Measuring the Latency Connectome in the Central Nervous Systems Using Neuroimaging and Neurophysiological Techniques

Summary

Background:

Little is known about the time it takes for nerve signals to go from one area of the brain to another. Using advanced methods for brain research, researchers want to look at the time it takes to send messages between different brain areas. They also want to develop new tests.

Objectives:

To develop tests to measure the sizes of nerve fibers in the peripheral nerve system and in the brain. Also to find out the different speeds that information travels in nerve fibers.

Eligibility:

Healthy, right-handed people ages 18-70

Design:

Participants will be screened with medical history and a physical exam.

Participants will have up to 7 visits depending on the tests they choose. Visits last about 2-4 hours and may involve the following tests:

* Physical exam
* Urine tests
* Magnetic resonance imaging (MRI). Participants lie on a table that slides into a scanner. They will be in the scanner for up to 1 hour. For some scans, sensors are placed on the skin. They will get earplugs for loud noises.
* Small, sticky pads on the skin will electrically stimulate nerves in the forearm.
* Transcranial magnetic stimulation (TMS). A wire coil will be held to the scalp. A brief electrical current passes through the coil to affect brain activity.
* Electroencephalography. TMS will be given to the brain. Small electrodes on the scalp measure brain activity. Participants may do small tasks.
* Electrodes on the scalp will send an electrical current to the brain.
* A cone with magnetic detectors will be lowered onto the head to record brain activity. Participants will perform various tasks.

Conditions

• Healthy Volunteers

Interventions

DEVICE

TMS

We will use TMS with paired-pulse technique to activate corticospinal neurons in the primary motor cortex and motorneurons in the brainstem, respectively (Hallett 2007; Ugawa et al. 1991; Ugawa et al.1994). Two stimulations will be separated with various interstimulus intervals to produce collision on nerve fibers with different conduction velocity in the corticospinal tract. The conduction time on nerve fibers in the corticospinal tract with different conduction velocity will be identified and the distribution of these fibers will be calculated.

DEVICE

MRI

MRI exams will consist of several sessions including calibration, anatomic, and diffusion MRI scanning (Avram et al. 2013; Avram et al. 2016; Pierpaoli et al. 1996). Data in each exam will be acquired in the left or right forearm (PNS).

Sponsors & Collaborators

• National Institute of Neurological Disorders and Stroke (NINDS)

  lead NIH

Principal Investigators

• Mark Hallett, M.D. · National Institute of Neurological Disorders and Stroke (NINDS)

Eligibility

Min Age

18 Years

Max Age

70 Years

Sex

ALL

Healthy Volunteers

Yes

Timeline & Regulatory

Start

2017-10-02

Primary Completion

2020-11-12

Completion

2021-02-26

FDA Device

Yes

Countries

• United States

Study Locations