Stable neuronal assemblies are generally regarded as neural correlates of mental representations. Their temporal sequence corresponds to the experience of a direction of time, sometimes called the psychological time arrow. We show that the stability of particular, biophysically motivated models of neuronal assemblies, called coupled map lattices, is supported by causal interactions among neurons and obstructed by non-causal or anti-causal interactions among neurons. This surprising relation between causality and stability suggests that those neuronal assemblies that are stable due to causal (...) neuronal interactions, and thus correlated with mental representations, generate a psychological time arrow. Yet this impact of causal interactions among neurons on the directed sequence of mental representations does not rule out the possibility of mentally less efficacious non-causal or anti-causal interactions among neurons. (shrink)

1. Introduction: The problems of time and consciousness What is time? St. Augustine remarked that when no one asked him, he knew what time was; however when someone asked him, he did not. Is time a process which flows? Is time a dimension in which processes occur? Does time actually exist? The notion that time is a process which "flows" directionally may be illusory (the "myth of passage") for if time did flow it would do so in some medium or (...) vessel (e.g. minutes per what?) [1]. But if time is a dimension in which processes occurred, e.g. as one component of a 4 dimensional spacetime, then why would processes occur unidirectionally in time? Yet we perceive time as an orderly, unidirectional process. An alternative explanation is that time does not exist as either a process or dimension, but that reality is a collage of discrete, disconnected and haphazardly arranged configurations of the universe, e.g. as described in Julian Barbour's "The end of time" [2]. In this view our perception of a unidirectional flow of time occurs because each moment, or "Now" as Barbour terms them, involves memory of other conceptually relevant moments, and the orderly flow of time is an illusion. Barbour's deconstruction of time contrasts the Newtonian reality of objects moving deterministically through 4 dimensional spacetime. Newton's contemporary (and rival) Leibniz [3] viewed the world in a manner consistent with Barbour (and with Mach's principle that the spatiotemporal structure of the universe is dependent on the distribution of mass, a foundation of Einstein's general relativity). According to Leibniz the world is to be understood not as matter/mass moving in a framework of space and time, but of more fundamental snapshot-like entities that momentarily fuse space and matter into single possible arrangements or configurations of the entire universe. Such configurations, which can be fabulously rich and complex considering the vastness of the universe, are the ultimate "things" of reality, which Leibniz termed "monads".. (shrink)