We are a multidisciplinary team of neurobiologists, psychologists, mathematicians and computer scientists. It is our mission to better understand cognitively complex learning and decision processes in laboratory rodents at the level of interacting neuronal circuits.

We combine behavioural paradigms with modern chronic in vivo multichannel recording technologies and pharmacological, molecular, optogenetic, mathematical and computational tools to study cortical network activity during learning and choice behaviour.

  • Science needs creativity. Creativity needs diversity.

    At the CortXplorer Research group we believe in an inclusive culture. We are committed to embracing any person across the spectrum of age, Color, religion, gender identity, sexual orientation, physical or mental ability, and ethnicity. We celebrate diverse voices within our team and beyond.


  • Head


    Max Happel's scientific mission in our group is to investigate the neuronal basis of cognitive resources which are subject to learning and memory processes. The central goal of this project is to better understand and manipulate plastic changes in neuronal circuits at the functional-systemic network level during flexible, cognitively demanding behavioral adjustments and long-term memory retrievals or the extinction of memory content.


    Short vita:

    • Study of biology and neurosciences in Frankfurt/Main and Magdeburg
    • Doctorate in neurobiology (summa cum laude)
    • Postdoc in Oxford, England
    • Habilitation in Neurobiology
    • Today learning researcher in the field of hearing research, cognitive learning mechanisms and pathophysiology of memory.
  • Members


    PD Dr. Max
    PhD students  
    Students & guests  
    Francesca Abela  
    Sümeyra Aksit+49-391-6263-94411   saksit(at)
    Shivam Maurya  
    Parthiban Saravanakumar +49-391-6263-94411 
    Claudia Glemser +49-391-6263-94411  
    Dr. Hartmut Niekisch  
    Martin Kisse  
    Amr Faharat  
    Mohammed El-Tabbal  
    Julia Steinhardt  
    Sara Bertazzoni  
    Erika Kaschinksi  
    Ivan Bykov  


  • Projects


    Modulation of value representation in oscillatory activity patterns in the sensory cortex

    Using chronic animal experimental in vivo multichannel derivations and human MEG measurements, we investigate ubiquitous network mechanisms during uncertain decision-making processes and use the obtained data sets to formulate general functional principles of flexible and adaptive value representation in the brain. We use methods of Multivariate Statistics (Support Vector Machine Learning) to classify mesoscopic activation patterns of cortical circuits, which are subject to decision processes, e.g. during uncertainty.

    Funding: SFB779 - 2016-2020; Collaborators: Marina Zempeltzi, Sümeyra Aksit, Shivam Maurya, Francesca Abela, Martin Kisse; Cooperation: Prof. Gerhard Jocham (Univ. Düsseldorf), Dr. Matthias Deliano

    Optogenetic activation of the dopaminergic reward system and in vivo derivations in laboratory rodents during cognitively complex learning tasks
    By chronic multichannel recordings in the auditory cortex of behaving laboratory rodents we investigate plastic changes during learning processes at the synaptic network level. By cell type-specific optogenetic stimulation of the ventral tegmental area (VTA) we try to modulate targeted reward learning.

    Funding: LPN/PAKT of the WGL - 2015-2017; Collaborators: Michael Brunk, Martin Kisse; Cooperation: Dr. Matthias Deliano, Dr. Michael Lippert

    Influence of cortical extracellular matrix (ECM) on cognitive learning processes in laboratory rodents and translational relevance for neuropsychiatric disorders
    We investigate in laboratory rodent species (desert gerbils, wt/ko mouse models) the influence of the extracellular matrix on cognitive learning processes and flexible long-term memory, as well as its changes in mouse models for depression and Alzheimer's disease. In collaboration with the group of Dr. Renato Frischknecht (FAU Erlangen) we use modern methods of molecular cell biology (e.g. RNA interference) and systemic neuroscience (optogenetics, chronic derivations).

