Brain Stimulation and Vision Testing
| Status: | Recruiting |
|---|---|
| Healthy: | No |
| Age Range: | 18 - 50 |
| Updated: | 3/20/2019 |
| Start Date: | May 22, 2012 |
| Contact: | Anna L Corriveau |
| Email: | anna.corriveau@nih.gov |
| Phone: | (301) 827-6117 |
TMS Investigations of the Human Visual System
Background:
- The brain has two systems for recognizing objects. One system recognizes what an object is,
and the other system recognizes where the object is located. However, there is much about how
the brain handles and interprets the information from these two systems that is still
unclear. Researchers want to study the parts of the brain that are involved in how vision is
processed. They will use magnetic resonance imaging (MRI) and transcranial magnetic
stimulation (TMS) on the brain. MRI measures what parts of the brain become more active when
tasks are performed. TMS uses magnetic pulses to temporarily change the activity in parts of
the brain.
Objectives:
- To better understand how people visually recognize different types of objects.
Eligibility:
- Healthy volunteers between 18 and 50 years of age.
Design:
- This study includes many different experiments on vision. Each experiment may combine
visual tasks, MRI scans, and TMS. Participants may be asked to have several different
tests. Each test will require a separate visit to the National Institutes of Health.
- Participants will be screened with a physical exam and medical history. They will have a
baseline brain scan at the first visit.
- Participants may do visual tasks alone, with MRI only, with TMS only, or with MRI and
TMS combined. For the visual tasks, they will look at pictures of objects on a computer
screen. Sometimes the images will appear very briefly (less than one-tenth of a second).
Sometimes they will appear for up to 5 seconds. These images will be of things like
faces, bodies, tools, and scenes. Participants will be asked to respond in different
ways to the pictures. They may respond by typing on a computer keyboard or by pressing a
button. Participants will have time to practice the tasks before the experiment.
- Participants will remain on the study for up to 3 years.
- The brain has two systems for recognizing objects. One system recognizes what an object is,
and the other system recognizes where the object is located. However, there is much about how
the brain handles and interprets the information from these two systems that is still
unclear. Researchers want to study the parts of the brain that are involved in how vision is
processed. They will use magnetic resonance imaging (MRI) and transcranial magnetic
stimulation (TMS) on the brain. MRI measures what parts of the brain become more active when
tasks are performed. TMS uses magnetic pulses to temporarily change the activity in parts of
the brain.
Objectives:
- To better understand how people visually recognize different types of objects.
Eligibility:
- Healthy volunteers between 18 and 50 years of age.
Design:
- This study includes many different experiments on vision. Each experiment may combine
visual tasks, MRI scans, and TMS. Participants may be asked to have several different
tests. Each test will require a separate visit to the National Institutes of Health.
- Participants will be screened with a physical exam and medical history. They will have a
baseline brain scan at the first visit.
- Participants may do visual tasks alone, with MRI only, with TMS only, or with MRI and
TMS combined. For the visual tasks, they will look at pictures of objects on a computer
screen. Sometimes the images will appear very briefly (less than one-tenth of a second).
Sometimes they will appear for up to 5 seconds. These images will be of things like
faces, bodies, tools, and scenes. Participants will be asked to respond in different
ways to the pictures. They may respond by typing on a computer keyboard or by pressing a
button. Participants will have time to practice the tasks before the experiment.
- Participants will remain on the study for up to 3 years.
Objective
An influential model of cortical organization proposes that the primate visual system is
divided into two functionally distinct pathways (Ungerleider & Mishkin, 1982). The ventral or
what visual pathway, which projects from occipital cortex into the ventral temporal cortex,
is principally used for object recognition and identification. The dorsal or where pathway,
which projects from occipital cortex into the parietal cortex, is principally used for
locating the position of objects in the visual field and for action planning (Milner &
Goodale, 1995; Kravitz et al., 2011). In the proposed series of experiments we will
investigate how neural representations in the ventral and dorsal pathways contribute to a
range of cognitive tasks including object and scene recognition, attentional selection and
face processing. These experiments will principally use transcranial magnetic stimulation
(TMS) in combination with functional magnetic resonance imaging (fMRI).
