THE DEVELOPMENT OF POSTURAL RESPONSE PATTERNS DURING REACHING IN HEALTHY INFANTS

Reaching movements in adults are accompanied by complex postural adjus tments which are controlled by spatial, temporal, and quantitative par ameters. The basic postural adjustments are selected on the basis of t he spatial parameter, whereas fine tuning of the pattern is guided by temporal and quantitative parameters. In specific conditions, such as during fast arm movements, postural adjustments have an anticipatory c haracter. Recently, the development of postural adjustments during rea ching was studied longitudinally in infants aged 3-18 months, placed i n supine and sitting positions. The data revealed that already at 4 mo nths, the age at which successful reaching emerges, reaching movements are accompanied by complex postural adjustments. The early postural p atterns resembled the adult ones in spatial features (dorso-ventral or dering), temporal characteristics (top-down recruitment), and position dependency. With increasing age the postural patterns changed conside rably, including a transient period of less extensive postural activit y at 6-8 months, the age at which rolling, sitting up and crawling dev elops. Postural anticipation during reaching was not consistently pres ent at any age. (C) 1998 Elsevier Science Ltd. All rights reserved.