Localization of hand motor activation in Broca's pli de passage moyen

Abstract

<jats:sec> <jats:title>Object</jats:title> <jats:p>The object of this study was to identify a reliable surface landmark for the hand motor area and to demonstrate that it corresponds to a specific structural component of the precentral gyrus.</jats:p></jats:sec> <jats:sec> <jats:title>Methods</jats:title> <jats:p>Positron emission tomography (PET) activation studies for hand motor function were reviewed in 12 patients in whom magnetic resonance imaging results were normal. Each patient performed a hand opening and closing task. Using a computer-assisted three-dimensional reconstruction of the surface of each hemisphere studied, the relationship of the hand motor area to cortical surface landmarks was evaluated.</jats:p></jats:sec> <jats:sec> <jats:title>Conclusions</jats:title> <jats:p>The region of hand motor activation can be reliably identified on the surface of the brain by assessing anatomical relationships to nearby structures. After identification of the central sulcus, the superior and middle frontal gyrus can be seen to arise from the precentral gyrus at a perpendicular angle. A bend or genu in the precentral gyrus is constantly seen between the superior and middle frontal gyrus, which points posteriorly (posteriorly convex). The location of hand motor function, identified using PET activation studies, is within the central sulcus at the apex of this posteriorly pointing genu. The apex of the genu of the precentral gyrus leads to a deep cortical fold connecting the pre- and postcentral gyri and elevating the floor of the central sulcus. This deep fold was described by Paul Broca as the <jats:bold>pli de passage fronto-pariétal moyen</jats:bold>, and the precentral bank of the <jats:bold>pli de passage</jats:bold> represents the anatomical substratum of hand motor function. Observers blinded to the results of the activation studies were able to identify the hand motor area reliably after instruction in using these surface landmarks.</jats:p></jats:sec>

Local Morphology Predicts Functional Organization of the Dorsal Premotor Region in the Human Brain

“…Finally, our data confirmed previous work that the representation of the hand in the primary motor cortex (area 4) is located in the precentral knob (Broca, 1888;Yousry et al, 1997;Boling et al, 1999), which is found in the depth of the central sulcus. Note that the location of the premotor visuomotor hand conditional activity was anterior to the primary motor representation of the hand (indicated in green in all subjects in Figs.…”

“…knob" (Yousry et al, 1997), also known as Broca's pli de passage moyen (Broca, 1888;Boling et al, 1999), in the left hemisphere in each individual subject [average MNI coordinates (x, y, z): Ϫ37.1 Ϯ 6.7 SD, Ϫ25.6 Ϯ 5.4 SD, 62.5 Ϯ 5 SD] (Figs. 2-4, 5d; Table 2).…”

A rapid fMRI task battery for mapping of visual, motor, cognitive, and emotional function

“…In clinical practice several paradigms are used to identify the sensory and motor areas (Lee, et al 1998;Boling, et al 1999) and language-related areas (Binder, et al 1997;FitzGerald, et al 1997;Benson, et al 1999;Fernandez, et al 2001). Some batteries have been developed for neurosurgical planning that include multiple, overlapping tasks for motor and language mapping (Tomczak, et al 2000;Heilbrun, et al 2001;Haberg, et al 2004), and one battery includes tasks for motor, sensory and language mapping (Hirsch, et al 2000).…”

The cerebral sulci and gyri

“…The precentral gyrus, in addition to its superior and inferior connections with the postcentral gyrus via the superior (paracentral lobule) and inferior frontoparietal fold (subcentral gyrus, or rolandic operculum), is usually also connected to the postcentral gyrus via a transverse gyrus that lies along the bottom of the central sulcus and constitutes the so-called Broca's medial frontoparietal pli de passage. 2,72 This fold is situated at the level of the middle knee of the precentral gyrus, which is itself normally situated at the level of the superior frontal sulcus, corresponding to the portion of the gyrus that functionally harbors the motor representation of the contralateral hand. Therefore, the superior frontal sulcus tends to point the way to the medial frontoparietal pli de passage, as well as to the middle knee of the precentral gyrus, with its respective motor representation of the hand.…”

“…The well-known variability in cortical function 1,2,17,47,53,75 calls for the aid of cortical mapping techniques to precisely identify specific sites related to cortical function. Nevertheless, detailed knowledge of the structure and form of the cerebral sulci and gyri continues to be mandatory for neuroimaging as well as intraoperative guidance.…”