Is there any research paper which identifies left and right brained behavior?

Is there any research paper which identifies left and right brained behavior?

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There are many web puzzle to identify, but does it really have any scientific proof?

something like -

any logic behind it?

In general I'd say "left and right brained behaviour" is total nonsense. I guess the origin of this kind of claim is a bad press release or something.

Let's start with something simple. Say hearing. When you hear a sound to your left ear, it is projected strongly to the contra-lateral side (right hemisphere), and weakly to the ipsi-lateral (left hemisphere) of your brain. So the brain response to a sound presented to the left ear is lateralized. Typically, this means that the other hemisphere is "more" responsible for processing the input. Similar thing happens for the other senses too.

So what is interesting about lateralized brain responses? Well, it would be very interesting to know for example are memories lateralized. It would tell something about the system: is it a kind of distributed system, where parts of a memory are scattered here and there, according to some logic, or is a single memory stored on a small area (and maybe only on the other side of the brain), etc. The distributed hypothesis seems more plausible according to recent research.

Let's talk about handedness next. Are you right handed? Or left handed? Or… something between? Actually, even something like handedness is not a binary thing. It is more like a value on a range from 0 ("very left handed") to 100 ("very right handed"). This is taken into account in decent research, where ~1 hr per participant is used to assess that value (if it is relevant to the study).

So we have now talked about lateralization. How about the "left and right brained behaviour" then? In the URL you have provided it is implied that certain behavioural attributes are somehow related to lateralization. Lateralization of what? All the attributes, e.g. "being rational" depend on so many things: seeing, hearing, thinking, retrieving memories,… that saying such a thing is not plausible.

Anyway, many brain processes are lateralized. That is the word to look up for for more information. But a thing like "behaviour" is too complex to be put to one hemisphere.

Reference: Accumulated wisdom from being a research assistant in a neuroscience project. (so you should trust more than me).

Maria Vasiliadis

We are aware that different parts of the brain are specialized to perform different functions. Over the years, scientists have devised increasingly sophisticated ways of exploring the geography of the brain, and they have succeeded in mapping it in considerable detail. One of the sources of information used is split-brain research, in which scientists study the effect of severing the corpus callosum, a bundle of millions of nerve fibers that connects the two halves of the brain and allows for communication between the hemispheres (3).(The operation is a rare one, done to treat intractable epilepsy.) By observing the performance of split-brain patients researchers have learned about the distinctive characteristics of the right and left hemispheres of the brain.

Surgeons treat some cases of epilepsy, when no other options are available, by cutting the corpus callosum, which connects the two cerebral hemispheres. Robert Sperry is a psychobiologist who conducted the landmark split-brain experiments. He discovered that human beings are of two minds. He found that the human brain has specialized functions on the right and left, and that the two sides can operate practically independently. In a normal brain, the stimulus entering one hemisphere is quickly transferred through the corpus callosum to the other hemisphere in order for the brain to function as a whole. In the split-brain patient the two hemispheres can not communicate. This procedure known as commissurotomy is done by opening the skull and exposing the corpus callosum between the two hemispheres. The surgeon then cuts through the corpus callosum, cutting the communication between the two hemispheres (4). This experiment demonstrated significant differences in the mental capabilities of the brain's two hemispheres. The left hemisphere was shown to be logical, analytic, quantitative, rational and verbal, whereas the right hemisphere was revealed to be conceptual, holistic, intuitive, imaginative and non-verbal.

The unusual behavior of the split brain patient has revealed many differences between the two brain hemispheres. Roger Sperry along with Michael Gazzaniga were the first to study the split brain in humans. Research showed that split brain patients present superiority on the right hemisphere when it comes to spatial tasks, such as arranging blocks. Researchers also showed drawings to the left and right hemispheres and the patient was asked to draw what he saw from both hemispheres. The conclusions were that the left-handed drawings were better drawn. Sperry and Gazzaniga also found that split-brain patients are less likely to talk about their feelings and emotions. In one of their patients, "Paul S." his right hemisphere was more developed in language ability before the operation. This is uncommon but does sometimes happen. The fact that Paul's right hemisphere was developed in verbal response enabled Sperry and Gazzaniga to interview both sides of the split brain. When the researchers asked the right side what he wanted to be, he answered an automobile racer while his left side stated he wanted to be a draftsman. Paul was asked other similar questions, which gave the researchers insight on the hidden differences between the hemispheres. Another patient also exhibited strange behaviors with his right and left hands. His right hand was trying to pull up his pants while the left hand was trying to pull then down. A similar incident occurred when a split-brain patient was having an argument with his wife. The patient was attacking his wife with his left hand while his right hand was defending her(5). These studies of split-brain abnormalities in patients as opposed to normal people are offering researchers insight on hemispheric differences and specialization. We can look at an example of callosal apraxia in both an intact brain and a split brain patient. Callosal apraxia, a type of limb apraxia is due to damage to the anterior corpus callosum. If a patient with limb apraxia is asked to raise both hands, the left side of the brain analyzes the verbal message and triggers the prefrontal cortex, which contains the memory of the movement. The information is then passed to the motor cortex, which controls the movement. In order for the right motor cortex to be signaled so the left hand can be raised the signals of the verbal command must be passed form the left to the right hemisphere through the corpus callosum. Therefore the right arm will be raised but the left arm will not. In a split-brain patient we observe something different. The patient shows a marked aparxia of the left hand to the verbal command. This is due to the fact that the right side, which controls the left hand, has less language understanding (5). Another interesting example of how the split brain affects the patient's perception of the outside world is seen in an experiment done by Roger Sperry and Ronald Meyers. An experiment was done by flashing a word so the right hemisphere of the brain would interpret the information. When the patient wrote down the word his left hand wrote down the correct word flashed. But when asked what he wrote done the patient did not know. Since the brain was split the information that was given to the right half could not relay the message to the left side (5).

