Attention and Eye Movement in Parkinson's Disease

Not Applicable

Not yet recruiting

• Conditions: Essential Tremor; Parkinson's Disease (PD)

• Registration Number: NCT06899022
• Lead Sponsor: University of Nebraska

Brief Summary

The goal of this observational and interventional study is to understand how therapeutic deep brain stimulation (DBS) affects attention, perception and cognition in participants with Parkinson's disease (PD) and essential tremor (ET). The main questions it aims to answer are:

* Does impaired control of attention and eye movement in PD alter how social cues are perceived and interpreted?

* Does therapeutic DBS improve or worsen attentional and perceptual deficits for social cues in PD and ET?

* Can DBS be optimized to restore normal attentional control in PD while remaining an effective therapy for other aspects of the disorder.

* What do parts of the brain targeted by DBS contribute to the control of attention?

Using an eye tracking camera, investigators will study how participants with PD and ET look at and perceive facial expressions of emotion before and after starting DBS therapy, in comparison to a group of healthy participants without ET, PD or DBS. Participants with PD and ET will see and rate morphed facial expressions on a computer screen in three conditions:

* Before starting DBS therapy (over approximately 1 hour).

* In the operating room, during the standard procedure to implant DBS electrodes, while the participant is awake (for no more than 15 minutes).

* After starting DBS therapy, with brief experimental changes of DBS stimulation level and frequency (over approximately 1 hour).

Detailed Description

Parkinson's disease (PD) is the second most common age-related neurodegenerative disorder, with approximately 90,000 new cases diagnosed annually in North America. Although motor symptoms define the disorder, PD also leads to cognitive and emotional changes, such as difficulties in recognizing facial expressions and regulating attention, which often overshadow motor issues as the disease progresses. The goal of this study is to better understand the link between attention, eye movement, and emotional perception in PD, testing the hypothesis that disrupted attention leads to altered perception of facial emotions. The study will also investigate how deep brain stimulation (DBS) of the subthalamic nucleus (STN) affects these processes, providing critical insights into the cognitive and perceptual consequences of the treatment.

This research addresses a critical gap in understanding non-motor symptoms of Parkinson's disease by exploring how attention, eye movement, and perception interact. Findings will provide evidence on whether cognitive and emotional symptoms in PD stem from impaired attentional control, offering a new framework for treating these deficits. Additionally, the study will shed light on how different DBS frequencies affect perception and cognition, potentially guiding personalized stimulation strategies to alleviate both motor and non-motor symptoms. The insights gained may influence future therapies for PD, advancing both scientific knowledge and patient care.

Participants will be divided into three groups: PD undergoing DBS, essential tremor (ET) undergoing DBS (as a comparison group for non-PD DBS effects) and healthy age- and sex-matched controls. Participants will complete facial morph rating tasks (rating faces as happy, neutral, or sad) and visual search tasks (finding faces among distractors), while their eye movements are tracked.

The first study aim is to measure how altered attention influences facial emotion perception in PD by tracking eye movements while participants view and categorize emotional face stimuli. The second aim is to characterize brain activity in the STN related to attentional and perceptual processes during awake DBS surgery by capturing microelectrode recordings (MER) of neural activity while participants view emotional faces, allowing researchers to map STN's role in guiding attention and eye movements. The third aim is to test how DBS stimulation at different frequencies (high, low, or off) affects attention, eye movement, and emotional perception by having participants perform visual and perceptual tasks under varying DBS settings to evaluate how brain stimulation influences cognitive and perceptual functions.

Study Timeline

• Status Verified: 2025-03
• Study First Submitted: 2025-03-14
• Study First Submitted QC: 2025-03-20
• Study First Posted: 2025-03-27
• Last Update Submitted: 2025-03-27
• Last Update Posted: 2025-04-02
• Study Start: 2025-05
• Primary Completion: 2027-12
• Study Completion: 2027-12

Recruitment & Eligibility

• Status: NOT_YET_RECRUITING
• Sex: All
• Target Recruitment: 138

Inclusion Criteria

Not provided

Exclusion Criteria

Not provided

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: SINGLE_GROUP

Primary Outcome Measures

Name	Time	Method
Facial Expression Rating	Over two experimental sessions, once prior to DBS surgery and once 2-3 weeks after surgery, following clinical optimization of DBS.	Participants will rate facial expression along a continuous scale using a computerized slider, following the affective bias task (ABT) of Bijanki et al. (2014). The scale is anchored with three descriptors, "Very Sad" at slider value 0 (left), "Neutral", at position 0.5 (middle), and "Very Happy" at 1.0 (right). Responses are compared between two time points: (1) at the initial pre-surgical testing session and post DBS implantation and (2) at the post-implantation session following clinical optimization of therapeutic parameters, 2-3 weeks after surgery. The comparison will examine both the direction of any bias of the rating, against normative ratings, and the magnitude of average deviation from normative ratings. Finally, the ratings will be incorporated into a generalized linear model of gaze position (Kovach 2014) to identify the association between perceived facial expression and characteristic fixation patterns.
Eye Tracking	Over two experimental sessions, once prior to DBS surgery and once 2-3 weeks after surgery, following clinical optimization of DBS.	The location and duration of gaze fixations will be recorded with a remote eye tracking camera. The location of gaze fixations will be treated as the dependent measure within a generalized linear modeling (GLM) framework for spatial point processes, described in Kovach and Adolphs (2014). Parameter estimates of the model give the log relative risk of fixation at different locations in the visual scene as a function of the independent measures of the model. Independent measures include the main effect of (1) Fourier basis functions encoding scene location and its interactions with (2) image rating in the affective bias task of Bijanki et. al (2014), (3) session and (4) DBS stimulation state. Measures derived from the GLM model will also include the statistical deviation (e.g. Kullback-Leibler divergence) from the average distribution of fixations observed in healthy comparison subjects for each image.

Trial Locations

Locations (1)

University of Nebraska Medical Center; 🇺🇸 Omaha, Nebraska, United States