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Research Interests

PD Dr. Christian J. Merz, Cognitive Psychology, Faculty of Psychology

In particular, my research interests concern the investigation of experimental questions regarding learning and memory processes, cognitive neuroscience, psychoneuroendocrinology, their clinical applications and neuronal correlates. One focus of my research is the exploration of the influence of stress and sex hormones on emotional learning. In humans, the sex-dependent effect of the stress hormone cortisol on fear acquisition and fear extinction was demonstrated for the first time. In several fMRI studies (Merz et al., 2010a, 2012a, 2013, 2014a; Tabbert et al., 2010), exogenous cortisol administration as well as acute stress reduced conditioned responding in the fear circuit in men, but enhanced it in women. However, this pattern only occured in women taking oral contraceptives. Besides, the neuronal correlates of fear extinction are also affected by the intake of oral contraceptives (Merz et al., 2012b). Furthermore, a direct effect of the cortisol administration on the fear extinction network could be observed (Merz et al., 2014a; 2018a).

In addition, the impact of stress on memory consolidation, reconsolidation and retrieval of social information and of fear associations was examined (Hamacher-Dang et al., 2015; Kinner et al., 2018; Meir Drexler et al., 2014, 2015, 2016, 2018; Merz, 2017; Merz et al., 2010b, 2014b, 2016a; Stock & Merz, 2018). The investigation of sex-specific cortisol effects on emotional learning processes is especially important for basic research questions as well as for their application in the clinical context of exposure therapy (for reviews: Merz & Wolf, 2015, 2017; Merz et al., 2016b, 2018b).

An overview on important methodological aspects concerning the investigation and application of fear conditioning paradigms as well as on individual differences was formulated (Lonsdorf & Merz, 2017; Lonsdorf et al., 2017) in cooperation with the DFG funded „Research network for the (European) Interdisciplinary study of Fear and Extinction Learning as well as the Return of Fear (EIFEL-ROF).


Hamacher-Dang, T.C., Merz, C.J., Wolf, O.T. (2015). Stress following extinction learning leads to a context-dependent return of fear. Psychophysiology, 52, 489-498.

Kinner, V.L., Wolf, O.T. & Merz, C.J. (2018). Cortisol increases the return of fear by strengthening amygdala signaling in men. Psychoneuroendocrinology, 91, 79-85.

Lonsdorf, T.B., Menz, M., Andreatta, M., Fullana, M., Golkar, A., Haaker, J., Heitland, I., Hermann, A., Kuhn, M., Kruse, O., Meir Drexler, S., Meulders, A., Nees, F., Pittig, A., Richter, J., Römer, S., Shiban, Y., Schmitz, A., Straube, B., Vervliet, B., Wendt, J., Baas, J.M.P., Merz, C.J. (2017). Don’t fear ‘fear conditioning’: Methodological considerations for the design and analysis of studies on human fear acquisition, extinction, and return of fear. Neuroscience and Biobehavioral Reviews, 77, 247-285.

Lonsdorf, T.B., Merz, C.J. (2017). More than just noise: Individual differences in fear acquisition, extinction and return of fear in humans - Biological, experiential, temperamental factors, and methodological pitfalls. Neuroscience and Biobehavioral Reviews, 80, 703-728.

Meir Drexler, S., Merz, C.J., Hamacher-Dang, T.C., Marquardt, V., Fritsch, N., Wolf, O.T. (2014). Effects of post-retrieval extinction learning on return of contextual-controlled cued fear. Behavioral Neuroscience, 128, 474–481.

Meir Drexler, S., Merz, C.J., Hamacher-Dang, T.C., Tegenthoff, M., Wolf, O.T. (2015). Cortisol enhances the reconsolidation of reactivated fear memories. Neuropsychopharmacology, 40, 3036-3043.

Meir Drexler, S., Merz, C.J., Hamacher-Dang, T.C., Wolf, O.T. (2016). Cortisol effects on fear memory reconsolidation in women. Psychopharmacology, 233, 2687-2697.

