Memory and decision making

Overview

My group studies at first glance very distinct research questions, i.e. not only
memory and decision making, but also how estrogen affects neural and cognitive processes. However, at the second sight these questions are not all only highly interesting themselves but also highly interrelated.

Why studying episodic memory?

Our subjective identity is a bundle of memories, in particular memories of episodes we experienced in our life. Not only which episodes of our life we remember but also the quality of these memories, for instance how vivid, how emotional, how detailed there are, influences how we think about us. Moreover, our memories of past experiences influence often also our decisions.
This relationship between our memories and our identity makes it particularly fascinating to study the cognitive, physiological and neural processes that modulate episodic memory formation, consolidation and retrieval as well as the interactions between memory and decision making.

Why studying the role of estrogen in the brain?

Estrogen is not only synthesized in the ovaries but also in the female and male brain. Besides its role in neural circuits coordinating the female reproductive cycle estrogen is an important neuromodulator for instance in the hippocampus, prefrontal cortex and the mesolimbic dopaminergic pathway of both, women and men. In the hippocampus for instance, E2 enhances synaptogenesis, the magnitude of LTP, stimulates NMDA receptor-mediated transmission and up-regulates NMDA receptor expression. Animal studies on the effects of estrogen on the dopaminergic system observed a modulation of dopamine-release, uptake, turnover and receptor binding, which might be also sexual dimorphic.
The fact that estrogen has two somewhat independent lives in our brains, one female specific and one in both sexes (although presumably partly sexual dimorphic) makes the investigation of its role particularly interesting.

  • In one line of research my group characterizes the enhancing effects of emotional arousal on item memory as well as its inhibitory effects on associative memory. In addition, we study whether and how estrogen affects emotional distinct from neutral memories.

    Prior knowledge or schemata influence which and how we encode and remember novel information which is another line of research we pursue.

    The ventral striatum is not only involved in reward processing and decision making but also in memory retrieval. We study how the striatum and the dopaminergic system exactly contribute to memory retrieval.

    Forming meaningful categories of stimuli based on feedback is essential for survival because it reduces the information we need to process and allow generalization to novel exemplars. Reinforcement learning and memory are closely interacting during real-life category learning which has not set been well understood. This interplay of memory and decision-making is therefore another of our research topics.

    Animal data show not only that estrogen affects the dopaminergic system and decision-making but also a higher vulnerability of females for drug addiction which might be relate to that (e.g. more rapid escalation from recreational use to abuse). To translate these findings to humans, we study sex differences and the effects of estrogen on reinforcement learning and putative dopaminergic activity.

    Another rather robust sex difference concerns spatial navigation for which reason we aim to dissociate the effects of structural (organizational) sex differences and estrogen on spatial abilities, navigation as well as brain activity related to these processes.

  • The institute provides a vibrant research environment due to the currently 11 research groups that stimulate close collaborations. We not only have our offices all in the 1.5 floors of the institute but there are also several regular common events as the presentation and discussion of planned projects, our cognitive neuroscience colloquium series and methods meetings. Moreover, the institute is part of the Hamburg Brain School that organizes training courses and events for doctoral students and postdocs. In addition, there are lots of interactions also with the great neuroscientific community of the UKE. The institute owns a 3T PRISMA MRI scanner and we are supported by our technical assistants and the MRI-physicists groups before and during scanning. In addition, the institute accommodates EEG, eye-tracking, TMS, virtual reality and behavioral labs that allow us to easily acquire data form a variety of complementing modalities.

  • Staff
  • Staff

    Dr. Tobias Sommer-Blöchl (Principal Investigator)

    Biographical sketch

    I studied Biology in Kiel, did my diploma thesis on potassium channels at the Center for Molecular Neurobiology of the UKE in Hamburg before I studied Psychology in Hamburg.

    During my studies I worked 6 month as a senior research specialist with Michael Posner at the Sackler Institute for Developmental Psychobiology at the Cornell Medical Center, New York, NY. I returned to the Sackler Institute for my Diploma thesis on the genetics of attentional networks. 2001 I started working as a research assistant at the Institute for Systems Neuroscience in Michael Rose’s group , before I did my PhD there with Christian Büchel. 2006 I became a postdoc at the institute and started then my own group. In 2010 I spent a couple of month as visiting scientist in the Stanford Memory Lab with Anthony Wagner.

    Just a short personal note to avoid confusion with respect to my name: Upon marrying in 2003, my official last name became ‘Sommer-Blöchl’. However, as this name is unpronouncable for most non-Germans and for simplicity's sake, I use my birth name ‘Sommer’ for scientific purposes.


