Measuring language lateralisation using ultrasound
What is the purpose of the study?
The right and left sides of the brain look similar, but have different functions. In most people, language tasks involve the left side more than the right, but this laterality varies from person to person. In this study we are evaluating some new tasks to see how far they engage the left and right sides of the brain.
Who is the study for?
We are advertising for native speakers of English aged 18 to 45 years for this study. To participate, you must not have a significant hearing loss, or history of neurological disease (e.g. epilepsy) or head injury. You must also have no history of reading or communication impairment.
What will happen if I take part?
If you volunteered to take part, you would first be given a short screening questionnaire to check your suitability for the study. You would be given two appointments, each for a session that will take around two hours to complete. The interval between sessions would be between 1 day (on consecutive days) and 3 months apart, depending on your availability. In each session, you would be asked to do some language tasks that involve generating words or judging the meaning of words or sentences while the blood flow in your brain is measured using a procedure called functional Transcranial Doppler Ultrasound.
The procedure for measuring blood flow in the brain is harmless and painless and carries no significant personal risk. A headset (see figure left) is placed on the head and adjusted to give a snug fit. A small amount of gel is placed just in front of each ear, and an ultrasound probe is held in place over this. Positioning of the probes to find the best signal from the arteries can take 10-15 minutes. The gel used to make the electrical contact is water based and can be wiped off easily with tissues or wet wipes.
Once the set-up is completed, you would be given three computer-based tasks that involve speaking or listening. Each task usually lasts around 20 minutes, with a brief break between tasks. Afterwards the headset would be removed and you would have a 10-15 minute break. You would then be asked to do two other tasks: one involves reading words which are flashed on a screen, and the other involving repeating words that you hear through insert earphones. We also assess your handedness using questionnaires and a simple peg-moving task.
We would ask you to let the researcher know if at any time the procedure becomes uncomfortable. In that case, we would terminate the study, without this having any negative consequences for you. In around one in twenty people, it is not possible to get a good signal from the arteries because the bone in this region of the skull is too thick. If this occurred, you would be paid for your participation in this session but not required to continue and not be invited to return for a further session.
In most cases, we are able to get a good signal showing the blood flow in the arteries, and where this is the case you would be invited to return for the second session, again lasting up to two hours, scheduled at a time to suit you. In this second session you would repeat the tasks that you had done previously.
The study will take place at Ewert House in Summertown, Oxford. We will compensate you £20 an hour for your time.
WHAT are the risks and benefits of taking PART?
There are no significant personal risks of taking part in this study. There are no direct benefits to volunteers, but you would be helping advance scientific knowledge of how the brain works.
WHAT will happen at the end of the study?
Once we have seen all the participants and gathered the information we will write about the results in the OSCCI newsletter, which is circulated among schools and families who have shown an interest in our projects. We will not report on the results of individuals. All data will be kept confidentially and anonymously. We will write our findings up for a scientific journal and present the findings to other researchers at conferences.
Funding and approval of this research
This study is part of an ERC funded project called ‘Cerebral Asymmetry: New Directions in Correlates and Etiology’. The study has been given ethical approval by the Central University Research Ethics Committee (MS-IDREC-R40410/RE001).
What to do next
If you would like to take part in this project, or you have a question about the study, please email firstname.lastname@example.org.