Korbian Brodmann (Brodmann, 1909) was the first neuroanatomist to provide a cytoarchitectonic description of the human cortex in the left hemisphere, analyzing one single brain. A more recent approach provides a semi-anatomically objective cytoarchitectonic analysis by calculating the density of different types of neurons in the different cortical layers in a number of brains leading to a more generalized map (Amunts et al., 1999; Amunts & Zilles, 2001; Link). This analysis allows to segregate different cortical regions into subregions.
In the frontal cortex of the left hemisphere the cytoarchitectonic approach proposes a subdivision of Broca’s area. Such a subdivision appears to be of particular importance since the region of Broca’s area has often been discussed as supporting different subprocesses during language processing (Bookheimer, 2002; Hagoort, 2005; Poldrack et al., 1999). Broca’s area is defined to consist of at least two parts, i.e. the cytoarchitectonically defined Brodmann area (BA) 44, the pars opercularis and BA 45, the pars triangularis (Amunts et al., 1999; Brodmann, 1909) (see Fig. 2).
The cytoarchitectonic description of the auditory and temporal cortices has only been refined recently. In the primary auditory cortex (PAC), classically BA 41, new cytoarchitectonic analyses have revealed three subregions in a medial-to-lateral direction with Te1.0 in the middle, Te1.1 located more medially and Te1.2 located more laterally (Morosan et al., 2001). The classical cytoarchitectonic analysis by Brodmann (1909) defined one region namely BA 22 to cover the posterior two thirds of the lateral convexity of the superior temporal gyrus (STG) (see Fig. 2). More recent cytoarchitectonic analyses have proposed a separation of the dorsal and ventral banks of the STG (:source: Morosan et al., 2005). For language processing the lateral STG proper excluding the dorsal and ventral banks is functionally relevant.