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.

Programmed death theory

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)

Mutation Accumulation Theory of Aging

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)

The antagonistic pleiotropy theory of aging

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.

William Hamilton (1936–2000) and Brian Charlesworth (1945- ) later proved these theories mathematically.

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.

Suggested Reading

Evolution of ageing since Darwin

The Evolutionary Theory of Aging

Evolutionary Theories of Aging and Longevity

Aging is not Senescence: A Short Computer Demonstration and Implications for Medical Practice

http://www.cornellcelldevbiology.org/sun/New%20Folder/Funny%20laterality.JPG

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.

http://members.shaw.ca/hidden-talents/brain/113-right.html

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!

Hemispheric Dominance Inventory Test

Coming soon…

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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.

What is a Syndrome?

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:

1- Attention deficits

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…

3- Disorganization

4- Emotional lability

5- Apathy

6- Poor judgement and insight

(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.

Suggested readings

Frontal Lobe Syndromes

Frontal Lobe Syndromes: Treatment & Medication

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

Psychopathology of Frontal Lobe Syndromes

Michael H. Thimble, F.R.C.P., F.R.C. Psych
Seminars in Neurology
Volume 10, No. 3
September 1990

Case Report

Forgotten Frontal Lobe Syndrome or “Executive Dysfunction Syndrome”

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

 This portrait of Henry Gustav Molaison, or H.M., was taken shortly before he underwent the experimental surgery that would destroy his ability to form long-term memories.

We knew him as H.M. from the beginning. He is by far the most important and famous patient in the neuroscience field.  You can find his initials in many neuroscience textbooks, and numerous articles.

What gave him this fame?

It was 1935. The Germans were not in Poland yet, and the World War II has not begun. It was an ordinary day in California and H.M. had an unfortunatebicycle accident at the age of nine. His tragedy started from that day; suffering from intractable epilepsy.  In 1953, HM was referred to William Scoville, a surgeon at Hartford Hospital, for treatment. This is how the most striking experience a human ever lived in neuroscience started. He got the operation for his epilepsy. On September 1, 1953, Scoville removed parts of HM’s MTL on both sides of his brain. HM lost approximately two-thirds of his hippocampus, parahippocampal gyrus, and amygdala. His hippocampus appeared entirely nonfunctional because the remaining 2 cm of hippocampal tissue appears atrophic and because the entire entorhinal cortex, which forms the major sensory input to the hippocampus, was destroyed. Some of his anterolateral temporal cortex was also destroyed (See the relevant entries Hippocampus: the seahorse that rides you and Amygdala: Yes, I love you and I remember you.)

He lost his short-term memory. His skill to take information and keep it as a long-term memory was gone with the epileptic tissues removed. The case was published in 1957, and his brain has been examined since then. There was nothing wrong with his ability to solve problems, he used to enjoy cross-word puzzles. He died at the age of 82, shedding light on the darkness on memory and teaching to the neuroscience community on the concept of memory through his sequelae after the epileptic surgical intervention.

Recently, his brain has been sectioned to be analyzed further at University of San Diego: in addition to the analysis done during his life by neuroimaging tools.  The slicing of his brain sample has been streamed on-line.

My picks as a neuroanatomist

3D MRI Human Brain Anatomy

Brain Anatomy and Functions

Human Anatomy – Brain

How the Body Works : The Regions of the Brain

How the Body Works : Center of Emotion and Memory

How the Body Works : Units of the Limbic System

 Anatomy of the Hypothalamus

October is the Autism Awareness Month in Canada.

April is the Autism Awareness Month in U.S.A. and in England.

April 2 is the Autism World Awareness Day. Here is the website of Autism World Awareness Day.

What is autism?

Contrary to common belief, autism is the “umbrella term” for a list of disorders as it is the same thing for epilepsy.

Autism spectrum disorder (ASD) is a range of complex neurodevelopment disorders, characterized by social impairments, communication difficulties, and restricted, repetitive, and stereotyped patterns of behavior. ASD occurs in 1 in 150 children (Amaral et al 2008).

Autistic disorder, sometimes called autism or classical ASD, is the most severe form of ASD, while other conditions along the spectrum include a milder form known as Asperger syndrome, the rare condition called Rett syndrome, and childhood disintegrative disorder and pervasive developmental disorder not otherwise specified (usually referred to as PDD-NOS). Although ASD varies significantly in character and severity, it occurs in all ethnic and socioeconomic groups and affects every age group. Experts estimate that three to six children out of every 1,000 will have ASD. Males are four times more likely to have ASD than females.