TMS provides a unique experimental tool for studies of human cognitive function because it
can be used to transiently and safely disrupt the neural processing in a targeted cortical
region while subjects perform concurrent behavioral tasks that depend on the operations of
that region. Furthermore TMS can be combined with neuroimaging techniques such as fMRI to
examine the remote effects of the induced neural disruption in other task-dependent regions
distributed across cortex. We plan to use TMS to address unanswered questions concerning the
functioning of the distributed neural networks for different categories of object recognition
and in the attention network of the human brain.
Study Population
We plan to test 320 neurologically normal subjects aged between 18 and 50 years old. Subjects
will also take part in an fMRI experiment prior to any subsequent TMS experiments in order to
localize the stimulation sites of interest.
Design
The aim of the proposed series of experiments is to examine the effects of the TMS induced
neural disruption on behavioral task performance and the neural correlates of the impaired
performance as measured with fMRI. Broadly these experiments can be divided into studies that
use online and offline TMS. In on-line experiments, TMS will be applied during behavioral
tasks. In off-line experiments, theta burst stimulation (TBS) will be delivered before the
experimental task and off-line experiments may combine TBS with fMRI.
- TMS target site localization
Prior to both online and offline studies subjects will take part in an fMRI experiment
designed to localize particular cortical regions of interest (ROIs). The fMRI experiment will
require the subject to view either a series of different object categories (e.g. faces,
bodies, scenes) or flickering sections of black and white checkerboards in the fMRI scanner.
The results of these fMRI experiments will be used to identify regions of cortex that will
then be targeted with TMS. We will identify TMS target sites using the stereotaxic Brainsight
co-registration software and the scalp location will be marked individually on each subject.
-Online behavioral TMS experiments
Online TMS experiments are designed to address the direct effects of the induced neural
disruption on the targeted TMS site only. TMS is delivered during every trial to assess the
effects on concurrent task performance. Subjects will perform a range of visual behavioral
tasks while online TMS is delivered over the cortical region of interest or over control
sites (e.g. vertex). Repetitive TMS will be delivered at a frequency of 10Hz for 500ms. In
some experiments we will alternatively deliver double-pulse TMS at different latencies after
stimulus onset to assess when the targeted region is likely to be involved in task
performance.
-Offline TBS experiments
Offline thetaburst (TBS) experiments are also designed to assess the effects of the induced
disruption in the stimulated region. However, rather than delivering TMS during every
experimental trial Thetaburst TMS (TBS) is delivered over the targeted region of interest
(ROI) for latencies up to 60 seconds prior to the subject performing any behavioral task. The
neural effects of this induced disruption have then been shown to last for up to 30 minutes
(Huang et al., 2005). In the offline TBS experiments we propose to deliver 60 seconds of the
TBS over the stimulated ROI. In some of the proposed experiment participants will then be
placed in an fMRI scanner before and after TBS stimulation. During both fMRI sessions
subjects will perform a series of visual discrimination tasks to assess the effects of TBS
disruption both on their behavior and on activity in remote cortical areas as measured with
BOLD activation.
Outcome measures
The dependent variables in the online behavioral TMS experiments will be performance
accuracy, sensitivity (d ) and reaction time (RT) measures collected during the concurrently
performed behavioral tasks. Dependent variables in the offline fMRI TBS experiments will be
task performance as well as reduced neuronal activity as measured by decreased BOLD
activation in the targeted and remote ROIs.
An influential model of cortical organization proposes that the primate visual system is
divided into two functionally distinct pathways (Ungerleider & Mishkin, 1982). The ventral or
what visual pathway, which projects from occipital cortex into the ventral temporal cortex,
is principally used for object recognition and identification. The dorsal or where pathway,
which projects from occipital cortex into the parietal cortex, is principally used for
locating the position of objects in the visual field and for action planning (Milner &
Goodale, 1995; Kravitz et al., 2011). In the proposed series of experiments we will
investigate how neural representations in the ventral and dorsal pathways contribute to a
range of cognitive tasks including object and scene recognition, attentional selection and
face processing. These experiments will principally use transcranial magnetic stimulation
(TMS) in combination with functional magnetic resonance imaging (fMRI).
TMS provides a unique experimental tool for studies of human cognitive function because it
can be used to transiently and safely disrupt the neural processing in a targeted cortical
region while subjects perform concurrent behavioral tasks that depend on the operations of
that region. Furthermore TMS can be combined with neuroimaging techniques such as fMRI to
examine the remote effects of the induced neural disruption in other task-dependent regions
distributed across cortex. We plan to use TMS to address unanswered questions concerning the
functioning of the distributed neural networks for different categories of object recognition
and in the attention network of the human brain.
