Читать книгу A History of Neuropsychology - Группа авторов - Страница 43

To confirm the anatomical localization of Broca’s area, Brodmann’s Areas 44 and 45 in the horizontal slices of brain, I made serial horizontal sections of neurologically normal autopsied brain which was marked in advance on the cortical surface of areas 44 and 45 and other language areas (Area 22 corresponding to the Wernicke’s area and Area 39 of the angular gyrus) with Indian ink (Fig. 2) [5]. Figure 3 shows the horizontally cut slice of thus marked normal brain at the same level of Sylvian fissure as the illustration of Pierre Marie showing the “zone lenticulaire” (Fig. 1). Comparing the Marie’s figure and the real brain slice, it is quite evident that both opercular and triangular parts of the inferior frontal gyrus corresponding to Area 44 and Area 45 of Brodmann, which are the most important areas in discussing the anatomo-pathological investigations of aphasia, are completely missing from the illustration of Pierre Marie [6].

Fig. 2. Piled up horizontally cut slices of the left hemisphere of a normal brain between 2 horizontal lines shown below. Cortical surface of the 3 language areas are marked with Indian ink (modified from Iwata [5]).

Fig. 3. Horizontally cut brain slice at the same level as Marie’s illustration (Fig. 1) showing Areas 44 and 45 (cortical surface of which are marked with Indian ink) and Area 46 (not marked). Slice level is shown on the right side.

Since the opercular part of the inferior frontal gyrus (Area 44) is separated from the inferior tip of the precentral gyrus only by a shallow precentral sulcus, both of these 2 cortices form a continuous cortical area which is clearly separated from the superior temporal gyrus by the posterior ramus of the Sylvian fissure and also separated from the triangular part of the inferior frontal gyrus by the deep ascending ramus of Sylvian fissure. Another portion of the Broca’s area, triangular part of the inferior frontal gyrus corresponding to Area 45 is separated posteriorly by the ascending ramus and anteriorly by the horizontal ramus of the Sylvian fissure. Consequently, the two cortical areas consisting of the Broca’s area, opercular part and the triangular part of the inferior frontal gyrus, are horizontally disconnected from other adjacent cortical areas and connected only vertically with the rest of the brain areas. As a consequence, these two cortical areas are usually completely detached from the rest of the horizontal slice through Sylvian fissure.