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AzTrials

HealthyNCT00006285

Use of Transcranial Magnetic Stimulation (TMS) and Magnetic Resonance Imaging (MRI) to Study Visual Attention

An observational study of Healthy, run by National Institute of Mental Health (NIMH) at 1 site in United States.

Completed

Finished. The study has ended and is not enrolling. Results may be posted on the official record.

Official record
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Trial summary

The purpose of this study is to learn more about how the brain allows people to focus on important objects and filter out unimportant ones when looking at visual images. Our senses provide us with a vast amount of information at any given moment in time. Read more about this study

Who is it for?
Ages 20 to 65 yearsHealthy volunteers can take part
Conditions the study is for
Healthy
How many people
30 participants
Where
1 siteUnited States
Study dates
14 Sep 2000to 1 Apr 2002
Phase
Observational
Are there results?
None posted in the registry

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

  • Ages 20 to 65 years
  • All sexes
  • Healthy volunteers accepted
  • Adult, Older adult

Who may be able to join

  • All subjects will be healthy, right-handed volunteers between the ages of 20 and 65.
  • Subjects must have normal or corrected-to-normal vision.

Who cannot join

  • Pregnant women will be excluded.
  • Subjects with a personal or family history of seizures will be excluded.
  • Subjects with a history of neurologic disease, ocular foreign body, increased intracranial pressure, open head injury or significant closed head injury will be excluded.
  • Subjects with cochlear implants, implanted brain stimulators, aneurysm clips or other metal in the head (except mouth) will be excluded.
  • Subjects taking tricyclic anti-depressants, neuroleptic agents or other drugs that lower the seizure threshold will be excluded.
  • Subjects with a history of illicit drug use or who are abusing or withdrawing from alcohol abuse will be excluded.
  • Subjects with a history of a major psychiatric disorder will be excluded.
  • Subjects with implanted medication pumps, pacemakers, intracardiac lines or significant heart disease will be excluded.

Trial locations and contacts

1 site in 1 country.

United States1 site
  • National Institutes of Health Clinical Center, 9000 Rockville Pike

    Bethesda, Maryland, 20892

Other trials in United States

About this study

Official title: Transcranial Magnetic Stimulation Studies of Visual Attention

The purpose of this study is to learn more about how the brain allows people to focus on important objects and filter out unimportant ones when looking at visual images.

Our senses provide us with a vast amount of information at any given moment in time. For example, visual scenes contain many different objects that cannot be processed simultaneously because of the limited processing capacity of the brain's visual system. Evidence suggests that a a network of brain regions selects relevant information and filters out irrelevant information when people view cluttered visual scenes. This study will use transcranial magnetic stimulation (TMS) and functional magnetic resonance imaging (fMRI) to determine how the different brain regions involved in attentional control and filtering interact.

Participants in this study will undergo computer tests, an MRI scan, and TMS. During the MRI, participants will look at pictures and count objects appearing on a screen. During the TMS, participants will perform a computer test. Participants' ability to pay attention will be tested with and without TMS. Participants may be asked to return for additional tests in the future....

Read the detailed description

Our senses provide us with a vast amount of information at any given moment in time. For example, visual scenes contain many different objects that cannot all be processed simultaneously because of the limited processing capacity of the visual system. Therefore, attentional mechanisms are required to select relevant objects and filter out irrelevant ones. There is converging evidence from single-cell recording and lesion studies in monkeys and functional brain imaging studies in humans that irrelevant information from cluttered visual scenes is filtered out in extrastriate visual cortex. Functional brain imaging studies also suggest that these attentional filtering mechanisms are mediated by top-down feedback signals arising in higher-order areas in frontal and parietal cortex. However, it is not clear from these studies whether these frontal and parietal brain regions are functionally significant in attentional control of behavior.

Transcranial magnetic stimulation (TMS) applied over a particular cortical region can interfere with cognitive processing in that region, thereby creating a virtual disruption in the intact human cerebral cortex. Hence, this tool can be used to determine if a brain region is functionally involved in the performance of a given cognitive function. In the proposed study, we wish to use TMS to test the hypothesis that attentional filter mechanisms operating in extrastriate cortex are under "top-down" control by regions in the frontal and parietal cortex. Our approach will use a combination of TMS and functional magnetic resonance imaging (fMRI).

First, subjects will participate in an fMRI experiment (93-M-0170) designed to localize the cortical regions of interest (ROIs) that are involved with attentional processing for each subject. Second, TMS will be used to create transient virtual disruptions in frontal and parietal ROIs of normal volunteers while they perform a task requiring spatial attention. We hypothesize that, when TMS is used to interfere with attentional processing, subjects will show impaired performance in a task that requires them to filter out irrelevant visual information. In contrast, performance during TMS should not suffer in a control task in which no irrelevant information needs to be filtered out.

Conditions
Healthy
Keywords
Transcranial Magnetic Stimulation, Parietal Lobe, fMRI, Cognition, Perception, Cortical Stimulation, Spatial Attention

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted18 Sep 2000 (estimated)
  2. Study start14 Sep 2000
  3. Primary completion1 Apr 2002
  4. Study completion1 Apr 2002

Resources

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design
Study type
Observational
Enrolment
30 participants
IDs, dates and publications
ClinicalTrials.gov ID
NCT00006285
Sponsor's protocol ID
000177
Other IDs
00-M-0177
Status last verified
8 Jun 2009
First submitted
16 Sep 2000
Last updated
2 Jul 2017
Results posted
No

Publications

  • Ashbridge E, Walsh V, Cowey A. Temporal aspects of visual search studied by transcranial magnetic stimulation. Neuropsychologia. 1997 Aug;35(8):1121-31. doi: 10.1016/s0028-3932(97)00003-1.

    PubMed 9256377
  • Amassian VE, Cracco RQ, Maccabee PJ, Cracco JB, Rudell AP, Eberle L. Transcranial magnetic stimulation in study of the visual pathway. J Clin Neurophysiol. 1998 Jul;15(4):288-304. doi: 10.1097/00004691-199807000-00002.

    PubMed 9736464
  • Chen R, Gerloff C, Classen J, Wassermann EM, Hallett M, Cohen LG. Safety of different inter-train intervals for repetitive transcranial magnetic stimulation and recommendations for safe ranges of stimulation parameters. Electroencephalogr Clin Neurophysiol. 1997 Dec;105(6):415-21. doi: 10.1016/s0924-980x(97)00036-2.

    PubMed 9448642

Questions about this trial

What is this clinical trial studying?

An observational study of Healthy, run by National Institute of Mental Health (NIMH) at 1 site in United States.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 2 inclusion and 8 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: finished, as of the sponsor's last update on 2 Jul 2017. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

Are results available for this study?

The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.

How can a doctor refer a patient or contact the research team?

The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT00006285, which also lists 3 linked publications.

Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 2 Jul 2017.

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