Research was also done at the McLean Hospital by Fredric Schiffer MD, who studied two split brain patients. The McLean researchers studied the fact that each side of the brain controls the movement of the hand on the opposite side of the body. They devised a way for the left hand to answer for the right brain and for the right hand to answer for the left brain. Their experiment consisted of placing a row of five pegs in front of both the left and right hands of the split brain patients. These pegs represented a response, ranging from no response to an extreme response. The response was made by pointing simultaneously and independently with each hand immediately after the questions were asked. Dr. Schiffer observed that the left brain reported little or no anger toward a question asked about past bullies who had attacked him when he was young. But, his right brain was still upset about his early experiences. Another patient's two brains were asked questions about perceptions of himself. His right side perceived him as good while his left hemisphere thought he was insufficient. Dr. Schiffer and his staff found that each patient's right and left hemisphere seems to have its own opinions and emotions (6).

The end result of all the crossing over from one side of the body to the other is a bewildering network of interlacing nerve fibers that extends the total length of the human spinal cord. The key question is, of course, what purpose is served by such an arrangement. At this point neuroscientists have yet to formulate a really convincing answer. Experiments such as the split-brain enable scientists to grasp a better understanding of how the brain functions. To put the matter differently: The human brain has yet to discover this aspect of the mystery of its own functioning. There is little doubt, however, that we need both sides of our brain. In fact, one can state with equal validity that we are not just the right and left sides of our brain but simply we are our brain and wouldn't want to lose any part of it if we had a choice.


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I enjoyed reading this article. I love finding new and interesting ways to challenge myself, and as a predominantly left-brainer, I’ve been finding information about how to also strengthen the right side of my brain as well. I’m also a classical pianist, so learning to use both hands proficiently with most tasks I think comes more naturally because of that (even though I can’t write or draw with my left hand). I do wonder about the relationship between the two hemispheres, and I’m curious about those of you who are ambidextrous. Do you find that you have strengths in both the left and right brain equally? (Categorically-speaking). Do you feel that you have any advantage or disadvantage in any way?

As a “both-sider,” this information was most helpful. I am easily more creative than average, taught math in secondary and college level for 25 years, and find directions when driving my greatest challenge. Earning a doctorate in historical theology was much easier for me than a masters in mathematics at the same university. I remain a “puzzlement” to those who claim to know me. Carolyn

One thing I see is that Arabic is written right to left. Were the inventors of written Arabic left handed?

Just an addendum: As a medical student at Harvard, our genetics faculty was convinced that handedness was defined by a typical dominant-recessive distribution. This would indicate that about 25% of our class would be left-handed. However, only about 12% was left handed – so much for a genetic explanation!

As a left hander, this concept has always intrigued me. Clearly, I used my left hand preferentially from birth but many influences in my life changed my pattern of activity. Probably the first was the effect of my grade school teachers who tried to convert, at least my handwriting, to my right hand. Fortunately my mother stopped that but did get to to straighten out my left handing when writing.
I have developed a right/left ‘dyslexia’ in that I tend to go the other way than right or left when thinking or told to do so. It is frustrating to this day and I have not been able to change. It did cause a few problems when I was a pilot of my own airplane but, not as a surgeon!
What was difficult in my career was the overwhelming emphasis on right-handedness in the operating room. Even the majority of instruments are designed specifically for right handers, to wit, scissors, needle holders and ratcheted clamps! The pejorative terms used have been annoying, especially when a nurse would respond, “oh, you use the wrong hand!”
So to this issue, I can’t say what side of the brain I am using and it really doesn’t make a difference. I can say after a right sided, frontal lobe CVA, that muscle control of my left arm is the prime issue, not speech, etc.

Ridiculous. We deal with right brain/ left brain stroke survivors which depict a definite difference in what they can do or not do. ie: numbers, speech, singing, behaviours.. “A DEFINITE DIFFERENCE”

Of course certain parts of the brain control certain functions, as noted in the “Location Matters” section – and yes, this is quite clear in stroke patients and others with brain disease but this piece is describing brain sidedness and less finite functions such as personality types, “being good at numbers” vs. being intuitive and so on.

Still a vast majority of people are unaware that growth of neurons forming human brain starts early and is almost complete by the age of 4 to 5 years and the basic hard wiring or circuitry connections patterns get developed in early childhood and neurons not used or sparingly used get decomposed. Parenting with good coaching and focus on ability of parents and teachers for a healthier upbringing and use of brain by children is the most important part. Good that lefties are at no major disadvantage except writing of scripts can be left to right only….
Do we use our brain to its full capacity? No . We do not use even the skills and knowledge gathered to even a quarter of the whole!

The amazing thing is that when I feel most in tune with God,
my brain feels clear and light. I hope there can be more studies done with people who use prayer to become more inspired.

I am amazed at how the Lord can forgive me and clear my brain, even after it has felt muddled or unclear.

Margaret in San Diego, CA

Robert is wrong.
Handedness is strictly hard-wired.
One can be forced to use the “other hand”, but it will be a lifetime hurt.
Also, it is everyday experience, that left-handed people have different menthality than right-handed ones.
Not better, just different.
Nobody can deny it, so don’t question it.
It can be a hypothesis, that it comes from the “brainness”.
But even if the science cannot prove it, you should accept that there is a main difference between righ-handed and left-handed people.
Maybe, a right-handed one can even “draw with right brain”.
Congratulations, well done.
However, the difference still exists between right-handed and left-handed people.

