Integrated Calendar

To unravel the functional properties of the brain, we need to
untangle how neurons interact with each other and coordinate in
large-scale recurrent networks. One way to address this question is
to measure the functional influence of individual neurons on each
other by perturbing them in vivo. Application of such single-neuron
perturbations in mouse visual cortex has recently revealed feature-
specific suppression between excitatory neurons, despite the presence
of highly specific excitatory connectivity, which was deemed to
underlie feature-specific amplification. Here, we studied which connectivity
profiles are consistent with these seemingly contradictory
observations, by modeling the effect of single-neuron perturbations
in large-scale neuronal networks. Our numerical simulations and
mathematical analysis revealed that, contrary to the prima facie
assumption, neither inhibition dominance nor broad inhibition
alone were sufficient to explain the experimental findings; instead,
strong and functionally specific excitatory–inhibitory connectivity
was necessary, consistent with recent findings in the primary visual
cortex of rodents. Such networks had a higher capacity to encode
and decode natural images, and this was accompanied by the emergence
of response gain nonlinearities at the population level. Our
study provides a general computational framework to investigate
how single-neuron perturbations are linked to cortical connectivity
and sensory coding and paves the road to map the perturbome of
neuronal networks in future studies.
Zoom Link: https://weizmann.zoom.us/j/95406893197?pwd=REt5L1g3SmprMUhrK3dpUDJVeHlrZz09
Meeting ID: 954 0689 3197
Password: 750421

Zoom: https://weizmann.zoom.us/j/95703489711?pwd=Tyt5cU1tV2YrMFhYUytBU001bm4yQT09


Viable, global-scale photoelectrochemical energy conversion of cheap, abundant resources such as water into chemical fuels (“solar fuels”) depends on the progress of semiconducting light-absorbers with good carrier transport properties, suitable band edge positions, and stability in direct-semiconductor/electrolyte junctions. Investigations concentrated mainly on metal-oxides that offer good chemical stability yet suffer from poor charge transport than non-oxide semiconductors (e.g., Si, GaAs). Fortunately, only a fraction of the possible ternary and quaternary combinations (together ~ 105 – 106 combinations) were studied, making it likely that the best materials are still awaiting discovery. Unfortunately, designing controlled synthesis routes of single-phase oxides with low defects concentration will become more difficult as the number of elements increases; and 2) there are currently no robust and proven strategies for identifying promising multi-elemental systems.
These challenges demand initial focusing on synthesis parameters of novel non-equilibrium synthesis approaches rather than chemical composition parameters by high-throughput combinatorial investigations of synthesis-parameter spaces. This would open new avenues for stabilizing metastable materials, discovering new chemical spaces, and obtaining light-absorbers with enhanced properties to study their physical working mechanisms in photoelectrochemical energy conversion.
I will introduce an approach to exploring non-equilibrium synthesis-parameter spaces by forming gradients in synthesis-parameters without modifying composition-parameters, utilizing two non-equilibrium synthesis components: pulsed laser deposition and rapid radiative-heating. Their combination enables reproducible, high-throughput combinatorial synthesis, resulting in high-resolution observation and analysis. Even minor changes in synthesis can impact significantly material properties, physical working mechanisms, and performances, as demonstrated by studies of the relationship between synthesis conditions, crystal structures of α-SnWO4, and properties over a range of thicknesses of CuBi2O4, both emerging light-absorbers for photoelectrochemical water-splitting that were used as model multinary oxides.