Motor Control in the Brain: Key Areas and Mechanisms

Brain Motor Control, Motor Cortex, Movement Coordination, Neural Pathways

Learning how the brain controls movements is key in neuroscience. The brain’s job in motor control changes fast based on the move you’re making. To find out how the brain controls movement, we look at the brain network in motor-related regions. We aim to study movement-related changes in brain network transitions. We used magnetoencephalography (MEG) to track brain signals during a reaching task.1 We focused on 24 areas important for movement. By looking at how these areas connect and interact, we can see how the brain networks change with different movements.1

Key Takeaways

  • The brain’s role in motor control changes rapidly according to movement states.
  • Analyzing brain network transitions during different movement states can elucidate the motor control mechanism.
  • Whole-brain magnetoencephalography (MEG) signals were used to extract source signals from 24 motor-related areas.
  • Functional connectivity and centralities were calculated to analyze changes in brain networks during motor planning and movement execution.
  • Understanding the brain’s role in motor control has implications for developing advanced brain-computer interfaces and neuroprosthetic technologies.

Understanding Brain’s Role in Motor Control

The lower levels of the motor hierarchy, like the spinal cord, work on basic muscle movements.2 When we choose to move, the motor and association cortex in our brains join in. They help plan our actions, put together movement schedules, and decide on how to move. After they figure this out, they tell our body what to do2.

Neural Pathways Governing Voluntary and Involuntary Movements

Our brain acts quickly to control our body when we move. It’s key to study how the brain’s structure changes in these times.2 By exploring this, we learn a lot about how our brain handles both our voluntary and involuntary movements.

Significance of Studying Motor Control Mechanisms

Figuring out how the brain moves our body is big in science. Our understanding grows as we look at how the brain works during different movements.2 It teaches us how our brain manages all kinds of motions, from when we decide to move to when our body moves without us thinking about it.

Brain StatisticValue
Brain weight in average adultAbout 3 pounds3
Cerebral cortex weightAbout half of the brain’s weight3
Cerebellum sizeA fist-sized portion of the brain3
Occipital lobe functionInvolved with vision3
Brain hemisphere lobesFour lobes: frontal, parietal, temporal, and occipital3
Pituitary gland locationA pea-sized structure found deep in the brain behind the bridge of the nose3
Brain ventriclesFour open areas that manufacture cerebrospinal fluid3
Pineal gland functionSecretes melatonin and regulates circadian rhythms3
Brain blood supplyReceives blood from the vertebral arteries and carotid arteries3

Motor Cortex: The Conductor of Voluntary Movements

The motor cortex helps us move voluntarily. It has three important parts: the primary motor cortex (M1), the premotor cortex, and the supplementary motor area (SMA).4

Primary Motor Cortex: The Central Hub

The main part of movement control is M1. It’s on the precentral gyrus. M1 uses Betz cells to send strong, quick signals for moving.4 Before you move, M1’s neurons start working. This shows they help send the move signals.5 Different parts of M1 control different body areas and muscles.

Premotor Cortex: Preparing and Guiding Movements

The premotor cortex gets us ready and guides movement. It helps with getting ready to move, how we move based on touch, and hitting targets.4 Before we move, this part helps plan and organize.4 Just watching someone else move gets our premotor cortex and nearby areas going. This shows it helps with watching spaces around us.5

Supplementary Motor Area: Sequence Planning and Coordination

The SMA helps us plan movements and use both hands together.4 It’s key for complicated moves and using both sides at once.5 A strong network in the brain helps SMA do its job well.5

Brain Network Transitions During Movement

Connectivity Changes in Motor Planning State

changes when we plan and move. When planning, areas for moving more have stronger connections.1 This means our brain gets ready for movement ahead of time.

Neural Activity During Movement Execution

But, when we actually move, different areas in the brain connect. Only the and work harder together. Others, including , slow down in communication.1 This shows our brain is busy with during movements, not so much with making new movement plans. for planning might be sharper than those during the actual movement. This impacts how we use and our knowledge of in .1

brain network

Motor Control in the Brain: Key Areas and Mechanisms

Primary Motor Cortex: Encoding Movement Parameters

The primary motor cortex does something important. It encodes how we move. For example, it figures out how much force we need for a specific movement. Before we move, specific neurons in this area get active, showing they help send commands for movement.1

Premotor Cortex: Sensory Guidance and Grasping

The premotor cortex guides our movements with our senses. It focuses on the area right around our bodies. It also helps shape our hands when we grasp things.1

Supplementary Motor Area: Sequence Planning and Bimanual Coordination

The supplementary motor area is key for planning how we move in sequence. It also helps our two sides coordinate movements.1

