Cortical Electrophysiology of Response Inhibition in Parkinson's Disease

NCT ID: NCT06234995

Last Updated: 2025-03-11

Basic Information

• Recruitment Status: RECRUITING
• Clinical Phase: PHASE4
• Total Enrollment: 80 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2021-08-09
• Study Completion Date: 2026-07-31

Brief Summary

Patients with Parkinson's Disease will be studied before, during, and after a deep brain stimulation implantation procedure to see if the stimulation location and the size of the electrical field produced by subthalamic nucleus (STN) DBS determine the degree to which DBS engages circuits that involve prefrontal cortex executive functions, and therefore have a direct impact on the patient's ability to inhibit actions.

Detailed Description

Patients with Parkinson's disease (PD) commonly develop difficulties with executive function due to neurodegeneration in neuronal networks that involve the prefrontal cortex and associative territories of the basal ganglia, even in early stages of the disease. Executive cognitive functions serve to direct behavior toward a goal and modify actions to accommodate changing demands. One of the key components of executive control is the ability to cancel or inhibit habitual responses. Motor response inhibition is critical in everyday life, for example, to stop crossing the street when a speeding car appears. In patients with PD, the failure of these inhibitory control mechanisms may manifest, for example, as an inability to stop festinating gait or as impulsively jumping out of a chair and losing balance. Beyond the failure of stopping or inhibiting motor responses, patients with PD are also prone to impulsivity and compulsions, leading to behaviors such as overeating or gambling. Approximately 15-20% of PD patients are diagnosed with impulse control disorders which can be exacerbated by dopaminergic medications. Furthermore, PD patients with deep brain stimulation (DBS) may develop additional impairments in executive function. Given the prevalence of executive dysfunction, the everyday-importance of this issue, and the connection with PD therapies, disease- or therapy-induced alterations in inhibitory control are an important area of research in PD.

The primary clinical objective for DBS therapy in PD has been to optimize motor function. The effect of stimulation on cognition and behavior, particularly in the subthalamic nucleus (STN), has been controversial. Behavioral side effects have been supported by reports of worsened cognition, increased impulsivity and even suicidal behavior. While large, randomized trials do not show significant detrimental changes in global cognition with DBS, meta-analyses and systematic reviews have shown adverse effects on executive functions, particularly response inhibition. Based on animal studies, the STN can be divided into a sensorimotor (dorsolateral), cognitive-associative (ventromedial) and limbic (medial) parts. Most DBS leads implanted into the STN contain four ring-shaped contacts, spaced over a total distance of 7.5-10.5mm. While surgeons generally target the dorsolateral sensorimotor region of the STN, the most ventral DBS contacts almost inevitably end up in the ventral associative or limbic regions of the nucleus. There are anecdotal observations of abrupt mood and behavioral changes (impulsivity, hypomania, depression) with STN DBS, perhaps due to spread of stimulation to the ventral STN regions. However, the effect of stimulation location on cognitive function is poorly understood and unaccounted for in clinical programming which may lead to suboptimal gains in quality of life.

Electrophysiology and imaging studies have demonstrated that the STN is a key node in the inhibitory network, although other basal ganglia nuclei are involved. The STN receives input from prefrontal cortical areas (via the prefrontal hyperdirect pathway) and is thought to provide a global inhibitory signal to the basal ganglia and thalamus to halt habitual responses and allow additional processing time in situations of conflict and uncertainty. STN DBS might (antidromically) disrupt the inhibitory signal from the cortex, leading to impulsive responses and inability to inhibit actions. However, it remains unclear whether stimulation in the STN worsens or improves motor response inhibition. It is also possible that some aspects of inhibitory control (proactive vs. reactive) can worsen during stimulation while others improve suggesting that the effects may be mediated by different pathways or mechanisms. Proactive inhibition refers to preparatory mechanisms that facilitate action inhibition (i.e. enables a person to act with restraint), while reactive inhibition is a sudden stopping process triggered by an external stimulus.

