By 7 months, most infants finally have sufficient postural Bcl-2 inhibitor control to reach while sitting independently. Given infants’ success at adopting context appropriate reaching responses by the end of the first year, it has been a longstanding puzzle as to why infants typically experience an increased rate of less adaptive two-handed reaching patterns at the start of their second year (e.g., Babik, 2010; Corbetta & Thelen, 1996; Fagard & Pezé, 1997; Goldfield & Michel, 1986; Ramsay, 1985). Corbetta and Bojczyk (2002) were
the first to suggest that infants’ tendency to return to two-handed reaching around the end of the first year was associated with changes in postural control upon the emergence of walking. By tracking nine infants weekly over the course of their transition to upright locomotion, including documenting arm position during walking and reaching patterns, Corbetta and Bojczyk (2002) demonstrated that infants who displayed competent and adaptive reaching responses prior to walking, such as reaching primarily with MK-1775 research buy one hand for small objects, typically began to reach more often with two hands
for small objects after walking onset. As infants’ balance control improved, the two-handed reaching pattern declined, suggesting that something unique about the motor constraints associated with the onset of walking played an important role in the developmental reorganization of reaching (Corbetta & Bojczyk, 2002). Walking is the culmination of a whole sequence of upright postures, making it difficult to fully interpret the mechanism underlying the relationship between its onset and infants’ return to bimanual reaching. In particular, we do not yet know whether there was something unique about walking or whether it was the general postural shift Ribose-5-phosphate isomerase to an upright position that reorganized the motor system. It could be that the onset of
the high guard posture used for balance control prompted the reorganization of infants’ reaching patterns. However, it is also possible that it was the more general switch to being upright that prompted the reorganization. In that case, we may see a relationship between the development of bimanual reaching and other upright postures like pulling-to-stand or cruising (moving sideways holding onto furniture with one or both hands for support). In fact, some recent preliminary work suggests that the onset of independent standing may be related to infants’ reaching patterns and that subsequent walking strategies shape the trajectory of changes in reaching preferences (Thurman et al., 2012).