Action Regulation Behavioral

Revealing the Action Regulation Mechanisms in the Human Brain

Parkinson's disease (PD) is a neurodegenerative disorder involving a part of the brain that is responsible for motor control, which not only results in changes or disruptions in movement, but also cognitive dysfunctions. Given that the decline of muscle control such as tremors, with difficulty walking or the ability to switch tasks once in movement, greatly affects the quality of daily life. Action regulation is a critical executive function (cognitive control over behavior), which includes actions such as suppressing activity when selecting between options, making decisions about stopping unwanted or inappropriate actions, and switching to new actions in response to environmental changes. Parkinson's disease (PD) has been shown to disrupt action inhibition which can be considered a measure to the progression of PD.

The purpose of this research study is to better understand the mechanism of action regulations in PD patients and how action regulations in PD can be improved using dopaminergic treatment, which is a drug that either releases or involves dopamine, which is a neurotransmitter involved in sending signals to nerve cells.

You are asked to participate in this research study because you are receiving a dopaminergic medication for treatment of your Parkinson's disease. There is currently no theory that integrates the mechanisms of action regulation into a unified framework, which this study aims to address. The researchers hope to learn more about the mechanisms of action regulation in PD patients and to help decrease action regulation disruptions in PD patients. This study will help characterize the motor behavior of PD patients.

Study Overview

• Status: Recruiting
• Conditions: Parkinson Disease
• Intervention / Treatment: Behavioral: Action Regulation Movement Task

• Study Type: Interventional
• Enrollment (Estimated): 50
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Nader Pouratian, MD, Phd; Phone Number: (214) 645-5465; Email: nader.pouratian@utsouthwestern.edu
• Study Contact Backup: Name: Sahil Chilukuri, BS; Phone Number: (214) 645-5465; Email: sahil.chilukuri@utsouthwestern.edu

Study Locations

• United States
  • Texas
    • Dallas, Texas, United States, 75390
      • Recruiting
      • University of Texas Southwestern Medical Center
      • Contact: Nader Pouratian; Email: nader.pouratian@utsouthwestern.edu
      • Contact: Sahil Chilukuri; Email: sahil.chilukuri@utsouthwestern.edu

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

Study Population

Study participant's are Parkinson's Disease patients currently taking levodopa medication for the management of their movement disorder and Healthy subjects.

Description

For Parkinson's Disease Patients:

Inclusion Criteria:

• Diagnosis of Parkinson's Disease by a movement disorder neurologist
• Levodopa responsive with clearly defined "on" periods, with at least 30% improvement in UPDRS III scores on vs off
• Willingness and ability to complete the behavioral experiments for up 3.5 hours
• No vision or hearing problems that impair ability to participate with the proposed tasks as assessed by the study investigators

Exclusion Criteria:

• Patients with history of secondary Parkinsonism, stroke, or progressive central nervous system disease other than Parkinson's Disease
• Patients with a disease or condition that prevents understanding or communication of informed consent, study demands, and testing protocol including cognitive decline, diagnosed forms of dementia, significant memory impairment (MoCA<23), or hearing loss that prevents adequate communication with researcher

For Healthy subjects:

Inclusion Criteria:

• No history any diagnosed neurological disease(s), including movement disorders or cognitive decline
• No vision or hearing problems that impair ability to participate with the proposed tasks as assessed by the study investigators

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Non-Randomized
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Parkinson's Disease Patients; Patients that have been diagnosed with Parkinson's Disease and are responsive to levodopa medication. Patients will complete a behavioral task.	Behavioral: Action Regulation Movement Task; A joystick is utilized to trace the movement of a visual stimulus on a computer screen. In stop signal task, the subjects are required to move a reference dot to reach to a target dot by controlling a joystick and stop their movements when the target turns red. During the switch task, subjects will be required to switch their joystick movement trajectory when the target location is switched to one of the other target locations.
Active Comparator: Healthy Controls; Men and women between the ages of 18-80. Spouse of PD patient who participates in this study with no history of any diagnosed neurological disease(s), including movement disorders or cognitive decline. No vision or hearing problems that impair ability to participate with the proposed tasks as assessed by the study investigators.	Behavioral: Action Regulation Movement Task; A joystick is utilized to trace the movement of a visual stimulus on a computer screen. In stop signal task, the subjects are required to move a reference dot to reach to a target dot by controlling a joystick and stop their movements when the target turns red. During the switch task, subjects will be required to switch their joystick movement trajectory when the target location is switched to one of the other target locations.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Stop-Signal Task	Each patient will complete a joystick-based stop-signal task which assesses reaction time, stop reaction time, accuracy, and joystick traces.	Baseline
Switch Task	Each patient will complete a joystick-based switch task which assess reaction time, switch reaction time, accuracy, and joystick traces.	Baseline

Collaborators and Investigators

• Sponsor: University of Texas Southwestern Medical Center
• Collaborators: University of California, Riverside

Study record dates

Study Major Dates

• Study Start (Actual): April 24, 2024
• Primary Completion (Estimated): November 1, 2026
• Study Completion (Estimated): November 1, 2027

Study Registration Dates

• First Submitted: June 26, 2024
• First Submitted That Met QC Criteria: July 2, 2024
• First Posted (Actual): July 8, 2024

Study Record Updates

• Last Update Posted (Actual): December 12, 2025
• Last Update Submitted That Met QC Criteria: December 10, 2025
• Last Verified: December 1, 2025

More Information

Terms related to this study

• Keywords: motor cortex; basal ganglia; Levodopa medication
• Additional Relevant MeSH Terms: Synucleinopathies; Brain Diseases; Central Nervous System Diseases; Nervous System Diseases; Neurodegenerative Diseases; Movement Disorders; Parkinsonian Disorders; Basal Ganglia Diseases; Parkinson Disease
• Other Study ID Numbers: STU-2022-0555

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: Following data acquisition, de-identified data will be shared with research team at University of California, Riverside.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No