Neurophysiology

How does the brain make use of its trillions of synapses to encode and store information underlying learning processes and memory formation? How do these alterations in turn lead to life-long behavioral adaptations? Although changes in synaptic pathways are believed to be one major force in these processes, surprisingly little is known about how synaptic plasticity, synaptic connectivity and neuronal network activity are linked to produce meaningful activity patterns that underlie memory storage and recall. Moreover, we need a better understanding of how these processes are regulated by the neuromodulatory systems of the brain. Different catecholaminergic, serotonergic and cholinergic systems interact to control the state of the brain and the body. These systems also control neuronal network dynamics, synaptic plasticity and global brain funtion.

To reveal how functional and structural connectivity at various levels of hierarchy are linked, we develop and employ optical methods and tools. With cutting-edge microscopy in vivo and in vitro, fiber photometry, optogenetics and electrophysiology we cover a wide spectrum of methods and approaches to tackle our research questions.

Central Research Topics

• Development and implementation of cutting-edge optogenetic technology
• Research on the interplay of networks at multiple scales ranging from synaptic networks to cellular ensembles
• Understanding the link between neuronal network dynamics and cognitive performance under different arousal and brain states
• Translational approaches to transfer knowledge between mouse model and humans

^{Formozov A, Dieter A, Wiegert JS. Cell Rep Methods. 2023. 3(3):100418. doi: 10.1016/j.crmeth.2023.100418
FFP system assembly: https://youtu.be/-qNlV_4r8Jw}

Selected national and international joint research projects

EU: ERC Proof of Concept grant: “Hyperspectral Fiber Photometry for Flexible, Multiplexed Optical Measurements of Brain Function (HyFiPhotometry)”. Project duration: since 2024

Health + Life Science Alliance Heidelberg Mannheim: AIH Fellowship Program 2023

• Project: Identifying predictive dynamical signatures of anaesthesia effects using deep dynamical systems reconstruction (together with Daniel Durstewitz, CIMH)

DFG: SPP 1926 “Next-generation optogenetics” 2^nd funding period: 10/2019 - 04/2023

• Project: Optogenetic silencing tools for precise, all-optical analysis of synaptic circuits.

DFG: FOR 2419 “Plasticity versus Stability - Molecular Mechanisms of Synaptic Strength”. 2^nd funding period: 07/2019 - 10/2023

• Subproject 6: Synaptic plasticity and stability in the context of hippocampal information processing.

DFG: SFB 936 "Multi-Site communication in the Brain” Subproject B08: Dopaminergic control of dorsal hippocampal networks during behavior. Project duration: 07/2019 - 06/2023

EU: ERC starting grant: “LIFE synapses”. Project duration: 06/2017 - 09/2022

DFG: SPP 1926 “Next-generation optogenetics” 1^st funding period: 08/2016 - 09/2019

• Project: Development of next-generation light-gated inhibitory ion channels to probe somatosensory integration in the Drosophila nociceptive circuit in vivo.

DFG: FOR 2419 “Plasticity versus Stability - Molecular Mechanisms of Synaptic Strength”. 1^st funding period: 07/2016 - 06/2019

• Subproject 5: Dynamic rewiring of hippocampal circuits following synaptic plasticity.

^{Legend: DFG = German Research Foundation, EU = European Union}

Selected publications

1. A flexible and versatile system for multi-color fiber photometry and optogenetic manipulation.
   Formozov A, Dieter A, Wiegert JS. Cell Rep Methods. 2023. 3(3):100418. doi: 10.1016/j.crmeth.2023.100418
2. Targeting Noradrenergic Neurons of the Locus Coeruleus: A Comparison of Model Systems and Strategies. 
   Wissing C, Maheu M, Wiegert JS and Dieter A. 2022. bioRxiv preprint: doi.org/10.1101/2022.01.22.477348
3. Aion is a bistable anion-conducting channelrhodopsin that provides temporally extended and reversible neuronal silencing.
   Rodriguez-Rozada S, Wietek J, Tenedini F, Sauter K, Dhiman N, Hegemann P, Soba P, Wiegert JS. Commun Biol. 2022. 5:687. doi: 10.1038/s42003-022-03636-x
4. Calcium Imaging and Electrophysiology of hippocampal Activity under Anesthesia and natural Sleep in Mice.
   Formozov A, Chini M, Dieter A, Yang W, Pöpplau JA, Hanganu-Opatz IL, Wiegert JS. Sci Data. 2022. 9(1):113. doi: 10.1038/s41597-022-01244-2
5. BiPOLES is an optogenetic tool developed for bidirectional dual-color control of neurons.
   Vierock J, Rodriguez-Rozada S, Dieter A, Pieper F, Sims R, Tenedini F, Bergs ACF, Bendifallah I, Zhou F, Zeitzschel N, Ahlbeck J, Augustin S, Sauter K, Papagiakoumou E, Gottschalk A, Soba P, Emiliani V, Engel AK, Hegemann P, Wiegert JS. Nat Commun. 2021. 12(1):4527. doi: 10.1038/s41467-021-24759-5.
6. Anesthetics fragment hippocampal network activity, alter spine dynamics, and affect memory consolidation.
   Yang W, Chini M, Popplau JA, Formozov A, Dieter A, Piechocinski P, Rais C, Morellini F, Sporns O, Hanganu-Opatz IL, Wiegert JS. PLoS Biology. 2021. 19:e3001146. doi: 0.1371/journal.pbio.3001146
7. How (not) to silence long-range projections with light.
   Wiegert JS, Oertner TG. Nat Neurosci. 2016. 19(4):527-8. doi: 10.1038/nn.4270
8. Neighborly synapses help each other out.
   Wiegert JS, Oertner TG. Nat Neurosci. 2015. 18(3):326-7. doi: 10.1038/nn.3955