When the Göttingen anatomist Rudolf Wagner examined a brain in 1856 that was later mistakenly believed to be that of the famous mathematician Gauss, he noticed an unknown peculiarity: a connection above the central fissure — which separates two parts of the brain — that he described as a "bridge." Twenty years later, in 1876, the Viennese anatomist Richard Heschl searched more than 1,000 brains for further instances of this "bridge" and was able to identify it in six of them. He also measured an ordinary brain winding at the same location, situated at the base of the fissure, as he suspected a connection between this "deep winding" and the "bridge": if the deep-lying winding occurred at varying heights, the "bridge" should appear at the same location, but at the brain's surface. The data confirmed his hypothesis. 150 years later, researchers from the German Primate Center – Leibniz Institute for Primate Research (DPZ) and the University of Göttingen, led by Renate Schweizer, a scientist in the Department of Functional Imaging at the DPZ, have now replicated Heschl's findings. For their work, Renate Schweizer, together with her co-authors Anna M. Müllen and Julius Stropel, has been awarded the Replication Prize of the Organization for Human Brain Mapping. The article on which the prize is based was published in 2025 in the journal Brain Structure and Function.

The brain of physician C. H. Fuchs leads researchers to the original study

The brain of the physician C. H. Fuchs — in which Rudolf Wagner had first described the extremely rare "bridge" in the central fissure — was most likely accidentally swapped with the brain of C. F. Gauss during scientific work in the 1860s. This mix-up was uncovered in 2013 by Renate Schweizer, and it was precisely the rare "bridge" in the central fissure that provided the crucial clue to the confusion. While researching historical publications, the neuroscientist then came across Richard Heschl's work, published in 1877.

The connection between the "bridge" and the ordinary brain winding

Until the replication study appeared, Heschl's work had been the only one to demonstrate not only how rare the "bridge" in the central fissure was, but also to describe the height distribution of the so-called "deep winding" — present in all brains — at the location of the "bridge." Both findings could only be established through a very large sample. In his "statistical" study, he therefore examined 1,087 brains from deceased patients at the Vienna General Hospital within the space of a year, confirming his hypothesis about the relationship between the two anatomical phenomena.

Renate Schweizer notes that this approach was remarkable: "What is so striking about this historical study is Heschl's surprisingly modern understanding of the large sample as the basis for a 'statistical study.' That is what made replicating it with modern methods particularly exciting."

Heschl's hypotheses confirmed after nearly 150 years — and extended by a possible new influencing factor

Renate Schweizer and her team have now confirmed the connection between the deep-lying convolution in the central fissure and the fully developed "bridge" at the same location. The researchers analyzed structural magnetic resonance imaging (MRI) scans of 1,112 healthy adults from the "Human Connectome Project Young Adult" dataset.

In the first part of the study, Heschl's findings on the occurrence of the "bridge" were replicated using a methodology inspired by his original approach — the visual analysis of complete brains — by generating so-called surface reconstructions from the MRI scans.

While Heschl had originally identified six cases of a "bridge" across the central fissure, corresponding to a prevalence of 0.6 percent, the modern sample yielded nine cases: a slightly higher prevalence of 0.8 percent. This modest increase may be attributable to the modern sample, which consists of 40 percent twins — a composition that also made a new finding possible.

The "bridge" was observed more frequently in twins: in 1.8 percent of fraternal twins and 1.1 percent of identical twins. However, since it is typically present in only one of the two twins, the researchers conclude that the "bridge" is not genetically determined but rather influenced by early environmental factors. Schweizer adds that "the bridged central fissure represents an anatomical variation, not an anomaly, and therefore has no currently known functional consequences — neither in terms of limitations nor enhancements of any abilities."

The second part of the replication involved measuring the height distribution of the "deep winding," for which a new computational method was developed by doctoral researcher Anna M. Müllen. Here too, the researchers found an identical trend to Heschl's results: despite deviations in the absolute numbers — attributable to the greater precision of the modern method — the height distribution of the "deep convolution" showed the same pattern of increases up to just below the brain's surface.

Historical study employed a surprisingly modern approach

In conclusion, Renate Schweizer highlights Heschl's methodological and conceptual foresight, which she considers extraordinarily advanced for his time: "Heschl not only championed and implemented a statistical approach, but also drew on the explanatory power of the height distribution of the 'deep winding' to clarify the relationship between rare and general anatomical structures — a central guiding principle of modern neuroanatomical research."

Prize ceremony of the Organization for Human Brain Mapping in Bordeaux

For their unique combination of historical inspiration and modern methods, Renate Schweizer, together with co-authors Anna M. Müllen and Julius Stropel, received the Replication Prize of the Organization for Human Brain Mapping at the organization's conference, held from 14 to 18 June 2026 in Bordeaux.