Tuesday, May 3, 2022

Which Lobe Of The Brain Controls Motor Activity

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Motor And Sensory Areas

2-Minute Neuroscience: Motor Cortex

The major motor and sensory areas are separated by the central sulcus and the immediate areas anterior and posterior , forming, respectively, the primary motor and sensory cortices. Neurons within theprimary motor cortex control voluntary movement by controlling somatic motor neurons in the deep brain and spinal cord, while neurons within the primary sensory cortex receive somatic sensory information from afferent neurons located within the skin and muscle that detect changes in pressure, pain vibration, taste, and temperature.

Dioneia Motta Monte-Serrat, Carlo Cattani, in, 2021

The Cell Structure Of The Brain

The brain is made up of two types of cells: neurons and glial cells, also known as neuroglia or glia. The neuron is responsible for sending and receiving nerve impulses or signals. Glial cells are non-neuronal cells that provide support and nutrition, maintain homeostasis, form myelin and facilitate signal transmission in the nervous system. In the human brain, glial cells outnumber neurons by about 50 to one. Glial cells are the most common cells found in primary brain tumors.

When a person is diagnosed with a brain tumor, a biopsy may be done, in which tissue is removed from the tumor for identification purposes by a pathologist. Pathologists identify the type of cells that are present in this brain tissue, and brain tumors are named based on this association. The type of brain tumor and cells involved impact patient prognosis and treatment.

What Are Some Important Structures In The Parietal Lobe

In addition to being divided into left and right hemispheres, the parietal lobe has a number of distinct structures, each with its own unique contribution to brain functioning. Those structures include:

  • Postcentral gyrus: This region is the brain’s primary somatosensory cortex, and maps sensory information onto what is known as a sensory homonculus. Some researchers also refer to this region as Brodmann area 3.
  • Posterior parietal cortex: This region is thought to play a vital role in coordinating movement and spatial reasoning. It also plays a role in attention, particularly attention driven by new stimuli, such as when an animal jumps into the road while you are driving.
  • Superior parietal lobule: This region helps you determine your own orientation in space, as well as the orientation of other objects. It also receives significant input from the hand, suggesting that it helps coordinate fine motor skills and sensory input from the hands.
  • Inferior parietal lobule: Sometimes called Gerschwind’s territory, this region aids in assessing facial expressions for emotional content. Some research suggests it plays a role in other functions, including language processing, basic mathematical operations, and even body image. It contains a number of sub-regions, including the angular and supramarginal gyrus.

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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.

Electrode Array Implantation Surgery

Using TMS to Study Fine Motor Skills

A single array composed of 100 silicon microelectrodes in a 10 × 10 grid was chronically implanted in the hand area of the primary motor cortex . A craniotomy was performed above M1, and the dura was incised and reflected. The electrode array was positioned on the crown of the right precentral gyrus, approximately in line with the superior ramus of the arcuate sulcus. In most cases, we used interoperative stimulation of the exposed cortical surface to determine the optimal implant site. A piece of artificial pericardium was applied above the array, the dura was closed using 4.0 Nurolon sutures, and another piece of pericardium was applied over it. The excised bone flap was replaced, and the skin was closed.

Sungzoon Cho, … Min Jang, in, 1997

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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.

Further reading:Were capable of infinite memory, but where in the brain is it stored, and what parts help retrieve it?

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.

Where Is The Frontal Lobe And What Does It Do

The brain has two hemispheres, or halves: left and the right. The hemispheres are divided into three sections: the forebrain, the midbrain, and the hindbrain.

Each section has specific functions:

  • The hindbrain controls involuntary functions like respiration and heart rate.
  • The midbrain is associated with coordination, alertness, vision, and hearing.
  • The forebrain controls a range of social, emotional, and cognitive functions, as well as motor function and memory.

The forebrain includes a major part of the brain called the cerebrum. The outer layer of the cerebrum is called the cerebral cortex.

The frontal lobe is one of the four lobes of the cerebral cortex. The other lobes are the temporal lobe, the parietal lobe, and the occipital lobe.

Each of the four lobes has specific functions. Damage to any one of them will cause problems with these functions. The sections below describe the main functions of the frontal lobe.

