Brain Multiphysics (Nov 2020)
On time and space in the brain: A relativistic pseudo-diffusion framework
Abstract
Considering that the propagation speed of action potentials in the brain connectome has a finite limit and that present is ill-defined in the brain we apply concepts borrowed from the theories of special and general relativity to introduce the view that time and space are tightly blended in the brain. It is shown that the brain functional and structural features can be unified through a combined brain “spacetime”. This 4-dimensional brain spacetime presents a functional curvature generated by brain activity, in a similar way gravitational masses give our 4-dimensional Universe spacetime its curvature. After laying its foundations and developing this framework using a relativistic pseudo-diffusion model of neural propagation, we explore how this whole-brain framework may shed light on brain functional features and dysfunction phenotypes (clinical expression of diseases) observed in some neuropsychiatric and consciousness disorders. Statement of Significance: Because action potentials in the brain connectome propagate with a finite velocity limit, simultaneity across brain nodes is only relative. A new concept is emerging where time and space in the brain, as in the Universe, are tightly mingled through a combined “spacetime”. This 4-dimensional spacetime merging brain structure and function presents a curvature generated by brain activity, in a similar way gravitational masses give our Universe spacetime its curvature, driving activity flow within the brain.
