Planning of spatially-oriented locomotion following focal brain damage in humans: A pilot study

• Motor impairments following brain damage are well documented.
• In particular, hemiparesis is a common feature of stroke patients. However, the navigational abilities (here, the ability to plan a path towards a distant target with vision or blindfolded) of such severely disabled patients have been poorly investigated.
• Here, we report that hemiparetic patients with significant lesions of the sensory-motor system following focal brain damage are not impaired during spatially-oriented locomotion performed with vision or blindfolded.
• This suggests that the motor cortex is involved in the sensorimotor implementation of locomotion but is not involved in the path planning stage in humans.
• Such findings open new avenues for post-stroke rehabilitation where specific tests (i.e., adapted versions of our paradigm) may allow parallel assessment of cognitive and locomotor functions recovery after stroke.

Motor impairments in human gait following stroke or focal brain damage are well documented. Here, we investigated whether stroke and/or focal brain damage also affect the navigational component of spatially oriented locomotion. Ten healthy adult participants and ten adult brain-damaged patients had to walk towards distant targets from different starting positions (with vision or blindfolded). No instructions as to which the path to follow were provided to them. We observed very similar geometrical forms of paths across the two groups of participants and across visual conditions. This spatial stereotypy of whole-body displacements was observed following brain damage, even in the most severely impaired (hemiparetic) patients. This contrasted with much more variability at the temporal level. In particular, healthy participants and non-hemiparetic patients varied their walking speed according to curvature changes along the path. On the contrary, the walking speed profiles were not stereotypical and were not systematically constrained by path geometry in hemiparetic patients where it was associated with different stepping behaviors. These observations confirm the dissociation between cognitive and motor aspects of gait recovery post-stroke. The impact of these findings on the understanding of the functional and anatomical organization of spatially-oriented locomotion and for rehabilitation purposes is discussed and contextualized in the light of recent advances in electrophysiological studies.