לוח שנה משולב

I will describe results from psychophysics, electrophysiology and imaging in humans and non-human primates that investigate the mechanisms underlying flexible adaptive learning. Specifically, I will focus on two models that bridge from learning-theory to anxiety-disorders: extinction of learning and generalization of learning. I will suggest that perception plays a role in the wider generalization following negative learning; describe how networks in the human brain contribute to the effect - both in healthy situations and in anxiety patients; and then describe single-cell network architecture in the primate amygdala that underlies wide generalization and resistance to extinction.

For centuries, lens-based microscopy, such as light, phase-contrast, fluorescence, confocal and electron microscopy, has played an important role in the evolution of modern science and tech-nology. In 1999, a novel form of microscopy, i.e. coherent diffraction microscopy, also termed coherent diffraction imaging (CDI) or lensless imaging, was developed and transformed our traditional view of microscopy, in which the diffraction pattern of a noncrystalline object or a nanocrystal was first measured and then directly phased to obtain an image. The well-known phase problem was solved by combining the oversampling method with iterative algorithms. In the first part of the talk, I will present the principle of CDI and illustrate some applications using synchrotron radiation, high harmonic generation and X-ray free electron lasers.

In the second part of the talk, I will present a general tomographic method for determining 3D local structures at atomic resolution. By combining scanning transmission electron microscopy with a novel data acquisition and image reconstruction approach known as equally sloped tomography, we achieved electron tomography at 2.4 Å resolution, observed nearly all the atoms in a multiply twinned Pt nanoparticle, revealed atomic steps at 3D twin boundaries, and imaged the 3D core structure of edge and screw dislocations at atomic resolution. We expect this general method to find application in physics, materials sciences, nanoscience, and chem-istry.


1. K. S. Raines, S. Salha, R. L. Sandberg, H. Jiang, J. A. Rodríguez, B. P. Fahimian, H. C. Kapteyn, J. Du and J. Miao, “Three-dimensional structure determination from a single view”, Nature 463, 214-217 (2010).
2. M. C. Scott, C.-C. Chen, M. Mecklenburg, C. Zhu, R. Xu, P. Ercius, U. Dahmen, B. C. Regan and J. Miao, “Electron tomography at 2.4-ångström resolution”, Nature 483, 444–447 (2012).
3. C.-C. Chen, C. Zhu, E. R. White, C.-Y. Chiu, M. C. Scott, B. C. Regan, L. D. Marks, Y. Huang and J. Miao, “Three-dimensional imaging of dislocations in nanoparticles at atomic resolution”, Nature 496, 74–77 (2013).