Neuromodulation of Cortical Control in Freezing of Gait

Freezing of gait (FOG) is a disabling feature of Parkinson’s Disease (PD) that results in a loss of automatic gait. Neuroimaging studies suggest that increased cortical involvement in gait is closely linked to a loss of automaticity. While non-invasive neuromodulation techniques, such as transcranial magnetic stimulation (TMS), show promise in targeting cortical control mechanisms involved in FOG, their effectiveness is limited by an incomplete understanding of the underlying interactions between cortical control of gait and FOG. Recent studies have brought into question whether increased cortical control of gait in people with FOG is adaptive or maladaptive. Here, we present evidence and literature supporting these two opposing frameworks. One perspective suggests increased cortical involvement serves a compensatory, adaptive role, helping to overcome the loss of automatic gait and mitigate FOG episodes. In contrast, the alternative view suggests that increased cortical control is maladaptive, resulting from a disruption of automatic motor processes that may exacerbate gait impairments. To review these conceptual models, we examine neuroimaging, non-invasive brain stimulation studies, pharmacological modulation, and physical therapy interventions in people with PD and FOG. We conclude that while the vast majority of studies have performed neuromodulation under the conceptual framework that increased cortical control is adaptive, there is limited evidence that this approach is in fact superior to the alternative framework. We encourage future studies to develop a causal, mechanistic understanding of how cortical control of gait impacts freezing behavior to advance the development of effective brain-based treatment strategies.