What about ambidextrous individual like me? I can use both hands in many ways though each hand is more adept in some functions than the other. I could not remember how I learned to write with my right hand but I can also write with my left if I need to.When I get tired using my left I can also switch to my right without any problems ( ex. slicing, ironing, holding, sweeping).
When I became conscious of my being ambidextrous , I began using my right hand as I learned new skills ( knitting, giving injections).
Is there any study about ambidextrous individuals? What percentage of the population and how many are indeed gifted in both brain functions?

letecia, you bring up an interesting point about being ambidextrous. I too am ambidextrous, but not to the full extent as you – my left/right handedness is completely random – i write left handed, brush my teeth left handed, but i use scissors with my right hand (I wouldn’t be able to cut something with my left hand to save my life). As a child in school I didn’t want the left handed scissors as they were incredibly awkward for me. I can write on a chalk board with my right hand, but prefer my left. I can say that I utilize my right hand/arm for most gross motor skills (tennis, golf). I would guess it’s mostly gross versus fine, but i can’t say conclusively.
i too would be interested in further research findings on this subject, because in truth, i’m about the most random mix of dichotomous characteristics one could find: i’m very black and white and analytical….but i lack superior math skills (or desire) because i’m riddled with ADD and fly by the seat of my pants in most scenarios. Most everyone thinks I’m highly organized, but i’m a flurry of chaos inside and out, and I always get the job done in superior fashion (but never remember how i did it two days later) – I can be overwhelmingly creative and whimsical, but it’s not a constant – as i tend (more comfortable) toward the logical path most often, and thinking outside of the box isn’t always my forte’ yet often times the most “out of the box” answer is ridiculously obvious to me when others can’t see it.
So, I’ve never related to the “left/right brain” concept because of my mixed bag of traits. While I tend to believe the findings in the article, ” lack of proof doesn’t prove the opposite.”

At age 66 my right shoulder rotator cuff was severely injured in a surfing accident. There was too much damage for surgery to be effective but with rehabilitation, I could use both arms to paddle for surfing. However, a lifetime sport, tennis, was out of the question. I decided to try with my left hand and with a lot of practice and patience, especially by my wife, I can now play almost as well with my left hand which is remarkable to me now age 68. I also grew up in an extremely alcoholic and dysfunctional family developing some nasty personal traits. This was aggravated by a ruptured right MCA aneurysm with a significant right brain insult, at age 28, causing some left sided weakness, pathfinding difficulties, and naming difficulties. I was in the middle of medical school and after 2 brain surgeries took a year off classes, but assisted in the anatomy lab and worked with a neurologist/physiatrist. When able, I began exercising, studying, and solving difficult mathematical problems in my head. Later, I began meditating and worked very hard on changing my very irritable personality. As my wife can attest, I changed remarkably over many years developing patience in addition to persistence, and becoming internally as well as externally calm. I did complete medical school and was first in the nation in my residency board exams, mentioned not to be self congratulating but to indicate how with hard work, even in the setting of a difficult childhood and a brain insult, one’s brain seems to have extensive plasticity as a young adult and even at an older age, but it does require very hard work.

Right brain/left brain, right?
Thank you for your enlightening discussion and information. I am a medical doctor trained in Nigeria, Switzerland and the United States. I am currently practicing in Nigeria where the issue of being Lesbian, Gay, Bisexual, Transsexual or Queer (LGBTQ) is a “Hot Button Issue!”. There is legislation against the act and recently a bunch of citizens were arrested for allegedly performing “Gay Acts” contrary to the law. This kind of action exists in some other African countries. After my exposure to Neuroscience in the US, and seeing and knowing personality changes that take place in people with brain damage after much common cerebrovascular disease in Nigeria, I came to the conclusion that, of course, certain areas of the brain, controls certain behaviors and specific actions. I personally believe that LGBTQ people are born that way. I respect all people of all creed and shades. In the country, people find it hard to understand that our brains may be different and that some people may have more, or fewer enhancements, rather biochemical, and less structural differences that influence their behaviors. There is evidence, that I have seen and studied myself, that the LGBTQ people are a variant of the mainstream and should be allowed to exist freely or protected. The question is: “has neuroscience conclusively, identified whether this group of people have a Right or Left sided brain dominance, or a biochemical difference in their brain activities that make them exist out of the mainstream of people? If so, I would appreciate more information and materials on this. In fact, there are many nuclear families here with children from the same parents, but one of them becomes an LGBTQ. The family cannot understand why and ascribes all kinds of non-scientific causes to the strange (to them) development. The person becomes miserable and lives a frustrated life. An estimated 60% of Nigerian families may be straight families consisting of a man a wife and children from both parents versus the likely 50% mixed marriage families that exist in the US, so the Nigerian family, where one person becomes an LGBTQ, may be an evidence of a genetic brain variant. I belong to the mainstream of the so called “straight people” but now confronted with the growing dilemma in the society and is neither an advocate or otherwise. Thank you.

Whenever I see ‘University of Utah’ I discount the findings. Didn’t they give us tabletop fusion and similar frauds? But your objection seems obviously sound. Unless the subject is engaged in drawing or calculating, equal activity levels don’t mean anything.

