Poster F70, Tuesday, March 28, 8:00 – 10:00 am, Pacific Concourse
A mechanism for the cortical computation of hierarchical linguistic structure
Andrea E. Martin1,2, Leonidas A. A. Doumas1; 1University of Edinburgh, 2Max Planck Institute for Psycholinguistics
To process language, the human brain must form hierarchical representations from a sequence of perceptual inputs distributed in time. What mechanism underlies this ability? One hypothesis is the brain repurposed an available neurobiological mechanism when hierarchical linguistic representation became an efficient solution to a computational problem posed to the organism. Under such an account, a single mechanism must have the capacity to perform multiple, functionally-related computations, e.g., detect the linguistic signal and perform other cognitive functions, while, ideally, oscillating like the human brain. We show that a computational model of analogy, built for an entirely different purpose - learning relational reasoning (Doumas, LAA et al. (2008) A theory of the discovery and predication of relational concepts. Psychological Review 115:1-43.) - can parse sentences, represent their meaning, and, crucially, exhibits oscillatory activation patterns that strongly resemble the cortical signals elicited by the same stimuli (Ding, N et al. (2016) Cortical tracking of hierarchical linguistic structures in connected speech. Nature Neuroscience 19(1):158-164). Such redundancy in the cortical and machine signals suggests a deep mechanistic alignment between representational structure building and ‘cortical’ oscillations. By inductive inference, this synergy indicates that the cortical signal reflects the generation of hierarchical linguistic structure - rather than mere tracking of it - just as the machine signal does. A single mechanism – using time to encode information within a layered neural network – generates the representational hierarchy that is crucial for human language, and offers a mechanistic linking hypothesis between linguistic representation and cortical computation.
Topic Area: LANGUAGE: Syntax