Phantom Limbs, Neuroprosthetics, and the Developmental Origins of Embodiment

Abstract

Amputees who wish to rid themselves of a phantom limb must weaken the neural representation of the absent limb. Conversely, amputees who wish to replace a lost limb must assimilate a neuroprosthetic with the existing neural representation. Whether we wish to remove a phantom limb or assimilate a synthetic one, we will benefit from knowing more about the developmental process that enables embodiment. A potentially critical contributor to that process is the spontaneous activity—in the form of limb twitches—that occurs exclusively and abundantly during active (REM) sleep, a particularly prominent state in early development. The sensorimotor circuits activated by twitching limbs, and the developmental context in which activation occurs, could provide a roadmap for creating neuroprosthetics that feel as if they are part of the body.

Developmental “awakening” of primary motor cortex to the sensory consequences of movement

“…For example, in finches, consolidation of song motor memories also depends on neural processes during active sleep (Brawn et al, 2010;Deregnaucourt et al, 2005). Such 1 3 findings fit within a broader context linking active sleep to developmental plasticity and memory consolidation (Blumberg and Dooley, 2017;Diekelmann and Born, 2010;Dumoulin Bridi et al, 2015;Maquet et al, 2000). Thus, all together, the present findings encourage a new conceptualization of how M1 is functionally organized and how it adapts to and supports learning across the lifespan.…”

Spatiotemporal organization of myoclonic twitching in sleeping human infants

“…Studies with infant rats established that twitches are produced predominantly by motor structures in the brainstem (Blumberg & Plumeau, ; Del Rio‐Bermudez, Sokoloff, & Blumberg, ). When a twitch occurs, the resulting sensory feedback (i.e., reafference) triggers a cascade of activity throughout the sensorimotor system, from spinal cord to cortex, and this activity drives neural plasticity to enable precise somatotopic organization (Blumberg & Dooley, ; Inácio, Nasretdinov, Lebedeva, & Khazipov, ; Khazipov et al, ; Petersson, Waldenström, Fåhraeus, & Schouenborg, ). More broadly, twitches provide opportunities for infants to embody their growing limbs, that is to assimilate them into their nervous system (Blumberg & Dooley, ).…”

Robotic interfaces for cognitive psychology and embodiment research: A research roadmap

“…With respect to the study of embodiment and embodied cognition, the crucial parameters for certain aspects of embodiment, such as the feeling of ownership or the feeling of agency, might be identified within this process. Typically, related research is currently based on behavioral experiments trying to induce embodiment over a virtual or artificial body part (Botvinick & Cohen, 1998), through the manipulation of multisensory or sensorimotor contingency. As opposed to that, or rather as a companion to it, the robotic approach might overcome the most important limitations and pitfalls of these studies, as it allows better-controlled, for example, more systematic variations of delays, more flexible and longer-term alterations of sensorimotor processes, which is crucial to study adaptation.…”