I am technically right-handed but do most things with my left hand. Brain-related or because my mother was a leftie and I do things the way she taught me? I don’t know. I believe I have mixed dominance my proof is almost universal confusion when I meet a revolving door — which way to push? I also often see things differently when I’m deep in right-brain mode and it can be bewildering. If I remember, LOL, I use a breathing technique to shift to left-brain mode and bingo, I can function better. It’s simple, involves holding one nostril closed, breathe in and count to four with opposite nostril, then hold that nostril closed and exhale with the first. Continue for five or six shifts. It really works. Would love for someone to test that!

On the recently TV brain competition show I watch, I wonder how some people able to sort their memory like a ‘file manager’. They can remember something and then they placed it somewhere in ‘their brain’. When they want to use it, they’ll remember it. It was said to be ‘thinking with your both sides of your brain’. If thinking with either left side or right side do exist, how do they or we control it? Is it also possible to use your both sides of the brain at the same time?

I guess it should follow that brain activity (i.e., electrical, blood flow or metabolism) indicates usage as in connecting with the outside world. But the brain is always metabolizing, receiving blood and producing some electrical activity. It is alive after all.

Is it possible that esoteric brain activities like intuition, analytical thinking and creative thinking might occur at the baseline or ground state of the human brain? Perhaps our observational tools cannot measure everything of importance going on in the brain.

Researches to resolve the righty-lefty issue should include deeper studies on the unified and coordinated roles of corpus callosum, the occipital lobes, the thalamus and the handedness phenomenon. Otherwise, all that right-left question remain a mystifying anomaly. One such example of this anomaly is me. I am writer with strong discursive skills in words and logic who is a visual artist — drawing, painting, sculpture, photography — right-handed and with strong physical preference for my left stances in martial arts. I and the few others like me would be curious about what science say on this myth.

I wonder about cross hemispheric individuals. I was tested in my youth and advised that indeed I had cross hemispheric or cross dominance symptoms. At the same time I was tested and found to have an IQ of 144. Not amazing as an IQ compared to many, but it did allow me to adapt and learn in new ways during my lifetime, at least to date.
I understand your thoughts on the research results. Certainly other research points to the fact that after brain trauma one can start to use other areas of the brain to take over functions for damaged areas.
The research you mention with the mathematician verses the artist brain scans were likely not conducted while the part was actively performing their said specialized skill (especially on the corpses). If so, then we would see certain areas of the brain that showed higher levels of activity that others. Also that the activity would be in many people in different areas since the neural pathways would have been built in their brain based on all environmental factors, age at the time of learning, and brain trauma earlier or later.
Also if you want your IQ to drop 50 points or more go to YouTube and you will find a renewed debate on Flat Earth. I went down that rabbit whole for 20 minutes today just out of interest in the failure of our educational system.

One of my co-workers believes in Flat Earth —in the 21st century. It boggles my mind.
He conscribes other ‘conspiracy theories’ as well, but believing in an idea in spite of overwhelming proof to the contrary takes the notion to whole further level of ignorance.

The failure of our educational system is very apparent on the roadways as you drive anywhere. People have become more and more stupid! Brain fog is everywhere. They think paying attention costs money!!

A person can either be right-brained or left-brained. It means that one side of the brain is dominant. The left-brained dominant people are methodical and analytical in nature. Those right-brained dominant are creative and artistic.

The left brain and right brain theory was created in the 1960s by a psychologist named Roger W. Sperry.

Left Brain, Right Brain: Two Sides, Always Working Together

Second of three monthly parts.

Researchers have known for decades that none of the sweeping assertions in the popular press about left brain/right brain differences are supported by solid science. (Roger Sperry, whose work unintentionally begin the pop-culture mythos, himself noted this… though his caveats were not widely heeded. More in part one of this thread.)

For example, the left hemisphere is often described as verbal and the right as perceptual—but this distinction doesn’t hold up as a generalization. In reality, both hemispheres typically contribute to both sorts of activities—but do so, often subtly, in different ways.

Consider language: Typically, the left hemisphere produces correct word order—to say, for instance, “I have two left feet” instead of “I two left feet have.” (Yoda’s fractured English may indicate that his alien brain didn’t include a human-standard left hemisphere.) But the right hemisphere also is crucial in language: It extracts the implied meaning—that the speaker doesn’t literally have two left feet but has trouble with physical coordination, much as a person would if she were cursed with actually having two feet shaped like the left one (each with the big toe on the right and the smallest toe on the far left).

And although it is true that the left hemisphere controls speech and plays a major role in grammar and comprehension, the right hemisphere plays a key role not only in our comprehending implied meaning but also in our understanding and producing verbal metaphors and humor, and it is largely responsible for helping us to decipher the meaning of changes in speaking tone, such as the rising tone at the end of a spoken question. And both hemispheres play critical roles in extracting meaning in general. Indeed, neuroimaging studies have conclusively shown that many aspects of language processing are distributed over both hemispheres.

Similarly, consider perception: For example, if you look at a house, the left hemisphere will allow you to register the shapes of the doors, windows, and other parts, while the right will allow you to take in the overall contours of the building. At the same time, the left hemisphere will specify the relative locations of the parts in terms of categories, such as “the window is left of the front door,” while the right hemisphere will specify locations in terms of specific distances, such as by indicating the precise distance the window is from the door. Again, brain imaging studies have conclusively shown that many aspects of perceptual processing are distributed over both hemispheres.

The sorts of documented differences between left-brain and right-brain functioning are hardly the stuff of popular generalizations, but they are fundamentally important to a genuine understanding of brain functioning. The fine print matters.

