When Spandrels Become Arches: Neural crosstalk and the evolution of consciousness

Rodrick Wallace

doi:10.1038/npre.2012.6115.2

Abstract

AbstractOnce cognition is recognized as having a 'dual' information source, the information theory chain rule implies that isolating coresident information sources from crosstalk requires more metabolic free energy than permitting correlation. This provides conditions for an evolutionary exaptation leading to the rapid, shifting global neural broadcasts of consciousness. The argument is quite analogous to the well-studied exaptation of noise to trigger stochastic resonance amplification in neurons and neuronal subsystems. Astrobiological implications are obvious.

Highlights

Researchers have long speculated and experimented on the role of noise in neural processes and subsystems via models of stochastic resonance (e.g., Park and Neelakanta, 1996; Gluckman et al, 1996; Ward, 2009; Kawaguchi et al, 2011)
The evolutionary exaptation of crosstalk appears to be the system of rapid, shifting global neural broadcasts we characterize as consciousness
Baars’ global workspace model of animal consciousness attributes the phenomenon to a dynamic array of unconscious cognitive modules that unite to become a global broadcast having a tunable perception threshold not unlike a theater spotlight, but whose range of attention is constrained by embedding contexts (e.g., Baars, 1988, 2005; Baars and Franklin, 2003)

Summary

Introduction

Researchers have long speculated and experimented on the role of noise in neural processes and subsystems via models of stochastic resonance (e.g., Park and Neelakanta, 1996; Gluckman et al, 1996; Ward, 2009; Kawaguchi et al, 2011). The necessary ubiquity of noise affecting information transmission underwent an evolutionary exaptation (e.g., Gould, 2002) to become a tool for amplification of weak signals. The evolutionary exaptation of crosstalk appears to be the system of rapid, shifting global neural broadcasts we characterize as consciousness. Spandrels are the triangular sectors of the intersecting arches that support a cathedral roof. They are simple byproducts of the need for arches, and their occurrence is in no way fundamental to the construction of a cathedral. Our assertion is that crosstalk between unconscious cognitive modules is a similar inessential byproduct that evolutionary process has exapted to construct the dynamic global broadcasts of consciousness: Evolution built a new arch from a spandrel. We first provide a minimal formal overview that will be reexpressed in more complex form, much like Onsager’s nonequilibrium thermodynamics

Cognition as ‘language’

Reaction to environmental signals

A formal model

Discussion and conclusions

10 Mathematical Appendix