Harmonics as a principle of brain function

The human brain consists of functionally specialized areas, which flexibly interact and integrate forming a multitude of complex functional networks. The principles underlying this functional differentiation and integration remain unknown. In this talk I will demonstrate that a fundamental principle ubiquitous in nature - harmonic modes - explains the orchestration of brain’s functional organization.

Harmonic patterns constitute a universal characteristic of natural phenomena, emerging in acoustics, optics, and electromagnetism as well as in biological processes such as morphogenesis. Recently, brain activity in awake, resting state is also shown to follow stable harmonic wave patterns emerging on the anatomical connectivity of the human brain [1,2]. In this talk, I will illustrate how the harmonic modes of brain’s communication structure - given by its functional connectivity in the resting state - reveal the functional organization of the human cortex [3]. These harmonic waves, referred to as “functional harmonics”, provide the frequency-ordered communication channels of the human brain and provide a new function basis to describe any pattern of brain activity. I will show that 47 brain activation patterns elicited by 7 different task categories in the Human Connectome Project task battery can be reconstructed from a very small subset of functional harmonics, suggesting a simple and universal account for the previously unknown relationship between task and resting state brain activity.