    Anne Bierbrauer

    Dr. Anne Bierbrauer (Postdoc)

    In most cases, research on episodic memory focuses on the memory of words, pictures, or movies to draw conclusions about real-life episodic memories.

    However, memories of real-life episodes have many aspects that cannot be assessed in classic paradigms. Therefore, Anne works on a longitudinal study following memory consolidation for real-life episodes for three years. Characterizing the quantity and nature of the memories on the one hand, and their representational structure using fMRI on the other hand, we aim at achieving a deeper understanding of their correspondence and the way they change while being consolidated.

    Finally, stress and emotions seem to play a crucial role for episodic memory consolidation. Our experimental manipulation hence includes a stress intervention to get an idea of quantitative and qualitative changes of memories for stressful episodes. Lars Schwabe is our collaborator on this project.


    Kelly

    Qiying (Kelly) Liu (PhD student)

    Event segmentation theories suggest that changes in both external and internal contexts create event boundaries, which help structure the continuous flow of information and shape memory formation. Qiying’s research explores the impact of emotional arousal—an important internal contextual factor—on event segmentation. This project is conducted in collaboration with Deborah Talmi at Cambridge University, where Qiying is pursuing her PhD. With support from the German Academic Exchange Service (DAAD), she is conducting an fMRI study to examine how emotional arousal influences the perception and processing of event boundaries.


    Leah

    Leah Stocker (Master student)

    Noradrenergic neuromodulation results in an increase in neural gain as proposed for instance by Mara Mather’s local hotspot theory. The goal of Leah’s thesis is to test a prediction of this theory using fMRI based representational similarity analyses and Locus coeruleus imaging. Arjen Alink collaborates with us for this project.


    Franziska Werner

    Franziska Werner (study psychologist)

    Franziska is heavily involved in Anne’s project on long-term memory formation. In her internship before starting the job as study psychologist she worked on the stability of the trait form of the widely used state-trait-anxiety-inventory (STAI). In particular, two samples with each more than 100 volunteers filled out the STAI-T with 3-5 years distance. Her analyses will speak to the longstanding debate about the situational and temporal stability of traits. This project is a collaboration with Maren Klingelhöfer-Jens and Tina Lonsdorf .


    Marie Knapp (MD thesis)
    Marie’s investigates whether the volume of the bed nucleus of the stria terminalis (bnst) together with volumes of amygdala nuclei is related to life adversity and affective traits. This project is a collaboration with Tina Lonsdorf’s group .

    Astrid Gieske (PhD student)
    Astrid PhD is on the interaction of noradrenergic and dopaminergic neuromodulation on episodic memory formation. Currently, Astrid is in maternal leave.

    Eva Klein (Student Assistant)

    Fiona Brown (Study psychologist)


    Alumni

    Dipl.-Psych. Pia Bandurski (diploma thesis)
    Prof. Janine Bayer (Phd student, postdoc)
    M.Sc. Gemma Barnacle (DAAD scholar, University of Manchester, England)
    Fiona Brown (research intern, study psychologist)
    Prof. Jeremy Caplan (Sabbatical, University of Alberta, Edmonton, Canada)
    Dr. Mareike Clos (postdoc)
    Dr. Alina Dinu (PhD student)
    Dr. Isabel Ellerbrock (research intern)
    Franzi Feuchtner (research intern, bachelor thesis)
    Prof. Esther Fujiwara (Sabbatical, University of Alberta, Edmonton Canada)
    Dr. Nora Hennies (postdoc)
    Meghan Jaedicke (master thesis)
    Dr. Gina Joue (postdoc)
    Eva Klein (bachelor thesis)
    Vivien Kleinow (research intern)
    Dr. Angela Klingmüller (MD thesis)
    Linus Kluth (study psychologist)
    Chris Madan, PhD (DAAD scholar, University of Alberta, Edmonton, Canada)
    Dr. Andreas Marschner (postdoc)
    Lisa Phillip (study physician)
    MSc. Katharina Richter (master thesis)
    MSc. Romy Schröter (study psychologist, master thesis)
    Dr. Dirk Schümann (study psychologist, PhD student)
    Dr. Heidrun Schultz (PhD student)
    Dr. Ulrike Schwarze (PhD student, postdoc)
    Dr. Michael Tobia (postdoc)
    Dr. Ole Wächtler (MD thesis)
    Dr. Antonius Wiehler (research intern)


