An x–y view of a section 2.5 mm from the top surface of a Thy1-eGFP PEGASOS-cleared brain. Close-up of the box with a rendered neuron. Insets provide magnified views of synaptic spines. Reto Fiolka

Our brain consists of countless nerve cells that transmit signals from one cell to the next. The connections between these cells, the synapses, provide a key to understanding how our memory works. An American research team in collaboration with Rainer Heintzmann from the Leibniz Institute of Photonic Technology (Leibniz IPHT) and the Friedrich Schiller University Jena has now succeeded in identifying these switching points in millimeter-sized tissue with a light microscope on the basis of their structure. The scientists published their results on 31 October 2019 in Nature Methods.

As the loading with curcumin (yellow) increases, the dissolution rate of the containers made of polymeric micelles (blue) decreases. (Picture: Ann-Christin Pöppler)

Nanocontainer for drugs can have their pitfalls: If they are too heavily loaded, they will only dissolve poorly. Why this happens is now reported by a Würzburg research group in "Angewandte Chemie". Nanocapsules and other containers can transport drugs through a patient's body directly to the origin of the disease and release them there in a controlled manner. Such sophisticated systems are occasionally used in cancer therapy. Because they work very specifically, they have fewer side effects than drugs that are distributed throughout the entire organism.

Small fraction of dendrites (gray) and synapses (orange) in a piece of mouse cortex, reconstructed from 3D electron microscopy data. Motta, Wissler (c) MPI for Brain Research

Mammalian brains, with their unmatched number of nerve cells and density of communication, are the most complex networks known. While methods to analyze neuronal networks sparsely have been available for decades, the dense mapping of neuronal circuits is a major scientific challenge. Researchers from the MPI for Brain Research have now succeeded in the dense connectomic mapping of brain tissue from the cerebral cortex, and quantify the possible imprint of learning in the circuit.

Energy transport in biomimetic nanotubes (left) and a three-dimensional spectrum (right). Bjoern Kriete (l.) / Stefan Mueller (r.)

It is crucial for photovoltaics and other technical applications, how efficiently energy spreads in a small volume. With new methods, the path of energy in the nanometer range can now be followed precisely. Plants and bacteria lead the way: They can capture the energy of sunlight with light-harvesting antennas and transfer it to a reaction centre. Transporting energy efficiently and in a targeted fashion in a minimum of space – this is also of interest to mankind. If scientists were to master it perfectly, they could significantly improve photovoltaics and optoelectronics.