Top-Down Attentional Control of Visual-Processing

This study is currently recruiting participants.
Verified August 2013 by National Institutes of Health Clinical Center (CC)
Sponsor:
Information provided by:
National Institutes of Health Clinical Center (CC)
ClinicalTrials.gov Identifier:
NCT01087281
First received: March 13, 2010
Last updated: March 14, 2014
Last verified: August 2013
  Purpose

Background:

- Previous studies have shown that people with certain types of brain damage may have particular problems paying attention and processing things that they see. Researchers are interested in comparing how people with brain damage and without brain damage process visual images.

Objectives:

- To better understand the areas of the brain involved in paying attention to things that are seen.

Eligibility:

- Individuals at least 18 years of age who either have had damage to one or both sides of specific parts of the brain (e.g., stroke, injury, certain neurosurgery procedures) or are healthy volunteers.

Design:

  • The study involves 4 to 10 visits to the NIH Clinical Center over 1 to 2 years. Each visit will last approximately 2 hours.
  • Participants will be screened with a medical history and physical examination, and may have the cognitive testing described below during the same visit.
  • On the first visit and for at least one visit thereafter, participants will have cognitive testing to evaluate thinking and memory. These tests will be either written tests or computer-based tests.
  • Some participants will qualify for functional magnetic resonance imaging (fMRI) as part of the study. This part will involve a decision-making task that will be performed on a computer during the fMRI scan. Additional scans may be required as directed by the study doctors.
  • Some randomly selected participants will be asked to have magnetoencephalography (MEG), a procedure to record very small magnetic field changes produced by brain activity.
  • During the behavioral training, or fMRI or MEG scanning, participants may be monitored with equipment to track eye movements.

Condition
Focal Brain Lesion
Focal Lesions
fMRI

Study Type: Observational
Study Design: Time Perspective: Prospective
Official Title: Top-Down Attentional Control of Visual-Processing

Resource links provided by NLM:


Further study details as provided by National Institutes of Health Clinical Center (CC):

Primary Outcome Measures:
  • To test the hypothesis that prefrontal cortex and parietal cortex are major sources of top-down signals that favor the processing of behaviorally relevant (attended) information.

Secondary Outcome Measures:
  • To determine the differential top-down contributions of prefrontal and parietal regions in processes selective and sustain attention, filtering of distracter information, orienting of attention, and attention engagement and disengagement.

Estimated Enrollment: 198
Study Start Date: February 2010
Detailed Description:

Attention is required for most, if not all, perceptual processes. There is a converging body of evidence from single-cell recording studies in monkeys and neuroimaging, behavioral, and clinical studies in humans showing that the processing of attended information is enhanced relative to the processing of unattended information.

What is the source of this attentional modulation? Because neuroimaging studies have demonstrated that multiple cortical regions are recruited during tasks involving selective attention, it has proven difficult thus far to determine the differential contributions of each region. A central goal of the proposed research is to characterize the contributions of prefrontal cortex and parietal cortex and test the hypothesis that these regions exert top-down modulatory influences over visual processing areas. Specifically, we wish to investigate the interaction between areas involved in attentional control and visual areas modulated by attention.

We propose to study patients with focal lesions and healthy volunteers while they perform tasks requiring attention. Subjects will participate, first, in a series of behavioral studies involving selective attention; the relative performance of different patient groups and neurologically healthy volunteers will be compared. Subjects will also be studied while performing similar tasks during functional magnetic resonance imaging (fMRI). We hypothesize that selective attention will be heavily impaired by lesions of key prefrontal (e.g., dorsolateral prefrontal cortex) and key parietal (e.g., superior parietal lobule) sites. We also expect that brain imaging data will show decreased activation in visual regions ipsilateral to the focal lesions in prefrontal and parietal cortex, thus providing evidence that prefrontal and parietal cortex are sources of top-down modulation. Although other research groups have compared the behavior of patients with various focal lesions or have performed fMRI studies of visual attention in neurologically normal patients, we are unaware of any concerted effort to perform fMRI in patients with focal lesions in order to functionally isolate the contributions of individual cortical regions that serve as critical nodes in the attentional network.

  Eligibility

Ages Eligible for Study:   18 Years and older
Genders Eligible for Study:   Both
Accepts Healthy Volunteers:   Yes
Criteria
  • INCLUSION CRITERIA:

All subjects will be 18 years of age or older and have at least a high school education.

Capacity to provide their own informed consent, understand and cooperate with study procedures.

Patients:

  1. Unilateral or bilateral focal lesions of prefrontal, parietal, or temporal cortex, or amygdala.
  2. At least six months post-stroke, lobectomy and or neurosurgical resection.

Healthy volunteers:

1. Neurologically normal and in good general health.

EXCLUSION CRITERIA

Patients:

  1. Any neurological or psychiatric disorder not related to the focal lesion (e.g., epilepsy, schizophrenia, etc.)
  2. Previous head injury.
  3. Present or past (within past 6 months) drug or alcohol abuse or addiction as determined by a qualified study neurologist/psychiatrist.
  4. Radiation treatment to the brain during a one-year period prior to the experiment.

Healthy Volunteers:

  1. Any neurological or psychiatric disorder (e.g., epilepsy, schizophrenia, etc.)
  2. Previous head injury.
  3. Present or past (within past 6 months) drug or alcohol abuse or addiction as determined by a qualified study neurologist/psychiatrist.

ADDITIONAL EXCLUSION CRITERIA FOR MRI SCAN:

Patients and Healthy volunteers:

  1. Women who are pregnant and women of child-bearing potential who refuse to undergo a urine pregnancy test will be excluded from fMRI experiments but included in cognitive experiments.
  2. Subjects who have contraindications to MRI scanning will be excluded from FMRI experiments but included in cognitive experiments. These contraindications include:

    1. central nervous system aneurysm clips;
    2. implanted neural stimulator;
    3. implanted cardiac pacemaker or defibrillator;
    4. cochlear implant;
    5. ocular foreign body (e.g., metal shavings);
    6. insulin pump;
    7. metal shrapnel or bullet;
    8. any implanted device that is incompatible with MRI.
  3. Conditions that preclude scanning, e.g., morbid obesity, claustrophobia.
  Contacts and Locations
Please refer to this study by its ClinicalTrials.gov identifier: NCT01087281

Contacts
Contact: Christine V Nikas (301) 402-7470 christine.nikas@nih.gov
Contact: Leslie G Ungerleider, Ph.D. (301) 435-4932 ungerlel@intra.nimh.nih.gov

Locations
United States, Maryland
National Institutes of Health Clinical Center, 9000 Rockville Pike Recruiting
Bethesda, Maryland, United States, 20892
Contact: For more information at the NIH Clinical Center contact Patient Recruitment and Public Liaison Office (PRPL)    800-411-1222 ext TTY8664111010    prpl@mail.cc.nih.gov   
Sponsors and Collaborators
Investigators
Principal Investigator: Leslie G Ungerleider, Ph.D. National Institute of Mental Health (NIMH)
  More Information

Additional Information:
Publications:
ClinicalTrials.gov Identifier: NCT01087281     History of Changes
Other Study ID Numbers: 100047, 10-M-0047
Study First Received: March 13, 2010
Last Updated: March 14, 2014
Health Authority: United States: Federal Government

Keywords provided by National Institutes of Health Clinical Center (CC):
Visual Attention
Visual Cortex
Focal Lesions
Neurological Disorder
Functional Magnetic Resonance Imaging (fMRI)
Focal Brain Lesion
Healthy Volunteer
HV

ClinicalTrials.gov processed this record on April 15, 2014