This study examined the effects of experience and practice on the coupling between visual information and trunk sway in infants with Down syndrome (DS). Five experienced and five novice sitters were exposed to a moving room, which was oscillated at 0.2 and 0.5 Hz. Infants remained in a sitting position and data were collected on the first, fourth, and seventh days. On the first day, experienced sitters were more influenced by room oscillation than were novices. On the following days, however, the influence of room oscillation decreased for experienced but increased for novice sitters. These results suggest that the relationship between sensory information and motor action in infants with DS can be changed with experience and practice.
Paula F. Polastri and and José A. Barela
Matheus M. Gomes and José A. Barela
The purpose of this study was to examine the effects of visual and somatosensory information on body sway in individuals with Down syndrome (DS). Nine adults with DS (19–29 years old) and nine control subjects (CS) (19–29 years old) stood in the upright stance in four experimental conditions: no vision and no touch; vision and no touch; no vision and touch; and vision and touch. In the vision condition, participants looked at a target placed in front of them; in the no vision condition, participants wore a black cotton mask. In the touch condition, participants touched a stationary surface with their right index finger; in the no touch condition, participants kept their arms hanging alongside their bodies. A force plate was used to estimate center of pressure excursion for both anterior-posterior and medial-lateral directions. MANOVA revealed that both the individuals with DS and the control subjects used vision and touch to reduce overall body sway, although individuals with DS still oscillated more than did the CS. These results indicate that adults with DS are able to use sensory information to reduce body sway, and they demonstrate that there is no difference in sensory integration between the individuals with DS and the CS.
Ana M. F. Barela, José A. Barela, Natália M. Rinaldi and Diana R. de Toledo
This study examined the influence of both optic flow characteristics and intention on postural control responses. Two groups of 10 adults each were exposed to the room’s movement either at 0.6 cm/s (low velocity group) or 1.0 cm/s (high velocity group). All the participants stood in the upright stance inside of a moving room and were informed about the room movement only after the fourth trial as they were asked to resist to its influence. Results revealed that participants from both groups were influenced by the imposed visual stimulus in the first trials, but the coupling strength was weaker for the high velocity group. The request to resist the visual influences decreased visual influences on body sway, but only for the low velocity group. These results indicate that intention might play a role in stimulus influences on body sway but it is stimulus dependent.