The Anatomy of the Retrosplenial Region: The Most Important 21 Pages In The Field of Neuroscience? Dr Korbinian Brodmann. The Man Who Mapped the Brain. Part 10

Figure 1 –Dr Korbinian Brodmann, German Neurologist, Frontpiece of ‘Localisation in the Cerebral Cortex’, 1909, Public Domain*

Video of this Post

Dr Korbinian Brodmann was a German Neurologist who revolutionised the study of the brain by creating a brain map which was grounded in the microscopic properties of the brain. For the first time, researchers and clinicians alike had access to a detailed map of the brain which was described in relation to the large brain structures such as the grooves (sulci) and ridges (gyri). Brodmann had assembled a significant collection of anatomical specimens from many species. This enabled him to compare the brain maps of different species and this in turn helped him to better understand the human brain map. Brodmann’s description of the Retrosplenial Region is a case in point. Brodmann writes that the microscopic anatomy of the discrete areas he found were confirmed by him only after a comparison with the brain maps of other species.

An important feature of the brain maps are the eponymously named Brodmann Areas – discrete areas within the brain regions Brodmann described. These areas are distinguishable by the structures formed by the neurons when viewed under the microscope – the cornerstone of Brodmann’s analysis. Brodmann’s analysis of the human brain is confined to 21 pages in one English translation. What is noticeable about Brodmann’s analysis is the relative lack of photomicrographs to illustrate the features of the individual Brodmann Areas. Indeed for a work which has had so profound an impact, the relative brevity of the description is remarkable. Nevertheless it has proved a robust model of the brain.

Turning to the Retrosplenial Region, Brodmann’s description contains three Brodmann Areas

Brodmann Area 26: The Ectosplenial Area

Brodmann Area 29: The Granular Retrolimbic Area

Brodmann Area 30: The Agranular Retrolimbic Area

 Figure 1 – Cytoarchitectonics of human brain according to Brodmann (1909), Public Domain*, The Top Diagram is the Lateral Surface of the Cortex, The Bottom Diagram is the Medial Surface

One interesting point of Brodmann’s description of the Retrosplenial Region is his reference to Figure 1. In the lower diagram, Brodmann acknowledges that the three Brodmann Areas cover a wider area than in reality in order to illustrate their  relationships more easily.

Figure 2 – Three drawings by Santiago Ramon y Cajal, taken from the book “Comparative study of the sensory areas of the human cortex”, pages 314, 361, and 363, Public Domain*

Left: Nissl-stained visual cortex Middle: Nissl-stained motor cortex Right: Golgi-stained cortex 

Brodmann also relates the Retrosplenial Region directly to the Corpus Callosum and the reader will benefit from considering the video illustration of the anatomy of the Corpus Callosum in the video below.

Video of the Corpus Callosum

Figure 3 – Brodmann Areas 26, 29 and 30, Derived from Gray’s Anatomy 20th Edition 1918 Lithograph Reproduction, Public Domain

Figure 4 – Hagmann et al,  (2008), Extract from Figure 1 from Mapping the Structural Core of Human Cerebral Cortex, PLoS Biol 6(7): e159, Creative Commons 2.5 License

Brodmann writes that the there Brodmann Area correspond to the Isthmus of the Corpus Callosum. I pointed out some interesting relationships with the structures in Figure 4 in a previous post which the reader is directed to when considering these relationships.

Area 26: The Ectosplenial Area – this area has poorly developed lamination according to Brodmann. BA 26 is closely related to the posterior aspect of the Corpus Callosum according to Brodmann and lies within the Callosal Sulcus.

Area 29: The Granular Retrolimbic Area – Brodmann writes that BA29 has a well developed inner granular layer (layer IV) but a poorly developed layer III. This area forms a semicircle around BA26 and like this area lies in the Callosal Sulcus.

Area 30: The Agranular Retrolimbic Area – Brodmann writes that layers III and V are well developed while layer IV is poorly developed. This area encircles the two areas above, corresponds to the edge of the Isthmus and extends onto the anterior aspect of the Calcarine Sulcus.

References

Brodmann’s Localisation in the Cerebral Cortex. 1909. Translated and Edited by Laurence J Garey. Springer. 2006.

*Public Domain in those countries where the Copyright term of the life of the author (Korbinian Brodmann 1868-1918) plus the additional country specific term has lapsed from Copyright at the time of writing

Appendix

The Most Important 21 Pages In The Field of Neuroscience? Dr Korbinian Brodmann. The Man Who Mapped the Brain. Part 1

The Most Important 21 Pages In The Field of Neuroscience? Dr Korbinian Brodmann. The Man Who Mapped the Brain. Part 2 – The Postcentral Region

The Most Important 21 Pages In The Field of Neuroscience? Dr Korbinian Brodmann. The Man Who Mapped the Brain. Part 3 – The Precentral Region

The Most Important 21 Pages In The Field of Neuroscience? Dr Korbinian Brodmann. The Man Who Mapped the Brain. Part 4 – The Frontal Region

The Most Important 21 Pages In The Field of Neuroscience? Dr Korbinian Brodmann. The Man Who Mapped the Brain. Part 5 – The Parietal Region

The Most Important 21 Pages In The Field of Neuroscience? Dr Korbinian Brodmann. The Man Who Mapped the Brain. Part 6 – The Occipital Region

The Most Important 21 Pages In The Field of Neuroscience? Dr Korbinian Brodmann. The Man Who Mapped the Brain. Part 7 – The Temporal Region

A 103 Year Old Neuroanatomical Mistake? The Most Important 21 Pages In The Field of Neuroscience? Dr Korbinian Brodmann. The Man Who Mapped the Brain. Part 8 – The Insular Region

The Anatomy of the Cingulate Region: The Most Important 21 Pages In The Field of Neuroscience? Dr Korbinian Brodmann. The Man Who Mapped the Brain. Part 9

Is it Time for Neuroscientists to Revisit the Brodmann Areas?

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One thought on “The Anatomy of the Retrosplenial Region: The Most Important 21 Pages In The Field of Neuroscience? Dr Korbinian Brodmann. The Man Who Mapped the Brain. Part 10

  1. Pingback: The Anatomy of the Hippocampal Region: The Most Important 21 Pages In The Field of Neuroscience? Dr Korbinian Brodmann. The Man Who Mapped the Brain. Part 10 « The Amazing World of Psychiatry: A Psychiatry Blog

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