consists of Brodmann’s Area 44 and Area 45, the former is located on the opercular part and the latter on the triangular part of the inferior frontal gyrus. Therefore, both of these cortices of Broca’s area are totally missing from the Marie’s illustration of “zone lenticulaire.”
Fig. 1.a Pierre Marie’s illustration showing “zone lenticulaire” (from Marie [1-3]), b the corresponding horizontal brain slice (modified from Matsui [4]).
Confirmation of the Missing Portions from the Brain Slice
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.
Pierre Marie’s Error in Identifying the Cortical Areas
In his first paper [1], Pierre Marie showed a patient who did not show any language disturbance in spite of a destructive lesion of Broca’s area, but the destructive lesion of the case of this patient is actually situated anterior to the horizontal ramus of Sylvian fissure (Fig. 4a), that is to say on Area 46 of Brodmann and we can never know whether Broca’s area (Area 44 and 45) is affected or not, because these 2 cortical areas are completely missing from the illustration.
Fig. 4.a Marie’s non-aphasic case with a destructive lesion which Marie thought had destroyed Broca’s area but actually the lesion is located in Area 46. b Marie’s case with Broca aphasia without lesion on the Broca’s area. Areas 44 and 45 are missing. c Dejerine’s case cited by Marie as a case of Broca aphasia without lesion on the Broca’s area. Area 45 of the Broca’s area is evidently affected. (a cited from [1], Band c cited from [2]).
In his second paper [2], Marie showed an illustration of brain slice of Case Bal…, who clinically showed Broca’s aphasia (Fig. 4b). According to Marie, the lesions of this patient affected the “zone lenticulaire” and the deep white matter of the Wernicke area together with the white matter of the temporal lobe. But again, since both opercular and triangular parts of Broca’s area are missing from the illustration, we can never know whether these most important cortical areas are intact or not. In this paper [2], Marie cited the illustration of the brain slice of Bernheim’s case with Broca’s aphasia which appeared in Dejerine’s book (Fig. 4c). Marie discussed the clinicopathological similarities between these two cases, but the illustration of the Bernheim’s patient cited in Marie’s paper clearly shows that the opercular part of the inferior frontal gyrus corresponding to Area 44 is preserved but the triangular part of the same gyrus corresponding to Area 45 of the Broca’s area is totally damaged and atrophied. Marie seemed to have repeatedly made errors in identifying the anatomical site of the Broca’s area not only in his own cases, but also with the anatomo-pathological reports of other investigators [6].
Why Marie Did Not Notice the Missing Parts?
Then the question arises. Why Pierre Marie had repeatedly made this kind of simple error to identify the cortical areas? The answer is given by one of his last pupils form the United States. Percival Bailey, the famous neurosurgeon, entered Marie’s clinic at the Salpêtrière in 1921 as foreign assistant. He wrote “Only rarely did he enter the wards and never the laboratory, for he was very sensitive to formalin and would look at fixed brains only through a window, and there dictate his description” [7]. Although the above-mentioned anatomo-pathological studies of patients with aphasia were done in the Hospice de Bicêtre, and not in the Salpêtrière, he was sure to use it to observe the already cut horizontal brain slices indirectly through a window, as Bailey described. As shown in the previous Figures 1 and 4,
