Evaluating Force Deficits During Bimanual Coordination in Parkinson's Disease: Insights from Multimodal Imaging

Parkinson’s disease (PD) is the fastest-growing neurological disorder globally, resulting in
debilitating motor impairments and, in some cases, cognitive challenges that significantly disrupt
daily life. While current treatments manage symptoms, they do not slow disease progression,
partly due to a limited understanding of the brain circuits involved in PD-related motor deficits,
especially in complex tasks that reflect real-world challenges. Although much research has
concentrated on unimanual movements, everyday activities frequently involve the need for
coordinated bimanual actions alongside cognitive demands, such as buttoning a shirt while
simultaneously maintaining selective attention during a conversation. People with PD experience
exacerbated motor symptoms in dual-task conditions - such as performing mental subtraction
while engaging in complex coordinated movements like walking - yet the underlying neural
mechanisms driving this interference are poorly understood, particularly in relation to bimanual
coordination, which has yet to be thoroughly studied. This study aims to fill a critical knowledge
gap by using advanced multimodal imaging to examine force control deficits and associated brain
changes in PD during single and dual-task bimanual coordination. We hypothesize that PD will
demonstrate altered brain activity during bimanual coordination tasks, with greater disruptions in
brain function under dual-task conditions. These disruptions are expected to result in more
pronounced motor and cognitive impairments in PD, especially when tasks involve additional
cognitive demands. Using functional magnetic resonance imaging (fMRI) and functional near-
infrared spectroscopy (fNIRS), we will measure brain activity during isometric bimanual force
tasks at low to moderate force levels, both in isolation and while participants engage in cognitive
challenges, such as selective attention tasks that require focusing on relevant stimuli while
ignoring distractions. fNIRS offers distinct advantages over fMRI, including greater flexibility in
participant positioning and the ability to assess brain responses in more naturalistic settings,
providing additional insights into cognitive-motor interactions. Furthermore, we will investigate
PD-related structural brain changes through diffusion MRI, which when combined with functional
measures of neural activity and behavioral performance will allow us to identify predictors of dual-
task interference. This research will deepen our understanding of the neural mechanisms
underlying bimanual coordination deficits and may guide the development of targeted
rehabilitation strategies aimed at improving both motor and cognitive performance.

Grant Number: 1R03NS146865-01
NIH Institute/Center: NIH
Principal Investigator: Roxana Burciu