Early life experience sets hard limits on motor learning as evidenced from artificial arm use

Abstract

The study or artificial arms provides a unique opportunity to address long-standing questions on sensorimotor plasticity and development. Learning to use an artificial arm arguably depends on fundamental building blocks of body representation and would therefore be impacted by early-life experience. We tested artificial arm motor-control in two adult populations with upper-limb deficiency: congenital one-handers – who were born with a partial arm, and amputees – who lost their biological arm in adulthood. Brain plasticity research teaches us that the earlier we train to acquire new skills (or use a new technology) the better we benefit from this practice as adults. Instead, we found that although one-hander started using an artificial arm as toddlers, they produced increased error noise and directional errors when reaching to visual targets, relative to amputees who performed similarly to controls. However, the earlier a one-hander was fitted with an artificial arm the better their motor control was. We suggest that visuomotor integration, underlying the observed deficits, is highly dependent on either biological or artificial arm experience at a very young age. Subsequently, opportunities for sensorimotor plasticity become more limited.

Lifelong learning of cognitive strategies for physical problem-solving: the effect of embodied experience

“…In either case, they might naturally come to appreciate the value of thinking more about solutions to physical problems before acting, and over time this could grow into a general strategy for interacting with the world. What is striking is that this learned strategy extends to a task in which action possibilities are equated across groups -indeed, individuals without limb differences were not slower to control the cursor in our task (see also Maimon-Mor et al, 2021).…”

“…Supporting this view, researchers have shown that when individuals’ bodies or skills are altered, e.g. through temporary training or by being born with limb differences, this can change their perceptual capacities (Aglioti, Cesari, Romani, & Urgesi, 2008; Hagura, Haggard, & Diedrichsen, 2017), spatial cognition (Makin, Wilf, Schwartz, & Zohary, 2010), body representation (Maimon-Mor, Schone, Moran, Brugger, & Makin, 2020), or motor skills (Maimon-Mor, Schone, Slater, Faisal, & Makin, 2021). Here we ask if these effects of embodiment can be broader, by testing whether differences in embodied experience (through limb differences) affect the ways that people think about acting in the world, even when their capacities for action are made equal.…”

“…Supporting this view, researchers have shown that when individuals' bodies or skills are altered, e.g. through temporary training or by being born with limb differences, this can change their perceptual capacities (Aglioti, Cesari, Romani, & Urgesi, 2008;Hagura, Haggard, & Diedrichsen, 2017), spatial cognition (Makin, Wilf, Schwartz, & Zohary, 2010), body representation (Maimon-Mor, Schone, Moran, Brugger, & Makin, 2020), or motor skills (Maimon-Mor, Schone, Slater, Faisal, & Makin, 2021).…”