Modeling bias in decision-making attractor networks

TL;DR

This paper investigates how parameters in attractor neural networks can be adjusted to modify decision-making biases by reshaping basins of attraction without altering the core decision encodings, using mathematical analysis of threshold linear models.

Contribution

It provides a mathematical framework showing how decision biases can be modeled as changes in basin sizes in attractor networks without affecting the decision attractors themselves.

Findings

Basins of attraction encode decision biases.

Parameters can reshape basins without changing attractors.

Mathematical analysis of threshold linear networks supports bias modeling.

Abstract

Attractor neural network models of cortical decision-making circuits represent them as dynamical systems in the state space of neural firing rates with the attractors of the network encoding possible decisions. While the attractors of these models are well studied, far less attention is paid to the basins of attraction even though their sizes can be said to encode the biases towards the corresponding decisions. The parameters of an attractor network control both the attractors and the basins of attraction. However, findings in behavioral economics suggest that the framing of a decision-making task can affect preferences even when the same choices are being offered. This suggests that the circuit encodes both choices and biases separately, that preferences can be changed without disrupting the encoding of the choices themselves. In the context of attractor networks, this would mean that the parameters can be adjusted to reshape the basins of attraction without changing the attractors themselves. How can this be realized and how do the parameters shape decision-making biases? In this PhD thesis we study this question mathematically in the context of threshold linear networks, a common firing rate model used in computational neuroscience. (Note: This is an abbreviated abstract. Please see the document for the full abstract.)