’s sensory experiences. This idea emphasized that an individual had the freedom to author his or her own personality. However, Locke believed that humans were born with some innate ability to process experience.

            Rene Descartes, a French philosopher, believed that humans were born with some pre-existing ideas. These ideas, according to him, included knowledge in mathematics and the belief in God.  
            Continental rationalist Gottfried Wilhelm Leibniz recognized that there must exist a middle ground between the two extreme ideas of Locke and Descartes. He believed that although rational ideas are innate, they must be “activated” by experience.

             Nowadays, it has been proven that most of the brain is preprogrammed to take in, process, and organize sensory input. These parts then improve their ability to perform their tasks throughout the person’s life.  The only part of the brain that has been proven to be a “blank slate” is the neo-cortex which is involved in thought and decision-making.

Analysis:

             Even before people had a deep understanding of the brain and the mind, philosophers like Aristotle and Plato were making predictions on whether intelligence was something inborn or something gained through experience.
            According to Locke and Aristotle humans were born with an empty mind and intelligence depended mostly on sensory experiences. On the other side of the argument were Descartes and Plato who believed that humans were already born with some type of innate intelligence. Leibniz unified both ideas to resemble something more like the ideas we have today. He said that the brain was already preprogrammed but that needed input in order to function.

Questions:
How could philosophers like Aristotle and Plato make predictions on whether intelligence was a matter of nature or nurture when they didn't even have an understanding on how the brain worked?

New World Encyclopedia. (2008, April 04). Tabula rusa. Retrieved from http://www.newworldencyclopedia.org/entry/Tabula_rasa

Summary:

          First of all, in order to make any further investigation into more complicated subjects, we have to define what intelligence is. This can be very complicated since not everyone agrees on what the definition of intelligence is. Many tests, like IQ tests, SAT, and GRE, are designed to measure someone's level of cognition. The scores for these tests have to be stable, valid, and they have to measure heritability. Stability means that the scores won't change throughout the lifespan of the person being tested. Validity means that the scores must have some predictive power. Heritability means that the scores will somewhat reveal the genetic causes for these scores.
      
           IQ tests consist of smaller divisions that tests different areas of intelligence. For example: short term memory, vocabulary, math skills, and spatial rotations. These are some of the basic things that could be found on most intelligence tests. On the other hand, there are more controversial areas like reaction time and pitch recognition.

          Since there is (for most people) a positive correlation in the different areas of the test, it is possible to put all the scores together to give one final number. Many people think that if someone is good at one of the subjects tested, then the scores will not be as high on other areas. But in reality, for most people, all these scores are positively correlated. All the scores put together can be defined as that person's g (general intelligence).

        From studying the correlation in IQ scores of twins and normal siblings, it can be said that g is highly heritable. These studies were done on identical twins that grew up together and on identical twins that grew up apart, and the correlation was not very different. This shows that environment does not have much of an impact on intelligence.

         Like other traits, for example height, intelligence depends on various alleles of a gene on the genome. What scientists are trying to do now is to identify the sites in the genome in which these "intelligence" genes can be found. At this point scientists still don’t know where these sites are located. But by how fast scientists are gaining more and more information on the human genome, it can be predicted that we will have this information within the next five to ten years.

Analysis:
        
           Intelligence can be defined as an overall group of different factors. Most of the times if someone is good at one area, then this person will do well on all the other areas. This positive correlation shows that, although intelligence depends on many factors, it can still be measured by putting these different factors together and averaging them out.

           The studies conducted on twins show that genes greatly affect intelligence. Since identical twins have identical genes, the only thing that could affect their scores would be outside environmental factors. The studies show that these factors don't affect the correlation as much as some people believe they do.

           It is impressive that with all the research being done on this topic, scientists still haven't  located the genes that are responsible for intelligence. Although we have a lot of information that we have gotten from studies like the twin studies, nothing can be certain until we locate and identify these genes in the genome.

Questions:

• There is evidence that environment has a minor impact on intelligence. What are the environmental factors that affect intelligence?
• Why is it so much harder to locate the genes that are responsible for intelligence than it is for any other trait?

Steve Hsu. (Performer) (2011). Genetics and intelligence [Web]. Retrieved from http://www.youtube.com/watch?v=62jZENi1ed8&feature=player_embedded