This study will address the following knowledge gaps:

1. Which cortical mechanisms (on the level of population-based electrophysiologic activity) are engaged in different aspects of inhibitory control (proactive control vs reactive; discrete movements vs continuous) in PD patients compared to healthy controls?

2. Does the effect of STN DBS on motor response inhibition depend on activation of the prefrontal hyperdirect pathway?

Successful completion of the proposed studies will provide substantial new knowledge about the frontal brain areas involved in inhibitory control, their topographic representation within the STN and means of cortico-subcortical communication. The results may inform future DBS targeting and programming strategies, aiming to avoid cognitive side effects of STN DBS. Recent engineering upgrades to clinical devices (e.g. segmented leads) allow more precise fine tuning of the stimulation field which can serve to design stimulation strategies that maximize motor benefit and minimize cognitive and behavioral side effects.

This study will enroll patients with Parkinson's Disease as well as health controls. Participation in this trial does not affect patient's clinical management. Patients' medication (levodopa) dosages and decision to undergo deep brain stimulation surgery are based on clinical needs.

There are 3 study aims:

Aim 1: To determine the effect of the PD disease process, levodopa treatment, and cognitive status on performance and cortical electrophysiology during motor response inhibition tasks. Participants with PD prior to surgery to implant the DBS leads and healthy controls are examined in Aim 1.

Aim 2: To characterize cortico-subthalamic connectivity during proactive motor response inhibition during surgery to implant clinically-indicated DBS leads in participants with PD.

Aim 3: To determine if activation of the prefrontal cortico-STN hyperdirect pathway impairs response inhibition in participants with PD from Aim 1 after implantation of DBS leads.

The experimental interventions considered in this study are: 1) medication state (PD patients are tested in levodopa-off and levodopa-on state), and 2) DBS stimulation settings (PD patients are tested under 4 stimulation settings: clinical, sham, maximizing prefrontal activation, and minimizing prefrontal activation). Healthy controls will attend two study visits, while patients with PD will be in the study for up to 18 months.

Conditions

Parkinson Disease

Study Design

• Allocation Method: NON_RANDOMIZED
• Intervention Model: PARALLEL
• Primary Study Purpose: BASIC_SCIENCE
• Blinding Strategy: SINGLE

Study Groups

Patients with Parkinson's Disease

Patients with PD complete motor response inhibitions tasks under multiple conditions, depending on the study aim they are participating in. Those who are participants in Aim 1 of the study are able to also participate in Aims 2 and 3 if they are having a clinically indicated DBS leads implanted. Patients with PD will participate in the study for approximately 18 months which includes one preoperative visit, intraoperative data collection and two post-operative visits. As part of the motor inhibition tasks, EEG signals will be recorded. A cap similar to a swim cap will be placed on the head of the subject, and gel will be applied to the hair to get a good signal. Electrodes will be attached to the cap for recording of brain signals. A few additional flat electrodes will be placed on the skin to record hand muscle activity (for GNG task) and near the eyes to record eye movements. Accelerometer sensors will be utilized to record arm movements (for MSS task).

Group Type: EXPERIMENTAL

Levodopa

Intervention Type: DRUG

Participants will take levodopa in dosages prescribed by their care provider. Patients will be instructed to not take their regularly prescribed PD medications for 12 hours prior to the study assessment, as is typical for clinical evaluations in patients with PD. Participants will be tested in both levodopa-off (after 12 hours of not having medication) and levodopa-on states.

Clinical DBS Setting

Intervention Type: DEVICE

Deep brain stimulation performed with the patients' optimized clinical setting.

Sham DBS

Intervention Type: DEVICE

Deep brain stimulation performed with sham stimulation.

DBS Setting Maximizing Prefrontal Activation

Intervention Type: DEVICE

Deep brain stimulation performed to maximize the activation of the prefrontal cortico-STN projections.

DBS Setting Minimizing Prefrontal Activation

Intervention Type: DEVICE

Deep brain stimulation performed to minimize the activation of the prefrontal cortico-STN projections.

