Reply: Does dominant pedunculopontine nucleus exist?

Sir,We appreciate the thoughtful comments and additional contributions from Lam and colleagues with regards to our recent manuscript in Brain , which demonstrated substantial asymmetry of structural connectivity strength within the locomotor network of individuals with Parkinson’s disease who experience freezing of gait (FOG+) (Fling et al. , 2013). Specifically, we reported reduced white matter tract volume between the right pedunculopontine nucleus (PPN) and the midline of the right frontal cortex, assessed by diffusion tensor imaging. This was in contrast to those patients with Parkinson’s disease who did not have freezing issues and age-matched controls. In addition, this asymmetric reduction of the right hemisphere’s locomotor network was strongly related to inhibitory cognitive control, a process that is uniquely lateralized to the right hemisphere (Aron, 2007). In their letter, Lam and colleagues report how the …