The FRA concept against a withdrawal reflex concept?

Abstract

T he Focus article concisely reviews the main problems that may arise when using spinal reflex connections in nociception and research. Therefore, it is appropriate that the Commentaries highlight and extend different topics of the article, thus facilitating its understanding. The short subjective view on the historical development of the pharmacologic belief and the appreciative translation of the different sections from motor group to pain group view of Dr. Duggan will facilitate the understanding of the article for both groups. This understanding is further supported by the detailed critical remarks of Dr. Carstens on the techniques in research. Carstens particularly pointed out that for tests in animal research, not only simplicity, reliability, sensitivity, and quantitation are of importance, but valldidity is also of crucial relevance. One important aspect, which was not mentioned in the Focus article, has been taken up by Dr. Pertovaara. It is the great importance of the history of the patient or the animal being investigated. For example, long-lasting or even short-lasting preceding episodes may distincly alter nociceptive by different central nervous factors. This may change not only the amplitude and character of a reflex, but also the influence of different drugs. As Pertovaara pointed out in this context, it should be realized that learning may play an important role in chronic or repeated experiments on nociception and pain, not only in humans but also in animals. Dr. Schouenborg outlined the great local specificity of withdrawal reflexes in the rat and criticized the flexor reflex afferent (FRA) terminology. Indeed, the term flexor reflex afferents led to considerable misunderstandings and it was Anders Lundberg himself who declared that the term is really a misnomer [7]; however, despite