19 April 2010 Monday
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bosuna gelme geri
There are “eternal fundamental questions” in life.
What will happen to us after we die?
What is the meaning of life?
Are we alone in the universe?
Why do we get old and die?” is one of these questions. To answer this question, evolution scientists had a lot to say on the causes behind aging and death.
Evolution immediately brings into mind a name and a concept; Charles Darwin and natural selection. Natural selection is simply about nature’s selection of the traits and its bearers in favour of survival and reproduction of the species. Therefore, it is not surprising that the evolutionary approach to uncover the mystery behind aging has been critical.
August Weismann (1834–1914)
Weisman has been the father of evolution of aging theories. Prior to his work in late 19th century, the general belief on the causes of aging relied on “wear and tear” theory. According to this historical theory we were getting older just as a knife’s edge becomes dulled with exposure to air and moisture.
He explained aging as a programmed process in the organism for the needs of species. The old should leave, so there would be room for the younger. His theory, however, lacked practical evidence.
Peter Medawar (1915 – 1987)
In the following century, Medawar put the work of Weismann and that of others together and proposed an exciting and interesting theory. According to Medawar aging was simply a by-product of natural selection. For example, the genes involved in fixation of bones in young age were in favour of survival and reproduction. In older ages, however, these genes would not be beneficial and the older would have bone fractures as a result. According to Medawar, natural selection declined by age and youth had a cost to pay; aging.
George C. Williams (1926- September 8, 2010)
Williams took Medawar’s theory further. He suggested that one particular gene not necessarily would have effect on one trait of the organism but rather on different traits (pleiotropy). The natural selection would be in favor of the young compared to the old. These genes will be maintained by nature as they will be beneficial at young age, but will be deleterious at older age. That is why his theory is also called as “Pay Later” theory.
Many species have been investigated in the field of evolution of aging, but by far the most popular has been a fruit fly; Drosophila melanogaster (Greek, dark-coloured belly). It has been practical to use them as it is easy to take care of them, the breed quickly by laying many eggs. Researchers were able to delay aging in Drosophila by only allowing older flies to reproduce. Although the results of some studies with Drosophila fruit fly favour Medawar’s theory of mutation accumulation rather than Williams’s antagonistic pleiotropy hypothesis, conflicting results also exist.
Interview with Prof. Charlesworth on evolution
We have a life span longer than our ancient ancestors. Will the average life span of the human past the age of 100? If so, what will the mechanisms be? The evolution theorists will tell us more in the future thanks to the scientists mentioned above and many others.
You are spiritual.
You look at the wholes mostly, not the parts.
You are a dreamer with a rich imagination.
You are prefer visual instructions.
You are creative.
You are using the right brain dominantly according to
the left-right brain hemispheric model…
Left brain – right brain hemispheric model, focuses particularly on skills , and stresses art and musical skill at the expense of language and mathematics (Flaherty AW, 2005). The public does think that there is no other model for the mapping of brain functioning. Again the public believes that a right-brained person where his or her right brain is dominant will show the prominent functions of the right brain…
So all the musicians are creative, so where is the problem here? Though, this theory is popular, it is theory.
Here is a paper by Alice W. Flaherty from Harvard University where she proposes a three-factor anatomical model of human idea generation and creative drive, where he proposes that it is about three anatomical areas…
The public relations of right brain is succesful one and it is a market now in different areas of business such as education, exercise. When you need the right brain;left or right you use it. Oh, if some features of either of them works not so well, you can educate it…I just support this model to promote more “creativity” at schools.
But I still believe these generalizations are over-rated…I can not find my way easily as a dreamer, for example.
Here are some measurements methods of right/left hemisphere dominance:
Behavioral measures of lateralization; neuropsychological test batteries; tachistoscopic presentations; dichotic listening tasks; verbal and performance sub-tests of intelligence tests; standardized measures of verbal and visual functions (Miran & Miran 1984)…
OR as this issue became a market, one of the test in the net…Just for fun though!
What is Frontal Lobe?
What is a Syndrome?
Finally…Frontal Lobe Syndromes.
What is Frontal Lobe?
What makes us human…
Lobe: Middle English, from Old French, from Late Latin lobus, hull, pod, from Greek lobos, lobe, pod.
Any rounded projection forming part of a larger structure.
The brain’s largest part is the telencephalon (cerebrum in Latin).
Encephalon means “in the head”, and tele means “distant” in ancient Greek (Television would be the distant image). It is the most superior part of the brain so it makes sense to have called it the distant part in the head. The brain lobes belong to the telencephalon, anything above the brainstem.
Cerebral hemispheres on both sides are made by the brain lobes. The lobes lie on the bones where they get their names from. The one which lies on the bone lying at the front side of the skull would be the frontal lobe.
Frontal lobe is responsible for the higher executive functions of the brain (judgement, reasoning, decision-making,etc.). They are also related to intellect, working memory, speech and personality.
Frontal lobe is the largest lobe in the brain.
Frontal lobe exists in the brains of mammals only.
Frontal lobe; especially more anterior part (the prefrontal cortex) is the CEO of the brain and the body.
Frontal lobe has different parts anatomically responsible for different functions.
Frontal lobe is the last part of the brain evolved.
The development of the frontal lobe finishes in a person in his/her 20s.
In medicine and psychology, the term syndrome refers to the association of several clinically recognizable features, signs (observed by a physician), symptoms (reported by the patient), phenomena or characteristics that often occur together, so that the presence of one feature alerts the physician to the presence of the others. The term syndrome derives from its Greek roots and means literally “run together”, as the features do.
Frontal Lobe Syndromes
Some think this term is old and must not be used for the sake of integrity of the brain. Not necessarily function and anatomy should overlap all the time. Frontal lobe syndromes represent situations where the there is a damage, degeneration related to frontal lobes: a traumatic injury, a type of dementia, brain tumors, Alzheimer’s disease, schizophrenia, cerebrovascular disease etc.
So what can we see in a patient when the frontal lobe, a part of it per say, is injured:
2- Disinhibition; social inappropriateness
We mammalians are social creatures and we owe this mostly to our frontal lobes: particularly the more anterior part -prefrontal cortex. We would not want to act socially inappropriate; thanks to our frontal lobes. Such as loosing your empathy…
(A screening test for all politicians in the world?)
One might see these (not all in one patient) and other symptoms basically depending on the site of the lesion in the frontal lobe and other factors.
Alberto J Espay, MD, MSc, Assistant Professor, Department of Neurology, University of Cincinnati ,Daniel H Jacobs, MD, Associate Professor of Neurology, University of Central Florida College of Medicine
A power point presentation on Frontal Lobe Syndromes by Katalin Gyömörey, Ph.D., M.D
Michael H. Thimble, F.R.C.P., F.R.C. Psych
Seminars in Neurology
Volume 10, No. 3
Constantine G. Lyketsos, M.D., M.H.S., Adam Rosenblatt, M.D., and Peter Rabins, M.D., M.P.H.
Psychosomatics 45:247-255, June 2004