The larger issue is not just that people are being classified as “right-brained” or “left-brained” by so-called experts. It’s that the hemispheres are being classified in terms of simple overreaching dichotomies—such as the left’s being verbal, analytic, and logical, and the right’s being perceptual, intuitive, and emotional. It just doesn’t work that way.

Another fundamental flaw of the left/right story is that each of the specialized brain areas does not work alone but rather works as part of a system that includes many other brain areas—including areas on the opposite side of the brain.

To understand language fully, for example, you need to understand the grammar (which dictates the structure of sentences, which is better accomplished by the left hemisphere), the meaning of changes in tone (which is better accomplished by the right hemisphere), and how meaning is deciphered (which is accomplished by both hemispheres working together). In other words, the two hemispheres are part of a single system. A computer is a good example of a system: It has keyboard, active memory (“RAM”), a hard disk (or solid state storage system) for retaining information over time, a screen, speakers, and so on. All of the parts are designed to work together to accomplish specific goals (allowing you to write, to play music, and so on). No one part alone would accomplish much the power of the system lies in how the parts all work together. The same is true of the brain.

So the hemispheres do differ, but at a more specific and detailed level than is claimed in the popular press and on the Internet. One half-brain is not “logical” and the other “intuitive,” nor is one more “analytical” and the other more “creative.” Both halves play important roles in logical and intuitive thinking, in analytical and creative thinking, and so forth. All of the popular distinctions involve complex functions, which are accomplished by multiple processes—some of which may operate better in the left hemisphere and some of which may operate better in the right hemisphere—but the overall functions cannot be said to be entirely the province of one or the other hemisphere.

And far from having separate lives, the two halves work together. They are not isolated systems that compete or engage in some kind of cerebral tug-of-war one is not an undisciplined child, the other a spoilsport that throws schoolyard tantrums. Rather, as we have stressed, the brain is a single, marvelously complicated, and deeply integrated system. Like those of a well-maintained bicycle, the parts of the brain do have different functions—but, like the parts of a bike, they are designed to work together.

Finally, as we discussed earlier, there is solid evidence that none of us relies primarily on one or the other hemisphere. We all use all of our brains none of us are truly “left-brained” or “right-brained.”

In our next post, in June, we'll trace the media coverage that led to establishment of a myth.

Frontal Lobe Syndrome

Neuroanatomically, the frontal lobe is the largest lobe of the brain lying in front of the central sulcus. It is divided into 3 major areas defined by their anatomy and function. They are the primary motor cortex, the supplemental and premotor cortex, and the prefrontal cortex. Damage to the primary motor, supplemental motor, and premotor areas lead to weakness and impaired execution of motor tasks of the contralateral side. The inferolateral areas of the dominant hemisphere are the expressive language area (Broca area, Brodmann areas 44 and 45), to which damage will result in a non-fluent expressive type of aphasia. Frontal lobe syndrome, in general, refers to a clinical syndrome resulting from damage, and impaired function of the prefrontal cortex, which is a large association area of the frontal lobe. The areas involved may include the anterior cingulate, the lateral prefrontal cortex, the orbitofrontal cortex, and the frontal poles.

Frontal lobe syndrome is a broad term used to describe the damage of higher functioning processes of the brain such as motivation, planning, social behavior, and language/speech production. Although the etiology may range from trauma to neurodegenerative disease, regardless of the cause frontal lobe syndrome poses a difficult and complicated condition for physicians. Classically considered unique among humans, the frontal lobes are involved in a variety of higher functioning processing, such as regulating emotions, social interactions, and personality. The frontal lobes are critical for more difficult decisions and interactions that are essential for human behavior. However, with the spread of neurosurgery and procedures such as lobotomy and leucotomy for the treatment of psychiatric disorders, a variety of cases have illustrated the significant behavioral and personality changes due to frontal lobe damage. Harlow first described this collection of symptoms as "frontal lobe syndrome" after his research on the famous Phineas Gage who suffered a dramatic change in behavior as a result of trauma. Thus, an abnormality in the frontal lobe could dramatically change not only processing but personality and goal-oriented directed behavior.

Prior research has sought to identify the major areas where lesions may occur to cause the behavioral changes in frontal lobe disorders.

Ventromedial Orbitofrontal Cortex

Commonly known to cause “frontal lobe personality”, lesions in the orbitofrontal areas classically cause dramatic changes in behavior leading to impulsivity and a lack of judgment. Lesions are usually found in Broadmann’s Areas 10, 11, 12, and 47 is associated with a loss of inhibition, emotional lability, and inability to function appropriately in social interactions. The most popular case involving a lesion in this area is the case of Phineas Gage who had major behavioral changes after his trauma. However, in a study by Tranel and Damasio et al., a variety of other etiologies such as stroke and neoplasms may cause “frontal lobe personality.”

Anterior Cingulate and Dorsolateral Syndromes

Lesions in the areas around Brodmann areas 9 and 46 may cause deficits within working memory, rule-learning, planning, attention, and motivation. Recent studies have reinforced that DLPFC is critical for working memory function and in particular for monitoring and manipulating the content of working memory. DLPFC may also affect attention as several cases have documented patients complaining of attentional deficits after brain trauma. There are also psychiatric implications due to injury to DPFMC. Previous studies have researched how lesions in the DLPFC may cause "pseudo-depressive" syndrome associated with DLPFC associated with a loss of initiative, decreased motivation, reduced verbal output, and behavioral slowness (abulia). Other processing issues include rule learning, task switching, planning/ problem solving, and novelty detection and exogenous attention. The anterior cingulate cortex is important for the motivation behind attention, but may also be involved in a variety of psychiatric disorders such as depression, post-traumatic stress disorder (PTSD), and obsessive-compulsive disorder (OCD).

