לוח שנה משולב

‘Biomimetic Chemistry’ presents a conceptual approach to the art of model building attempting to imitate the activity of a biological system by emphasis on the function of a substrate rather than on its detailed molecular structure.
In the talk today I will center on the approach, governing the fundamental phenomenon of molecular recognition. The end goal is to formulate a set of rules essential to the design of molecules matching a specific biological system. Microbial iron-carriers, Siderophores, provide a useful platform for studying these principles. Several series of ferrichrome biomimetic analogs varying in length and polarity of the chains separating between the tripodal scaffold and the pendent FeIII chelating hydroxamic acid groups were prepared and studied. Microbial growth promotion was conducted on bacteria (E. coli, and P. putida) and fungi (U. maydis). These studies show a wide range of siderophore activity: from a rare case of species-specific growth promotor in P. putida to an analog with broad-spectrum activity matching ferrichrome in cross-phylum activity and uptake pathway. A fluorescent conjugate, to the broad-rang analog, provide clear images of the iron-free siderophore final destination in bacteria (periplasmic space) vs fungi (cytosol) mapping distinctly new therapeutic targets. Quantum Dots (QD) decorated with the most potent ferrichrome (FC) analog provided a tool for immobilization of FC-recognizing bacteria. Bacterial clusters formed around QDs, provide a platform for their selection and concentration.
The fascinating field of lanthanide-clusters will be introduces and their unique properties describe, possible future opportunities and application will be discussed.

The study of perceptual decision-making is key to understanding complex cognitive behavior. Two decades of recordings in primate parietal cortex suggest that neurons in the lateral intraparietal (LIP) cortex integrate sensory evidence from upstream neurons (presumably MT) in favor of making a decision. However, the causal role of LIP in decision-making had not been tested directly.
In this talk, I will present recent experiments that tested whether area LIP—which exhibits strong decision-related activity—is causally related to perceptual decision-making. In contrast to the generally accepted model, we found that inactivation in area LIP had no measurable impact on decision-making behavior (despite having exerted effects in a control task). This finding suggests that strong decision-related activity does not guarantee a causal role in decision-making. To better understand the MT-LIP circuit we then applied a Generalized Linear Model (GLM) to simultaneously recorded MT and LIP neurons. We found that much of MT & LIP responses may be interpreted in simple sensorimotor terms, as opposed to appealing to nuanced cognitive phenomena. These results shift our understanding of decision-related activity in the primate brain and motivate new approaches to further dissecting the circuit.

Perception of connected speech relies on accurate syllabic segmentation and phonemic encoding. These processes are essential because they determine the building blocks that we can manipulate mentally to understand and produce speech. Segmentation and encoding might be underpinned by specific interactions between the acoustic rhythms of speech and coupled neural oscillations in the theta and low-gamma band. To address how neural oscillations interact with speech, we used a neurocomputational model of speech processing generating biophysically plausible coupled theta and gamma oscillations. We show that speech could be well decoded from this purely bottom-up artificial network’s low-gamma activity, when the phase of theta activity was taken into account. Because speech is not only a bottom-up process, we set out to develop another type of neurocomputational model that takes into account the influence of linguistic predictions on acoustic processing. I will present preliminary results obtained with such a model and discuss the advantage of incorporating neural oscillations in models of speech processing.