Gaby Maimon: How brains add vectors

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Title & Abstract

Many cognitive computations rely on the nervous system estimating mathematical vectors, but aside from computer models, how brains represent vectors or perform vector operations remains unknown. In this talk, I will describe how the fruit fly brain performs vector arithmetic. Specifically, I will show that flies have a neural signal that tracks the direction in which their body is traveling in reference to external cues, like the sun. By combining this newly discovered traveling-direction signal with traveling speed, and integrating these signals over time, it becomes sensible to imagine what a spatial memory looks like in the fly brain.

I will then provide evidence that this external-world referenced traveling direction signal is constructed via a neural circuit that rotates, scales and adds four two-dimensional vectors. Each vector is explicitly represented by a sinusoidal activity pattern across a distinct neuronal population, with the sinusoid's amplitude representing the vector's length and its phase representing the vector's angle. The central features of this vector calculator inside the insect brain may generalize to other nervous systems and other cognitive domains beyond navigation where vector operations are required.

Duration of the talk:

Approx. 50 minutes, then general and specialized discussion.

More about the speaker and his research

Laboratory of Integrative Brain Function⁵

Host

Andrew Straw⁶

Image source

Bernstein Center Freiburg