Things That Can Go Wrong With The Brain
Because the brain controls just about everything, when something goes wrong with it, its often serious and can affect many different parts of the body. Inherited diseases, brain disorders associated with mental illness, and head injuries can all affect the way the brain works and upset the daily activities of the rest of the body.
Problems that can affect the brain include:
Brain tumors. A brain tumor is an abnormal tissue growth in the brain. A tumor in the brain may grow slowly and produce few symptoms until it becomes large, or it can grow and spread rapidly, causing severe and quickly worsening symptoms. Brain tumors in children can be benign or malignant. Benign tumors usually grow in one place and may be curable through surgery if theyre located in a place where they can be removed without damaging the normal tissue near the tumor. A malignant tumor is cancerous and more likely to grow rapidly and spread.
Epilepsy. This condition is made up of a wide variety of seizure disorders. Partial seizures involve specific areas of the brain, and symptoms vary depending on the location of the seizure activity. Other seizures, called generalized seizures, involve a larger portion of the brain and usually cause uncontrolled movements of the entire body and loss of consciousness when they occur. Although the specific cause is unknown in many cases, epilepsy can be related to brain injury, tumors, or infections. The tendency to develop epilepsy may be inherited in families.
Chemical And Electrical Signals
The actual signals transmitted throughout the brain come in two forms, electrical and chemical. The two forms are interdependent and meet at the synapse, where chemical substances can alter the electrical conditions within and outside the cell membrane.
A nerve cell at rest holds a slight negative charge with respect to the exterior the cell membrane is said to be polarized. The negative charge, the resting potential of the membrane, arises from a very slight excess of negatively charged molecules inside the cell.
A membrane at rest is more or less impermeable to positively charged sodium ions , but when stimulated it is transiently open to their passage. The Na+ ions thus flow in, attracted by the negative charge inside, and the membrane temporarily reverses its polarity, with a higher positive charge inside than out. This stage lasts less than a millisecond, and then the sodium channels close again. Potassium channels open, and K+ ions move out through the membrane, reversing the flow of positively charged ions. Over the next 3 milliseconds, the membrane becomes slightly hyperpolarized, with a charge of about -80 mV, and then returns to its resting potential. During this time the sodium channels remain closed the membrane is in a refractory phase.
Anatomy Of The Nervous System
If you think of the brain as a central computer that controls all bodily functions, then the nervous system is like a network that relays messages back and forth from the brain to different parts of the body. It does this via the spinal cord, which runs from the brain down through the back and contains threadlike nerves that branch out to every organ and body part.
When a message comes into the brain from anywhere in the body, the brain tells the body how to react. For example, if you accidentally touch a hot stove, the nerves in your skin shoot a message of pain to your brain. The brain then sends a message back telling the muscles in your hand to pull away. Luckily, this neurological relay race takes a lot less time than it just took to read about it.
Considering everything it does, the human brain is incredibly compact, weighing just 3 pounds. Its many folds and grooves, though, provide it with the additional surface area necessary for storing all of the bodys important information.
The spinal cord, on the other hand, is a long bundle of nerve tissue about 18 inches long and ¾ inch thick. It extends from the lower part of the brain down through spine. Along the way, various nerves branch out to the entire body. These make up the peripheral nervous system.
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Anatomy Of The Brain And Spine
Learn more about the anatomy and the functions of the brain and spine
- Information and support
- Anatomy of the brain and spine
The brain and spine are vital to keep the body alive and functioning. Everything we do depends on the messages that are sent from the brain, along the spinal cord and on to the rest of the body.
Exercises And Critical Thinking
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Brain Stem Keeps You Breathing And More
Another brain part that’s small but mighty is the brain stem. The brain stem sits beneath the cerebrum and in front of the cerebellum. It connects the rest of the brain to the spinal cord, which runs down your neck and back. The brain stem is in charge of all the functions your body needs to stay alive, like breathing air, digesting food, and circulating blood.
Part of the brain stem’s job is to control your involuntary muscles the ones that work automatically, without you even thinking about it. There are involuntary muscles in the heart and stomach, and it’s the brain stem that tells your heart to pump more blood when you’re biking or your stomach to start digesting your lunch. The brain stem also sorts through the millions of messages that the brain and the rest of the body send back and forth. Whew! It’s a big job being the brain’s secretary!
