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Pigeonholing or ‘thinking in boxes’ is omnipresent, you find it all over: in music genres, political labels, and in medical or psychological diagnostics. Better yet, you even find it within the neurosciences, regardless of all they know about the brain. The temptation to assign brain area X to whatever function Y is a severe one. Perhaps the most notorious example of this would be “phrenology”, the ancient and by now totally rejected idea that your character could be read out from bumps on your skull. While this idea has long been degraded to the realm of bad jokes and windowsill decoration, the flexibility with which people invent new ways to rigidify thought is quite staggering.
Functional formatting
In current day neuroscience, plenty pigeonholes remain. Take the fusiform face area, abbreviated FFA. This part of the cortex became famous for its remarkable sensitivity to faces; it fires strongly and consistently when the cortex-owner is presented a face. Labeling it face area, however, simplifies matters too much. For instance, experiments show that in people with various sorts of visual expertise—such as birdspotters or car enthusiasts—the FFA fires just as strongly when they see a bird or car. In fact, it fired just as well seeing them from the side, where no ‘face’ equivalent of the bird or car was visible. The simple assignment of face perception is thus too crude. More accurate is to link the area to functions enabling face, bird, and car recognition, such as distinguishing fine-grained visual features (various noses, wings, headlights). This shows that the sensitivity of an area depends on how it processes information, but also on what it gets to process.
Whatever’s for dinner
A more sensational example comes from an experiment with ferrets. There, ferret’s visual signals were re-routed to areas ordinarily occupied with processing sounds. You might expect that this auditory area would remain auditorily-inclined. But no: the brain tissue developed characteristics very similar to those of the visual cortex, such as structured sensitivity to different orientations of objects in the visual world. This shows that what makes a brain lobe auditory or visual is not necessarily its location, but rather the type of signal it receives there, and what it can do with it. Furthermore, it suggests that different areas of the brain employ the same principles to process information—a general rule.
Unboxing
The study of how the brain works should be seen less as a treasure hunt; after all, there are no reliable treasure maps. The exact location where information is processed is less relevant than how it is processed. With the ferret experiment in mind, we might, for example, ask ourselves what these general rules for information processing are that make the brain function as it does. Because that mechanism is what we ultimately want to understand. However much structure these categories may seem to offer, they mainly encourage a game of territorial squabbling, with the cortex as the playing board. The bigger picture never becomes clear by staring at individual puzzle pieces—however manageable they may be.
Author: Wieger Scheurer
Buddy: Lucas Geelen
Translator: Wieger Scheurer
Header image by Juan Gris via National Gallery of Art
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