Effect of mental set on the primitive motor reflexes in cerebral palsy

Abstract

The aim of this study was to examine how three kinds of primitive motor reflexes in cerebral palsy (Babinski reflex, asymmetric tonic neck reflex, stretch reflex) were effected by various changes of subject's attention to stimulation.Mental work problems and tasks of voluntary muscle tension were adopted and the subjects underwent these tasks under two different conditions of attention to stimulation, i.e., positive attention and negative attention (condition of averted attention).As to the results of Babinski reflex and asymmetric tonic neck reflex, the subjects showed low response scores in the following order of conditions: (1) muscle tension task with positive attention, (2) mental work problems with positive attention, (3) muscle tension task with negative attention, (4) standard condition (no instruction), (5) mental work problems with negative attention.In stretch reflex, changes in the amount of tension and three types of reflexes were observed both in muscles of biceps brachii and triceps brachii. Responses under all task conditions increased in comparison with those under standard one, which discriminates from the results of Babinski reflex and asymmetric tonic neck reflex.These results showed that there were many patterns of primitive motor reflexes and the abnormal reflexes in cerebral palsy were determined not only by the pathological brain damages but also by subject's mental set.