Abstracts

RATIONALE: The aim of this study was to determine if there is advantage in right ear in the perception of words in two groups of healthy subjects (left-handed and right-handed) and one group of epileptic patients by a Dichotic Listening Task. METHODS: We used 30 pairs of words in which controlled the simultaneous presentation, duration and end of each pair of stimuli, which were presented twice to each subject, constituting a total of 60 pairs for each participant. We included 80 healthy subjects (50 left-handed and 30 right-handed according to a scale of manual preference) and 30 epileptic patients. The Laterality Index (LI) was obtained with the amount of words perceived in each ear as follows: (L-R) / (L+R)=LI. Strong left lateralization (+0.50 to +1), Weak left lateralization (+0.24 to +0.49), Bilateral representation (+0.25 to -0.25), Weak right lateralization (-0.24 to -0.49) and Strong right lateralization (-0.50 to -1). RESULTS: The results show that in contrast to the left-handed group, right handed subjects have a significant difference (<0.0001) in the perception of words between the right and left ear. Also, there is a clear difference in the frequency distribution of laterality of language among both groups. The group of epileptic patients has a right ear advantage too, but different distribution. CONCLUSIONS: It is possible to observe differences in brain organization of language between patients with epilepsy and healthy subjects using a dichotic listening task, which represents an available option for determining hemispheric dominance for countries in development.