Is Single Cell Electrophoresis (”Comet Assay”) an “Imaging Technology”?
Hi Susanne — this is an awesome one:
(from Metasystems)
I’ve been browsing around for a while. These are cool images, yes. But do they involve “imaging”?
Aren’t they rather “images” that serve as approximate “measures” in a metonymical way, as a “stand-ins” for physical parameters, in this case the “degree of DNA breakage”? Like this variant:
(from Mariusz Jankowski’s website, University of Southern Maine)
“Imaging”, on the other hand, would, in my view, be a technology which, in this case, produced an “image” of the break “itself”. Like Ehrlich’s “beautiful pictures” depicted the alleged side-chains on the surface of cells …
20 Apr 2006 Thomas
Hi Thomas, I agree that the comet assay works as a “stand-in” - through metonymy rather than immediate reference to the DNA breaks. I thought of ‘imaging’ as a technique of processing signals/data into a visual mode (as opposed to numerical), the above 3D graph would be a border case between them, where you (still) have the numerical references, and the presence of measures and parameters. I think I see ‘scientific visualisation’ and ‘imaging’ as a continuum, where indicators, surrogate variables, different media and signal separation techniques, contrast substances etc. are used to make visible signals of an object, thereby recording and ‘picturing’ sth. otherwise invisible. - Now I wonder what makes ‘scientific visualisations’ becoming ‘images’ and doing ‘imaging’ - (which) degree of mediation/immediateness or reference in the representation? Is it about perception, about the visualisations’ falling into some iconographic tradition of the object or its model (here: the DNA double helix)? How immediate could an image of a DNA strand break ‘itself’ become?
Hi Susanne and Thomas –
I would personally call ‘imaging’ the visual representations that claim to have a ‘causal’ relation to a physical referent, and are inscribed within an iconographic tradition of causal relation to reality (in Roger Scruton’s words: “[a] photograph is a photograph _of_ something. But the relation here is causal and not intentional.”). They can therefore produce the illusion of ’seeing’/’showing’ (in a photographical sense). In comparison, some representations like the DNA double helix/strand are explicitly models - or what do you say?
So I would spontaneously give the ‘imaging’-label to representation practices as a function of their claimed relation to the world (even implicitly, through their iconographic frames/traditions) rather than how they actually are built.
In that sense, the first picture of cell electrophoresis can be considered as imaging (for what I remember about electrophoresis): the shape of the comet is that of an electrophoresis as seen with the naked eye, even if the colors actually code for things that are not visible. On the other hand, the 3D-graph of the same assay, although containing exactly the same information, is produced within a tradition of mathematical representation and does therefore not claim to be a causally mediated ‘picture’ or snapshot of something…
In that sense, images of DNA/RNA/etc processes within the cell may be images (microscope pictures/”photographs”, possibly with the help of different markers) or models (like the double helix) depending on how they are produced and presented.
Is it cheap to refer to implicit iconographic/pictorial traditions/frames? Amit Prasad had an interesting reflection about images (MRI and Visible Human Project) in a 2005 article in Science, Technology & HUman Values (vol.30 nr2, 291-316): “…even though these pictures are supposed to represent what is inside the body, there is no “original copy” with codes to interpret them, such that one can arrive at one fixed interpretation. […] Medical science representations […] are produced as “similitudes” to other such representations, as seen through a cross-referential network, but are argued to be a “resemblance” of an “original copy” whose marks and traces, which are seen through cross-referencing, becomes “signatures” of the “original copy.” (p.304)
Representations are mediated - almost always technologically. So the question may be rather about what “original copies” representations claim similitude to? and in what frames of interpretation does that place them? How would that apply to the example of DNA strand break?