Meir Drexler, S., Merz, C.J., Wolf, O.T. (2018). Pre-extinction stress prevents context-related renewal of fear. Behavior Therapy, 49, 1008-1019.

Merz, C.J. (2017). Contribution of stress and sex hormones to memory encoding. Psychoneuroendocrinology, 82, 51-58.

Merz, C.J., Dietsch, F., Schneider, M. (2016a). The impact of psychosocial stress on conceptual knowledge retrieval. Neurobiology of Learning and Memory, 134, 392-399.

Merz, C.J., Elzinga, B.M., Schwabe, L. (2016b). Stress, fear, and memory in healthy individuals. In J.D. Bremner (Ed.), Post-traumatic stress disorder: From neurobiology to treatment. Malden, MA: Wiley-Blackwell.

Merz, C.J., Hamacher-Dang, T.C., Stark, R., Wolf, O.T., Hermann, A. (2018a). Neural underpinnings of cortisol effects on fear extinction and extinction retrieval. Neuropsychopharmacology, 43, 384-392.

Merz, C.J., Hamacher-Dang, T.C., Wolf, O.T. (2014b). Exposure to stress attenuates fear retrieval in healthy men. Psychoneuroendocrinology, 41, 89-96.

Merz, C.J., Hermann, A., Stark, R., Wolf, O.T. (2014a). Cortisol modifies extinction learning of recently acquired fear in men. Social Cognitive and Affective Neuroscience, 9, 1426-1434.

Merz, C.J., Kinner, V.L., Wolf, O.T. (2018b). Let’s talk about sex … differences in human fear conditioning. Currrent Opinion in Behavioral Sciences, 23, 7-12.

Merz, C.J., Tabbert, K., Schweckendiek, J., Klucken, T., Vaitl, D., Stark, R., Wolf, O.T. (2010a). Investigating the impact of sex and cortisol on implicit fear conditioning with fMRI. Psychoneuroendocrinology, 35, 33-46.

Merz, C.J., Tabbert, K., Schweckendiek, J., Klucken, T., Vaitl, D., Stark, R., Wolf, O.T. (2012a). Neuronal correlates of extinction learning are modulated by sex hormones. Social Cognitive and Affective Neuroscience, 7, 819-830.

Merz, C.J., Tabbert, K., Schweckendiek, J., Klucken, T., Vaitl, D., Stark, R., Wolf, O.T. (2012b). Oral contraceptive usage alters the effects of cortisol on implicit fear learning. Hormones and Behavior, 62, 531-538.

Merz, C.J., Wolf, O.T. (2015). Stress and emotional learning in humans: Evidence for sex differences. In R.M. Shansky (Ed.), Sex differences in the central nervous system. London, San Diego, Waltham, Oxford: Academic Press, pp. 149-170.

Merz, C.J., Wolf, O.T. (2017). Sex differences in stress effects on emotional learning. Journal of Neuroscience Research, 95, 93-105.

Merz, C.J., Wolf, O.T., Hennig, J. (2010b). Stress impairs retrieval of socially relevant information. Behavioral Neuroscience, 124, 288-293.

Merz, C.J., Wolf, O.T., Schweckendiek, J., Klucken, T., Vaitl, D. Stark, R. (2013). Stress differentially affects fear conditioning in men and women. Psychoneuroendocrinology, 38, 2529-2541.

Stock, L.-M., Merz, C.J. (2018). Memory retrieval of everyday information under stress. Neurobiology of Learning and Memory, 152, 32-38.

Tabbert, K., Merz, C.J., Klucken, T., Schweckendiek, J., Vaitl, D., Wolf, O.T., Stark, R. (2010). Cortisol enhances neural differentiation during fear acquisition and extinction in contingency aware young women. Neurobiology of Learning and Memory, 94, 392-401.