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Here is an essay on ‘Behavioural Neuroscience’ for class 11 and 12. Find paragraphs, long and short essays on ‘Behavioural Neuroscience’ especially written for school and college students.
Essay on Behavioural Neuroscience
Essay Contents:
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- Essay on the Introduction to Behavioural Neuroscience
- Essay on Behavioural Neuroscience and Human Consciousness
- Essay on the Nature of Behavioural Neuroscience
- Essay on the Biological Roots of Behavioural Neuroscience
Essay # 1. Introduction to Behavioural Neuroscience:
Behavioural neuroscience, also known as biological psychology, biopsychology, or psychobiology is the application of the principles of biology, to the study of physiological, genetic, and developmental mechanisms of behaviour in human and non-human animals. It typically investigates at the level of nerves, neurotransmitters, brain circuitry and the basic biological processes that underlie normal and abnormal behaviour.
Most typically, experiments in behavioural neuroscience involve non-human animal models which have implications for better understanding of human pathology and therefore contribute to evidence-based practice.
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Behavioural neuroscience as a scientific discipline emerged from a variety of scientific and philosophical traditions in the 18th and 19th centuries. In philosophy, men like Rene Descartes proposed physical models to explain animal and human behaviour.
Descartes, for example, suggested that the pineal gland, a midline unpaired structure in the brain of many organisms, was the point of contact between mind and body. Descartes also elaborated on a theory in which the pneumatics of bodily fluids could explain reflexes and other motor behaviour. This theory was inspired by moving statues in a garden in Paris.
From the earliest historical times, people have believed that they possessed something intangible that animated them- a mind, a soul, or a spirit. This belief stems from the fact that each of us is aware of his or her own existence.
Within our bodies, the nervous system plays a central role, receiving information from the sensory organs and controlling the movements of the muscle—but what is the mind, and what role does it play? Does it control the nervous system? Is it a part of the nervous system? Is it physical and tangible, like the rest of the body, or is it a spirit that will always remain hidden?
In many cases, humans may serve as experimental subjects in behavioural neuroscience experiments; however, a great deal of the experimental literature in behavioural neuroscience comes from the study of non-human species, most frequently rats, mice, and monkeys.
As a result, a critical assumption in behavioural neuroscience is that organisms share biological and behavioural similarities, enough to permit extrapolations across species. This allies behavioural neuroscience closely with comparative psychology, evolutionary psychology, evolutionary biology, and neurobiology.
Behavioural neuroscience also has paradigmatic and methodological similarities to neuropsychology, which relies heavily on the study of the behaviour of humans with nervous system dysfunction.
Essay # 2. Behavioural Neuroscience and Human Consciousness:
How can behavioural neuroscientists study human consciousness? First, let’s define our terms. The word consciousness can be used to refer to a variety of concepts, including simple wakefulness. Thus, a researcher may write about an experiment using “conscious rats,” referring to the fact that the rats were awake and not anesthetized.
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We know that brain damage or drugs can profoundly affect consciousness. Because consciousness can be altered by changes in the structure or chemistry of the brain, we may hypothesize that consciousness is a physiological function, just as behaviour is. We can even speculate about the origins of this self-awareness.
Verbal communication makes cooperation possible and permits us to establish customs and laws of behaviour. Perhaps the evolution of this ability is what has given rise to the phenomenon of consciousness.
Split Brains:
Studies of humans who have undergone a particular surgical procedure demonstrate dramatically how disconnecting parts of the brain that are involved with perceptions from parts involved with verbal behaviour also disconnects them from consciousness. These results suggest that the parts of the brain involved in verbal behaviour may be the ones responsible for consciousness.
The surgical procedure is one that has been used for people with very severe epilepsy that cannot be controlled by drugs. In these people, nerve cells in one side of the brain become overactive, and the over-activity is transmitted to the other side of the brain by a structure called the corpus callosum. The corpus callosum is a large bundle of nerve fibers that connect corresponding parts of one side of the brain with those of the other.
Both sides of the brain then engage in wild activity and stimulate each other, causing a generalized epileptic seizure. These seizures can occur many times each day, preventing the person from leading a normal life. Neurosurgeons discovered that cutting the corpus callosum greatly reduced the frequency of the epileptic seizures.
