142 CHAPTER 7 supplementary motor area. Peripheral nerve injury can lead to reorganization outside the primary sensorimotor network as well, including in associative regions in posterior parietal and parieto-occipital cortex. 162, 195-199 We were therefore expecting to find altered brain activity in any of the areas involved in motor planning: in core somatomotor/sensory regions such as precentral gyrus (primary motor cortex, premotor cortex, supplementary motor area) and postcentral gyrus (somatosensory cortex), as well as in associative areas in posterior parietal cortex and the occipito-parietal extrastriate body area. The fact that we found deficits in associative occipito-parietal regions, but not in the core sensorimotor system was somewhat surprising in light of its involvement in many other peripheral nerve disorders. This could mean that either there are no adaptations in the core sensorimotor system in NA patients, or that the paradigm we used throughout this thesis was not sensitive enough to detect such changes. I will first discuss factors related to our paradigm and NA disease characteristics that may have contributed to reduced sensitivity, after which I will go into what it could mean if there are indeed no adaptations in the core sensorimotor system in NA and what we can learn from the changes that we did find. The hand laterality judgment task has been used extensively to study sensorimotor representations in healthy individuals and a variety of nervous system disorders. Its use in combination with neuroimaging techniques (specifically fMRI) is however limited in patient populations. Studies that do use this combined approach find cerebral adaptations more consistently in associative areas than in core motor and sensory regions: altered activity has been reported in several posterior parietal and parieto-occipital regions in patients with Parkinson’s disease, 40, 60 lower limb amputation202 and developmental coordination disorder, 203 disorders with known changes in the core sensorimotor system. This could suggest that the hand laterality judgment task may simply be more sensitive to cerebral changes in associative parietal/occipital regions. Nevertheless, reports in other neurological disorders do include adaptations in the core sensorimotor system, including altered activity in somatosensory cortex59 and altered connectivity between extrastriate body area and the dorsal premotor area. 40, 204 Why then did we not find any such adaptations in NA? The answer may be found in disease characteristics that are specific to NA. First, the imagined movement evoked by the hand laterality judgement task mainly involves endo- and exorotation of the shoulder. Although many patients with NA do experience impaired endo- and exorotation, the most prominent issue is lifting of and reaching with the upper extremity. 6, 8 Perhaps the imagined movement in this task did not sufficiently activate the processes that patients struggle with most in daily life to reveal changes in the core sensorimotor regions. To resolve this issue, future studies could employ motor (imagery) paradigms that involve lifting of and reaching with the upper extremity. Paradigms that could be explored include motor execution or explicit motor imagery of reaching movements (goal-directed or not), or different implicit motor imagery tasks such as Rosenbaum’s bar grasp task. 205 Second, along the same line of thought, the MRI scanner environment may have been a contributing factor. A factor that is specific to NA relates to the characteristic winging of the scapula and subsequent instability of the shoulder. 6-8 Our patients performed the task in a supine position in the MRI scanner. Patients in our clinic typically start coordinative training in this position as the scapular support provided by the examination table greatly aids