Perceptual Decision Making Under Conditions of Visual Uncertainty
|Study Design:||Intervention Model: Single Group Assignment
Masking: Single Blind (Subject)
Primary Purpose: Basic Science
|Official Title:||Perceptual Decision Making Under Conditions of Visual Uncertainty|
- Choice performance - % correct responses out of total number of trials [ Time Frame: at the end of each testing session - 2 hours ] [ Designated as safety issue: No ]data from each subject will be assessed at the end of each session to monitor and measure outcome measures.
- Reaction Time to make a choice - measured in milliseconds [ Time Frame: at the end of each testing session - 2 hours ] [ Designated as safety issue: No ]data from each subject will be assessed at the end of each session to monitor and measure outcome measures.
|Study Start Date:||April 2013|
|Estimated Study Completion Date:||December 2015|
|Estimated Primary Completion Date:||December 2015 (Final data collection date for primary outcome measure)|
Deep Brain Stimulator
Some of our subjects that participate to the study have Deep Brain Stimulation implanted. They will perform the behavioral task twice, with the stimulation ON or OFF.
Procedure: Deep Brain Stimulation (DBS)
Patients with DBS will participate to the study both when the stimulation is off and on.
In this study, the investigators aim determine whether patients with Parkinson's disease (PD) have altered perceptual decision-making. The results of these experiments will shed important light on some of the enigmatic symptoms seen in patients with disorders of movement.
In this study the subjects perform a computer generated visual task which involves reporting the direction of an arrow that is more or less difficult to see on the computer screen. Eye movements will be monitored using a video eye tracker. The system is completely non-invasive and positioned in front, out of the subject's line of sight to avoid interfering with their ability to perform the task.
Subjects will report their decision with either an eye movement in the same direction as the perception of the arrow direction. Trials will proceed as follows: a central point will appear on the screen. Subjects are asked to look at the fixation point. After this random delay time, a patch of spots will appear in place of the center fixation spot, embedded in the patch will be an arrow. The contrast between the arrow and the patch will vary from high values to low. At high contrasts the direction at which the arrow points will be very clear and at low contrasts it will be unclear. The task of the subject is to make a rapid eye movement as soon as they decide which direction the arrow points. A sound will be played to indicate a correct choice. On trials in which the sensory information is ambiguous subjects will be told to 'make their best guess' to which target the arrow points. Unknown to the subject the investigators will manipulate the probability that one of the targets is the correct one. This latter manipulation will test whether subjects can use probability information to inform their decisions. The investigators are particularly interested in whether this probability information is used preferentially when the sensory information is ambiguous.
The total number of subjects to be enrolled in the study is approximately 120. Subject groups are as follows: Healthy humans between the ages of 30 and 80 and those with PD (between ages of 45 and 80), dystonia (ages 30-80) and cerebellar lesions (ages 30-80) including those who have undergone DBS surgery to treat their PD or dystonia. The total duration of each session is approximately 2 hours. Each patient group including those with DBS will perform two sessions of the same task - one while on medication and one while off medication, hence the total duration of the study will be 4 hours for these groups (2 different sessions during different days). These patient groups are free to do these sessions at the same time as their routine physician visits or any other time that works best for them.
Please refer to this study by its ClinicalTrials.gov identifier: NCT01845883
|Contact: Alessandra Perugini, PhD||3108250278||APerugini@mednet.ucla.edu|
|United States, California|
|Neuroscience Research Building||Recruiting|
|Los Angeles, California, United States, 90095|
|Principal Investigator: Michele Basso, PhD|
|Sub-Investigator: Alessandra Perugini, PhD|
|Principal Investigator:||Michele Basso, PhD||UCLA David Geffen School of Medicine|