לוח שנה משולב

Pyramidal neurons in supragranular layers II and III of rodent sensory cortices are a main target of ascending sensory information conveyed by columnar projections of layer IV as well as contextual information from neighboring columns or higher cortical areas. However, layer II is not separable from layer III on cytoarchitectonic grounds. We therefore investigated to which extent pyramidal neurons in the supragranular layers differ in their input-output connectivity. We obtained detailed spatial maps of layer-specific intracortical functional input connectivity for electrophysiologically and morphologically identified supragranular pyramidal neurons by combining local photolysis of caged glutamate with whole-cell patch-clamp recordings using biocytin-containing pipettes in rat barrel cortex in vitro. The main source of excitatory inputs onto all supragranular pyramidal cells was layer IV of the same column. This translaminar excitatory source was even more prominent than local and transcolumnar excitatory inputs from within the supragranular layers, both in density and strength. Additionally, many pyramidal neurons received a prominent excitatory layer Va input, often originating from beyond the “home” column. Among those pyramidal neurons we detected a significantly higher fraction of cells located in a putative layer II than in TZ or putative layer III. Our results indicate a strong but differential information transmission from layer IV as well as layer Va, both important cortical entry points for parallel streams of sensory information, toward the supragranular layers. Within supragranular layers, information processing in pyramidal neurons can be "fine tuned" through local and transcolumnar excitatory networks. Finally this integrated information is forwarded with a prominent transcolumnar component by putative layer II pyramidal cells but with an intracolumnar preponderance, including significant layer IV-backprojections, by putative layer III pyramidal neurons

Lecture will take place in the Perlman Building, room 402

Research on dye molecules has been continuing to be at the forefront of new developments in chemistry owing to their versatile functional properties associated with -conjugation. On a supramolecular level, appropriately controlled spatial arrangement of dyes enables pivotal functions in nature, the most intriguing examples being provided by the light-harvesting systems of purple and green bacteria which contain a large number of chlorophyll and carotene chromophores organized in cyclic arrays or tubular architectures by non-covalent interactions.

During the last few years, we have intensively investigated the organization of merocyanine, chlorin, and perylene bisimide dyes by non-covalent forces into desirable nanoscale architectures as well as liquid-crystalline and crystalline solid state materials. In this lecture, I will provide an overview on our achievements in the preparation of defined dye assemblies and their functional properties that originate from proper -stacking [1]. In particular, charge and exciton transport in dye aggregates [2,3] FRET processes in dye vesicles [4], and photovoltaic performance of dye-based bulk heterojunction solar cells [5] will be discussed.


[1] Z. Chen, A. Lohr, C. R. Saha-Möller, F. Würthner, Chem. Soc. Rev. 2009, 38, 564–584.
[2] Z. Chen, V. Stepanenko, V. Dehm, P. Prins, L. D. A. Siebbeles, J. Seibt, P. Marquetand, V. Engel, F. Würthner, Chem. Eur. J. 2007, 13, 436–449
[3] H. Lin, R. Camacho, Y. Tian, T. E. Kaiser, F. Würthner, I. G. Scheblykin, Nano Lett. 2010, 10, 620–626.
[4] X. Zhang, S. Rehm, M. M. Safont-Sempere, F. Würthner, Nature Chem. 2009, 1, 623–629.
[5] U. Mayerhöffer, K. Deing, K. Gruß, H. Braunschweig, K. Meerholz, F. Würthner, Angew. Chem. Int. Ed. 2009, 48, 8776–8779.