Functional imaging of locomotion and navigation. Physiology and neurodegeneration

In humans, central control of gait and spatial orientation can be visualized by functional neuroimaging techniques. However, in many cases data acquisition has to be uncoupled from the actual movement in space. Optic and PET methods allow the measurement of brain activity during real overground walking. Virtual reality, mental imagination, and the reduction to basic movement components (foot movement) are used in functional MRI to image different aspects of the locomotor network. Results show that in humans as in cats - the locomotor signal is transmitted from the frontal cortex via basal ganglia and locomotor regions in the brain stem and cerebellum to the spinal pattern generators. The hippocampal formation (on the right side) and its interaction with frontal and parietal cortex are essential for spatial navigation. Functional imaging of gait in patients is still in its infancy, but already broadens the knowledge on the pathophysiology of gait disturbances in degenerative brain disease.