Images are metaphors.

Frozen in time, immortalized on paper—or worse—in a textbook, where images appear as fact—or worse—reality. 

In school when I have learned biology I’ve felt bombarded with images: diagrams, signaling pathways, pictures of what the heart or the stomach or the spinal cord supposedly looks like. I learn these images, drawing or tracing or memorizing them to understand them not only as universal but as truth. Although surely some scientists have a more nuanced perspective, from a student’s or an outsider’s perspective, biology, neuroscience, and physiology treat images as truth and expect me to understand them as fact.

But images are metaphors. 

And all metaphors break down eventually. Some more quickly than others. To watch this happen, I’ll turn to the history of neurophysiology, to a famous debate in 1906 between two eminent scientists, Camillo Golgi and Santiago Ramón y Cajal. 

Using new cellular staining technology developed in Golgi’s lab, the two were able to observe neurons with an unprecedented degree of precision. On the surface, their debate concerned the structural basis of the nervous system: Cajal believed in the “histological autonomy,” or modularity, of each neuron; Golgi believed that the axonal branches of neurons formed an inextricable net for communication. In other words, their units of analysis differed (1,2). 

Golgi’s neuronal theory, which emphasized the interconnectedness of the nervous system, was distinct from Cajal’s, whose theory fixated on the morphology of the individual nerve cell. Because their theories were derived directly from images, the debate between the two scientists became centered fundamentally around the epistemics of image production and objectivity (1). Cajal saw his image production process as more objective and by extension, more scientifically sound than Golgi’s interpretive methods, which involved deliberate interventions to essentialize the image and make it a more effective tool for communication (1). 

Historian Projit Banarjee Mukharji would argue that this debate is evidence of the historical contingency of anatomical knowledge (3). In other words, “truths” (or perhaps I should say knowledges) about the body are constructed by scientists based on their understandings of the body as objects of investigation. Those understandings change as technology changes. But as Mukharji says, “anatomical knowledge is neither neutral, nor a priori universal” and “the naturalistic reality of the body as such does not exist, it is created by scientists as the object of scientific investigation” (3). And even though we think of mechanical methods of knowledge construction as advancement, we have to question the presumption that teleology is a narrative of progress. 

Golgi and Cajal were equally committed to “accurate” depiction, and were working within similar historical contexts (1). Yet issues still arose because of the subjectivity inherent to the process of image creation and as a result, of knowledge production. It would be easy to say that Cajal’s more objective process was more modern and that’s why his results turned out to be correct. 

But even Cajal admitted to a lifelong struggle to “find a way to ‘see clearly’” (1). He knew that it was subjective ground on which his conclusions stood. And although we think of neurons as modular units today, we must recognize that our present biomedical knowledge is constructed too. Cajal won only in the sense that his conclusions more closely align with biomedicine’s current understanding of neuroanatomy. If we are going to question teleology as a narrative of progress, we need to question the idea that something is more correct simply because it is more recent. 

Yet I am still a person who studies neuroscience. I will study images; I will create images. Should I go on normally, despite this nagging notion that the images given to me by my biomedical education constitute an imaginative fiction?

I’m writing a review paper about ketamine and the cellular mechanisms that underlie its potential therapeutic effects. The mechanisms ketamine triggers are messy. They are entirely uncertain. Yet a reviewer asks me to create a figure to summarize my paragraph describing the confusion in the literature. I get it. I love when papers have good figures, with clear, simple signaling pathways. Even better if those pathways are linear. 

The scientific peer review process forced me to create a figure that belied what I saw as true physiological uncertainty. What is the point of all this metaphor and modeling that has become so integral to biomedicine? What is the point of creating these physiological images or depictions? 

Historian Shigehisa Kuriyama wrote, “Versions of the truth sometimes differ so startlingly that the very idea of truth becomes suspect” (4). As we see through Golgi and Cajal, anatomical images are not a foolproof method for accessing anatomical truth; this epistemological problem makes the whole idea of corporeal reality confusing. How do you separate the thing from the representation of or narrative about the thing? Can you? Is it possible to distinguish? 

 

Works Cited

1. Daston, Lorraine and Peter Galison. Objectivity. New York: Zone Books, 2007. 
2. Golgi, Camillo. “The neuron doctrine – theory and facts.” Nobel Lecture December 11, 1906: 190-217.
3. Mukharji, Projit Bihari. Doctoring Traditions: Ayurveda, Small Technologies, and Braided Sciences. Chicago: University of Chicago Press, 2016. 
4. Kuriyama, Shigehisa. The Expressiveness of the Body and the Divergence of Greek and Chinese Medicine. New York: Zone Books, 2002.