    Funding: WGL/LIN Special project - 2012-2016; collaborators: Hartmut Niekisch, Mohammad El-Tabbal, cooperation: Dr. Renato Frischknecht (Erlangen), Prof. Anna Fejtova (Erlangen), Prof. Martin Walter (Tübingen)

    Optogenetic control of synaptic integration by modulation of calcium channel dynamics
    In cooperation with Prof. Martin Heine (Mainz), we manipulate the channel dynamics of voltage-controlled calcium channels (VGCCs) in cell-type-specific cell populations by light-induced clustering in the presynapse using modern optogenetic techniques. We investigate the effect on synaptic integration and network physiology in vivo.

    Funding: WGL/LIN Special project - 2018-2021; Collaborator: Katrina Deane, Cooperation: Prof. Martin Heine (Mainz)

    Laser-induced lesion of corticothalamic circuits in the auditory system of ferrets
    In collaboration with Prof. Andrew King (University of Oxford) we investigate the cellular basis of the perception of time-complex tone stimuli in ferrets after laser-induced apoptosis of corticothalamic projection neurons.

    Funding: DAAD 2012 and Wellcome Principal Research Fellowship (PI Prof. King) 2013-2019

    Reorganization of cortical circuits after sound trauma as cause of central tinnitus
    We investigate the network pathophysiology of sound trauma-induced tinnitus in laboratory rodents as a cause for the development and manifestation of a central tinnitus.

    Cooperation: Prof. Holger Schulze (Erlangen), Dr. Marcus Jeschke (Göttingen)


  • Current Third Party Funds

    Current Third Party Funds

    2020 - 2023 
    DFG Einzelantrag (Kooperation Dr. Frischknecht, FAU Erlangen)
    Regulation of the extracellular matrix by dopamine during adult learning

    2019 - 2021
    Leibniz Special Project, intramurale Förderung der Leibniz-Gesellschaft 
    "Optogenetic control of synaptic integration by modulation of calcium channel dynamics"

    2016 – 2020     
    Teilprojekt B16N im SFB779 (Neurobiologie motivierten Verhaltens)
    „Werte-Repräsentation in sensorischen kortikalen Arealen während Entscheidungsprozessen: Netzwerkmechanismen und Neuromodulation“


  • Publications



    Zempeltzi MM, Kisse M,  Brunk MGK, Glemser C, Aksit S,  Deane KE, Maurya S, Schneider S,  Ohl FW,  Deliano M,  Happel MFK(2020) Task rule and choice are reflected by layer-specific processing in ro-dent auditory cortical microcircuits. Communications Biology (in press)

    Deane K, Brunk MGK, Curran AW, Zempeltzi MM, Ma J, Lin X, Abela F, Aksit S, Deliano M, Ohl FW, Happel MFK (2020) Ketamine anesthesia induces gain enhancement via recurrent excitation in granular input layers of the auditory cortex. J Physiol, 00.0, 1-15; doi: 10.1113/JP279705

    Mitlöhner J, Kaushik R, Niekisch H, Blondiaux A, Gee CE, Happel MFK, Gundelfinger E, Dityatev A, Frischknecht R, Seidenbecher C. (2020) Dopamine modulates the integrity of the perisynaptic extracellular matrix at excitatory synapses. Cells 2020 Jan 21;9(2). pii: E260. doi:



    Brunk M, Deane KE, Kisse M, Vieweg S, Deliano M, Ohl FW, Lippert MT, Happel MFK (2019) The VTA modulates a frequency-specific gain of thalamocortical inputs in infragranular layers of the gerbil auditory cortex. Sci Rep 9, 20385; doi:; IF: 4.12

    Niekisch, H., Steinhardt, J., Berghäuser, J., Bertazzoni, S., Kaschinski, E., Kasper, J., Kisse, M., Mitlöhner, J., Singh, J.B., Weber, J., Frischknecht, R., Happel, M.F.K. (2019) Learning induces transient upregulation of brevican in the auditory cortex during consolidation of long-term memories. J Neurosci. 39(36):7049-7060

    Deane K, Brunk MGK, Curran AW, Zempeltzi MM, Ma J, Lin X, Abela F, Aksit S, Deliano M, Ohl FW, Happel MFK* (2019) Ketamine anesthesia induces gain enhancement via recurrent excitation in granular input layers of the auditory cortex. bioRxiv 810978; doi: 810978