Healthy Controls

Healthy participants complete motor response inhibition tasks during two study visits. Healthy controls will participate for approximately one month, which includes two study visits. As part of the motor inhibition tasks, EEG signals will be recorded. A cap similar to a swim cap will be placed on the head of the subject, and gel will be applied to the hair to get a good signal. Electrodes will be attached to the cap for recording of brain signals. A few additional flat electrodes will be placed on the skin to record hand muscle activity (for GNG task) and near the eyes to record eye movements. Accelerometer sensors will be utilized to record arm movements (for MSS task).

Group Type: NO_INTERVENTION

No interventions assigned to this group

Interventions

Levodopa

Participants will take levodopa in dosages prescribed by their care provider. Patients will be instructed to not take their regularly prescribed PD medications for 12 hours prior to the study assessment, as is typical for clinical evaluations in patients with PD. Participants will be tested in both levodopa-off (after 12 hours of not having medication) and levodopa-on states.

Intervention Type: DRUG

Clinical DBS Setting

Deep brain stimulation performed with the patients' optimized clinical setting.

Intervention Type: DEVICE

Sham DBS

Deep brain stimulation performed with sham stimulation.

Intervention Type: DEVICE

DBS Setting Maximizing Prefrontal Activation

Deep brain stimulation performed to maximize the activation of the prefrontal cortico-STN projections.

Intervention Type: DEVICE

DBS Setting Minimizing Prefrontal Activation

Deep brain stimulation performed to minimize the activation of the prefrontal cortico-STN projections.

Intervention Type: DEVICE

Other Intervention Names

L-Dopa

Eligibility Criteria

Inclusion Criteria

• diagnosis of idiopathic Parkinson's disease (PD)
• Hoehn and Yahr (H&Y) stage 2-4 (off medication)

• diagnosis of idiopathic PD
• there is a clinical indication for DBS surgery
• normal preoperative MRI
• ability to tolerate microelectrode-guided neurosurgery in an awake state

• diagnosis of idiopathic PD
• functioning DBS system

• age 45-75

Exclusion Criteria

• severe tremor at rest or severe dyskinesia which would cause significant artifacts in electrophysiological signals
• inability to hold antiparkinsonian medications for research recordings
• dementia
• non-English speaker

• presence of a coagulopathy
• uncontrolled hypertension
• heart disease
• other medical conditions considered to increase the patient's risk for surgical complications

• severe tremor at rest or severe dyskinesia which would cause significant artifacts in electrophysiological signals
• inability to hold antiparkinsonian medications for research recordings
• inability to tolerate temporary discontinuation of DBS therapy or alteration of stimulation settings for research purposes
• other medical conditions considered to increase the patient's risk for surgical complications

• history of a neuropsychiatric disorder and/or treatment with psychotropic medications
• non-English speaker

• Minimum Eligible Age: 45 Years
• Maximum Eligible Age: 75 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: Yes

Sponsors

National Institute of Neurological Disorders and Stroke (NINDS)

NIH

Sponsor Role: collaborator

Emory University

OTHER

Sponsor Role: lead

Responsible Party

Svjetlana Miocinovic

Associate Professor

Responsibility Role: PRINCIPAL_INVESTIGATOR

Principal Investigators

Svjetlana Miocinovic, MD, PhD

Role: PRINCIPAL_INVESTIGATOR

Emory University

Locations

Emory University Hospital

Atlanta, Georgia, United States

Site Status: RECRUITING

Emory Brain Health Center

Atlanta, Georgia, United States

Site Status: RECRUITING

Countries

United States

Central Contacts

Jonna Seppa

Role: CONTACT

jonna.k.seppa@emory.edu

404-727-1509

Svjetlana Miocinovic, MD, PhD

Role: CONTACT

404-712-9065

Other Identifiers

P50NS123103

Identifier Type: NIH

Identifier Source: secondary_id

View Link

STUDY00007291

Identifier Type: -

Identifier Source: org_study_id