A new area of research within the dorsolateral frontal cortices revolves around "intuition." The frontal lobes can communicate with the limbic system and association cortex. In turn, this emotional influence associated with abstract decisions to create more efficient or “intuitive” decisions in a short span of time.

The Embryo Project Encyclopedia

In the 1950s and 1960s, Roger Sperry performed experiments on cats, monkeys, and humans to study functional differences between the two hemispheres of the brain in the United States. To do so he studied the corpus callosum, which is a large bundle of neurons that connects the two hemispheres of the brain. Sperry severed the corpus callosum in cats and monkeys to study the function of each side of the brain. He found that if hemispheres were not connected, they functioned independently of one another, which he called a split-brain. The split-brain enabled animals to memorize double the information. Later, Sperry tested the same idea in humans with their corpus callosum severed as treatment for epilepsy, a seizure disorder. He found that the hemispheres in human brains had different functions. The left hemisphere interpreted language but not the right. Sperry shared the Nobel Prize in Physiology or Medicine in 1981for his split-brain research.

Sperry also studied other aspects of brain function and connections in mammals and humans, beyond split-brains, in 1940s and 1950s. In 1963, he developed the chemoaffinity hypothesis, which held that the axons, the long fiber-like process of brain cells, connected to their target organs with special chemical markers. This explained how complex nervous systems could develop from a set of individual nerves. Sperry then also studied brain patterns in frogs, cats, monkeys, and human volunteers. Sperry performed much of his research on the split-brain at California Institute of Technology, or Caltech, in Pasadena, California, where he moved in 1954.

Sperry began his research on split-brain in late 1950s to determine the function of the corpus callosum. He noted that humans with a severed corpus callosum did not show any significant difference in function from humans with intact corpus callosum, even though their hemispheres could not communicate due to the severing of the corpus callosum. Sperry postulated that there should be major consequences from cutting the brain structure, as the corpus callosum connected the two hemispheres of the brain, was large, and must have an important function. Sperry began designing experiments to document the effects of a severed corpus callosum. At the time, he knew that each hemisphere of the brain is responsible for movement and vision on the opposite side of the body, so the right hemisphere was responsible for the left eye and vice versa. Therefore, Sperry designed experiments in which he could carefully monitor what each eye saw and therefore what information is was going to each hemisphere.

Sperry experimented with cats, monkeys, and humans. His experiments started with split-brain cats. He closed one of their eyes and presented them with two different blocks, one of which had food under it. After that, he switched the eye patch to the other eye of the cat and put the food under the other block. The cat memorized those events separately and could not distinguish between the blocks with both eyes open. Next, Sperry performed a similar experiment in monkeys, but made them use both eyes at the same time, which was possible due to special projectors and light filters. The split-brain monkeys memorized two mutually exclusive scenarios in the same time a normal monkey memorized one. Sperry concluded that with a severed corpus callosum, the hemispheres cannot communicate and each one acts as the only brain.

Sperry moved on to human volunteers who had a severed corpus callosum. He showed a word to one of the eyes and found that split-brain people could only remember the word they saw with their right eye. Next, Sperry showed the participants two different objects, one to their left eye only and one to their right eye only and then asked them to draw what they saw. All participants drew what they saw with their left eye and described what they saw with their right eye. Sperry concluded that the left hemisphere of the brain could recognize and analyze speech, while the right hemisphere could not.

In the 1960s when Sperry conducted his split-brain research on humans, multiple scientists were studying brain lateralization, the idea that one hemisphere of the brain is better at performing some functions than the other hemisphere. However, researchers did not know which tasks each side of the brain was responsible for, or if each hemisphere acted independently from the other.

Sperry describes his research in cats in the article "Cerebral Organization and Behavior" published in 1961. To test how the cutting of the corpus callosum affected mammals, Sperry cut the corpus callosum of multiple cats and had them perform some tasks that involved their vision and response to a visual stimulus. After severing each cat´s corpus callosum, he covered one of the cat´s eyes to monitor with which eye the cat could see. Sperry could switch the eye patch from one eye to the other, depending on which visual field he wanted the cat to use. Next, Sperry showed the cats two wooden blocks with different designs, a cross and a circle. Sperry put food for the cat under one of the blocks. He taught the cats that when they saw the blocks with one eye, for instance, the right eye, the food was under the circle block, but when they saw it with the left eye, the food was under the block with a cross. Sperry taught the cats to differentiate between those two objects with their paws, pushing the correct wooden block away to get the food.

When Sperry removed the eye patch and the cats could see with both eyes, he performed the same experiment. When the cats could use both eyes, they hesitated and then chose both blocks almost equally. The right eye connects to the left hemisphere and the left eye connects to the right hemispheres. Sperry suspected that since he cut the corpus callosum in those cats, the hemispheres could not communicate. If the hemispheres could not communicate and the information from one eye only went to one hemisphere, then only that hemisphere would remember which block usually had food under it. From that, Sperry concluded that the cats remembered two different scenarios with two different hemispheres. He suspected that the cats technically had two different brains, as their hemispheres could not interact and acted as if the other one did not exist.