  • Research topics

    • modulation of memory encoding and consolidation by cognitive, affective and physiological factors
    • •modulation of estrogen on brain functions
    • interaction of striatum and medial temporal lobe in episodic memory
    • •interaction of episodic memory and decision making

    Research methods

    • •fMRI
    • behavioral experiments
    • •eye tracking and peripheral physiology
    • •pharmacological and genetic approaches

  • For full publication lists see:

    Google Scholar publication list

    UKE reasearch information system publication list

    Key Publications

    Sommer T, Hennies, N Lewis PA, Alink A (2022). The assimilation of novel information into schemata and its efficient consolidation. Journal of Neuroscience 42 (30), 5916-5929

    Joue G, Chakroun K, Bayer J, Gläscher J, Zhang Z, Fuss, J, Hennies, N, Sommer T (2022). Sex differences and exogenous estrogen influence learning and brain responses to prediction errors. Cerebral Cortex 32 (9), 2022-2036

    Clos M, Bunzeck N, Sommer T. (2019) Dopamine Enhances Item Novelty Detection via Hippocampal and Associative Recall via Left Lateral Prefrontal Cortex Mechanisms. J Neurosci. 2019 Oct 2;39(40):7920-7933.

    Bayer J, Gläscher J, Finsterbusch J, Schulte LH, Sommer T. (2018). Linear and inverted U-shaped dose-response functions describe estrogen effects on hippocampal activity in young women. Nature communications; 9(1):1220.

    Madan CR, Fujiwara E, Caplan JB, Sommer T. (2017). Emotional arousal impairs association-memory: Roles of amygdala and hippocampus. NeuroImage; 156:14-28.

  • Funding

    2025 Long-term Systems Consolidation of Memory for Real-Life Stressful Episodes – Extension (DFG, T. Sommer)

    2021 Long-term Systems Consolidation of Memory for Real-Life Stressful Episodes (DFG, T. Sommer)

    Past funding

    2021 Differential impact of stress on category learning systems (UKE, A. Dinu)

    2020 A computational psychiatric approach to understanding category representation in autism spectrum disorder (DFG, J. Bayer)

    2017 Aufgabenspezifischer Stress und flexibles Lernen (Landesforschungsförderung Hanmburg; T. Sommer & J. Gläscher)

    2017 Dopaminerge Verstärkung von Gedächtnisleistung beim Erinnern – eine pharmakologische fMRT-Studie mit gesunden Probanden (UKE FFM; M. Clos)

    2016 Entwicklung eines kognitiven Modells der Wirkung von Östrogen (DGPFG, Bayer)

    2015 Sex specific effects of estrogen on the neural substrates of episodic and fear memory (DFG, Sommer)

    2014 Auswirkung der Interaktion zwischen Östrogen und Dopamin auf die, den kognitiven Funktionen zugrundeliegenden, synaptische und Netzwerk-Aktivität bei Mäusen und Menschen (Landesforschungsförderung Hamburg; Büchel, Sommer, Bunzeck, Morrelini)

    2014 The influence of estrogen on hippocampal and amygdala dependent emotional memory (DFG; T. Sommer & J. Gläscher)

    2011 Functional significance of the ventral striatum during recognition memory (DFG; T. Sommer & N. Bunzeck)

    2010 Visiting scholar at the Stanford Memory Lab, Stanford University, headed by Prof. Anthony Wagner (DAAD; T. Sommer)

    2010 Emotional modulation of memory encoding and retrieval in the Concealed Information Test (DFG; M. Gamer, T. Sommer, C. Büchel, & G. Vossel)

    2009 Neurodapt! Core Project (Excellence Intiviative Hamburg; T. Sommer, & K. Kutsche)

    2009 Functional organization of the human medial temporal lobe (DFG; J. Peters, T. Sommer, & C. Büchel)

    2009 Using Computational Models to Understand Mechanisms Underlying Complex Human Learning and its Genetic Basis Across the Life-Span (BMBF Bernstein; C. Büchel & T. Sommer)

    2008 Localization and Functional Relevance of the Central Nervous Estrogen Synthesis (DFG; T. Sommer, C. Büchel, & G. Rune)

    1999 Visiting scientist at the Sackler Institute for Developmental Psychobiology, New York, (Volkswagen Foundation; T. Sommer)

  • Jeremy Caplan, University of Alberta, Edmonton, Canada

    Lars Schwabe, University of Hamburg

    Deborah Talmi, University of Manchester, England

    Anthony Wagner, Stanford University, USA

    Thomas Wolbers, German Center for Neurodegenerative Diseases, Magdeburg

  • You are always welcome to apply as an intern or for your Master/MD thesis.