Brain structures affected with most consistent findings

Structural MRI findings have been inconsistent to an extent, however, recently more solid information has been gathered on the brain structures which play role in the mechanism of autism. The brain is enlarged in autism (Mosconi et al 2006).

Postmortem and structural magnetic resonance imaging (see the structural MRI entry for more information) studies have highlighted the frontal lobes, amygdala and cerebellum as pathological in autism. However, there is no clear and consistent pathology that has emerged for autism. Moreover, recent studies emphasize that the time course of brain development rather than the final product is most disturbed in autism (Gordon 2007). It is believed that the patients with autism are not born with the changes in the brain, these changes appear through the development of the child in the first year of life (Mosconi et al 2006).

Cerebellum

Although cerebellum has been implicated as taking role in several neurological and psychiatric disorders such as in schizophrenia, temporal lobe epilepsy, bipolar disorder (see Cerebellum: Dark side of the moon entry for more information on cerebellum), the changes in cerebellum (e.g., cerebellar size) have reported more consistently and cerebellum is relatively more important in autism. It has been suggested that increase in the volume of the cerebellum might indicate abnormalities in the cerebellar–cerebral circuits that most probably result in the learning difficulties (Gordon 2007). Not only volumetric studies, but also functional studies also imply a developmental problem in the cerebellum in autism (Gowen & Miall 2007). In neuropathological studies (in post-mortem brains) decreases in cerebellar Purkinje cells and other changes have been reported in patients with autism (Palmen et al 2004).

Amygdala

Amygdala (see the entry on amygdala for more information about the structure) was reported as enlarged in children with autism. It has been suggested that amygdala enlargement was associated with more severe anxiety and worse social and communication skills (c.ref. Amaral et al 2008) such as a relation between nonverbal social impairment and amygdala volume was reported by Nacewicz et al (2006).

Frontal lobe

Both functional and anatomical abnormalities are seen in patients with ASD. These change in the frontal lobe are related to changes in cognitive performance such as reduction in the cognitive processing speed (Schmitz et al 2007).

Some other brain structures

Although cerebellum, amygdala and frontal lobe are the structures with most consistent findings in autism, other brain structures have also been found to be affected in autistic patients (Baron-Cohen 2004). Volume deficit found in parietal lobe of autistic patients was correlated with narrowed spatial focus of attention (c.ref. Baron-Cohen 2004). Hippocampus is another limbic system structure changes of which has been reported in autistic patients (Palmen et al 2004).

Decreases in the corpus callosum size; the white matter between the two hemispheres of the brain conveying information between these two hemispheres. Relations between several cognitive performance tests and size of corpus callosum were reported in patients with autism (Keary et al 2009). The changes in corpus callosum supports the fact that there might be a decrease in the connection between the two hemispheres (Hardan et al 2009).

Caudate nucleus; is a part of the basal ganglia. The structures of basal ganglia play a role in task we do where we do not need to remember to do them, like riding a bike or typing. We do them automatically once we learn how to do them. Parallel to the function of caudate nucleus, a relation between caudate nucleus and repetitive behaviors was reported in autistic patients (Rojas et al 2006; see the second reference in the suggested readings to reach the free full-text on-line). Enlarged caudate nucleus was found in high-functioning medication-free autistic patients which is a valuable finding, as the medication used for the treatment of autism affects the size of the caudate nuclei (plural for nucleus; Langen et al 2007).

Brainstem (related to sensorial information pathology in autism), thalamus, and anterior cingulate cortex, superior temporal gyrus are among the other brain structures of which changes were reported in autism.

Functional studies

Functional studies such as functional MRI , electrophysiological studies give us more information about the deficits in the brain networks. All these psychiatric disorders are now believed to be disorders with problems in the functioning of networks. A network is made by the several brain structures specific for a given task. A structure might belong to more than one network. Functional studies show problems in the functioning of some networks in autism. One of them is fronto-parietal systems/network specific for spatial (3-D) attention task. The pathways between cerebellum and cerebrum (the rest of the brain) contribute to this network. Although the role of cerebellum in attention in autistic patients has been questioned (Gowen & Miall 2007).

Suggested readings:

Understanding autism and related disorders: what has imaging taught us?

Regional gray matter volumetric changes in autism associated with social and repetitive behavior symptoms.

A boy with Asperger’s syndrome prepares a video on his thoughts about his disease with his mom.