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Parietal Lobe: Function Location And Structure

The parietal lobe receives and manages sensory input and is located just under the parietal bone of the skull.

  • Parietal Lobe

Neuroscientists have long divided the brain into four distinct lobes. Originally this division was based solely on the location of the lobes within the skull, but we now know that each lobe carries out a number of highly specialized functions. The parietal lobe is located just under the parietal bone of the skull. This important brain lobe helps integrate sensory input and process language.

Primary Motor Cortex Functions

Frontal Lobe – Human Brain Series – Part 5

The primary motor cortex is a strip of brain tissue located in the frontal lobe. It is responsible for initiating purposeful and intentional movements. These purposeful movements include everything from moving your hands, arms, and legs to controlling facial expressions and even swallowing.

In a normal functioning primary motor cortex, signals cross over the center of the body to activate muscles on the opposite side. This means that the movements on the right side of your body are controlled by the left hemisphere of the primary motor cortex, and vice versa.

Additionally, different areas of the primary motor cortex control different parts of the body. While every body part is represented in the primary motor cortex, not every part has equal amounts of brain matter devoted to it.

For example, complex movements that require precise control take up larger amounts of space in the brain than simple motions do. A significant portion of the motor cortex is devoted to finger movements and facial expressions, while a smaller portion of the brain is responsible for leg motions.

This explains why many individuals struggle with fine motor control or facial paralysis after brain injury. Because those movements are controlled by a larger portion of the motor cortex, they have a much higher likelihood of becoming damaged during an injury.

To help you understand what happens when the motor cortex is damaged, the following section will discuss potential secondary effects.

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Muscle Relaxants/ Botox Injections

High muscle tone can significantly limit a persons range of motion. To relax the muscles, individuals with primary motor cortex damage may be recommended muscle relaxants such as baclofen or nerve blockers such as Botox.

Depending on how much of the body is affected, various forms of relief may be recommended. For example, oral muscle relaxants affect the entire body while injections allow for more localized relief.

Its also important to understand that these medications only provide temporary relief. Therefore, it is recommended that individuals take advantage of the reduced muscle tone to participate in therapeutic exercises and activities to sustain more long-term relief.

Diagram Of The Brain And Its Functions

We know what is the brain, we also know what it looks like but How does it work? How does it convert a whim into an electric signal? If these are the questions swirling in your brain, then this article detailing the diagram of the brain and its functions will definitely whet your appetite regarding brain functions and parts.

We know what is the brain, we also know what it looks like but How does it work? How does it convert a whim into an electric signal? If these are the questions swirling in your brain, then this article detailing the diagram of the brain and its functions will definitely whet your appetite regarding brain functions and parts.

Of all the human body systems, the nervous system is the most complicated system in the body. The brain is the central part of the nervous system. It is an intriguing organ, that has been studied right from the time it develops in the fetus. The human brain weighs about 1.5 kg in adults. The cerebrum, which forms the bulk of this organ, is divided into two hemispheres, the right hemisphere and the left hemisphere.

There are many ways of dividing the brain for studying its various aspects. However, it is conventionally divided into three parts: the forebrain, the midbrain and the hindbrain. The brain also contains four interconnected cavities called ventricles, which contain cerebrospinal fluid. We will study the diagram of the brain and its functions in this article, along with a detailed study of the brain anatomy.

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S Of The Brain Involved In Speech

In recent decades, there has been an explosion of research into language processing in the brain. Its now generally accepted that the control of speech is part of a complex network in the brain.

The formation of speech requires many different processes, from putting thoughts into words, forming a comprehensible sentence, and then actually making the mouth move to make the correct sounds.

There are several areas of the brain known to play a role in speech:

General Inability To Speak And Understand Language

The human

Widespread damage to the brains language centers can result in global aphasia. People with global aphasia will have an extremely hard time expressing and understanding language.

People with neurodegenerative diseases, such as Alzheimers disease, often experience loss of speech slowly over time. This is called primary progressive aphasia .

PPA is not Alzheimers disease but can be a symptom of Alzheimers disease. PPA can also be an isolated disorder without the other symptoms of Alzheimers disease. Some people with PPA have normal memories and can continue leisure activities and sometimes even work.

