Cajal, Fig. 26–March of the excitation in auditory pathways. 

This Cajal illustration outlines the sensory neurons of the auditory system, originating at the cochlear hair cells, projecting through the midbrain, and terminating at the auditory cortex. It was originally published in Cajal’s seminal work, “Textura del Sistema Nervioso del Hombre y de los Vertebrados”. As the title suggests, it was originally published in Cajal’s native Spanish, and despite its brilliance, the language barrier meant that the “Textura” “was addressed to the few scientists who could understand and discuss his innovative ideas.” (Sotelo, x)  

The image is hand-drawn based on the observed results from a silver nitrate stain of neural tissue, and traces specific neuronal connections through dispersed brain regions. Although this stain is performed with fixed tissue samples, light microscopy often causes samples to bleach and fade, which is why Cajal reproduced his images by hand. Furthermore, directly imaging this pathway would be an extremely complicated ordeal, even with modern 3D-modeling microscopy technologies.

Cajal chooses to direct his focus on the path that the sensory neurons take up to the auditory cortex, and how they interconnect with one another. He highlights a few important nuclei to help orient us to the rough location of each neuron, but ancillary structures are not drawn in much detail. In light of the technological limitations of the late 19th/early 20th centuries, we are not meant to interpret this image as a brain atlas, but rather expect that it will clarify the way sensory auditory neurons synapse onto one another and how sound information is relayed throughout the brain. I will begin my recreations using relatively basic tools to faithfully reproduce Cajal’s work, just as he tried to faithfully reproduce the results he observed from his stains. I will start with pens and pencils on tracing paper, and expand upon this based on my field notes. For my final product, I may try to alter the visual perspective, without losing any relevant information that the original conveys.

 

FIELD NOTE 1 OF 3

Date: 2/18/2020

People Involved: Myself

Location: Will Rice College New Dorm, 3rd Floor Lounge

Reconstruction conditions: Sitting at a desk in a public study lounge. I attempted to prop up and stabilize my phone with my books, keys, and wallet — my efforts were in vain, and my phone fell over at some point during the timelapse without me realizing it. People would occasionally walk down the hall towards their dorm rooms.

Time and duration of reconstruction: 

Approximately 2 hours, 23:00-01:00. However, I did have to step away about halfway through to address a noise complaint (I’m the Chief Justice at my residential college). 

Equipment and tools used:

• Pentel GraphGear 500 mechanical drafting pencil (0.7mm)
• Staedtler high polymer eraser
• Tracing paper 

Subjective factors, e.g., how things smelled/looked/felt:

The study room was noticeably austere, with concrete floor and ceiling and white plaster walls, along with a giant concrete pillar right in the middle of the space. It was lit by a bright fluorescent light — not a “warm” tone of light at all, even less so than most fluorescent lights. This was also my first time using this particular type of pencil, and it felt very heavy in my hand compared to most other pencils I’ve used before. The grip is metal, cylindrical, and fairly thick  which I didn’t think would make much of a difference at first. However, I noticed how different it felt from the brand of mechanical pencils I normally use, which are very narrow, and have a triangular, hard plastic grip. To compensate, I unconsciously started to press my free hand down onto the sketchpad pretty hard, so hard that I eventually noticed that I was leaving fingerprints on my recreation (there’s a pretty dark one just to the left of the middle segment of the tracing). The chair I was sitting in was made of plastic and noticeably wobbly, but this faded into the background relatively quickly.

Prior knowledge that you have: 

Most of my prior knowledge about auditory projections comes from neuroscience courses I’ve taken here at Rice — namely NEUR 380 and NEUR 385. However, in those classes, there’s far greater emphasis placed on the structure of the cochlea and the hair cells within it than the exact neuronal pathway up to the auditory cortex, but we can see that in this image the cochlea is totally omitted. 

Reflection on your practice: 

My approach to this first field note was to reproduce the image without much conscious thought towards my personal methodology. I chose to do this so that I could commit to the ideal of mechanical objectivity as much as Golgi and Cajal did, and by trying to eliminate my own interpretations and placing myself in the role of a microscope/camera, maybe I could get a better sense of the image’s character. 

One of my biggest takeaways from this approach was the way I unconsciously chose to trace the image — rather than tracing the auditory pathway bottom-up, from its origin in the hair cell all the way up to the cortex, I started from the middle of the page and worked my way out. I think this was because the image has a sort of quadrangular character: it fits very neatly inside a box, which was probably Cajal’s intention, so that the image would be flush with its accompanying block of text. In order to do this, it looks like he dramatically reduced the scale when drawing the cortex — in a totally objective reproduction, the cortex would be far larger than the midbrain structures and hair cells, but Cajal draws each of the three main structures about the same size. It was here that I noticed a bit of an incongruence between artist and image. Cajal was committed to representing the nervous system as objectively, and criticized Golgi for “hav[ing] utterly failed to articulate properly the arrangements that Cajal had so painfully elicited from the silver chromate.” (Daston and Galison, 116) However, Cajal’s aims to achieve total mechanical objectivity don’t really align with his subjective decision to scale down the cortex, so that the figure may better fit the page. This seems to support Daston and Galison’s idea that human subjectivity can never really be eliminated from scientific images.   

