Integrating Functional Neuroimaging With DBS and rTMS to Evaluate Neurobehavioral-Cognitive and Motor Outcomes in Parkinson’s Disease
DOI: Pending DOI
Synopsis
Neuromodulation techniques such as subthalamic deep brain stimulation (STN-DBS) and repetitive transcranial magnetic stimulation (rTMS) alter neural activity across motor and cognitive circuits in Parkinson’s disease. Functional neuroimaging shows that rTMS can normalize abnormal cortical activation (¹), while DBS produces widespread network changes linked to both motor improvement and cognitive variability (²,⁴). Neurobehavioral complications such as executive dysfunction may arise from unintended stimulation of associative pathways (³). Integrating imaging findings
Background
Parkinson’s disease disrupts basal ganglia–cortical circuits responsible for both motor control and higher cognitive domains. Neuromodulatory treatments aim to correct these abnormal patterns. Functional neuroimaging research demonstrates that rTMS produces measurable cortical activation changes that may restore more normal network function (¹). Imaging combined with DBS reveals how stimulation alters activity across motor, premotor, and frontal associative regions (²).
STN-DBS is well established for motor improvement, reducing rigidity, tremor, and bradykinesia, especially in medication-off states (⁴). However, this benefit occurs alongside potential risks. Reports describe postoperative executive, behavioral, and motivational changes due to stimulation spreading to limbic or associative pathways (³). Cognitive outcomes after DBS vary: some patients show improvement in prefrontal attention and response control, while others experience decline in memory and visuospatial processing (⁴).
Together, these studies highlight the need to integrate functional neuroimaging with neuromodulation to better understand mechanisms of benefit and the origins of cognitive or behavioral side effects.
Methods
This synthesis draws from four key studies examining neuromodulation in Parkinson’s disease. Wu (¹) reviewed functional neuroimaging data describing how rTMS modifies cortical activation patterns. Obeso et al. (²) analyzed how imaging paired with DBS and rTMS helps map stimulation-induced changes in motor and cognitive circuits. Van Horn et al. (³) reviewed clinicaland behavioral data documenting neuropsychiatric risks after STN-DBS. Alegre et al. (⁴) conducted an observational before–after study assessing motor status and neuropsychological performance three months after STN-DBS implantation.
Across studies, neuroimaging modalities included functional MRI, PET, and task-based cortical activation mapping. Motor outcomes were evaluated through standard PD motor scoring and clinical observation (⁴). Cognitive outcomes included memory, visuospatial ability, and executive function testing. Results were compared qualitatively to identify convergent patterns relating stimulation parameters, network-level effects, motor improvement, and neurobehavioral risk.
Results
Across studies, neuromodulation consistently altered activity within basal ganglia–frontal networks. rTMS produced measurable modifications of cortical activation, particularly in motor and premotor regions, supporting its potential to normalize PD-related dysfunction (¹). Obeso et al. showed that combining imaging with stimulation techniques reveals stimulation-dependent modulation of subcortical and cortical nodes, helping separate therapeutic activity from compensatory activation (²).
Motor outcomes were consistently positive after STN-DBS. Alegre et al. demonstrated clear improvements in motor function, particularly in medication-off states, with better prefrontal task engagement and reduced motor disability (⁴). DBS produced stabilization of motor symptoms and reduction of motor fluctuations, consistent with established therapeutic expectations. Obeso et al. also noted robust motor improvement with STN-DBS across imaging-linked studies (²).
Cognitive outcomes were mixed. Alegre et al. found moderate deterioration in verbal memory and visuospatial function but improvements in prefrontal attention and executive control (⁴). Van Horn et al. reported neurobehavioral risks—apathy, impulsivity, and executive dysfunction—due to stimulation spreading into limbic-associative territories (³). These findings emphasize that cognitive and emotional side effects arise when stimulation impacts non-motor circuits.
Integrated across all studies, functional neuroimaging consistently revealed that DBS and rTMS induce widespread network changes beyond motor pathways. These correlates explain variability across patients: some benefit cognitively when frontal networks are re-regulated, while others decline when associative circuits are disrupted. Neuroimaging emerges as essential for predicting treatment response, identifying maladaptive activation patterns, and tailoring stimulation parameters to maximize motor benefit while reducing behavioral and cognitive risks (¹–⁴).
Discussion
The combined evidence demonstrates that functional neuroimaging is critical for understanding the mechanisms through which DBS and rTMS modulate neural circuits in Parkinson’s disease. Imaging reveals the specific motor pathways responsible for robust improvements after STN-DBS (²,⁴) while also identifying how unintended spread into associative or limbic circuits can cause cognitive or behavioral complications (³). rTMS provides a noninvasive means of modulating cortical activity, with imaging confirming its capacity to normalize dysfunctional patterns (¹).
Integrating imaging into routine neuromodulation practice may improve patient selection, refine operative targeting, and guide personalized programming to maximize motor gains and minimize neuropsychological risk. Imaging-based biomarkers have the potential to predict treatment response and identify patients vulnerable to cognitive decline, offering a pathway toward safer and more effective neuromodulation therapies.
Disclosures
The Author has no financial relationships or conflicts of interest to disclose.
References
1. Wu AD. Functional Neuroimaging and Repetitive Transcranial Magnetic Stimulation in Parkinson’s Disease. 2007.
2. Obeso I et al. Combining Functional Imaging With Brain Stimulation in Parkinson’s Disease. 2011.
3. Van Horn G et al. Subthalamic Deep Brain Stimulation: Neurobehavioral Concerns. 2001.
4. Alegre M et al. Effects of Bilateral Subthalamic Stimulation on Cognitive Function in Parkinson Disease. 2001.