The Parietal And Temporal Lobes
We cant talk about the occipital lobe without giving a little credit to these two. While the occipital lobe carries most of the visual burden, its the parietal and temporal lobes that help us make sense of what were seeing.
The parietal lobe plays a big role in visuospatial cognition, our ability to recognize and adapt to the physical space around us. This includes abilities like depth perception, navigation and movement.
When you want to change the channel on TV, youre first using the occipital lobe to see the remote. But the parietal lobes visuospatial recognition is used to gauge how much distance is between you and the remote an important detail once you decide to reach for it.
The temporal lobe controls memory it assigns meaning to the images we see. After the occipital lobe registers the image of the TV remote, structures in the temporal lobe subconsciously remind us that the remote is used to change the channel, that it needs to be pointed at the TV, and which button we need to press to get to the channel were seeking.
The frontal lobe is usually not considered to be directly involved with vision, but scientists dont think it should be left out completely. According to the Georgia Institute of Technology, new research actually suggests it might play a role in vision after all.
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Understanding Parts Of The Brain
Learn about the parts of the brain and how dementia damages them, as well as about the symptoms the damage causes.
Dementia is caused when the brain is damaged by diseases, such as Alzheimers disease or a series of strokes. Alzheimers disease is the most common cause of dementia, but not the only one.
A person with dementia will experience symptoms depending on the parts of the brain that are damaged, and the disease that is causing the dementia.
Functions Of The Cortex
When the German physicists Gustav Fritsch and Eduard Hitzig applied mild electric stimulation to different parts of a dogs cortex, they discovered that they could make different parts of the dogs body move. Furthermore, they discovered an important and unexpected principle of brain activity. They found that stimulating the right side of the brain produced movement in the left side of the dogs body, and vice versa. This finding follows from a general principle about how the brain is structured, called contralateral control, meaning the brain is wired such that in most cases the left hemisphere receives sensations from and controls the right side of the body, and vice versa.
Just as the motor cortex sends out messages to the specific parts of the body, the somatosensory cortex, an area just behind and parallel to the motor cortex at the back of the frontal lobe, receives information from the skins sensory receptors and the movements of different body parts. Again, the more sensitive the body region, the more area is dedicated to it in the sensory cortex. Our sensitive lips, for example, occupy a large area in the sensory cortex, as do our fingers and genitals.
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How Did We Test Motor Adaptation
To test motor adaptation, we asked everyone to sit in front of the machine shown in Figure 2. Imagine you are one of our participants. The goal is to learn to move the cursor from a start position to a target. You have to learn to do this because the cursor moves in a different direction than your hand. You have sensors on your arm that measure the direction your arm and hand move. Your arm is under the mirror so you cannot see it. All you see displayed on the mirror are circles for the start, the target, and the cursor. The cursor is a small circle with an x in the middle, which gives you visual feedback about your hand position as you move from start to target. First, in the baseline condition, we give you correct visual feedback, meaning that we show your arm the way it actually moves. Second, in the adaptation condition, we give you visual feedback of your arm that is wrong. So, even when your arm is moving up and down, the visual feedback shows your arm moving to the left. You would adapt by gradually moving your arm to the right in order to make the visual feedback go vertical. With practice you learn to adjust the direction of your movement to accurately hit the target, despite the bad feedback.
Look at this movie a couple of times to get a better idea of how adaptation occurs during the beginning, middle and end of the adaptation condition.
Research Focus: Identifying The Unique Functions Of The Left And Right Hemispheres Using Split
We have seen that the left hemisphere of the brain primarily senses and controls the motor movements on the right side of the body, and vice versa. This fact provides an interesting way to study brain lateralization the idea that the left and the right hemispheres of the brain are specialized to perform different functions. Gazzaniga, Bogen, and Sperry studied a patient, known as W. J., who had undergone an operation to relieve severe seizures. In this surgery, the region that normally connects the two halves of the brain and supports communication between the hemispheres, known as the corpus callosum, is severed. As a result, the patient essentially becomes a person with two separate brains. Because the left and right hemispheres are separated, each hemisphere develops a mind of its own, with its own sensations, concepts, and motivations .
Although Gazzanigas research demonstrated that the brain is in fact lateralized, such that the two hemispheres specialize in different activities, this does not mean that when people behave in a certain way or perform a certain activity they are only using one hemisphere of their brains at a time. That would be drastically oversimplifying the concept of brain differences. We normally use both hemispheres at the same time, and the difference between the abilities of the two hemispheres is not absolute .
