Integrated Calendar

Abstract: Arm amputation provides a powerful model for studying plasticity, as it results in massive input and output loss consequential to losing a hand. Amputation also leads to profound changes in behaviour, driven by individuals’ need to compensate for severe disability (adaptive behaviour). Despite this strong behavioural pressure, research on amputation has been largely restricted to deprivation-driven (and supposedly passive) brain reorganisation, with little regard for the potential interaction between deprivation and behavioural related plasticity. As a consequence, sensory deprivation is widely held to cause maladaptive plasticity, resulting in phantom pain. Using a range of neuroimaging approaches I examine the extent to which experience modulates brain structure and function in amputees and individuals with congenital hand absence. I present evidence to challenge the proposed link between cortical reorganisation and phantom pain, and instead demonstrate preservation of topographic representations of the missing (‘phantom’) hand. I will show that phantom pain is associated with maintained representation of the phantom hand as opposed to brain plasticity, with potential implications on future treatment. Instead I provide new evidence that adaptive behaviour leads to extensive reorganisation, such that the limb engaging in compensation for disability takes over the cortical territory of the missing hand. In amputees, this process of adaptive plasticity occurs well beyond the traditionally conceptualised “critical period”. Finally, I provide new evidence for the relationship between lateralised limb-use patterns and lateralised structural and functional organisation in the resting brain. Based on this evidence, I suggest that plasticity in amputees is experience-dependant, and is not inherently maladaptive.

Recent years have seen the development of several experimental systems capable of tuning local parameters of quantum Hamiltonians, including ultracold atoms, trapped ions, superconducting circuits and photonic crystals. These systems excel in studying the physics of bosons in disorder-free settings. A solid state analog, in which Hamiltonians of interacting electrons are designed and studied, remains a major open challenge, since in conventional solids electrons exist inside an imperfect host material that generates uncontrolled disorder. In this talk, I will describe our newly-developed platform for realizing in suspended carbon nanotubes such disorder-free, locally-tunable electronic systems. This platform bcomes possible due to a new technique for nano-assembly of carbon nanotubes on complex electrical circuits without damaging their pristine electronic behavior. I will demonstrate how these systems enable us to modify the fundamental interactions in the solid-state, using two specific examples: The engineering of an artificial, tailorable coupling between electrons and phonons, and the creation of attraction between electrons using only their repulsion – a problem that has been open for half a century. These new interactions pave the way for the formation, in engineered solids, artificial superconductivity that is very different from that found in nature.