Work in progress — pages and figures are still being written.

Alicia Zeng

All research

Cognition

Whether two kinds of thought share machinery in the brain is usually tested with one small experiment per kind, followed by a check for overlap between the regions each activates.

That design has a flaw it cannot correct for. Each experiment arrives with its own task and its own confounds, so any overlap found between them reflects how the two experiments were built as much as it reflects the brain.

A stimulus that already contains all of them removes the need for that comparison. Someone telling a story counts things, places them and times them continuously, in one stream of words, so a single recording and a single model can produce a map for each, and those maps can be compared directly. What it demands in return is a model whose features are separable to begin with, which is the problem the work under Bayesian addresses.

Number, space and time–

Walsh’s theory of magnitude, from 2003, holds that the brain measures how many, how far and how long with one shared system. Behaviour supports it; imaging studies have disagreed with each other. Read out of story listening, where all three arrive in the same stream and each gets its own axis in the model, the maps overlap in the intraparietal sulcus and the inferior frontal gyrus, in both hemispheres and across listeners. At nineteen listeners the picture is a distributed temporal, parietal and frontal network, selective for a single quantity in some regions and responsive to all three in others.

The video switches the three channels on and off over the group map, which is something the viewer will do on click.

Birdsong in state space–

This is the earliest work here. A zebra finch’s song can be treated as one measured channel of a dynamical system rather than as a sequence of syllables, which lets the state space behind it be reconstructed by delay embedding. The delay comes from the first minimum of the mutual information, and the procedure is checked against systems whose answers are known. The video is one song’s reconstructed state space, turning.