    Zempeltzi MM, Kisse M,  Brunk MGK, Glemser C, Aksit S,  Deane KE, Maurya S, Schneider S,  Ohl FW,  Deliano M,  Happel MFK*(2019) Task rule and choice are reflected by layer-specific processing in ro-dent auditory cortical microcircuits. bioRxiv, doi:


    Deliano, M., Brunk, MG, El-Tabbal, M., Zempeltzi, M., Happel, M.F.K., Ohl, F.W. (2018) Dopaminergic neuromodulation of high-gamma stimulus phase-locking in gerbil primary auditory cortex mediated by D1/D5-receptors. Eur J Neurosci. doi:

    Brunk, M. Sputh, S., Doose, S., van der Linde, S. Terpitz, U. (2018) HyphaTracker: An ImageJ toolbox for time-resolved analysis of spore germination in filamentous fungi. Scientific Reports 8:605


    Homma, N.Y.#, Happel, M.F.K.#, Nodal, F.R., Ohl, F.W., King, A.J., Bajo, V.L. (2017) A Role for Auditory Corticothalamic Feedback in the Perception of Complex Sounds. J Neurosci, 37(25):0397-17, #shared contribution

    Happel, M.F.K.*, Ohl, F.W. (2017). Compensating Level-Dependent Frequency Representation in Auditory Cortex by Synaptic Integration of Corticocortical Input. PLoS ONE 12(1):e0169461


    Homma, N.Y., Bajo, V.M., Happel, M.F.K., Nodal, F.R., King, A.J. (2016) Mistuning detection performance of ferrets in a go/no-go task. J Acoust Soc Am 139(6):EL246

    Happel, M.F.K.*(2016) Dopaminergic impact on local and global cortical circuit processing during learning. Behav Brain Res. doi:

    Frischknecht, R.*, Happel, M.F.K.* (2016) Impact of the extracellular matrix on plasticity in juvenile and adult brains. NeuroForum 1/2016

    Happel, M.F.K.*, Frischknecht, R.* (2016) Neuronal Plasticity in the Juvenile and Adult Brain Regulated by the Extracellular Matrix; published in „Composition and Function of the Extracellular Matrix in the Human body“ edited by Travascio, F.; Jun 15-2016; doi:


    Tziridis, K., Ahlf, S., Jeschke, M., Happel, M.F.K., Ohl, F.W., Schulze, H. (2015) Noise trauma induced neural plasticity throughout the auditory system of Mongolian gerbils: differences between tinnitus developing and non-developing animals. Front Neurol 6:22. doi: fneur.2015.00022

    Mylius, J., Happel, M.F.K., Gorkin, A.G., Huang, Y., Scheich, H., Brosch, M. (2015) Fast transformation from the dopaminergic ventral midbrain to the sensory cortex of awake primates; Brain Struct Funct, doi:

    Happel, M.F.K., Deliano, M., Ohl, F.W. (2015) Combined Shuttle-box Training with Electro-physiological Cortex Recording and Stimulation as a Tool to Study Perception and Learning. J Vis Exp, e53002, doi:


    Happel, M.F.K., Deliano, M., Handschuh, J., Ohl, F.W.* (2014a) Dopamine-modulated recurrent corticoefferent feedback in primary sensory cortex promotes detection of behaviorally relevant stimuli. J Neurosci, 34(4):1234-47

    Happel, M.F.K.*, Niekisch, H., Castiblanco Rivera, L.L., Ohl, F.W., Deliano, M., Frischknecht, R.* (2014b) Enhanced cognitive flexibility in reversal learning induced by removal of the extracellular matrix in auditory cortex. Proc Natl Acad Sci U S A, 111(7):2800-5

    Meyer, A., Diepenbrock, J., Happel, M.F.K., Ohl, F.W., Anemüller, J. (2014) Discriminative Learning of Receptive Fields from Responses to non-Gaussian Stimulus Ensembles. PLoS one, doi:

