While an undergraduate chemistry major at Caltech, David Van Essen read The Machinery of the Brain by Dean Woolridge. Published in 1963, the book gives an engineer’s perspective of the biological foundation of brain function, likening it to a computer.
“That immediately hooked me on neuroscience, and I never looked back in terms of career choices,” says Van Essen who is now at Washington University in St. Louis.
Fifty years later, Van Essen is a world-renown expert in on the structure, function, connectivity, and development of cerebral cortex in humans and nonhuman primate. The 2017 recipient of the George A. Miller Prize, Van Essen will be delivering a lecture at the CNS annual meeting in San Francisco on recent efforts to map the cerebral cortex.
He spoke with CNS about how he got started studying the cerebral cortex, recent work with the Human Connectome Project (for which he is a principle investigator), and thoughts for the future of the field.
CNS: Why did you decide to study the cerebral cortex?
Van Essen: As a graduate student at Harvard, I wanted to study a ‘simple’ nervous system, so I did my thesis research on the leech with John Nicholls. However, I was fascinated by the work of David Hubel and Torsten Wiesel, future Nobel laureates whose lab was down the hall, and I arranged to do postdoctoral research with them to study cat visual cortex. That experience hooked me on the visual system, though I also maintained parallel research interests on simpler systems.
As a postdoc at University College London, I studied visual cortex in the macaque monkey and developed a ‘pencil-and-tracing-paper’ method for making 2-dimensional cortical flat maps. On returning to Caltech as a faculty member, I extended these flat maps to the entire cerebral cortex; this prompted an abiding interest in atlases of cortical organization and in developing methods for computerized brain mapping, especially cortical surface-based analyses.
CNS: What questions do you most want to answer in your exploration of the cortex?
Van Essen:
i) Does mechanical tension in long-distance axons cause the cortex to fold, and does tension in dendrites explain why the cortex is a thin sheet, as I hypothesized in 1997?
ii) How does the pattern of long-distance connections (the ‘macro-connectome’) contribute to functional specialization, and how do differences in brain connectivity contribute to differences in behavior across individuals and across the lifespan?
ii) What are the species differences in cortical organization between monkeys, apes, and humans?
CNS: What has the Human Connectome Project (HCP) done for understanding the cortex?
Van Essen: One major contribution is the recent identification of a multimodal parcellation of human cerebral cortex that contains 180 distinct areas in each hemisphere, 97 of which were previously unidentified (Glasser et al., Nature, 2016). This represents an important advance in our understanding of cortical organization and function, especially since the parcellation can be mapped in individual subjects who have been scanned using appropriate high-resolution imaging methods.
CNS: Can you give us an example of applications of the results from the HCP mapping of the cortex?
Van Essen: Hundreds of publications have already taken advantage of HCP data to report observations and insights regarding a variety of characteristics, including factors underlying individual variability in brain function. On the other hand, these are still early days – the final HCP datasets have yet to be released! – and we can anticipate many exciting discoveries in the future. Among these will be analyses of the heritability of brain circuits and function that capitalize on the hundreds of twin pairs in the HCP study design.
CNS: Why compare the cortical areas of humans to nonhuman primates? What types of information does that provide?
Van Essen: Cerebral cortex has 10-fold greater surface area in humans compared to macaques, but likely has only about half again as many cortical areas. Accurate characterization of species similarities and differences in cortical organization is likely to yield important insights into the profound differences in cognitive capabilities that make us uniquely human.
“the coming decades offer great opportunities for progress in cognitive neuroscience”
CNS: What are you most excited about that is on the horizon for the study of the cortex and the field of cognitive neuroscience as a whole?
Van Essen: Recent advances in multimodal data acquisition and analysis (“HCP-style neuroimaging”) offer opportunities for accelerated progress in exploring many aspects of human brain function, how it varies across individuals, and how it relates to behavior in health and disease.
CNS: What do you want to be the take-home message of your CNS 2017 lecture?
Van Essen: Advances in multimodal neuroimaging can facilitate accelerated progress in deciphering brain organization, function, and connectivity. However, it remains critically important to avoid overinterpreting or misinterpreting complex results, given the limitations of each neuroimaging method.
CNS: Anything else you’d like to add?
Van Essen: To the younger generation: the coming decades offer great opportunities for progress in cognitive neuroscience. However, training that is both broad and deep is increasingly important, as is the ability to collaborate in teams whose collective expertise facilitates progress at the frontiers of cognitive neuroscience.
-Lisa M.P. Munoz
Van Essen will give his award lecture on Sunday, March 26, 2017 from 4:00-5:00pm at the Hyatt Regency San Francisco.
Related: Watch the Great Debate on Connectomics from CNS 2016
