Protocol Number: 03-N-0163

Title:

Cross-Modal Plasticity of Verbal Memory in the Blind

Number:

03-N-0163

Summary:

This study will examine whether blind people develop changes in the brain that improve memory function. Previous studies have shown that blind people, on average, perform better in memory tasks than sighted people. A possible reason for this is that parts of the brain that process visual information in sighted individuals are engaged in processing mnemonic (remembering) information in blind people.

Blind and sighted people 18 years of age and older are eligible for this study. Healthy, sighted individuals may participate in Part 1 of the study, which is designed to find appropriate words to use in tests for Part 2 of the study. Part 2 will include sighted people and blind people. It will examine whether the (visual) brain in blind people is processing mnemonic information in a way that helps with day-to-day memory functions. Blind participants in this study must have lost their sight by age 4. Candidates will be screened with a medical interview and examination and a brief test of short-term and long-term verbal memory. Sighted patients will also be tested for visual memory and for handedness.

Part 1 - Word Recognition Testing (2 sessions)

- Session 1: Participants listen to a number of words over a loudspeaker and try to remember them for a memory test that will be given 30 minutes later. For the test, subjects listen to words again and press one of three buttons as quickly as possible after hearing the word. The buttons signal whether the subject does or does not recognize the word with a 1) high level of confidence or 2) low level of confidence.

- Session 2: Participants hear a noun over a loudspeaker and have to find an appropriate verb for it, such as the verb (read) for the noun (book).

Part 2 - MRI Scanning and TMS Experiments (5 - 7 sessions)

- Magnetic resonance imaging (MRI): Participants perform the same procedures as described above for Part 1 while undergoing MRI of the brain. For this test, the subject lies on a table inside the MRI scanner - a narrow cylindrical tube with a strong magnetic field. Scanning time varies from 20 minutes to 3 hours, with most scans lasting between 45 and 90 minutes. (Earphones are used to hear the words for this test instead of a loudspeaker.)

- Transcranial magnetic stimulation (TMS): Participants undergo TMS while performing the same procedures described for Part 1. For TMS, a wire coil is held over the scalp. A brief electrical current is passed through the coil, creating a magnetic pulse that stimulates the brain. Subjects may hear a click and feel a pulling sensation on the skin under the coil. There may be a twitch in muscles of the arm or leg. During the TMS, electrical muscle activity is recorded through the electrodes with a computer or other recording device. Each session lasts a maximum of 3 hours.

Sponsoring Institute:

National Institute of Neurological Disorders and Stroke (NINDS)

Recruitment Detail

Type: Active Accrual Of New Subjects

Gender: Male & Female

Referral Letter Required: No

Population Exclusion(s): Children

Eligibility Criteria:

ELIGIBILITY:

Early Blind Subjects: Only compliant early blind subjects who have lost their vision before age 4 years due to diseases affecting the peripheral components of the visual system, i.e., blind subjects without any further neurological problems, and with normal MRI scans, will be selected.

Late Blind Subjects: Only compliant late blind subjects who have lost their vision after age 4 years due to diseases affecting the peripheral components of the visual system, i.e., blind subjects without any further neurological problems, and with normal MRI scans, will be selected.

Sighted Controls: Only compliant adult healthy volunteers with no history of neurological and psychiatric illness who are able to concentrate and to perform simple attentional tasks are eligible.

INCLUSION CRITERIA:

Blind Subjects: Early and late blind subjects (aged 18 or over) will be included in this protocol. Handedness will be assessed by the Edinburgh inventory scale. All experimental sessions will be studied on outpatient basis.

Sighted Subjects: Healthy sighted (normal or corrected-to normal vision) matched in age, sex and level of education to the blind subjects. Handedness will be assessed by the Edinburgh inventory scale.

EXCLUSION CRITERIA:

Exclusion criteria for the study will be any current medical or surgical condition or psychiatric or neurological illness. Furthermore, any individual who is on medication with potential influence on nervous system function, who has a history of surgery with metallic implants or known history of metallic particles in the eye, cardiac pacemaker, intracardiac lines, neural stimulators, cochlear implants, pregnancy, or history of drug abuse, will be excluded from the study.

Special Instructions: Currently Not Provided

Keywords:

Occipital Cortex

Prefrontal Cortex

Transcranial Magnetic Stimulation

Inhibition

Cortical Excitability

Recruitment Keywords:

Blindness

Healthy Volunteer

HV

Conditions:

Blindness

Investigational Drug(s):

None

Investigational Device(s):

Magstim Rapid Magnetic Stimulator

Contacts:

Patient Recruitment and Public Liaison Office
Building 61
10 Cloister Court
Bethesda, Maryland 20892-4754
Toll Free: 1-800-411-1222
TTY: 301-594-9774 (local),1-866-411-1010 (toll free)
Fax: 301-480-9793

Electronic Mail:prpl@mail.cc.nih.gov

Citations:

Alho K, Kujala T, Paavilainen P, Summala H, Naatanen R.

Auditory processing in visual brain areas of the early blind: evidence from event-related potentials. Electroencephalogr Clin Neurophysiol. 1993 Jun;86(6):418-27. PMID: 7686476

Bridgers SL, Delaney RC. Transcranial magnetic stimulation: an assessment of cognitive and other cerebral effects. Neurology. 1989 Mar;39(3):417-9. PMID: 2927652

Burton H, Snyder AZ, Diamond JB, Raichle ME. Adaptive changes in early and late blind: a FMRI study of verb generation to heard nouns. J Neurophysiol. 2002 Dec;88(6):3359-71. PMID: 12466452

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