לוח שנה משולב

Light is the source of life on Earth, and is used in numerous ways in the plant and animal kingdoms for a variety of applications, including photosynthesis, vision, camouflage, communication, thermal management and more. As such, evolution has led to the creation of intricate optical systems with highly controlled and regulated properties. The talk will present an overview of some of these unique optical systems, focusing on the ubiquitous guanine-based optical reflectors and on mineral deposits in leaves of higher plants. In particular, correlated optical and structural characterization will be shown to reveal new information about the function of some of the more poorly understood biological light manipulation systems and to reveal clues about their evolution.

Communities of coexisting species are shaped by the interactions between them, and by the motion of organisms. How does the network of interactions organize in response to these processes? Using a systematic analytical framework we calculate properties of the matrix of pair-interactions, reduced to the subset of species that are able to coexist. This reduced matrix acquires new statistical structure such as correlations between its elements. Yet to fully explain species coexistence one must go beyond simple correlations, to find a structure that is closely related to memory patterns in models of neural networks.

It is established that the brain is capable of large-scale reorganization following sensory deprivation or injury. What is less clear is what are the rules that guide it. In the blind, many visual regions preserve their task specificity despite being recruited for different sensory input; ventral visual areas, for example, become engaged in auditory and tactile object-recognition. However, we are interested in two questions. First, is sensory deprivation necessary for such task-specific reorganization, or can it happen in non-deprived individuals? In this series of experiments, during 9 months we taught Braille, a tactile alphabet, to sighted individuals and observed the resulting changes with structural and functional MRI. (Siuda, Krzywicka, Bola et al, eLife, 2016). Second, we wondered whether task-specific reorganization is unique to the visual cortex, or alternatively, is it a general principle applying to other cortical areas. Here, we enrolled deaf and hearing adults into an fMRI experiment, during which they discriminated between rhythms. In hearing individuals, rhythm processing is performed mostly in the auditory domain. Our prediction was that if task-specific reorganization applies to the human auditory cortex, performing this function visually should recruit the auditory cortex in the deaf (Bola, Zimmerman et al., PNAS, 2017).