Additional motor zone (brain): parts and functions

Moving is fundamental to our survival. However, not every action we perform is performed by magic: it requires a series of complex processes of preparation and planning and finally the initiation of the sequence of movements necessary for that action.

In the brain, we find that the motor cortex is the main brain region (but not the only one) responsible for this control. And among the different areas that shape it and help in starting and carrying out the movement, we can find additional engine areaOne of the most important parts of the brain when interacting with the environment.

    Additional motor area: part of the motor cortex

    The additional engine area it is a region of the brain that is part of the motor cortex, Being one of the main areas of the brain that allow the accomplishment of voluntary movements in the musculoskeletal system.

    This area can be found in a band at the top and in the middle of both hemispheres, in the frontal lobe. Specifically, it is located in front of the primary motor cortex, which in turn is located just before Rolando’s cleft. It corresponds to Brodman zone 6.

    The additional engine area it is associated with the premotor zone of the secondary motor cortex, This makes it possible to plan, program and initiate the control of movements that the primary motor zone will perform later.

    Regarding the supplementary motor zone specifically, although some of its functions and importance are not fully understood, it has been found to have relevant implication in the initiation of movement and motivation and activation. necessary to produce movement.

    Its connection with the limbic system and the basal ganglia generates a relationship between movement and motivation. it is important not only in the initiation of the movement but also in its preparation and follow-up. For example, a relationship has been observed between this domain and motor coordination in situations that require precise and complex control.

      Divisions of this part of the brain

      The research conducted differentiates at least two parts in the additional motor field.

      Additional engine area

      This part of the additional engine area it is characterized by the activation and generation of movements linked to external stimulation. In other words, it is the part that generates the start of the movement as a reaction to the middle

      Own additional engine area

      In this region, neuronal activity does not depend on stimulation but rather on the voluntary realization of his own movement. It is the one who initiates the command sequence to move without having to react to any stimulation for it.

      the functions

      The extra motor zone is important in planning and coordinating movements, as well as in the motivation to start and achieve it. Although its real importance and some of its functions are not completely known (for example its resection alters various functions but nevertheless in many cases after a recovery time), some of which are attributed to it are as follows.

      1. Motivation and start of movement

      One of the functions most closely related to the supplemental motor zone is to generate the motivation necessary to perform and initiate the movement. This has been seen in situations where this region has been injured, appearing as akinesia or lack of voluntary movement.

      2. Start of speech

      In the previous point, we mentioned that the extra motor zone affects the initiative to move. Within the different possible movements language is also included, Which is essential to establish communication between the subject and others.

      3. Coordination of precise movements

      The realization of complex motor sequences which require great precision, Such as those which require the use of both hands, depend on different areas of the brain. One of them is the additional motor zone, which shows the activation in this type of event.

      4. Preparation for movement

      The extra motor zone is also related to preparation for movement, activating when someone imagines performing complex movements. even if you don’t run them.

      5. Reaction to stimuli

      As shown, one of the parts of the additional engine area it is related to the initiation and planning of movement in response to environmental stimulation. We are not talking about reflexes but about the realization of voluntary movements in specific situations.

      Alterations caused by his injury

      Additional motor zone syndrome has been identified following surgical resection or injury to the area. Resection of the supplementary motor zone has been observed to generate initial global kinesis and speech impairment, followed by incoordination, facial paralysis and hemiplegia contralateral to the lesion. Also engine control issues, although functionality can be regained in a period of up to six months. However, sometimes some problems remain in fine movement, especially of the hands.

      Injury to the left supplementary motor area usually results in transcortical motor aphasia, In which the language production is not very smooth while retaining the ability to repeat another person’s words. In general, there is a lack of initiative and motivation to establish communication, and it is common for dysnomy (difficulty naming) and slowing down, with telegraphic language and sometimes echolalia. It is also not uncommon for mutism to occur and the subject neither speaking nor communicating.

      In terms of movement, too, these are minimized in what is called akinesia, although loss of will to move is predominant in the proximal parts of the body. It is common for problems to arise when performing automated movements, although if the patient moves voluntarily, changes usually do not occur.

        Bibliographical references:

        • Cervio, A .; Espeche, M .; Mormandi, R .; Alcorta, SC and Salvat, S. (2007). Postoperative supplementary motor zone syndrome. Report a case. Argentine Journal of Neurosurgery, 21 (3). Autonomous City of Buenos Aires.
        • Herrera, RF (2012). Clinical syndrome due to the removal of the additional motor zone in patients with cerebral gliomas. Doctoral thesis. Inter-American Open University. Regional seat of the Rosary. Faculty of Medicine and Health Sciences.
        • Monterroso, ME; Avilez, AB and Vanegas, MAA (2008). Additional engine area. Bow. Neurocien, 13 (2): 118-124. Mexico.

        Leave a Comment