Conceptual Spaces

In a Nautilis piece, New Evidence for the Strange Geometry of Thought, Adithya Rajagopalan reports on the fascinating topic of conceptual or cognitive spaces. He begins with the work of the philosopher and cognitive scientist Peter Gärdenfors who wrote about this in a 2000 book, Conceptual Spaces. Then last year, there was published a Science paper by several neuroscientists: Jacob Bellmund, Christian Doeller, and Edvard Moser. It has to do with the brain’s “inner GPS.”

Anyone who has followed my blog for a while should see the interest this has for me. There is Julian Jaynes’ thought on consciousness, of course. And there are all kinds of other thinkers as well. I could throw out Iain McGilchrist and James L. Kugel who, though critical of Jaynes, make similar points about identity and the divided mind.

The work of Gärdenfors and the above neuroscientists helps explain numerous phenomenon, specifically in what way splintering and dissociation operates. How a Nazi doctor could torture Jewish children at work and then go home to play with his own children. How the typical person can be pious at church on Sunday and yet act in complete contradiction to this for the rest of the week. How we can know that the world is being destroyed through climate change and still go on about our lives as if everything remains the same.How we can simultaneously know and not know so many things. Et cetera.

It might begin to give us some more details in explaining the differences between the bicameral mind and Jaynesian consciousness, between Ernest Hartmann’s thin and thick boundaries of the mind, and much else. Also, in light of Lynne Kelly’s work on traditional mnemonic systems, we might be in a better position of understanding the phenomenal memory feats humans are capable of and why they are so often spatial in organization (e.g., the Songlines of Australian Aborigines) and why these often involve shifts in mental states. It might also clarify how people can temporarily or permanently change personalities and identities, how people can compartmentalize parts of themselves such as their childhood selves and maybe help explain why others fail at compartmentalizing.

The potential significance is immense. Our minds are mansions with many rooms. Below is the meat of Rajagopalan’s article.

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“Cognitive spaces are a way of thinking about how our brain might organize our knowledge of the world,” Bellmund said. It’s an approach that concerns not only geographical data, but also relationships between objects and experience. “We were intrigued by evidence from many different groups that suggested that the principles of spatial coding in the hippocampus seem to be relevant beyond the realms of just spatial navigation,” Bellmund said. The hippocampus’ place and grid cells, in other words, map not only physical space but conceptual space. It appears that our representation of objects and concepts is very tightly linked with our representation of space.

Work spanning decades has found that regions in the brain—the hippocampus and entorhinal cortex—act like a GPS. Their cells form a grid-like representation of the brain’s surroundings and keep track of its location on it. Specifically, neurons in the entorhinal cortex activate at evenly distributed locations in space: If you drew lines between each location in the environment where these cells activate, you would end up sketching a triangular grid, or a hexagonal lattice. The activity of these aptly named “grid” cells contains information that another kind of cell uses to locate your body in a particular place. The explanation of how these “place” cells work was stunning enough to award scientists John O’Keefe, May-Britt Moser, and Edvard Moser, the 2014 Nobel Prize in Physiology or Medicine. These cells activate only when you are in one particular location in space, or the grid, represented by your grid cells. Meanwhile, head-direction cells define which direction your head is pointing. Yet other cells indicate when you’re at the border of your environment—a wall or cliff. Rodent models have elucidated the nature of the brain’s spatial grids, but, with functional magnetic resonance imaging, they have also been validated in humans.

Recent fMRI studies show that cognitive spaces reside in the hippocampal network—supporting the idea that these spaces lie at the heart of much subconscious processing. For example, subjects of a 2016 study—headed by neuroscientists at Oxford—were shown a video of a bird’s neck and legs morph in size. Previously they had learned to associate a particular bird shape with a Christmas symbol, such as Santa or a Gingerbread man. The researchers discovered the subjects made the connections with a “mental picture” that could not be described spatially, on a two-dimensional map. Yet grid-cell responses in the fMRI data resembled what one would see if subjects were imagining themselves walking in a physical environment. This kind of mental processing might also apply to how we think about our family and friends. We might picture them “on the basis of their height, humor, or income, coding them as tall or short, humorous or humorless, or more or less wealthy,” Doeller said. And, depending on whichever of these dimensions matters in the moment, the brain would store one friend mentally closer to, or farther from, another friend.

But the usefulness of a cognitive space isn’t just restricted to already familiar object comparisons. “One of the ways these cognitive spaces can benefit our behavior is when we encounter something we have never seen before,” Bellmund said. “Based on the features of the new object we can position it in our cognitive space. We can then use our old knowledge to infer how to behave in this novel situation.” Representing knowledge in this structured way allows us to make sense of how we should behave in new circumstances.

Data also suggests that this region may represent information with different levels of abstraction. If you imagine moving through the hippocampus, from the top of the head toward the chin, you will find many different groups of place cells that completely map the entire environment but with different degrees of magnification. Put another way, moving through the hippocampus is like zooming in and out on your phone’s map app. The area in space represented by a single place cell gets larger. Such size differences could be the basis for how humans are able to move between lower and higher levels of abstraction—from “dog” to “pet” to “sentient being,” for example. In this cognitive space, more zoomed-out place cells would represent a relatively broad category consisting of many types, while zoomed-in place cells would be more narrow.

Yet the mind is not just capable of conceptual abstraction but also flexibility—it can represent a wide range of concepts. To be able to do this, the regions of the brain involved need to be able to switch between concepts without any informational cross-contamination: It wouldn’t be ideal if our concept for bird, for example, were affected by our concept for car. Rodent studies have shown that when animals move from one environment to another—from a blue-walled cage to a black-walled experiment room, for example—place-cell firing is unrelated between the environments. Researchers looked at where cells were active in one environment and compared it to where they were active in the other. If a cell fired in the corner of the blue cage as well as the black room, there might be some cross-contamination between environments. The researchers didn’t see any such correlation in the place-cell activity. It appears that the hippocampus is able to represent two environments without confounding the two. This property of place cells could be useful for constructing cognitive spaces, where avoiding cross-contamination would be essential. “By connecting all these previous discoveries,” Bellmund said, “we came to the assumption that the brain stores a mental map, regardless of whether we are thinking about a real space or the space between dimensions of our thoughts.”