Upper Limb Immobilisation: A Neural Plasticity Model with Relevance to Poststroke Motor Rehabilitation

Figure 2

(a) highlights the similarity between the maladaptive neural plasticity patterns that often occur after a hemiparetic stroke and that are currently thought to play an important role in mediating the individual’s motor deficits (see Figure 1(a) for comparison) and the neural plasticity patterns that are induced by upper limb immobilisation (red crossed circle) in otherwise healthy individuals. Light green circle: depression, that is, decreased size and/or excitability, of the cortical motor representation(s) corresponding to the immobilised body part(s). Dark green circle: overactivity of the homologous cortical motor representation(s) in the opposite cerebral hemisphere. Light blue arrow: decreased transcallosal inhibition. Dark blue arrow: increased transcallosal inhibition. (b) indicates potential interventions that could be delivered during a paradigm of upper limb immobilisation in healthy individuals in order to prevent maladaptive or promote adaptive neural plasticity in the motor system. These interventions might include, for instance, covert motor strategies, such as action observation (AO) and (likely) motor imagery (MI) (red-yellow balloon), and adjunctive therapies, such as excitatory and inhibitory brain stimulation (+BS and −BS, resp.) and peripheral somatosensory stimulation (PSS) (red-yellow bolts). White tick upward arrow: increase activity in the motor cortex contralateral to the immobilisation. White tick downward arrow: decrease activity in the motor cortex ipsilateral to the immobilisation. The idea here is that this might contribute to the development of alternative motor rehabilitation strategies for treating poststroke upper limb hemiparesis. See text for further details.