Sperry performed a similar experiment with monkeys, in which he also cut their corpus callosum. He wanted to test if both hemispheres could operate at the same time, even though they were not connected. That required separation of visual fields, or making sure that the right eye saw a circle, while the left eye saw a cross, like in the cat experiment, but without an eye patch and both eyes would see something at the same time instead of interchanging between the open eyes. Sperry solved that by using two projectors that were positioned side-by-side at an angle and showed mutually exclusive images. For example, the projector on the right showed a circle on the left and a cross on the right, while the projector on the left showed a cross on the left and a circle on the right. Sperry placed special light filters in front of each of the monkey´s eyes. The light filters made it so that each eye saw the images from only one of the projectors. That meant one of the eyes saw the circle on the right and the cross on the left, while the other eye saw the cross on the right and the circle on the left. From his experiments with cats, Sperry knew that there was no sharing of information from right and the left hemispheres, so he made the monkeys memorize two different scenarios at the same time.

The left eye saw a scenario where food would be dispersed when the monkey pressed the button corresponding to a cross, while the right eye saw a scenario where food would be dispersed when the monkey pressed a button corresponding to a circle. Ultimately, it was the same button, but the eyes saw it differently because of two projectors and special light filters. Sperry concluded that both hemispheres of the brain were learning two different, reversed, problems at the same time. He noted that the split-brain monkeys learned two problems in the time that it would take a normal monkey to learn one, which supported the assumption that the hemispheres were not communicating and each one was acting as the only brain. That seemed as a benefit of cutting corpus callosum, and Sperry questioned whether there were drawbacks to the procedure.

Sperry performed the next set of experiments on human volunteers, who had their corpus callosum severed previously due to outside factors, such as epilepsy. Sperry asked volunteers to perform multiple tests. From his previous experiments with cats and monkeys, Sperry knew that one, the opposite, hemisphere of the brain would only analyze information from one eye and the hemispheres would not be able to communicate to each other what they saw. He asked the participants to look at a white screen with a black dot in the middle. The black dot was the dividing point for the fields of view for a person, so the right hemisphere of the brain analyzed everything to the left of the dot and the left hemisphere of the brain analyzed everything that appeared to the right of the dot. Next, Sperry showed the participants a word on one side of the black dot for less than a second and asked them to tell him what they saw. When the participants saw the word with their right eye, the left hemisphere of the brain analyzed it and they were able to say what they saw. However, if the participants saw the word with their left eye, processed by right hemisphere, they could not remember what the word was. Sperry concluded that the left hemisphere could recognize and articulate language, while the right one could not.

Sperry then tested the function of the right hemisphere. He asked the participants of the same experiment that could not remember the word because it was in the left visual field to close their eyes and draw the object with their left hand, operated by the right hemisphere, to which he presented the word. Most people could draw the picture of the word they saw and recognize it. Sperry also noted that if he showed the word to the same visual field twice, then the person would recognize it as a word they saw, but if he showed it to the different visual fields, then the participants would not know that they saw the word before. Sperry concluded that the left hemisphere was responsible not only for articulating language, but also for understanding and remembering it, while the right hemisphere could only recognize words, but was not able to articulate them. That supported the previously known idea that the language center was in the left hemisphere.

Sperry performed another similar experiment in humans to further study the ability of the right hemisphere to recognize words. During that experiment, Sperry asked volunteers to place their left hand into a box with different tools that they could not see. After that, the participants saw a word that described one of the objects in the box in their left field of view only. Sperry noted that most participants then picked up the needed object from the box without seeing it, but if Sperry asked them for the name of the object, they could not say it and they did not know why they were holding that object. That led Sperry to conclude that the right hemisphere had some language recognition ability, but no speech articulation, which meant that the right hemisphere could recognize or read a word, but it could not pronounce that word, so the person would not be able to say it or know what it was.

In his last series of experiments in humans, Sperry showed one object to the right eye of the participants and another object to their left eye. Sperry asked the volunteers to draw what they saw with their left hand only, with closed eyes. All the participants drew the object that they saw with their left eye, controlled by the right hemisphere, and described the object that they saw with their right eye, controlled by the left hemisphere. That supported Sperry´s hypothesis that the hemispheres of brain functioned separately as two different brains and did not acknowledge the existence of the other hemisphere, as the description of the object did not match the drawing. Sperry concluded that even though there were no apparent signs of disability in people with a severed corpus callosum, the hemispheres did not communicate, so it compromised the full function of the brain.

Sperry received the 1981 Nobel Prize in Physiology or Medicine for his split-brain research. Sperry discovered that the left hemisphere of the brain was responsible for language understanding and articulation, while the right hemisphere could recognize a word, but could not articulate it. Many researchers repeated Sperry´sf experiments to study the split-brain patterns and lateralization of function.

Joining the two (ages 4 to 10)

  • Provide the child with finger paint paper along with a variety of colors of finger paint. Play music while he explores the finger paint encouraging him to make lines and shapes along to the music.
  • Once the finger paint is dry, the child can use a black marker to create a drawing over the finger paint. Encourage him to find shapes and lines to connect together in creating a realistic finished drawing. Allow the child to work in silence while he’s finishing his drawing.
  • After the child has completed his artwork, discuss the finished piece giving his frontal lobe and visual cortex a boost.

No matter the age of the child, spend time looking at, discussing, and creating art. This will stimulate his frontal lobe, visual cortex, and help train his right and left-brain to work together.

About the author - Sarah Lipoff

Sarah is an art educator and parent. You can visit her website here.

The left brain/ right brain myth

This "right brain vs left brain test" from the Herald Sun is doing the rounds on the internet today. The article contains the so-called "spinning silhouette" optical illusion (below), and states that if you see the the dancer rotating in a clockwise direction "you use more of the right side of your brain and vice versa."

