Christine Philippsen

Publications (3)11.58 Total impact

• Source

  Available from: Melanie Hahn

  Article: Cardiovascular reactivity to mental stress is not affected by alpha2-adrenoreceptor activation or inhibition.

  Christine Philippsen, Melanie Hahn, Lars Schwabe, Steffen Richter, Jürgen Drewe, Hartmut Schachinger
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  ABSTRACT: It has been postulated that cardiovascular reactivity to mental stress varies with tonic central sympathetic nervous system activity, but pharmacological evidence is missing. To test whether modulation of central sympathetic nervous system activity by alpha2-adrenergic agonism and antagonism affects cardiovascular reactivity to mental stress. On three five-stepped dose/concentration-response study days, 12 healthy male volunteers received intravenous infusions of dexmedetomidine (alpha2-agonist, target plasma concentrations: 0.04-0.32 ng/ml), yohimbine (alpha2-antagonist, doses: 0.016-0.125 mg/kg), and placebo, respectively. During each dose step, subjects performed a 5-Choice Reaction Time Task (CRTT) and a Paced Auditory Serial Addition Task (PASAT) to induce moderate mental stress. Prestress baseline, as well as stress-induced responses of heart rate, and noninvasive finger arterial blood pressure (Finapres) were assessed. Prestress baseline heart rate and blood pressure decreased with increasing doses of dexmedetomidine and increased with increasing doses of yohimbine. However, dexmedetomidine and yohimbine did not affect stress-induced heart-rate and blood-pressure changes. Cardiovascular reactivity to mental stress is not related to pharmacologically manipulated tonic central sympathetic nervous system activity by alpha2-adrenergic agonists and antagonists. These results do not support the assumption that cardiovascular reactivity is an index of tonic central sympathetic nervous system activity.
  Psychopharmacology 03/2007; 190(2):181-8. · 4.08 Impact Factor
• Article: Evidence that baroreflex feedback influences long-term incidental visual memory in men.

  Tobias Moor, Lukas Mundorff, Andreas Bohringer, Christine Philippsen, Wolf Langewitz, Silvia Tenés Reino, Hartmut Schachinger
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  ABSTRACT: Sympathetic nervous system (SNS) activity at the time of acquisition is associated with human memory. However, rather than SNS activity per se, it may be afferent baroreflex feedback that is responsible for this effect. A pharmacological design was employed to unload (SNP, sodium nitro-prusside) and load (norepinephrine) baroreceptors. In addition to two placebo periods, epinephrine and esmolol (a peripherally acting beta1-blocker) served as control conditions for altered cardiac perception. During drug infusion blood pressure, heart rate, and perception of heartbeat were tested. Twenty-four healthy men were participated. The participants viewed emotional slides while their electromyographic eye blink responses to random noise bursts were measured (affective startle modulation paradigm) to determine potential drug impact on emotional processing. Subjects were not informed that memory testing would take place after 4 weeks. Drugs did not impact startle, thus indicating unbiased emotional processing at the time of acquisition. Norepinephrine had no effect on heartbeat perception, but improved (p = .002) recognition memory. SNP (p = .0001) increased heartbeat perception but impaired (p = .038) recognition memory. Epinephrine, on the other hand, increased heartbeat perception (p = .0001) yet did not impair but partially improve memory (effect on high arousing pictures only: p = .05). Heartbeat perception in the placebo condition did not correlate with recognition memory (p's > .5). We suggest that baroreflex unloading, with subsequent feedback activation of the SNS, impairs long-term incidental visual recognition memory in humans while baroreflex loading enhances it. Further, we propose that these memory effects are neither secondary to cardiac sensations that accompany SNS activation nor to altered emotional picture processing at the time of acquisition.
  Neurobiology of Learning and Memory 11/2005; 84(3):168-74. · 3.42 Impact Factor
• Article: Stress modulates the use of spatial versus stimulus-response learning strategies in humans.

  Lars Schwabe, Melly S Oitzl, Christine Philippsen, Steffen Richter, Andreas Bohringer, Werner Wippich, Hartmut Schachinger
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  ABSTRACT: Animal studies provided evidence that stress modulates multiple memory systems, favoring caudate nucleus-based "habit" memory over hippocampus-based "cognitive" memory. However, effects of stress on learning strategy and memory consolidation were not differentiated. We specifically address the effects of psychosocial stress on the applied learning strategy in humans. We designed a spatial learning task that allowed differentiating spatial from stimulus-response learning strategies during acquisition. In 13 subsequent trials, participants (88 male and female students) had to locate a "win" card out of four placed at a fixed location in a 3D model of a room. Relocating one cue in the last trial allowed inferring the applied learning strategy. Half of them participated first in the "Trier Social Stress Test." Salivary cortisol and heart rate measurements were taken. Stressed participants used a stimulus-response strategy significantly more often than controls. Subsequent verbal report revealed that spatial learners had a more complete awareness of response options than stimulus-response learners. Importantly, learning performance was not affected by stress. Taken together, stress prior to learning facilitated simple stimulus-response learning strategies in humans-at the expense of a more cognitive learning strategy. Depending on the context, we consider this as an adaptive response.
  Learning & memory (Cold Spring Harbor, N.Y.) 14(1):109-16. · 4.08 Impact Factor