Interdisciplinary Center for Neural Computation, Hebrew University, Jerusalem, Israel. akaufman@alice.nc.huji.ac.il|Interdisciplinary Center for Neural Computation, Hebrew University, Jerusalem, Israel. akaufman@alice.nc.huji.ac.il|Interdisciplinary Center for Neural Computation, Hebrew University, Jerusalem, Israel. akaufman@alice.nc.huji.ac.il|Interdisciplinary Center for Neural Computation, Hebrew University, Jerusalem, Israel. akaufman@alice.nc.huji.ac.il