Even though the image can easily be separated into thirds (cortex, inferior colliculus, hair cells/superior olive), there’s this small diamond-shaped figure right in the center of the drawing, which is what drew my immediate attention and where I began my first tracing. Even though there’s no real three-dimensional perspective to this image, the diamond almost gives the image a vanishing point, kind of reminiscent of how you would reproduce the sense of looking down a long hallway — the edges of the walls start out far apart and then meet each other at the horizon. My unconscious middle-out approach to this reproduction gives me a good starting point for my second field note, as I may try and factor in the perspective change that the diamond evokes.  

Part 1: https://www.youtube.com/watch?v=5oZLtTyTxsY

Part 2: https://www.youtube.com/watch?v=angeeUdZvW4

 

Fingerprints

 

Final Product

Field Note 2

FIELD NOTE 2 OF 3

Date: 2/20/2020

People Involved: Myself

Location: Will Rice College Old Dorm, Attic Study Room

Reconstruction conditions: Sitting at a desk in a windowless room, with one other person studying behind and to the left of me, mostly silent but occasionally typing. I could also hear sounds of the building’s plumbing intermittently. The room itself was fairly stuffy, on account of the steam from people taking showers in the bathroom down the hall. 

Time and duration of reconstruction: 

Approximately 1 hour, 11:00-12:00.

Equipment and tools used:

• Bic Cristal ballpoint pens (red, blue, black)
• Pentel GraphGear 500 mechanical drafting pencil (0.7mm)
• Staedtler high polymer eraser
• Tracing paper
• Masking tape (to tape my phone in the correct position for recording)

Subjective factors, e.g., how things smelled/looked/felt:

I smudged the illustration slightly because the ink hadn’t dried in some places, and because I tend to drag my hand while I write. Rather than illustrate from left to right in order to avoid smudging, I was focusing on following the neuronal pathways as they project from the cochlea to the cortex. Because I switched to ballpoint pens for drawing the neurons, I found it harder to draw the axons as smooth as they look in my first tracing and the original image. Drawing the arrows in pen was also a challenge, as it was harder to vary my pressure and line weight as I was able to do with a pencil.

That being said, I was a lot more relaxed for this tracing than the last one, which I think was mainly because of the setting. I did this tracing in Will Rice Old Dorm, and my first one in New Dorm, which have two very different atmospheres as living and study spaces. As I mentioned in my previous field note, the New Dorm study lounge is very austere and sterile-looking, which reflects New Dorm’s quieter culture. This is opposed to Old Dorm, which I find to be a warmer study and living atmosphere, with hardwood floors, warm lights, and generally more social culture than New Dorm. I found that I wasn’t pressing down on the paper as hard as I was before, and was able to find a better “route” and achieved a deeper flow state than my first recreation. 

Prior knowledge that you have: 

I went into this field note with a focus on a diamond-shaped structure in the center of the illustration, which I perceived as a sort of “vanishing point” that bisects the diagram into four quadrants. Even though I’m definitely not any sort of expert on drawing techniques, I remember the concept of a vanishing point from watching a cartoon animator livestream his work on Twitch. I was amazed at the way he showed that something as simple as drawing an X in the background of his animations could ground his scenes in a 3-D space, and accomplish such a strong sense of perspective.    

Reflection on your practice: 

I went into this reproduction trying to focus on the illustration as if the diamond shape at its center was a vanishing point. This seemed fairly straightforward to me at first, since this particular illustration seems to shrink as you get closer to the center. Much like objects in one’s field of view will shrink and get closer together as you look closer towards the horizon, the neurons in this drawing branch out proximally at the top and bottom of the image, then get closer together in the middle third of the image. I tried maintaining this perspective as I traced the neuronal projections upstream, which turned out to be a lot more difficult than I thought, even after I drew a scene of a road shrinking toward a sunset in the corner so that I could keep the vanishing point perspective fresh in my mind. I think that because I placed more focus on tracing the neurons themselves in this field note, a new perspective started to emerge that I couldn’t ignore. 

I noticed that after crossing hemispheres near the trapezoid body (E), Cajal drew the axons straight up toward the inferior colliculus (F). It struck me that this was meant to signify an axial projection straight up towards the top of the head. The bottom two-thirds of the image were two axial sections of the midbrain, and Cajal was able to convey the way in which these two parts of the brain were stereotaxically related to one another. However, as the auditory pathway projects up to the temporal cortex at the top of the image, Cajal changes the perspective. Rather than maintaining an axial (top-down) view of the pathway, he illustrates the cortex in the coronal plane (head-on). Although the cortex is not the main focus of this illustration, the choice to draw it from a different point of view as the two midbrain sections was jarring the first time I noticed it, and diminished my ability to visualize this pathway in 3-D space.