Symmetrie und Symmetriebrechung

In spite of their growing specialization, modern natural sciences intend to reduce their theories to some fundamental structures: Physics tries to unify the different physical forces in one fundamental force. Chemistry tries to explain the structure of chemical substances by the quantum mechanics of molecules. Biology tries to reduce the processes of life to biochemical and biophysical laws. Mathematically, the unification of natural science can be described by structures of symmetry, the specialization of science, the variety, and emergence of new phenomena by symmetry breaking. In the following, the successes and lacks of the reductionistic program are shown in recent developments of physics, chemistry, and biology. Philosophical discussions on holism, reductionism, and unification of science can be clarified by structures of symmetry and symmetry breaking. Alternative non-reductionistic view-points are not only possible, but desirable for the lacks in the reductionistic program. Nevertheless, the categorical framework of symmetry and symmetry breaking supports interdisciplinary work and gives new insight in a common structure and theory of natural science.     

Brain dopamine and kinematics of graphomotor functions

Three experiments were performed in an attempt to achieve a better understanding of the effect of dopamine on handwriting. In the first experiment, kinematic aspects of handwriting movements were compared between healthy participants and patients with Parkinson's disease (PD) on their usual dopaminergic treatment and following withdrawal of dopaminergic medication. In the second experiment, the writing performance of healthy participants with a hyperechogenicity of the substantia nigra as detected by transcranial sonography (TCS) was compared with the performance of healthy participants with low echogenicity of the substantia nigra. The third experiment examined the effect of central dopamine reduction on kinematic aspects of handwriting movements in healthy adults using acute phenylalanine and tyrosine depletion (APTD). A digitising tablet was used for the assessment of handwriting movements. Participants were asked to perform a simple writing task. Movement time, distance, velocity, acceleration and measures of fluency of handwriting movements were measured. The kinematic analysis of handwriting movements revealed that alterations of central dopaminergic neurotransmission adversely affect movement execution during handwriting. In comparison to the automatic processing of handwriting movements displayed by control participants, participants with an altered dopaminergic neurotransmission shifted from an automatic to a controlled processing of movement execution. Central dopamine appears to be of particular importance with regard to the automatic execution of well-learned movements.     

The experimental task influences cue competition in human causal learning

Participants were shown A+ and C- trials followed by AB+ and CD+ trials. These trials were embedded in a causal learning task in which participants had to learn either the relationship between different foods and allergic reactions or the relationship between different stocks and an increase in the stock market index. The authors orthogonally varied the manner in which the different cues were presented to participants during training. Cue competition was related to the causal learning scenario but not to the manner in which the different cues were presented. These results question claims of a human bias toward configural processing that were based on difficulties in finding cue competition in some previous causal learning experiments.     

Retrieval of incidental stimulus-response associations as a source of negative priming

Priming effects of ignored distractor words were investigated in a task-switching situation that allowed an orthogonal variation of priming and response compatibility between prime and probe. Across 3 experiments, the authors obtained a disordinal interaction of priming and response relation. Responding was delayed in the ignored repetition condition if different responses were required for identical stimuli in the prime and probe (negative priming). Repeating the prime distractor in the probe facilitated responding if the same response was required in the prime and in the probe (positive priming). The same pattern of results was replicated in a letter-matching task without task switching (Experiment 4). Findings lend support to a new model that explains negative priming in terms of an automatic retrieval of incidental stimulus-response associations.     

Agonistic screams in wild chimpanzees (Pan troglodytes schweinfurthii) vary as a function of social role

Some nonhuman primates have demonstrated the capacity to communicate about external objects or events, suggesting primate vocalizations can function as referential signals. However, there is little convincing evidence for functionally referential communication in any great ape species. Here, the authors demonstrate that wild chimpanzees (Pan troglodytes schweinfurthii) of Budongo forest, Uganda, give acoustically distinct screams during agonistic interactions depending on the role they play in a conflict. The authors analyzed the acoustic structure of screams of 14 individuals, in the role of both aggressor and victim. The authors found consistent differences in the acoustic structure of the screams, across individuals, depending on the social role the individual played during the conflict. The authors propose that these 2 distinct scream variants, produced by victims and aggressors during agonistic interactions, may be promising candidates for functioning as referential signals.     

The facial pattern of disgust, appetence, excited joy and relaxed joy: an improved facial EMG study

The purpose of the study was to investigate the facial muscle pattern of disgust in comparison to appetence and joy, using an improved facial EMG method. We analyzed the activity of nine facial muscles in forty healthy subjects. The subject group was randomly divided into two groups (oversaturated vs. hungry) of ten women and ten men each. Four different emotions (disgust, appetence, excited-joy and relaxed-joy) were induced by showing pictures from the IAPS. Pre-visible facial muscle activity was measured with a new facial EMG. A Visual Analog Scale (VAS) was established. Disgust is represented by a specific facial muscle pattern involving M.corrugator and M.orbicularis oculi, clearly distinguishing it from the facial patterns of appetence and joy. The intensity of disgust is stronger in a state of hunger than under oversaturation and is altogether stronger in females than in males. Our findings indicate the possibility to explore the entire emotion system successfully through a state-of-the-art psychophysiological method like our EMG device.