The Left and Right Brain Hemispheres: Independent Centers of Consciousness?
"I'm of two minds on the matter." "I can't make up my mind." "I'm having an internal argument." Our language is full of idioms that make it sound as if there were two disagreeing voices inside our heads. Often, that is indeed how it feels. But is that sensation physiologically supported? Can a brain fight with itself? Can there be multiple independent centers of consciousness in a single head? Until the 1960s, there was no way for us to test this feeling of internal disagreement. But when a surgery aimed at alleviating epileptic seizures also isolated the two hemispheres of the patient's brain, science was surprisingly afforded that opportunity.
Background
The left and right hemispheres of the brain are connected by a dense bundle of neurons called the corpus callosum. This bundle is primarily responsible for communication of information between the two hemispheres, connecting them with approximately 200 million callosal axons (in humans.) (1) In some cases of multifocal epilepsy, the electrical discharges that cause seizures can start in one hemisphere and spread to the other by way of the corpus callosum, greatly increasing the severity of the fit. Sometimes this condition is unresponsive to medication, at which point the spasms can only be controlled with more drastic measures.(2)
In 1961, Dr. Michael Gazzaniga performed an operation which had been pioneered on animals by Drs. Ronald Meyers and Roger Sperry, but which had never before been tested on human patients. In this procedure, called a commissurotomy, the surgeon opens the skull, lays back the brain coverings with a cerebral retractor, and cuts through the corpus callosum. While this prevents a seizure from spreading, it also prevents information from being passed between hemispheres. Thanks to Dr. P. J. Vogel, we now know that severing the anterior ¾ of the corpus callosum can effectively stop the spread of a seizure, while allowing full communication between the hemispheres to remain. (3) However, the behavior of full-commissurotomy patients has been extensively documented, and provides fascinating insight into the specialization of the hemispheres, the nature of the brain, and the nature of consciousness itself.
Results
To understand these behaviors, one must first remember that neurological wiring of the body is, for the most part, contralateral. Signals travel from the left side of the body to the right hemisphere of the brain and back, and vice versa.
The concept about the split-brain cases is two hemisphere separate apart, where means the left side focus on the left side, the right side focus on the right side (Parfit 378). He thinks that the concept of the split-brain and the normal brain are both true. Parfit denies that there are no person involved, also the ego theory doesn’t exist. He believes that once the brain has split apart, it has two separate streams of consciousness (Parfit 378). So, he claims that instead of asking “what happened to the original self?,” he says there is no ‘self’ (Parfit 379). Even though there are different events happened at the same time, that is not equal to different egos. “There are not here two different possibilities, one of which be true. These are
Derek Parfit, one of the most important defender of Hume, addresses the puzzle of the non-identity problem. Parfit claims that there is no self. This statement argues against the Ego Theory, which claims that beneath experience, a subject or self exists. Ego Theorists claims that the unity of a person’s whole life including life experiences is also known as the Cartesian view, which claims that each person is a “persisting purely mental thing.” Parfit uses the Split-Brain Case, which tells us something interesting about personal identity, to invalidate the Ego Theory. During the Split Brain procedure, there are neither ‘persons’ nor ‘persons’ before the brain was split. Within the experiment, the patient has control of their arms, and sees what is in half of their visual fields with only one of their hemispheres. However, when the right and left hemisphere disconnect, the patient is able to receive two different written questions targeted to the two halves of their visual field; thus, per hand, they write two different answers. In a split brain case, there are two streams of consciousness and Parfit claims that the number of persons involved is none. The scenario involves the disconnection of hemispheres in the brain. The patient is then placed in front of a screen where the left half of a screen is red and the right half is blue. When the color is shown to one hemisphere and the patient is asked, “How many colors do you see,” the patient, with both hands, will write only one color. But when colors are shown to both sides of the hemisphere, the patient with one hand writes red and the other writes blue.
views on marginal places, activities, and things, and think that everyone should have their own
Scientists are on the brink of doing the unthinkable-replenishing the brains of people who have suffered strokes or head injuries to make them whole again. If that is not astonishing enough, they think they may be able to reverse paralysis. The door is at last open to lifting the terrifying sentence these disorders still decree-loss of physical function, cognitive skills, memory, and personality.
Epilepsy, also known as “seizure disorder,” or “seizure attack,” is the fourth most common neurological disorder known to mankind, affecting an estimated 2.3 million adults and 467,711 children in the United States. Unfortunately this disorder is becoming far more common and widespread worldwide. This staggering number of cases of people suffering from Epilepsy also involves an average growth rate of 150,000 new cases each year in the United States alone. Generally, many of the people who develop who are a part of the new are mainly either young children or older adults. Your brain communicates through chemical and electrical signals that are all specialized for specific tasks. However, through the process of communication, chemical messengers, also known as neurotransmitters can suddenly fail, resulting in what is known as a seizure attack. Epilepsy occurs when a few too many brain cells become excited, or activated simultaneously, so that the brain cannot function properly and to it’s highest potential. Epilepsy is characterized when there is an abnormal imbalance in the chemical activity of the brain, leading to a disruption in the electrical activity of the brain. This disruption specifically occurs in the central nervous system (CNS), which is the part of the nervous system that contains the brain and spinal cord. This causes an interruption in communication between presynaptic neurons and postsynaptic neurons; between the axon of one neuron, the message sender and the dendrite of another neuron, the message recipient. Consequently, the effects that epileptic seizures may induce may range anywhere from mild to severe, life-threatening ramifications and complications. There are many different types of seizures associa...
Recently, however, intracortical recordings of epileptic patients and of mouse brain during sleep found evidence that the brain can have region...
