Time, space, memory and brain–body rhythms

Abstract

Time and space are crucial concepts in neuroscience, because our personal memories are tied to specific events that occur ‘in’ a particular space and on a ‘timeline’. Thus, we seek to understand how the brain constructs time and space and how these are related to episodic memory. Place cells and time cells have been identified in the brain and have been proposed to ‘represent’ space and time via single-neuron or population coding, thus acting as hypothetical coordinates within a Newtonian framework of space and time. However, there is a fundamental tension between the linear and unidirectional flow of physical time and the variable nature of experienced time. Moreover, modern physics no longer views space as a fixed container and time as something in which events occur. Here, I articulate an alternative view: that time (physical and experienced) is an abstracted relational measure of change. Physical time is measured using arbitrary units and artificial clocks, whereas experienced time is linked to a hierarchy of brain–body rhythms that provide a range of reference scales that reflect the full span of experienced time. Changes in body and brain circuits, tied to these rhythms, may be the source of our subjective feeling of time. Understanding how the brain represents experienced time and how representations of space and time are integrated to form episodic memories has been a goal of much neuroscientific research. In this Perspective, Buzsáki discusses classical and contemporary ideas about time perception and proposes that a hierarchy of brain–body rhythms contributes to our subjective experience of time.