The corpus callosum enables the two hemispheres to share information so that each side knows what the other side perceives and what is being done. After the split-brain operation is performed, the two hemispheres are disconnected and operate independently. Their sensory mechanisms, memories, and motor systems can no longer exchange information.
The effects of these disconnections are not obvious to the casual observer, for the simple reason that only one hemisphere—in most people, the left—controls speech. The right hemisphere of an epileptic person with a split brain appears to be able to understand verbal instructions reasonably well, but it is incapable of producing speech.
Because only one side of the brain can talk about what it is experiencing, people who speak with a person with a split brain are conversing with only one hemisphere- the left. The operations of the right hemisphere are more difficult to detect. Even the patient’s left hemisphere has to learn about the independent existence of the right hemisphere. One of the first things that these patients say they notice after the operation is that their left hand seems to have a “mind of its own.”
One exception to the crossed representation of sensory information is the olfactory system; that is, when a person sniffs a flower through the left nostril, only the left brain receives a sensation of the odour. Thus, if the right nostril of a patient with a split brain is closed, leaving only the left nostril open, the patient will be able to tell us what the odours are.
However, if the odour enters the right nostril, the patient will say that he or she smells nothing when, in fact, the right brain has perceived the odour and can identify it. To show that this is so, we ask the patient to smell an odour with the right nostril and then reach for some objects that are hidden from view by a partition.
If asked to use the left hand, controlled by the hemisphere that detected the smell, the patient will select the object that corresponds to the odour—a plastic flower for a floral odour, a toy fish for a fishy odour, a model tree for the odour of pine, and so forth. However, if asked to use the right hand, the patient fails the test because the right hand is connected to the left hemisphere, which did not smell the odour.
The effects of cutting the corpus callosum reinforce the conclusion that we become conscious of something only if information about it is able to reach the parts of the brain responsible for verbal communication, which are located in the left hemisphere. If the information does not reach these parts of the brain, then that information does not reach the consciousness associated with these mechanisms.
Essay # 3. Nature of Behavioural Neuroscience:
The modern history of behavioural neuroscience has been written by psychologists who have combined the experimental methods of psychology with those of physiology and have applied them to the issues that concern all psychologists.
Thus, we have studied perceptual processes, control of movement, sleep and waking, reproductive behaviours, ingestive behaviours, emotional behaviours, learning, and language. In recent years, we have begun to study the physiology of human pathological conditions, such as addictions and mental disorders.
Goals of Research:
The goal of all scientists is to explain the phenomena they study. But what do we mean by explain? Scientific explanation takes two forms- generalization and reduction. Most psychologists deal with generalization. They explain particular instances of behaviour as examples of general laws, which they deduce from their experiments.
For instance, most psychologists would explain a pathologically strong fear of dogs as an example of a particular form of learning called classical conditioning. Presumably, the person was frightened earlier in life by a dog. An unpleasant stimulus was paired with the sight of the animal, and the subsequent sight of dogs evokes the earlier response- fear.
Most physiologists deal with reduction. They explain complex phenomena in terms of simpler ones. For example, they may explain the movement of a muscle in terms of the changes in the membranes of muscle cells, the entry of particular chemicals, and the interactions among protein molecules within these cells.
By contrast, a molecular biologist would explain these events in terms of forces that bind various molecules together and cause various parts of the molecules to be attracted to one another. In turn, the job of an atomic physicist is to describe matter and energy themselves and to account for the various forces found in nature.
Practitioners of each branch of science use reduction to call on sets of more elementary generalizations to explain the phenomena they study. The task of the behavioural neuroscientist is to explain behaviour in physiological terms—but behavioural neuroscientists cannot simply be reductionists.
It is not enough to observe behaviours and correlate them with physiological events that occur at the same time. Identical behaviours may occur for different reasons and thus may be initiated by different physiological mechanisms. Therefore, we must understand “psychologically” why a particular behaviour occurs before we can understand what physiological events made it occur.
A non-pregnant mouse will build a nest only if the weather is cool, whereas a pregnant mouse will build one regardless of the temperature. The same behaviour occurs for different reasons. In fact, nest-building behaviour is controlled by two different physiological mechanisms.