Study Population
We plan to test 320 neurologically normal subjects aged between 18 and 50 years old. Subjects
will also take part in an fMRI experiment prior to any subsequent TMS experiments in order to
localize the stimulation sites of interest.
Design
The aim of the proposed series of experiments is to examine the effects of the TMS induced
neural disruption on behavioral task performance and the neural correlates of the impaired
performance as measured with fMRI. Broadly these experiments can be divided into studies that
use online and offline TMS. In on-line experiments, TMS will be applied during behavioral
tasks. In off-line experiments, theta burst stimulation (TBS) will be delivered before the
experimental task and off-line experiments may combine TBS with fMRI.
- TMS target site localization
Prior to both online and offline studies subjects will take part in an fMRI experiment
designed to localize particular cortical regions of interest (ROIs). The fMRI experiment will
require the subject to view either a series of different object categories (e.g. faces,
bodies, scenes) or flickering sections of black and white checkerboards in the fMRI scanner.
The results of these fMRI experiments will be used to identify regions of cortex that will
then be targeted with TMS. We will identify TMS target sites using the stereotaxic Brainsight
co-registration software and the scalp location will be marked individually on each subject.
-Online behavioral TMS experiments
Online TMS experiments are designed to address the direct effects of the induced neural
disruption on the targeted TMS site only. TMS is delivered during every trial to assess the
effects on concurrent task performance. Subjects will perform a range of visual behavioral
tasks while online TMS is delivered over the cortical region of interest or over control
sites (e.g. vertex). Repetitive TMS will be delivered at a frequency of 10Hz for 500ms. In
some experiments we will alternatively deliver double-pulse TMS at different latencies after
stimulus onset to assess when the targeted region is likely to be involved in task
performance.
-Offline TBS experiments
Offline thetaburst (TBS) experiments are also designed to assess the effects of the induced
disruption in the stimulated region. However, rather than delivering TMS during every
experimental trial Thetaburst TMS (TBS) is delivered over the targeted region of interest
(ROI) for latencies up to 60 seconds prior to the subject performing any behavioral task. The
neural effects of this induced disruption have then been shown to last for up to 30 minutes
(Huang et al., 2005). In the offline TBS experiments we propose to deliver 60 seconds of the
TBS over the stimulated ROI. In some of the proposed experiment participants will then be
placed in an fMRI scanner before and after TBS stimulation. During both fMRI sessions
subjects will perform a series of visual discrimination tasks to assess the effects of TBS
disruption both on their behavior and on activity in remote cortical areas as measured with
BOLD activation.
Outcome measures
The dependent variables in the online behavioral TMS experiments will be performance
accuracy, sensitivity (d ) and reaction time (RT) measures collected during the concurrently
performed behavioral tasks. Dependent variables in the offline fMRI TBS experiments will be
task performance as well as reduced neuronal activity as measured by decreased BOLD
activation in the targeted and remote ROIs.
- INCLUSION CRITERIA:
Healthy
Ages 18-50 years (inclusive)
EXCLUSION CRITERIA:
Individuals with conditions that could pose a risk relating to the safety of the MRI
procedure, the TMS procedure or the combined TBS and fMRI procedure will be excluded from
the protocol such as:
- Those with ferromagnetic metal in the cranial cavity or eye, e.g. aneurysm clip,
implanted neural stimulator, cochlear implant, ocular foreign body.
- Those with an abnormality on a structural MRI.
- Those with an implanted cardiac pacemaker or auto-defibrillator
- Those with an insulin pump.
- Those with an irremovable body piercing
- Pregnant women
- Those with a visual impairment that will prevent them from performing the task
- Those without consent capacity will not be enrolled
- Those who do not understand the study instructions
- Those with a history of neurological problems. Neurological problems include, but are
not limited to; family history of epilepsy, history of seizures and recurrent
migraines.
- Those using medicines that can lower the seizure threshold. These can include but are
not limited to; imipramine, amitriptyline, doxepine, nortriptyline, maprotiline,
chlorpromazine, clozapine, foscarnet, ganciclovir, ritonavir, amphetamines.
- Those with a visual impairment that will prevent them from performing the task
- Those who have a significant psychiatric illness or have a history of psychiatric
illness.
- NIMH employees
We found this trial at
1
site
9000 Rockville Pike
Bethesda, Maryland 20892
Bethesda, Maryland 20892
Phone: 800-411-1222
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