The ontogeny of the neurophysiological mechanisms of stereognosis: An EEG study

Abstract

Age-related characteristics of the systemic organization of intra- and interhemispheric interactions during a stereognostic task (tactile shape recognition with the right or left hand) were studied in adults and children aged five to six, seven to eight, and nine to ten years. A combined pattern of cortical interactions was found in adults. It was expressed in a considerable enhancement of relationships between cortical bioelectric potentials compared to the baseline accompanied by a substantial increase in the intensity of the systemic interactions between anterior and posterior cortical areas. This pattern was revealed by both coherence and cross-correlation analyses of the electroencephalogram (EEG). In the EEGs of children, the enhancement of interhemispheric relationships was observed at an age as early as five to six years and was the highest in seven- to eight-year-old children, whereas the increase in the cross-correlation of cortical bioelectric potentials in the frontal—occipital direction developed gradually, approaching the definitive level typical of adults by the age of nine to ten years. The results suggest that the central mechanisms of stereognosis, a function important for manual and occupational activities, gradually develop during postnatal ontogeny. Heterochronic involvement of intra- and interhemispheric interactions in the performance of stereognostic task may be related to gradual, heterochronic myelination of commissural and associative pathways.