Hausdorff Forum - April 29, 2016 - 14h

Location: Lipschitz-Saal

Martin Zirnbauer (Universität zu Köln): "A simple model of disordered lattice vibrations"

In this talk a long standing problem of condensed matter physics will be reviewed: the anomalous thermal properties of disordered crystals and amorphous solids at low temperatures. We then propose a disordered masses-and-springs model as a simple theoretical description of the observed behavior, and we present some analytical and numerical results for it.


Jakob Macke (Caesar): "Understanding the statistics of neural population activity"

Understanding how neurons collectively represent sensory input, perform computations and guide behaviour is one of the central goals of neuroscience. Large-scale recording methods are starting to make it possible to measure neural activity in large populations and to gain insights into their collective dynamics. However, even advanced recording methods can only sparsely sample activity in local circuits. What can we learn about the principles of neural dynamics and sensory processing from measurements of neural activity?

One hypothesis that has emerged from the analysis of multi-cell activity is that neural populations are  poised at a thermodynamic critical point. Support for this notion has come from a recent series of studies which identified signatures of criticality  in the statistics of neural activity recorded from populations of retinal ganglion cells, and hypothesized that this might reflect an organizing principle of neural computation. What mechanisms can explain these observations? Do they require the neural system to be fine-tuned to be poised at the critical point, or do they robustly emerge in generic circuits? In this talk, I will address these questions, give some answers, and pose more questions.