Research: Evolutionary Development of Brain Networks

Among complex systems, the brain stands distinguished by several features but one is often over-looked: it is self-assembling. No planners, engineers or technicians are at hand, just a developmental program which has been honed by evolution. Using mathematical models, I investigate how that developmental program evolved in mammals. The aim is to better understand the emergence of the brain’s network structure from the growth of billions of individual neurons in both normal and disrupted development.

This is a pivotal time in neuroscience. Sophisticated brain imaging techniques are making the field rich with data. The remarkable conjunction of modern axon tract-tracing techniques and methods from network science are elucidating the structure of the brain as never before. Bewildering volumes of data on the complex patterns of connections formed by axons running between brain regions are being tamed in light of network concepts like hubs and small-world connectivity. Ultimately, our insights into these patterns of connections will be the foundation for a better understanding of cognitive function in humans and other animals.

Quite apart from the functions these anatomical networks support, their structure is determined in large part by their early development. Comprehending why brain networks are as we find them will require understanding what is possible within their developmental program. Equally, understanding how misalignments in development lead to malformed brain networks may illuminate the origin of pathologies such as autism and ADHD which implicate brain connectivity. That understanding is currently lacking. What key aspects of brain developmental programs shape the resulting networks? Currently, I’m investigating three stages in cortical development: (i) the process of neurogenesis which populates the cortex with neurons, (ii) the formation of early network structure linking those young neurons and (iii) the refinement of that early structure by activity driven re-wiring.

Contact Information

Diarmuid Cahalane
Cornell University
Center for Applied Mathematics
657 Rhodes Hall
Ithaca, NY 14853

E-mail: djc338 "AT" cornell "DOT" edu


Papers and posters

A PDF of our poster at Neuroscience 2011, on developmental gradients in neuron production, is here. (Posters are best viewed with Adobe Reader, not a browser plug-in.)

Our poster presented at Neuroscience 2010, on building networks from axon growth patterns, is available for download here.

Our 2011 PLoS ONE paper titled "Network Structure Implied by Initial Axon Outgrowth in Rodent Cortex: Empirical Measurement and Models" can be found here.


In Fall 2010, I am the teaching assistant for Math 4200 - Differential Equations and Dynamical Systems. The course is taught by Prof. Steven Strogatz.

People with whom I work

Barbara Finlay
Department of Psychology, Cornell.
Barb makes sense of the evolution and development of the nervous system by seeking developmental strategies which are conserved across species.

Veit Elser
Department of Physics, Cornell.
Veit, my Advisor, is a condensed matter physicist working on, among other things, algorithms that can solve sudoku puzzles, find optimal packing arrangements for solid objects and predict protein folding patterns.

Olaf Sporns
Neuroscience Program, Indiana University.
Olaf is a computational neuroscientist and has done pioneering work employing network techniques in cognitive neuroscience.