Lower frontal rotation of the brain: its characteristics and functions

The brain contains many folds and convolutions that make up different anatomical structures, among which is the lower frontal bend, which we will talk about in this article.

This brain region is part of the prefrontal cortex and contains areas as important as Broca’s, essential for the production of language.

Below, we explain what it is and where the inferior frontal gyrus is located, what functions it performs, and what are the main disorders associated with injury in this area of ​​the brain.

    Inferior frontal gyrus: definition, structure and anatomical location

    The lower front turn is one of the many convolutions contained in the human brain; folds which make up the characteristic relief of this organ and which give it this wrinkled appearance on its external surface, the cerebral cortex.

    This turn is located under the lower front groove, and extends forward from the lower part of the precentral groove. It is bounded by its anterior part with the lateral slit or Silvio. Up to three different parts can be identified in the inferior frontal tour: the opercular pair, behind the anterior ascending branch; the triangular pair, between the ascending and horizontal branches; and the orbital pair, under the anterior horizontal branch of the slit.

    The limit of flow of the opercular pair is the inferior precentral groove and its rostral limit is the ascending anterior branch of the lateral cleft.. Sometimes an additional groove is usually identified: the diagonal groove, inside the opercular pairs. When this is present, it can remain separate or it can blend with the upward groove.

    On the other hand, there are authors who have divided the lower front turn into a back and a front. While it is true that this groove can be seen to extend, ventrally, almost to the lateral margin of the frontal orbital region, this may be a false impression due to the fusion of the anterior part of the lower frontal groove. with another groove that often forms the anterior end of the triangular pair: the pre-triangular groove.

    the functions

    The inferior frontal gyrus is one of the parts that make up the prefrontal cortex of the brain, the main functions have to do with executive control and planning of complex behaviors, decision making or management and adaptation of behavior to social norms.

    In recent years, research has focused on the role of the lower frontal turn in a specific aspect of executive control: behavioral inhibition or inhibition of response. It can be defined, in general terms, as the ability we have to control and retain responses to routine or predominant internal or external stimuli that appear during the performance of a task.

    Tasks that examine response inhibition typically involve the development of a routine response, followed by cancellation of the response when an infrequent signal is detected. For example, with the Go / No go task, in which there are two starting conditions, and in some tests it is necessary to respond to stimuli (Go test) and in others it is not necessary to respond (No go), so that the examiner can then gauge the individual’s ability to inhibit their responses.

    Another function in which the lower frontal rotation would be involved is attentional control. To measure a subject’s attention span, “Stop Signal” tasks are often used, an experimental test that serves to measure inhibitory processes and the automaticity of subjects’ responses, and which also uses Go tasks. / no Go.

    Latest findings based on studies with functional MRI confirm that lower frontal rotation also plays a general role in attentional control as a necessary structure for the person to adapt and respond to relevant stimuli and to be inhibited in the face of irrelevant or distracting stimuli.

    We should also note the role that the inferior frontal turn plays in language processing, the Broca zone being part of this convolution. This region of the brain, located in the left hemisphere, is essential in expressing language and producing speech, as it is responsible for planning the sequence of movements necessary for us to articulate the words we speak.

      mirror neurons

      Mirror neurons are a special class of neurons that are activated, both by observing the behavior of others and by performing it on our own. They are called mirrors because they allow us to infer what other people think and feel, and are closely related to aspects such as empathy, imitation, or social behavior.

      There is some evidence that mirror neurons exist in several regions of the brain, including the inferior frontal opercular gyrus and the inferior parietal lobe, although it is also suggested that there may be nuclei of these neurons in other areas such as islet, anterior cingulate, and superior temporal gyrus.

      Studies in people with autism spectrum disorders (ASD) show the existence of alterations in the activity of their mirror neurons, particularly in the inferior frontal gyrus, insula and cingulate cortex. These alterations would explain the inability of these people to grasp the intentions of others and to feel empathy., Just like people without ASD.

      related disorders

      Research in patients with prefrontal lobe lesions that include the inferior frontal gyrus has revealed that these generally have a deficit of inhibition of the response. It has been suggested that there is a centrally located inhibitory mechanism that suppresses irrelevant responses, and that this inhibition is primarily located in the right inferior frontal gyrus.

      On the other hand, the same inhibitory control mechanism appears to be altered in patients with obsessive-compulsive disorder (OCD). In a study comparing healthy subjects to individuals with this disorder, significant alterations in structural connectivity were found, possibly associated with a lack of myelination and axonal problems in the inferior frontal gyrus of patients with OCD.

      Finally, lesions in Broca’s zone, corresponding to Brodmann’s zone 44 and zone 45 (opercular pair and triangular pair of the lower frontal rotation in the left hemisphere, respectively) were found to involve language difficulties such as the following:

      • Problems in generating and extracting meaning from actions.
      • Difficulties in sequencing motor and expressive elements.
      • Semantic and syntactic problems.
      • Impoverishment of the language. In extreme cases, there may be kinetic mutism or hypolalia (decreased or delayed verbal expression).
      • Decreased verbal fluency, both in phonological and semantic tasks.
      • Inability to understand proverbs or phrases.

      Bibliographical references:

      • Ardila, A. (2012). Prefrontal cortex, language and executive functions. In neuropsychology of the prefrontal cortex and executive functions (pp. 299-314).
      • Aron AR, Robbins TW, Poldrack RA Inhibition and the right lower frontal cortex. Cognitive tendencies. Science. 2004; 8: 170-177.
      • Hampshire, A., Chamberlain, SR, Monti, MM, Duncan, J. & Owen, AM (2010). The role of the right lower frontal gyrus: inhibition and attentional control. Neuroimaging, 50 (3), 1313-1319.

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