

"A continuous semantic space describes the representation of thousands of object and action categories across the human brain"

Here is the abstract of the study:

Humans can see and name thousands of distinct object and action categories, so it is unlikely that each category is represented in a distinct brain area. A more efficient scheme would be to represent categories as locations in a continuous semantic space mapped smoothly across the cortical surface. To search for such a space, we used functional magnetic resonance imaging (fMRI) to measure human brain activity evoked by natural movies. We then used voxel-wise models to examine the cortical representation of 1705 object and action categories. The first few dimensions of the underlying semantic space were recovered from the fit models by principal components analysis. Projection of the recovered semantic space onto cortical flat maps shows that semantic selectivity is organized into smooth gradients that cover much of visual and non- visual cortex. Furthermore, both the recovered semantic space and the cortical organization of the space are shared across different individuals.

Or in the vulgate, from ExtremeTech:

The study (PDF), led by neuroscience doctoral student Alexander Huth, had five participants watch two hours of movie trailers that contained over 1,700 categories of actions and objects. During that time, their brain activity was recorded using functional Magnetic Resonance Imaging (fMRI), measuring blood flow in various spots in the brain. Using linear regression, the scientists were then able to analyze the collected data, and subsequently build a model showing how all of those actions and objects fit into around 30,000 locations within the cortex.

Brain Map - LargeAfter that point the researchers translated the model to a visual form. Using principal component analysis – a mathematical procedure used to provide a synopsis for a large amount of data — the scientists were able to visualize those 1,700 categories and how they related to one another, creating the chart shown to the right.

The map is made “semantic neighborhoods,” which are essentially just categories of things that the brain finds similar to each other. The researchers found that, for instance, the brain organizes the catefgories of “humans” and “animals” in a related manner, whereas “eyeball” and “car” are stored in completely different areas of the brain. Along with finding out how the brain organizes different categories of objects, the researchers also found out that different people’s brains organize things in similar ways.

What I wonder is whether brains across cultures (especially cultures that use languages from different families) organize categories the same way, or not. I'm guessing no.

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