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Our research focuses on "Brain, Hormones and Behavior".

An important aspect that we wish to cover in our human-experimental studies is interdisciplinary research connecting biology, medicine (endocrinology, anesthesiology, gynecology) and neurosciences. The hormones predominantly studied are stress hormones, sex hormones and insulin. The paradigms employed are classical conditioning, stress paradigms as well as dispositions for the detection of odor and taste perception.

Classical (Pavlovian) Conditioning

Fear conditioning: Effects of stress and stress reaction mediators on fear acquisition and extinction
Classical conditioning of fear is an important model for acquisition, extinction and extinction retrieval of anxiety disorders as well as stressor- and trauma-relateddisorders (e.g. posttraumatic stress disorder [PTSD]). Since these disorders often develop in stress-triggering situations, we study the effects of stress on acquisition, extinction and the extinction retrieval of the classical conditioned fear response. In order to investigate the differential function of the different components of the stress reaction (stress reaction mediators), we select stressors which either stimulate the noradrenergic system and therefore the so-called "first wave" of a stress reaction (cold pressor test) or psychosocial stressors that have strong effects on the release of cortisol (as part of the so-called "second wave" of the stress reaction). Conditions for the unlearning of the disorders mentioned above are also to be derived by investigating stress effects on extinction and extinction retrieval.

Fear conditioning and importance of sex hormones (estradiol, progesterone) and the menstrual cycle status

Since the prevalence of anxiety disorders as well as stressor- and trauma-related disorders (such as the PTSD) is higher in women than in men, the the above-mentioned conditioning processes are investigated in different menstrual cycle phases of women with natural cycles and women taking hormonal contraceptives. These processes are also investigated in men and the endocrine status (17-ß estradiol, progesterone) is determined for all groups. An important question is the interaction between stress (hormones) and sex hormones.

Conditioning of endocrine and immunological parameters in the administration of drugs  -  Placebo reactions

The classical conditioning or the underlying associative processes of conditioning are also  very suitable models for creating and thus also explaining placebo reactions.

We investigate (a) the classical conditioning and conditioning potential when administrating insulin (also intranasal) and glucose in healthy volunteers and the effects on the blood glucose, endogenous insulin release, hormones of glucoregulation (noradrenaline, adrenaline, cortisol, leptin) and on symptoms of hypo- and hyperglycaemia. (b) In the case of chemotherapy patients, we have examined whether changes in selected immune parameters (activity of natural killer cells, pro and anti-inflammatory cytokines) occur when a change of context (from the home environment to the clinical setting) takes place and the patients return to the clinic-setting, being exposed to its chemotherapy-associated, conditioned stimuli.

Conditioning of nausea (under chemotherapy and rotation)

A robust phenomenon of classical conditioning is the taste-aversion learning which provides the organism with the ability to avoid nausea-associated stimuli.

(a) Chemotherapy: The paradigm can also be applied to the administration of nausea-inducing drugs (for example in the context of chemotherapy or radiotherapy of patients): Approximately 30% of chemotherapy-treated cancer patients develop nausea and possibly vomit even before the onset of a new chemotherapy when they are again exposed to chemotherapy-associated stimuli. Anticipatory symptoms can be explained by classical conditioning. There is also empirical evidence that the anticipatory symptoms can be prevented or treated by techniques of classical conditioning (here: overshadowing).

(b) Rotation: In order to investigate conditions of the development and therapy of conditioned nausea, we applied a nausea model in healthy people: rotation in a swivel chair. We examined the preventive effects of the conditioning techniques overshadowing and latent inhibition (promoted by the Welcome Trust).

Function and effects of insulin in the central nervous system (CNS)

Insulin in the CNS
Insulin receptors are located in the central nervous system (CNS) in the hypothalamus, in the hippocampus, in the mesolimbic areas and in the cerebral cortex and with the highest density in the olfactory bulb. In DFG-funded (DFG is the German Research Association) projects (STO 323 / 1-1 and STO 323 / 1-2) the effects of intranasally administered and thus centrally effective insulin on eating habits and body weight, olfactory performance, memory and metabolic processes as well as the classical conditioning of insulin effects are investigated. Future research fields are possible deficits of the CNS-effect of insulin in overweight and Alzheimer's dementia and the importance of central insulin in functions mediated via the mesolimbic system (e.g. the reward value of food).

Odor and taste perception under metabolic control

Insulin receptor density in the CNS are highest in the olfactory bulb (Bulbus olfactorius). Moreover,they are localized in the olfactory mucosa. This suggests that insulin is also involved in odor perception and that the sense of smell is sensitive to the nutritional status and the metabolic state. We therefore investigate effects of different saturation states on odor perception and their association with the blood glucose level. In addition, the effects on taste perception are determined.

Function and effects of estrogen and progesterone in the CNS

We examine the reproduction of declarative memory contents with different emotional contents (emotionally negative vs. neutral) in different menstrual cycle phases of  women with natural cycles and women taking contraceptives. We are thus also looking into the importance of sex hormones for cognitive processes and for the processing of emotional contents

Stress in simulated emergency situations (stress reaction profiles and determinants)

In the now completed DFG project (STO / 323 / 2-1), emergency scenarios in anesthesia were generated with so-called full-scale simulators in a realistic manner. We examined, among other things, whether the psychological and endocrine stress reactions induced in the simulator corresponded to, or even exceeded, those of the established laboratory stressors and what they could predict concerning medical performance. Furthermore, the effect of previous experience of uncontrollable (instead of controllable) emergency situations on medical performance and stress reactions in subsequent emergencies was examined.