Nest building can be studied as a behavior, related to the process of temperature regulation, or it can be studied in the context of parental behaviour. In practice, the research efforts of behavioural neuroscientists involve both forms of explanation- generalization and reduction.
Ideas for experiments are stimulated by the investigator’s knowledge both of psychological generalizations about behaviour and of physiological mechanisms. A good behavioural neuro-scientist must therefore be both a good psychologist and a good physiologist.
Essay # 4. Biological Roots of Behavioural Neuroscience:
Study of (or speculations about) the physiology of behaviour has its roots in antiquity. Because its movement is necessary for life and because emotions cause it to beat more strongly, many ancient cultures, including the Egyptian, Indian, and Chinese, considered the heart to be the seat of thought and emotions. The ancient Greeks did, too, but Hippocrates concluded that this role should be assigned to the brain.
Not all ancient Greek scholars agreed with Hippocrates. Aristotle did not; he thought that the brain served to cool the passions of the heart. But Galen, who had the greatest respect for Aristotle, concluded that Aristotle’s role for the brain was utterly absurd, since in that case Nature would not have placed the encephalon so far from the heart,… and she would not have attached the sources of all the senses to it. Galen gone through enough of the brain to dissect and study the brains of cattle, sheep, pigs, cats, dogs, weasels, monkeys, and apes.
René Descartes, a seventeenth-century French philosopher and mathematician, has been called the father of modern philosophy. Although he was not a biologist, his speculations about the roles of the mind and brain in the control of behaviour provide a good starting point in the history of behavioural neuroscience.
Descartes assumed that the world was a purely mechanical entity that, once having been set in motion by God, ran its course without divine interference. Thus, to understand the world, one had to understand how it was constructed. To Descartes, animals were mechanical devices; their behaviour was controlled by environmental stimuli.
His view of the human body was much the same — It was a machine. As Descartes observed, some movements of the human body were automatic and involuntary. For example, if a person’s finger touched a hot object, the arm would immediately withdraw from the source of stimulation.
Reactions like this did not require participation of the mind; they occurred automatically. Descartes called these actions reflexes. Energy coming from the outside source would be reflected back through the nervous system to the muscles, which would contract. The term is still in use today, but of course we explain the operation of a reflex differently.
Like most philosophers of his time, Descartes was a dualist; he believed that each person possesses a mind — a uniquely human attribute that is not subject to the laws of the universe. But his thinking differed from that of his predecessors in one important way- He was the first to suggest that a link exists between the human mind and its purely physical housing, the brain.
He believed that the sense organs of the body supply the mind with information about what is happening in the environment, and that the mind, using this information, controls the movements of the body. In particular, he hypothesized that the interaction between mind and body takes place in the pineal body, a small organ situated on top of the brain stem, buried beneath the cerebral hemispheres.
He noted that the brain contains hollow chambers (the ventricles) that are filled with fluid, and he believed that this fluid is under pressure. In his theory, when the mind decides to perform an action, it tilts the pineal body in a particular direction like a little joystick, causing pressurized fluid to flow from the brain into the appropriate set of nerves. This flow of fluid causes the same muscles to inflate and move.
As we saw in the prologue, the young Rene Descartes was greatly impressed by the moving statues in the royal gardens. These devices served as models for Descartes in theorizing about how the body worked. The pressurized water of the moving statues was replaced by pressurized fluid in the ventricles; the pipes were replaced by nerves; the cylinders by muscles; and finally, the hidden valves by the pineal body.
This story illustrates one of the first times that a technological device was used as a model for explaining how the nervous system works. In science, a model is a relatively simple system that works on known principles and is able to do at least some of the things that a more complex system can do.
For example, when scientists discovered that elements of the nervous system communicate by means of electrical impulses, researchers developed models of the brain based upon telephone switchboards and, more recently, computers. Abstract models, which are completely mathematical in their properties, have also been developed.
Descartes’s model was useful because, unlike purely philosophical speculations, it could be tested experimentally. In fact, it did not take long for biologists to prove that Descartes was wrong. For example, Luigi Galvani, a seventeenth-century Italian physiologist, found that electrical stimulation of a frog’s nerve caused contraction of the muscle to which it was attached.