You've probably heard this left/ right brain dichotomy before. It goes something like this: the left hemisphere of the brain is logical, deductive, mathematical, etc., while the right hemisphere is artistic, visual and imaginative. The idea stems at least partly from the classic studies of split brain patients performed by Sperry and Gazzaniga in the 1960s.

There are some functional asymmetries in the brain, and it is true that certain regions of both hemispheres are specialized for particular functions. Speech illustrates this, but also shows that nothing is ever so simple when it comes to the brain: in most right-handed people, speech is processed in both hemispheres, but predominantly in the left. In some left-handers, speech is processed either predominantly in the right hemisphere or on both sides.

So the notion that someone is "left-brained" or "right-brained" is absolute nonsense. All complex behaviours and cognitive functions require the integrated actions of multiple brain regions in both hemispheres of the brain. All types of information are probably processed in both the left and right hemispheres (perhaps in different ways, so that the processing carried out on one side of the brain complements, rather than substitutes, that being carried out on the other).

When I first saw this illusion, I perceived the silhouette as spinning in a clockwise direction. But after staring at it for a while, it appeared to be rotating in the opposite direction. It took some time, but it happened eventually.

The effect can also be achieved by covering the silhouette and focusing on the shadow after you've looked at the illusion. When you uncover it, the image will suddenly appear to be rotating in the opposite direction.

Optical illusions can tell us much about the functioning of the brain's visual system. They work because the visual system reconstructs stimuli not according to how they actually are, but by making certain assumptions about their properties in order to "fill in the gaps".

It is unclear exactly how this illusion works, but it probably has something to do with the brain's representation of an ambiguous object. The silhouette is two-dimensional, but because almost all the objects we encounter are three-dimensional, the visual system reconstructs it as such. And the silhouette is not actually spinning - that is one of the assumptions made by the visual system. So, we perceive it as spinning in one direction one minute, and in the other the next.

A discovery that "literally changes the textbook"

The network of nerves connecting our eyes to our brains is sophisticated and researchers have now shown that it evolved much earlier than previously thought, thanks to an unexpected source: the gar fish.

Michigan State University's Ingo Braasch has helped an international research team show that this connection scheme was already present in ancient fish at least 450 million years ago. That makes it about 100 million years older than previously believed.

"It's the first time for me that one of our publications literally changes the textbook that I am teaching with," said Braasch, as assistant professor in the Department of Integrative Biology in the College of Natural Science.

This work, published in the journal Science on April 8, also means that this type of eye-brain connection predates animals living on land. The existing theory had been that this connection first evolved in terrestrial creatures and, from there, carried on into humans where scientists believe it helps with our depth perception and 3D vision.

And this work, which was led by researchers at France's Inserm public research organization, does more than reshape our understanding of the past. It also has implications for future health research.

Studying animal models is an invaluable way for researchers to learn about health and disease, but drawing connections to human conditions from these models can be challenging.

Zebrafish are a popular model animal, for example, but their eye-brain wiring is very distinct from a human's. In fact, that helps explain why scientists thought the human connection first evolved in four-limbed terrestrial creatures, or tetrapods.

"Modern fish, they don't have this type of eye-brain connection," Braasch said. "That's one of the reasons that people thought it was a new thing in tetrapods."

Braasch is one of the world's leading experts in a different type of fish known as gar. Gar have evolved more slowly than zebrafish, meaning gar are more similar to the last common ancestor shared by fish and humans. These similarities could make gar a powerful animal model for health studies, which is why Braasch and his team are working to better understand gar biology and genetics.

That, in turn, is why Inserm's researchers sought out Braasch for this study.

"Without his help, this project wouldn't have been possible," said Alain Chédotal, director of research at Inserm and a group leader of the Vision Institute in Paris. "We did not have access to spotted gar, a fish that does not exist in Europe and occupies a key position in the tree of life."

To do the study, Chédotal and his colleague, Filippo Del Bene, used a groundbreaking technique to see the nerves connecting eyes to brains in several different fish species. This included the well-studied zebrafish, but also rarer specimens such as Braasch's gar and Australian lungfish provided by a collaborator at the University of Queensland.

In a zebrafish, each eye has one nerve connecting it to the opposite side of the fish's brain. That is, one nerve connects the left eye to the brain's right hemisphere and another nerve connects its right eye to the left side of its brain.

The other, more "ancient" fish do things differently. They have what's called ipsilateral or bilateral visual projections. Here, each eye has two nerve connections, one going to either side of the brain, which is also what humans have.

Armed with an understanding of genetics and evolution, the team could look back in time to estimate when these bilateral projections first appeared. Looking forward, the team is excited to build on this work to better understand and explore the biology of visual systems.

"What we found in this study was just the tip of the iceberg," Chédotal said. "It was highly motivating to see Ingo's enthusiastic reaction and warm support when we presented him the first results. We can't wait to continue the project with him."

Both Braasch and Chédotal noted how powerful this study was thanks to a robust collaboration that allowed the team to examine so many different animals, which Braasch said is a growing trend in the field.

The study also reminded Braasch of another trend.

"We're finding more and more that many things that we thought evolved relatively late are actually very old," Braasch said, which actually makes him feel a little more connected to nature. "I learn something about myself when looking at these weird fish and understanding how old parts of our own bodies are. I'm excited to tell the story of eye evolution with a new twist this semester in our Comparative Anatomy class."

(Note for media: Please include a link to the original paper in online coverage: https:/ / doi. org/ 10. 1126/ science. abe7790)

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