Freitag, 23. Februar 2018

A report of a presentation entitled “Anatomy of the Brain from Galen to Avicenna: Translation and Transformation” by Shahrzad Irannejad.

A weblog entry by Antonio Puleri

Have you ever heard, in the book One Thousand and One Nights, of Scheherazade’s tale about the slave girl Tawuddud, the hasty merchant and the caliph Harun al-Rashid? Have you ever heard of how the so-called ‘theory of inner senses’ spread in the medieval world, of Avicenna’s Canon of Medicine and its Galenic influence? What do you know of labelling and describing things? 

Whether you are familiar with all these topics or not, it is absolutely worth getting to know Shahrzad’s fascinating research-project presented at the Plenumssitzung of the Graduiertenkolleg held on February 8th 2018, which also broadened our knowledge of some anatomical and terminological issues. 

The theory of inner senses and ventricles 

As already mentioned, Shahrzad’s presentation begins with an intriguing reference to the literary work One Thousand and One Nights. Tawuddud, a smart but enslaved girl – Scheherazade tells the king Shahryār – is answering many and variegated questions asked by experts in order to prove her smartness. When a physician, speaking of brain anatomy, asks her how many ventricles there are in a man’s head, Tawuddud answers three. The human head – the girl goes on – has indeed three holes, in which five inner senses are localized. Such a theory, which was the most widespread both in the Islamicate and Latin medieval worlds, seems to have reached its final development with Avicenna, a Persian polymath living between the 10th and 11th centuries and regarded as one of the most significant personalities of that period. One of his main works is The Canon of Medicine, a medical encyclopedia that remained a standard text for physicians for several centuries. 

As Shahrzad underlines, Avicenna’s inner senses – composite sense, retentive imagination, compositive imagination, estimation and memory – seem to have developed from earlier Aristotelian concepts. Nevertheless, his brain anatomy mostly derives from Galen, whereas the localization of the five faculties in the ventricles is inherited from Nemesius, bishop of Emese living in the 4th century. The overall scheme of the Avicennean version of the theory of Inner Senses can be seen in Figure 1

What is then the ventricular system of the brain? How could we describe it? The ventricular system is a set of four cavities in the brain, the so-called ventricles, which are interconnected and filled with the cerebrospinal fluid. What Shahrzad tells us is that Avicenna lingers over these complicated structures of the brain since they are ‘required’ in the physiology of the inner senses, that is, they are needed to explain an underlying physiological theory. Despite this, Avicenna only makes use of the Arabic word batn, ‘ventricle’, and of its attributes, without using other specific terms to indicate the specific parts of these structures. 

Fig 1. The overall scheme of the “Ventricular Localization of the Inner Senses” according to Avicenna (slide by Shahrzad Irannejad) 

Labels and descriptions in brain anatomy. Two terminological case studies 

In her discussion, as we had already heard at the international workshop "Resurrecting the Ancient Mind" held on December 5th and 6th 2017, Shahrzad focuses on two terminological examples and takes into account two intracranial structures, namely the ‘wine-press’ and the ‘net’. 

Speaking of the first case study, the wine-press, Shahrzad informs us that nowadays this structure of the brain is known as Torcular herophili or ‘confluence of sinuses’, since it represents the connecting point of several sinuses. The Greek term Galen uses to point to this structure is ληνός, which can be translated into English as ‘wine-press’ or ‘treading floor’. Regardless of the most appropriate translation, we notice that the Greek word has been taken by Galen from his domestic landscape as source domain and transferred to the brain’s landscape with a new meaning. The Arabic translation of Galen’s two anatomical works made by Hunyan and Hubaysh, dating back to the 9th century, shows us that the Greek word ληνός has been translated as mi‘sara, which can stand both for the instrument where grapes are squeezed or the site where the pressing process takes place. This is a striking example of what Shahrzad presents us as translation of a ‘label’, using the terminology of the linguistic Helmut Lüdtke. In a nutshell, a label is the shortest way to point to a concept, whose longer form is the description. Both label and description are different ways of ‘naming’ things, a topic on which Galen himself wrote in his medical works. 

The second example takes into consideration a net-like structure of the brain that is well described by Galen and also mentioned in Avicenna’s Canon. Nowadays, this structure is known as rete mirabile and consists of a complex of veins and arteries lying very close to each other. Galen gives this structure an important role, since the vital pneuma deriving from the heart goes up to the rete mirabile, where it is cocted and turned into psychic pneuma. Nevertheless, Shahrzad tells us the Greek writer refers to this brain component not by using a single label, rather by making use of various periphrases such as ‘the marvelous net’, ‘the net that is entangled’ or ‘the net-like complex’. While making a list of the different parts of the head, Avicenna mentions this structure of the brain in his work by means of the Arabic word sabakah, which literally means ‘net’. We thus notice that, in so doing, the Arabic tradition turned a description (or several descriptions) referring to the same concept into a single label. Nonetheless, the anatomist Andreas Vesalius found out, in the 16th century, that this brain structure only exists in some vertebrates. There is no track of that in the human brain! Such a striking discovery weakened no doubt the anatomical theories of Galen and his successors. 

Aristotle and Galen’s inheritance in Avicenna’s Canon 

Shahrzad goes on with her presentation by explaining how Aristotle and Galen’s thoughts influenced Avicenna’s main medical work, the Canon of Medicine. Speaking of the substance of the brain, Avicenna says that it is cold and wet, since its task is to refrigerate the hot pneuma that, ascending from the heart, comes up to the brain. This theory seems to be inherited from Aristotle, who, as Shahrzad correctly reminds us, has a cardiocentric view and whom Galen, some centuries later, harshly blames for his shameful statements: “Aristotle, what a thing for you to say!” scornfully utters the Greek physician. On the other hand, the third book of Avicenna’s Canon turns out to be a synopsis of Arabic translations of two of Galen’s medical works, Anatomical procedures and On the usefulness of the parts of the body. Avicenna draws on some Galen’s concepts, such as the distinction between the cerebrum and the cerebellum or between the rear and frontal parts of the brain, stating that the former is harder than the latter. Despite this, Avicenna only mentions the Greek author at the beginning of the chapter on the disease of the head and then ceases to do it. To sum up, Avicenna seems to find a compromise between Aristotle’s cardiocentric view and some anatomical theories of Galen, as Shahrzad explains. 

Medical works or speculative anatomy? 

With great public approval, Shahrzad’s speech ended. Yet, her remarkable conclusion raised a long-lasting but productive debate on several pressing issues, among which a quite provocative statement on medical books such as Avicenna’s. Namely, his work was defined as mere speculative anatomy or – even more radical – a philosophical exercise based on non-medical studies. In other words, Avicenna’s oeuvre would have nothing to do with real medical progress. Indeed, there are doubts – and Shahrzad agrees – that Avicenna practiced real medicine, as his main goal was to create a comprehensive, encyclopedic work holding all the previous anatomical knowledge. Many writers like Avicenna have been writing over centuries on the same topic, trying with much effort to refine theories on brain anatomy and so improve the medical literature, not the medical science. On the other side, one argued that such a great effort made in re-elaborating anatomical theories thoroughly should make one appreciate these authors so keen on discovering natural sciences. That is the reason why their works cannot be easily discarded as simply speculative literature. 

The discussion was interrupted due to a shortage of time, thus many questions remained unasked and many thoughts unsaid. However, there will be for sure time to reopen it in the future and we are pretty sure Shahrzad will provide us with new interesting insights. We all look forward to listening again to her!

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