Does post-lesional subcortical plasticity exist in the human brain?

Post-lesional plasticity was extensively studied in human brain, especially using functional neuroimaging. However, because this technique maps only the grey matter, most of reports analyzed cortical reshaping, while subcortical structures received less attention. Yet, the global process of cerebral redistribution cannot be understood without taking account white matter tract in addition to the cortex. Here, the aim is to study whether subcortical structures are able to actively reorganize by themselves (rewiring), or whether it is only a passive consequence of the cortical remapping. The mechanisms of compensation following white matter damage are considered: unmasking of perilesional latent networks, recruitment of accessory pathways, introduction of additional relays within the circuit, involvement of parallel long-distance association pathways. Although different patterns of subcortical plasticity were identified, the real capacity to build a new structural connectivity leading to functional recovery is not yet demonstrated in humans. The next step is to perform longitudinal and integrated anatomo-functional correlations both at cortical and subcortical levels, in a "hodological" view of brain processing, to show whether the capacity of anatomic rewiring actually exists in human brain. (C) 2009 Elsevier Ireland Ltd and the Japan Neuroscience Society. All rights reserved.