Emergent organization of multiple visuotopic maps without a feature hierarchy

The primate visual system is comprised of multiple visual areas. Despite their foundational relevance, there are no normative accounts for why there are multiple areas nor why they have their signature “mirrored map” topography. Here I show that the stereotyped cortical organization of multiple mirrored areas naturally emerges in simulated cortex, in which self-organizing processes are used to map a multi-scale representation of visual space smoothly onto a two-dimensional cortical sheet. Predominant accounts of multiple areas emphasize hierarchical processing, where each area extends and elaborates on the previous areas’ representation. Here, no explicit hierarchical relationships were required to manifest this multi-areal organization, suggesting that feature hierarchies may be the derived rather than the driving force of this organization. This modeling work thus provides a simple computational explanation for the hallmark features of early visual topography, and the presence of multiple areas, as emergent from a single functional goal — to smoothly represent the visual field at multiple spatial scales.One Sentence SummaryThis work presents a formal model of simulated cortex with multiple visual areas, where purely spatial relationships underlie the large-scale motifs of visual cortex.

Scandinavian umlaut and contrastive feature hierarchies

With the application of the Contrastive Hierarchy Theory, the contrastive features of preliterary Scandinavian vowels are here inferred from the interaction between targets and triggers for metaphonic fronting, rounding and breaking. One Proto-Scandinavian feature hierarchy is reconstructed for prominent syllables and another for non-prominent ones. The former hierarchy sustained contrasts that differed from the latter, including contrast for rounding and a preserved distinction between Pre-Germanic */i/ and */e/. A prominence system is reconstructed that predicts both the outcome of syncope and the distribution of the two vowel systems between syllables. The analysis neatly accounts for many notorious cruxes of umlaut and breaking that correlate with the prosodic position of the trigger, including the frequent absence of i-umlaut in light syllables.