Recording and Modulation of Brain Activity Through Chronically Implanted Stimulation Electrodes

For decades, deep brain stimulation (DBS) therapies have been employed very successfully to alleviate segmental motor symptoms (tremor, brady-kinesia or rigidity) in patients with Parkinson's disease (PD). Unfortunately these therapies often fail to alleviate, or can even aggravate, axial deficits such gait and balance disorders. This is presumably due to the divergence in the dynamics of the circuits that control leg function, which are not well addressed with commonly employed stimulation protocols. To date, patients still endure life-long debilitating gait difficulties that severely affect their everyday mobility, independence and quality of life. In recent years, a handful of studies have proposed new paradigms, for instance using different stimulation parameters that are thought to be better suited for targeting the circuits that control lower limb function. Although promising, the resulting observations have been far from conclusive. As a result, the relevant approaches for therapeutic intervention remain unclear, and the underlying mechanisms largely unknown. Advances on the use of implantable neuromodulation devices and of tech-nologies for monitoring whole-body movement currently allow to study locomotor deficits in ecological environments, enabling the recording and modulation of motor and neural signals while patients perform activities of daily living, chronically, wirelessly and in real time.