A nice article in the Wall Street Journal describing Jack Gallant’s recent FMRI work. They didn’t just subtract conditions and come up with a typical imaging map with one or a few isolated bits of activation. Jack L. Gallant, Tolga Çukur and colleagues used sophisticated analyses to find the relationship between the patterns of whole brain activity and the content of videos watched by the subjects. This revealed wide networks, not isolated patches, of neurons engaged by attention to different things in the video (humans vs vehicles, etc).
It also showed how dynamic and flexible the brain is. When subjects looked for humans, large portions of the cortex were sensitive to humans and less sensitive to vehicles. When subjects looked for vehicles, large portions of the cortex became vehicle detectors. Many of the same brain areas were involved in multiple networks, changing when people changed the focus of their attention. Thus, rather than the cortex being composed of modules with strict specializations, high-level information is spread across wide-ranging cortical networks of neurons that participate in many different functions, adapting their properties to current cognitive demands.
We have long argued that mixed selectivity, adaptive coding neurons are crucial for hallmarks of cognition like flexibility. And in forthcoming paper (Rigotti et al), we show computationally that you can’t build a complex brain w/o them.
For a brief discussion of this issue, read this Preview of a paper by Stokes et al:
Miller, E.K. and Fusi, S. (2013) Limber neurons for a nimble mind. Neuron. 78:211-213. View PDF
And stay tuned for this paper:
Rigotti, M., Barak, O., Warden, M.R., Wang, X., Daw, N.D., Miller, E.K., & Fusi, S. (in press) The importance of mixed selectivity in complex cognitive tasks. Nature.
About the Author
The Miller Lab uses experimental and theoretical approaches to study the neural basis of the high-level cognitive functions that underlie complex goal-directed behavior. ekmillerlab.mit.edu