A landmark study: How the geometry of the human brain shapes its function

Amazing stuff!

"For over a century, researchers have thought that the patterns of brain activity that define our experiences, hopes and dreams are determined by how different brain regions communicate with each other through a complex web of trillions of cellular connections.

Now, a ... study has examined more than 10,000 different maps of human brain activity and found that the overall shape of a person’s brain exerts a far greater influence on how we think, feel and behave than its intricate neuronal connectivity. ...

study reveals that structured patterns of activity are excited across nearly the entire brain, just like the way in which a musical note arises from vibrations occurring along the entire length of a violin string, and not just an isolated segment ...

The research team used magnetic resonance imaging (MRI) to study eigenmodes, which are the natural patterns of vibration or excitation in a system, where different parts of the system are all excited at the same frequency. Eigenmodes are normally used to study physical systems in areas such as physics and engineering and have only recently been adapted to study the brain. ..."

"The wrinkles that give the human brain its familiar walnut-like appearance have a large effect on brain activity, in much the same way that the shape of a bell determines the quality of its sound, a study suggests. The findings run counter to a commonly held theory about which aspect of brain anatomy drives function. ..."

From the abstract:

"The anatomy of the brain necessarily constrains its function, but precisely how remains unclear. The classical and dominant paradigm in neuroscience is that neuronal dynamics are driven by interactions between discrete, functionally specialized cell populations connected by a complex array of axonal fibres. However, predictions from neural field theory, an established mathematical framework for modelling large-scale brain activity, suggest that the geometry of the brain may represent a more fundamental constraint on dynamics than complex interregional connectivity. Here, we confirm these theoretical predictions by analysing human magnetic resonance imaging data acquired under spontaneous and diverse task-evoked conditions. Specifically, we show that cortical and subcortical activity can be parsimoniously understood as resulting from excitations of fundamental, resonant modes of the brain’s geometry (that is, its shape) rather than from modes of complex interregional connectivity, as classically assumed. We then use these geometric modes to show that task-evoked activations across over 10,000 brain maps are not confined to focal areas, as widely believed, but instead excite brain-wide modes with wavelengths spanning over 60 mm. Finally, we confirm predictions that the close link between geometry and function is explained by a dominant role for wave-like activity, showing that wave dynamics can reproduce numerous canonical spatiotemporal properties of spontaneous and evoked recordings. Our findings challenge prevailing views and identify a previously underappreciated role of geometry in shaping function, as predicted by a unifying and physically principled model of brain-wide dynamics."

MRI study challenges our knowledge of how the human brain works – Physics World

Landmark study finds that the shape of the brain influences the way it works

The geometry of the human brain shapes its function Brain activity is structured in space and time. The resulting activity patterns are conventionally thought to depend on an intricate web of anatomical connections that link specialized populations of cells. This work challenges this paradigm by showing that macroscale neuronal dynamics of the human brain are fundamentally shaped by its physical geometry.

The human brain’s characteristic wrinkles help to drive how it works A model of the brain’s geometry better explains neuronal activity than a model based on the ‘connectome’.

Geometric constraints on human brain function (open access)

Shape of the brain influences the way it works - Animation (YouTube video)

Fig. 1: Reconstruction of neocortical activity with geometric eigenmodes.