    Saldeitis, K., Happel, M.F.K., Ohl, F.W., Scheich, H., Budinger, E. (2014) Anatomy of the auditory thalamocortical system in the Mongolian gerbil: Nuclear origins and cortical field-, layer-, and frequency-specificities. J Comp Neurol, doi:


    Lison, H., Happel, M.F.K., Schneider, F., Baldauf, K., Kerbstat, S., Seelbinder, B., Schneeberg, J., Zappe, M., Goldschmidt, J., Budinger, E., Schröder, U.H., Ohl, F.W., Schilling, S., Demuth, H.U., Scheich, H., Reymann, K.G., Rönicke, R. (2013) Disrupted cross-laminar cortical processing in β amyloid pathology precedes cell death. Neurobiol Dis, 63:62-73


    Happel, M.F.K., Jeschke, M., Ohl, F.W. (2010). Spectral integration in primary auditory cortex attributable to temporally precise convergence of thalamocortical and intracortical input. J Neurosci, 30(33): 11.114-11.127

    Moeller, C.K., Kurt, S., Happel, M.F.K., Schulze, H. (2010). Long-range effects of GABAergic inhibition in gerbil primary auditory cortex. Eur J Neurosci 31(1): 49-59

    Goldschmidt, J., Wanger, T., Engelhorn, A., Friedrich, H., Happel, M.F.K., Ilango, A., Engelmann, M., Stürmer, I.W., Ohl, F.W., Scheich, H. (2010). High-resolution mapping of neuronal activity using the lipophilic thallium chelate complex TlDDC: Protocol and validation of the method. NeuroImage, 49(1):303-315


    Meyer, A., Happel, M.F.K., Ohl, F.W., Anemüller, J. (2009) Estimation of spectro-temporal receptive fields based on linear support vector machine classification.BMC Neurosci,doi:


    Happel, M.F.K.*, Müller, S., Anemüller, J., Ohl, F.W. (2008) Predictability of STRFs in auditory cortex neurons depends on stimulus class. Proc Conf Int Speech Comm Ass Interspeech, p.670

  • Teaching & Internships

    Teaching & Internships

    We are involved in the Master's program "Integrative Neuroscience" and the Bachelor's program "Philosophy, Neurosciences, Cognition" and offer among other things:

    • Lecture Introduction to Nervous Systems, Bachelor of Philosophy, Neurosciences, Cognition 
    • Block Internship and Seminar Auditory Neurophysiology, Master Program Integrative Neuroscience
    • Lecture Behavioral Pharmacology in the Master's Program Integrative Neuroscience
    • Lecture Psychophysiology in the Master's Programme Psychology

    We are always looking for motivated people, who want to get in touch with our research and have a keen interest in getting involved. We encourage young scientist to join our running projects or develop their own research ideas in our lab with respect to Bachelor- or Master-theses or HiWi-positions.

    Topics we offer for instance on a regular basis are:

    • Behavioural training of laboratory rodents in complex learning tasks
    • Histological/anatomical projects in collaboration with PD Dr. Eike Budinger
    • Programming and computational projects (Matlab, Python, R) for statistical data analysis (Linear models, multivariate statistics, RL-models, video tracking)

    If you are interested to get in touch with us, do not hesitate to come around or contact us at: agcortxplorer(at)


  • Open positions

    Open positions

    We search for

    Motivated students with multidisciplinary backgrounds, who want to join our young research group.


    We regularly advertise research assiatnt positions with different topics, and also offer the environment and supervision for Bachelor/Master theses.

    In case you…

    • are enthusiastic about doing brain science
    • have experience with programming (Matlab, Phyton, R)
    • and are willing to team-work….

    …we offer:

    • to support us in studying neuronal circuits and neuromodulatory systems during learning and memory,
    • learning state-of-the-art methods
    • a dynamic working environment in a young, interdisciplinary team
    • possibilities of graduation theses


    Interested? Please do not hestitate to contact us at: agcortxplorer(at)


    Currently we have the following open positions:

    • Research assistant in Optogenetics and Circuit physiology
    • Research assistant in Statistics in Brain Science
  • Cooperations
  • Media coverage
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