Descending Motor Pathways and Cortical Connections

The motor cortex controls muscles through various descending motor pathways. The main one, the corticospinal tract, connects it directly to spinal motor neurons. This allows for exact control of muscle movement.6

Moreover, it uses other pathways, like the rubrospinal, tectospinal, and reticulospinal tracts, through special connections. This includes the corticorubral, corticotectal, and corticoreticular tracts.7 It also communicates with the basal ganglia and cerebellum, helping it indirectly adjust subcortical motor circuits.7

Corticospinal Tract: Direct Control of Spinal Motor Neurons

The corticospinal tract links the motor cortex straight to spinal motor neurons. This setup allows for the direct command of muscle actions.6 It’s key for making voluntary movements and perfecting motor skills.6

Indirect Pathways: Modulating Brainstem and Cerebellar Circuits

Besides the corticospinal tract, the motor cortex affects other descending motor pathways, too. This includes the rubrospinal, tectospinal, and reticulospinal tracts.7 Through these, it adjusts the activity of brainstem circuits and cerebellar circuits. These circuits are crucial for movement and posture control.7

By using both direct and indirect paths, the motor cortex has full control over voluntary movements and motor function coordination.67

Cytoarchitecture of Motor Cortex

The brain’s primary motor cortex has six layers. The standout layer is Layer 5, known for Betz cells.6 These cells are key as they form around 30% of the corticospinal tract. This tract links the motor cortex directly to the spinal cord.6 Other parts of the tract get their fibers from the premotor cortex, supplementary motor area, somatosensory cortex, and posterior parietal cortex.6

Layer V: Giant Betz Cells and Corticospinal Output

The role of Betz cells in the motor cortex is still a subject of study.68 It’s thought that Betz cells help in controlling spinal motor neurons. They aid in the precise movement of muscles during voluntary actions.

motor cortex cytoarchitecture

Role of Parietal Cortex in Motor Control

The posterior parietal cortex is key in motor control. It’s not part of the main motor cortex. It helps turn what we see, feel, and know about our body’s position into actions.9 This part of the brain is crucial for deciding how we move, using all our senses.10 It also works closely with other areas in the brain. Together, they make sure our movements are right for what our senses are telling us.

Sensorimotor Integration and Motor Planning

In making us move correctly, the posterior parietal cortex does a lot. It combines things we see, feel, and sense about our body. Then, it helps plan and carry out movements.9 This type of planning is needed for many everyday activities.10 The parietal cortex teams up with different parts of the brain. They work together for making sure our movements match what we need to do.

Issues in the parietal cortex can cause movement problems. For example, it might be hard to pick things up or know where our body is in space.9 Recognizing what the parietal cortex does is vital. It can help us find better ways to help those with movement issues.

Motor Control Disorders and Implications

Problems with the motor control system in the brain can cause movement disorders. Examples include Parkinson’s disease and Huntington’s disease. They come from damage in specific brain parts. These parts are the basal ganglia and cerebellum.11 People with these conditions may experience muscle atrophy and weakness. They can also have hypertonia, making movements stiff or spastic.11

Movement Disorders and Brain Lesions

If lower alpha motor neurons are affected, this can cause a lower motor neuron syndrome. It may happen due to spinal cord lesions. This leads to muscle weakness and loss with hypotonia.11 Alternatively, upper motor neuron syndrome often comes from causes like stroke or tumors. It shows muscle weakness and spasticity without fasciculations.11 The Babinski test checks for damage in the corticospinal tract. The test involves stroking the sole of the foot.11

Brain-Computer Interfaces and Neuroprosthetics

Learning about neural mechanisms for motor control is key for brain-computer interfaces and neuroprosthetics. These new technologies can help restore movement for people with disabilities.12 They decode the brain’s signals to help with motor skills.12 Studies show they can control neuroprosthetic devices with the brain.12 This includes arms for self-feeding and robotic arms that help people with tetraplegia to move.12

There is ongoing research to improve brain-computer interfaces and neuroprosthetics. Advances in brain decoding and sensorimotor rhythms are being used. The goal is to improve the lives of those with motor disorders.12

Ongoing Research and Future Directions

The brain’s motor control is a hot topic in neuroscience. Researchers are diving into how our brain controls both voluntary and involuntary actions.12 They want to understand how the brain’s wiring changes during movement. They also aim to find out which parts of the brain are key for controlling our actions. Plus, they’re working on making better brain-computer interfaces and prosthetics for those who need them.13

Thanks to new ways to look into the brain and computer models, we’re learning a lot more.12 This could mean big steps in helping people with movement issues. By digging into how the brain really works, we’re figuring out how to help more.13

Neuroscience, engineering, and medicine are joining forces. This teamwork is vital in moving research forward and tapping into the full power of understanding the brain’s control over movement.13

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