Unlike aphasia that results from stroke or brain trauma, PPA results from slow deterioration of one or more areas of the brain used in speech and language.

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Brain Injury And Speech

What happens if one or more of these parts is injured, damaged, or abnormal?

If you have a problem speaking or understanding speech, its a condition called aphasia. If you have trouble putting together the correct muscle movements necessary to produce speech, its a condition called .

Both aphasia and apraxia are most often caused by a stroke or trauma to the brain, usually when the left side of the brain is affected. Other less common causes are brain tumors and infections.

Symptoms of aphasia or apraxia depend on where the damage occurs in the brain and the severity of the damage. These symptoms include:

The Supplementary Motor Cortex

Penfield described a cortical motor area, the supplementary motor area , on the top or dorsal part of the cortex. Each neuron in the SMA may influence many muscles, many body parts, and both sides of the body. The map of the body in SMA is therefore extensively overlapping. SMA projects directly to the spinal cord and may play some direct role in the control of movement.

Based on early work using brain imaging techniques in the human brain, Roland suggested that the SMA was especially active during the internally generated plan to make a sequence of movements. In the monkey brain, neurons in the SMA are active in association with specific learned sequences of movement.

Others have suggested that, because the SMA appears to control movement bilaterally, it may play a role in inter-manual coordination.

Yet others have suggested that, because of the direct projection of SMA to the spinal cord and because of its activity during simple movements, it may play a direct role in motor control rather than solely a high level role in planning sequences.

On the basis of the movements evoked during electrical stimulation, it has been suggested that the SMA may have evolved in primates as a specialist in the part of the motor repertoire involving climbing and other complex locomotion.

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What Is The Motor Cortex And What Does It Do

In 1870 physicians Gustav Theodor Fritsch and Eduard Hitzig, using awake dogs as their subjects, electrically stimulated the area of the brain we now know as the motor cortex and found that the stimulation caused the dogs to move involuntarily. Additionally, they found that stimulating the motor cortex in different locations caused different muscles to move. This experiment led to the identification of the motor cortex as the primary area of our brain involved with planning and executing voluntary movements.

There are several distinct regions within the motor cortex. The area found to be the most sensitive to electrical stimulation–in that it requires the least amount of stimulation to produce a corresponding muscle movement–is the primary motor cortex. The primary motor cortex is arranged such that different parts of the region are associated with motor control of different parts of the body, a topographic organization that is similar–although less precise–than that seen in the somatosensory cortex.

Ataxia Caused By Toxins

Motor Control, Motor Learning and Brain-Computer Interfaces

The cerebellum is vulnerable to poisons, including alcohol and certain prescription medications.

These poisons damage nerve cells in the cerebellum, leading to ataxia.

The following toxins might cause ataxia:

  • alcohol
  • drugs, especially barbiturates and benzodiazepines
  • heavy metals, including mercury and lead
  • solvents, such as paint thinners

Treatment and expected recovery time depend on the toxin involved and the extent of brain damage.

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Diseases And Conditions Related To The Frontal Brain Lobe

One of the first conditions we will address is depression. Today, we know with certainty that one of the main characteristics of virtually all depressed persons – regardless of the underlying cause of depression – is a significant decrease in blood flow to the frontal lobe and its impaired activity.

This reduced activity is found in the most prominent part of the frontal lobe. It is called the “prefrontal cortex“. It is the part of the brain that truly represents the control center of the brain.

However, it is much more than that. We know that the prefrontal cortex is responsible for behavioral planning, decision making, emotional control, self-awareness, and independence from other people.

Depression can be caused by a stroke in the medial part of the frontal lobe. The consequences of these strokes include emotional instability. Generally speaking, depression is not caused by strokes in other parts of the brain.

Moreover, frontal brain lobe damage can result from surgical removal, injury, or stroke. It can also be a consequence of Alzheimer’s disease. Regardless of the process that damages the frontal lobe, the consequences are generally the same.

Patients suffering from Alzheimer’s disease who had frontal lobe damage were significantly more depressed. They were also much more likely to have other behavioral problems such as anxiety, self-delusions, and lack of self-discipline.

Damage to the inferolateral area causes motor aphasia .

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