Anorexic behavior is complex because it is all about the need for control. Someone suffering from anorexia has a distorted body image of himself or herself. He/she believes to be overweight, even though twenty percent of the time he/she is not (Yancey 59). The image of being overweight causes a low self-esteem. Symptoms of low self-esteem are loneliness, inadequacy in talents, a lack of trust in people and themselves, insecurity, identification with a specific peer group, and sadness. The media displays the ideal human body as thin and beautiful. Anorexic’s lives are full of confusion and lack of control. To the anorexic, to be thin is to be in control. The state of control to the anorexic is the ideal life without confusion and difficulties. In most cases, the anorexic is intelligent; popular among his/her peers, athletic, talented, and viewed as a role model to most people he/she comes in contact with. In reality, the issues in daily living are too difficult for the anorexic resulting in a lack of control in his/her life. The anorexic’s answer to a confusing life is to starve the body. The behavioral symptoms of the anorexia are counting calories, eating little food, baking treats for everyone and giving them away in hope of controlling not only the anorexic’s intake of his/her food, but also others. “Playing” with food at meal times is common behavior of the anorexic. When the meal is complete, the anorexic has disguised food intake by pushing the food around on the plate and hiding food in napkins. To dress in layers to hide the distinct weight loss and to avoid social activities where eating is involved are common behavioral symptoms. Behavioral symptoms of the anorexic can go unnoticed by most people. These symptoms are very secretive and oblivious to outsiders because the behavior is not out of the ordinary. Although the behavioral symptoms of the anore...
This paper is going to discuss the condition Epilepsy. Epilepsy is defined as a disorder of the brain characterized by the recurrence of unprovoked seizures (Shorvon, 2009). Epilepsy starts in your brain, the brain is like a computer, it is made up of a mass of cells, called neurons, which connect to each other in very complicated ways (Routh, 2004). Electrical messages are constantly being passed from one neuron to another down nerves to the muscles in the body (Mair, 2004). If a person has epilepsy, these cells sometimes send a sudden, unexpected burst of electrical impulses, which causes a seizure (Routh, 2004). When the seizure finishes the brain behaves normally again. For some people with epilepsy these seizures happen every day. For others they may happen only once or twice a year (Routh, 2004). There are over 40 different types of seizure and each person is slightly different, but there are a few common types (Routh, 2004). Generalized seizures which affect the whole brain and partial seizures which affect a small part of the brain (Miller, 2013). The most common types of ge...
The brain has four major lobes. The frontal lobe, the parietal lobe, the occipital lobe, and temporal lobe are responsible for all of the activities of the body, from seeing, hearing, tasting, to touching, moving, and even memory. After many years of debating, scientist presents what they called the localization issue, Garret explains how Fritsch and Hitzig studied dog with conforming observations, but the cases of Phineas Gage’s accident in 1848 and Paul Broca’s autopsy of a man brain in 1861 really grabbed the attention of an enthusiastic scientific community (Garret 2015 p.6)
Brain Lateralization is a complex and ongoing process by which differing regions of the brain “take over” the functioning of specific behaviors and cognitive skills. Lateralization literally means that certain functions are located (in part or total) on one side of the brain.
The diagnosis of epilepsy is usually made after the patient experiences a second unprovoked seizure (Leppik, 2002). Diagnosis is often difficult, however, since it is unlikely that the physician will actually see the patient experience and epileptic seizure, and therefore must rely heavily on patient’s history. An electroencephalography (EEG) is often used to examine the patient’s brain waves, and some forms of epilepsy can be revealed by a characteristic disturbance in electrical frequency (Bassick, 1993). The variations in frequency can take form as spikes or sharp waves (Fisher, 1995). The variations are divided into two groups, ictal electrograph abnormalities, which are disturbances resulting from seizure activity, and interictal electrograph abnormalities, or disturbances between seizures. The EEG can also give clues as to which region of the brain the disturbances arise from. Interictal temporal spikes will predict the side of seizure origin in 95% of patients if three times as ...
Roger Sperry is one of the big Neurobiologists in the 1950’s. Sperry studied the relationship of the right and left hemispheres of the brain. In one of his experiments he flashed the word “Fork” in front of the patient. If the patient was asked to say the word he could not but if asked to right the word he would start to right the word “Fork”. This happed when the two brain hemispheres were disconnected from each other. At an another experiment he placed a toothbrush in the patients left hand and blind folded the patient and was asked to identify it they could not do it. But if placed in the right hand the patient would know right away what it was. That is just one of the types of study he did in his time.
In philosophy, the critical analysis on the relationship between the brain and mind is known the mind body problem. The following schools of thought have tried to solve the mind body problem. Dualism, this school of thought subscribes to the belief that the mind and brain exist independently of each other. Other dualists deny the fact that the mind is a part of the brain. This is because the mind and brain don’t share same
Sperry, R. W. (1982, September 24). Some Effects of Disconnecting the Cerebral Hemispheres. Science Megazine, 217, 1223-1226.
In the video "Powerful Stoke of Insight," Dr. Taylor share a personal story of how she experienced when she had a stoke years ago. She vividly illustrated the distinct functions of left hemisphere and right hemisphere. Since her stoke occurred in the left hemisphere, she had a hard time to process language during the tragic event happened. She was paralysis and could not understand any of the word from 911 telephone operator when she finally reached the phone. According to Dr. Taylor, "Our right human hemisphere is all about this present moment, [and] our left hemisphere thinks linearly and methodically." Due to the reason that her stoke damaged her left hemisphere, she could not think logically at the moment. This presentation thoroughly explain the concept of lateralization in biological psychology research method. I find it very interesting because I never learn that each hemisphere do in charge of different functions that affecting our