Contraction occurred even when the nerve and muscle were detached from the rest of the body, so the ability of the muscle to contract and the ability of the nerve to send a message to the muscle were characteristics of these tissues themselves. Thus, the brain did not inflate muscles by directing pressurized fluid through the nerve.
Galvani’s experiment prompted others to study the nature of the message transmitted by the nerve and the means by which muscles contracted. The results of these efforts gave rise to an accumulation of knowledge about the physiology of behaviour.
One of the most important figures in the development of experimental physiology was Johannes Müller, a nineteenth-century German physiologist. Müller was a forceful advocate of the application of experimental techniques to physiology. Previously, the activities of most natural scientists were limited to observation and classification.
Although these activities are essential, Müller insisted that major advances in our understanding of the workings of the body would be achieved only by experimentally removing or isolating animals’ organs, testing their responses to various chemicals, and otherwise altering the environment to see how the organs responded.
His most important contribution to the study of the physiology of behaviour was his doctrine of specific nerve energies. Müller observed that although all nerves carry the same basic message, an electrical impulse, we perceive the messages of different nerves in different ways. For example, messages carried by the optic nerves produce sensations of visual images, and those carried by the auditory nerves produce sensations of sounds. How can different sensations arise from the same basic message?
The answer is that the messages occur in different channels. The portion of the brain that receives messages from the optic nerves interprets, the activity as visual stimulation, even if the nerves are actually stimulated mechanically. Because different parts of the brain receive messages from different nerves, the brain must be functionally divided. Some parts perform some functions, while other parts perform others.
Müller’s advocacy of experimentation and the logical deductions from his doctrine of specific nerve energies set the stage for performing experiments directly on the brain. Indeed, Pierre Flourens, a nineteenth-century French physiologist, did just that. Flourens removed various parts of animals’ brains and observed their behaviour.
By seeing what the animal could no longer do, he could infer the function of the missing portion of the brain. This method is called experimental ablation. Flourens claimed to have discovered the regions of the brain that control heart rate and breathing, purposeful movements, and visual and auditory reflexes.
Soon after Flourens performed his experiments, Paul Broca, a French surgeon, applied the principle of experimental ablation to the human brain. Of course, he did not intentionally remove parts of human brains to see how they worked. Instead, he observed the behaviour of people whose brains had been damaged by strokes.
In 1861, he performed an autopsy on the brain of a man who had had a stroke that resulted in the loss of the ability to speak. Broca’s observations led him to conclude that a portion of the cerebral cortex on the left side of the brain performs functions necessary for speech.
Other physicians soon obtained evidence supporting his conclusions. The control of speech is not localized in a particular region of the brain. Indeed, speech requires many different functions, which are organized throughout the brain. Nonetheless, the method of experimental ablation remains important to our understanding of the brains of both humans and laboratory animals.
Luigi Galvani used electricity to demonstrate that muscles contain the source of the energy that powers their contractions. In 1870, German physiologists Gustav Fritsch and Eduard Hitzig used electrical stimulation as a tool for understanding the physiology of the brain. They applied weak electrical current to the exposed surface of a dog’s brain and observed the effects of the stimulation.
One of the most brilliant contributors to nineteenth- century science was the German physicist and physiologist Hermann von Helmholtz. Helmholtz devised a mathematical formulation of the law of conservation of energy, invented the ophthalmoscope, and devised an important and influential theory of colour vision and colour blindness, and studied audition, music, and many physiological processes.
Although Helmholtz had studied under Müller, he opposed Müller’s belief that human organs are endowed with a vital nonmaterial force that coordinates their operations. Helmholtz believed that all aspects of physiology are mechanistic, subject to experimental investigation.
Helmholtz was also the first scientist to attempt to measure the speed of conduction through nerves. Scientists had previously believed that such conduction was identical to the conduction that occurs in wires, travelling at approximately the speed of light, but Helmholtz found that neural conduction was much slower—only about 90 feet per second.
This measurement proved that neural conduction was more than a simple electrical message. Twentieth-century developments in experimental physiology include many important inventions, such as sensitive amplifiers to detect weak electrical signals, neurochemical techniques to analyse chemical changes within and between cells, and histological techniques to see cells and their constituents because these developments belong to the modern era.