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Conditions That Affect The Cerebellum
When your cerebellum is damaged, nerve cells break down and die and can cause the following:
- Ataxia: The loss of control of voluntary movement
- Cognitive impairment: A reduction in conscious mental activities, including thinking, learning, memory, and concentration
- Dystonia: Involuntary contraction of muscles that normally work in cooperation so that a body part is held in an unusual and often painful position as a result
- Tremors: Involuntary, rhythmic contraction of muscles that can lead to shaking movements in the hands, legs, face, head, or vocal cords
- Unsteady gait: Walking unsteadily or clumsily
- Vertigo:The dizziness sensation of spinning, swaying, or tilting, which is frequently associated with balance problems and often accompanied by nausea, vomiting, headache, or hearing loss
In addition, researchers are studying the link between cerebellum dysfunction and the following:
- Anxiety disorders: A category of disorders including panic disorder and social anxiety disorder that are marked by excessive or irrational anxiety or fear that is disproportionate to the actual threat
- Autism spectrum disorder: A developmental condition that causes impairments in social interactions and communication
- Dyslexia: A disorder that makes it difficult to process speech and results in problems with reading, writing, and spelling
- Schizophrenia: A psychotic disorder characterized by distorted perceptions, thoughts, emotions, and beliefs that are not connected to reality
What Happens When The Cerebellum Is Damaged
When the cerebellum is injured, some of its functions can be compromised and cause motor problems. There may be a loss of the ability to precisely control the direction, force, speed and amplitude of movements, as well as the ability to adapt output patterns to changing conditions.
The deficits can be produced suddenly by injury, or gradually by degeneration of the cerebellum. The cerebellar syndrome can be caused by injury to the cerebellum or the cerebellar pathways.
Organ damage can lead to two different symptomatic syndromes: vermian syndrome with alterations in static and gait, and cerebellar hemispheric syndrome with alterations in movement coordination.
The lesion of the afferent pathways produces an archicerebellar syndrome, and that of the efferent pathways is manifested by a neocerebellar syndrome.
A person with a cerebellar injury may find it difficult to maintain a seasonal posture , and trying to do so leads to tremors.
It is also common to detect abnormalities in balance, gait, speech and even in the control of eye movements. So movements of all kinds can be affected. It is difficult for those who suffer from it to learn new motor sequences.
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Does Using Your Non
Clinical Counseling Hypnotherapist , MBA
It may be known to you that your brain operates in a complex manner. Your left brain controls the actions and movements of your right body part, while your right brain controls the actions and movements of your left body part. Therefore, it may be possible to use only one side of your brain to control your dominant hand. Would doing some daily activities with your non-dominant hand improve the quality of your memory?
Right-handed people stimulate their left brains most of the time. When you use your left hand to perform certain tasks, you can also stimulate your right side of the brain. This action awakens your creative and intuitive faculties. If, however, you are a left-handed person, and you use your right hand to do simple tasks, then you are stimulating your rational and organized side of your brain. In Using Both Sides of the Brain, Tony Buzan argues that utilizing both sides of the brain improves performance. As a result of doing simple exercises like this, one’s mental function will be enhanced, and at the same time, one’s brainpower is going to improve as well. When a person does so continuously, they may remain mentally sharp and youthful for a long time.
Neuroplasticity And Movement Rehabilitation
As with other parts of the brain, when neurons of the primary motor cortex are damaged they will never regrow or repair. However, the brain can heal itself and regain some lost function through neuroplasticity. This means undamaged parts can change their connections and remap to other areas of the body to take over function, compensating for damaged parts of the motor cortex.
Neuroplasticity is the fundamental principle in physical rehabilitation, such as physiotherapy for patients following stroke, that allows patients to regain motor function and recover. Through neuroplasticity, the more a particular movement is performed, the stronger the brain pathways for that movement become and the easier it gets to perform that movement in the future.
Lets look at an example of a stroke patient, Harry, who has problems with movement in his left leg. Harry might have altered patterns of walking due to damage in the leg area of the motor cortex of the right side of his brain. To help Harry regain efficient walking ability, the physiotherapist helps him perform sequences or patterns of walking by practising activation and control of specific muscle groups in his left leg.
This article was co-written with Zita Arends, who is a physiotherapist in stroke rehabilitation and aged care.
Read other articles in our Brain Control series, here.
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