[Psychobiology of fear]

Fear is an affective experience and a normal psychobiologic reaction preparing the organism for defense or avoidance of threats. It is only abnormal when extent, expression and duration do not match the real danger. Three processes are elementary components of fear: 1. the perception of a signal for threat, 2. expectation, defined as inner mobilisation and augmented directional attention, 3. feeling arising from impending loss of control over the inner and outer milieu. Mutual dependence and interference between the three processes are often the basis for vicious circles in pathologic states of fear. Various aspects of fear, mainly of the anticipated fear can be explained by conditioned behaviour, a fact of significance not at last for rational psychotherapy. The form of expression and the extent of a reaction to fear is according to the hypothesis of Gray regulated by a complex functional central nervous system. The primary role of the latter consists in an inhibition of the actual behaviour in order to allow for alternative reactions adapted to the new circumstances. Intensity and quality of alarming signals ultimately determining the outcome of the reaction are mediated by neurotransmitters. These assure the correct transmission within the neuronal network and regulate the extent of activation off all neuronal cells. Three neurotransmitters are assumed to have an essential role in fear: norepinephrine, serotonin and gamma-amino-butyric-acid (GABA). The action of GABA has been documented best so far. An increase of inhibitory GABA-effects is also the main mechanism of action of benzodiazepines and benzodiazepine-like anxiolytics.