What happens if motor cortex is damaged

Thus, the loss of the nigrostriatal dopaminergic pathway upsets the fine balance of excitation and inhibition in the basal ganglia and reduces the excitation of motor cortex. In ways that are not understood, this reduction of thalamic excitation interferes with the ability of the motor cortex to generate commands for voluntary movement, resulting in the poverty of movement of Parkinsonian patients.

It is as if all of the motor programs stored in cortex are constantly inhibited by the indirect pathway, with not enough excitation of the direct pathway for the desired motor program to become activated. Three therapeutic interventions are L-Dopa therapy, pallidotomy, and deep brain stimulation. Because dopamine itself does not cross the blood-brain barrier, L-Dopa , a chemical precursor to dopamine, was used to replenish the supply of dopamine.

Amazingly, flooding the system with L-Dopa resulted in profound improvements in the symptoms of patients. Unfortunately, this improvement is temporary, and typically symptoms return after a number of years. Surgical intervention, such as making lesions to the globus pallidus internal segment pallidotomy , has shown effectiveness in some patients. In recent years, a new therapy, deep brain stimulation of the subthalamic nucleus, has been gaining in popularity.

In this treatment, an electrical stimulator is implanted in the subthalamic nucleus. It is not known why this procedure works, or what its long-term efficacy is. Because the projection from the subthalamic nucleus is excitatory onto globus pallidus neurons, which inhibit the thalamus, it is paradoxical that such stimulation should increase motor cortex activity. One thought is that the stimulation might actually overload the subthalamic nucleus, thereby inhibiting it and disinhibiting the thalamus.

The affected gene codes for a protein known as huntingtin, the function of which is not known. The effect of the mutated version of the gene, however, is to kill the indirect pathway neurons in the striatum, particularly those of the caudate nucleus.

In addition, the disease in advanced stages is associated with dementia. Recall that the net effect of the indirect pathway is to inhibit motor cortex. With the loss of these neurons, the excitatory effect of the direct pathway is no longer kept in check by the inhibition of the indirect pathway.

Thus, the motor cortex gets too much excitatory input from the thalamus, disrupting its normal functioning and sending involuntary movement commands to the brain stem and spinal cord.

Because inappropriate motor programs are not inhibited normally, the cortex continuously sends involuntary commands for movements and movement sequences to the muscles. Hemiballismus results from a unilateral lesion to the subthalamic nucleus, usually caused by a stroke. This lesion results in ballismus on the contralateral side of the body, while the ipsilateral side is normal hence the term hemiballismus.

The involuntary, ballistic movements result from the loss of the excitatory subthalamic nucleus projection to the globus pallidus Figure 6. Because the globus pallidus internal segment normally inhibits the thalamus when excited, the loss of the subthalamic component lessens the inhibition of the thalamus, making it more likely to send spurious excitation to the motor cortex.

Some surgical operations have been performed to relieve the symptoms of hemiballismus, and new pharmacological treatments are in use to relieve the disorder. Like the basal ganglia, the cerebellum has historically been considered part of the motor system because damage to it produces motor disturbances.

Unlike the basal ganglia, damage to the cerebellum does not result in lack of movement or poverty of movement. Instead, cerebellar dysfunction is characterized by a lack of movement coordination. Also unlike basal ganglia and motor cortex , damage to the cerebellum causes impairments on the ipsilateral side of the body. A normal subject can easily perform rhythmic movements like rapidly pronating and supinating the hands and forearms click NORMAL. A patient with a cerebellum lesion cannot perform this task.

A patient with a cerebellum lesion displays an intention tremor, in which the movement starts smoothly toward the target but then oscillates back and forth until the hand slowly contacts the target click ABNORMAL.

Following a strenuous workout with his neighborhood team, a right-handed, year-old former professional basketball player awoke the next morning with paralysis of the right lower extremity. A neurological exam revealed an exaggerated stretch reflex. There was no disturbance of position sense, pain sensation or tactile discrimination. Where is the problem localized? Although it is not possible to repair damaged neurons of the motor cortex, muscle control functions can be recovered after damage to this area of the brain.

The brain has the ability for neuroplasticity, which is the ability for the brain to reorganise neurons and compensate for damaged areas. Thus, the brain can change its structure slightly so that parts of the brain that are healthier can take control of muscle movements in place of the motor cortex.

Neuroplasticity is often an aim in physical and occupational therapies for individuals with motor cortex damage. This ability can usually be triggered through repetitive exercise and activities with the therapist in order to activate a particular muscle group.

The more that this is practiced, the more those muscle pathways will be reinforced, until eventually, new pathways will be established so individuals can perform movements easier. Olivia has been working as a support worker for adults with learning disabilities in Bristol for the last four years. Guy-Evans, O. Motor cortex function and location. Simply Psychology.

Purves, D. Neuroscience 2nd edition. Types of Eye Movements and Their Functions. Neuroscientifically Challenged , October Know Your Brain: Motor Cortex. Knierim, J. Chapter 3: Motor Cortex. Neuroscience Online. Flint Rehab , November Toggle navigation. How to reference this article: How to reference this article: Guy-Evans, O.

Back to top. Related Articles. Central Nervous System What is a Neuron? We understand that privacy is very important to your security.

Our Privacy Policy will stay up to date as new procedures are implemented. All information collected from any visitors is regarded as private information and will be kept confidential. Every visitor to this website is recognized by our web server and it records the users domain and what pages were visited during that visitors time on the website. This method will also tell what search engine or referring site the user used to reach our website.

The information obtained is used solely to increase the value of this site. This Privacy Policy applies to our website and our subscription service. This Privacy Policy governs our data collection, processing, and usage practices.

By using the website or the subscription service, you consent to the data practices described in this Privacy Policy. If you do not agree with the data practices described in this Privacy Policy, you should not use this website or subscription service. Spinal cord injuries are traumatic for patients and their families. They cause disruptive changes to every aspect of your life and there is a lot of new information to navigate and understand. Our experts have collected everything in one place to help you learn more about your injury, locate doctors and treatment centers, find financial support, and get assistance navigating your next move.

The motor cortex is a region of the brain, located in the frontal lobe, which is involved in controlling and ordering voluntary movements of an individual. Author: Spinalcord. What is the motor cortex? What does it have to do with spinal cord injury? So, what will be the problem with the motor cortex after SCI? Is there any treatment? Laws frequently change, so the accuracy of information cannot be guaranteed. Spinal Injury Types. Additional Spinal Injury Information. Spinal Cord Injury.

Brain Injury. Finding Treatment.