Neuroscience
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Neuroimaging Field Methods Using Functional Near Infrared Spectroscopy (NIRS) Neuroimaging to Study Global Child Development: Rural Sub-Saharan Africa
Chapters
Summary February 2nd, 2018
Portable neuroimaging approaches (functional Near Infrared Spectroscopy) provide advances to the study of the brain in previously inaccessible regions; here, rural Côte d'Ivoire. Innovation in methods and development of culturally-appropriate neuroimaging protocols permits novel study of the brain's development and children's learning outcomes in environments with significant poverty and adversity.
Transcript
The overall goal of this Field Neuro Imaging Protocol, is to study children's brain development, and cognitive and learning outcomes, using portable functional near infrared spectroscopy, known as FNIRS, in remote understudied, low resource settings such as impoverished rural communities, in Sub-Saharan Africa. This method can help us answer key questions about brain development in high risk environments. For example, how the brain's network for reading develops in communities with high risk of illiteracy.
This method also addresses important theoretical issues in global child development, regarding how both biological development and diverse, and often negative experiences, impact the brain. And can reveal new information about developmental, sensitive periods. To begin, invest in the formation of collaborations, and provide opportunities, within the research framework, to local researchers.
Establish partnerships with local, scientific institutions for the purpose of inclusivity, as recognition from peers at the local level is important in communicating research findings in the region. Prepare for rainy climate conditions, in the field, as temperature and humidity conditions can vary significantly from laboratory settings, which may effect equipment function and longevity, and participant comfort. Demonstrating the procedure will be Lais Freitas, a visiting scholar in my laboratory, from the Federal University of San Pallo, and Violet Kozloff, our laboratory manager.
Begin by undergoing a consent procedure, in a local or preferred language of the participant, that is culturally appropriate, and ensures that participants, their families, and communities are informed about research and their decision to participate in the study. Then, escort the participants to the testing room, and have them sit on a chair. Explain to the participant that a head measurement will be taken.
Using a standard tape measure, measure the distances between the nasion and inion around the head, the nasion and inion over the top of the head, through the midline central, or CC, and the distance between the left and right ear tragus, over the top of the head, through CC.Next, place the fNIRS optode holder cap onto the participants head, aligning the cap to the International 10-20 system, for scalp locations. Secure the cap with the strap. Once the cap is positioned, instruct the participant to sit still, while a 3D digitizer measurement of the key 10-20 system scalp positions, and each optode place holder is taken.
Then, arrange the 3D digitizer equipment, by placing one sensor on the participant's head, at CC, and affixed securely, and placing the second sensor on the table directly behind the participant's head. Move 3D digitizer stylist to each probe location, and across the key 10-20 system positions. After the 3D digitizer data are collected, direct the participant to be seated comfortably, in front of the stimulus presentation computer.
Using the fNIRS built in software, select the probe arrangement that corresponds to the experiment's design. Ensure it is placed to maximally overlay left hemisphere language areas, and their right hemisphere homologues, as well as the frontal lobe. Ensure that both emitter and detector probes are numbered according to the probe arrangement map.
Using the optode map and the fNIRS inbuilt software as a guide, place each optode in it's respective opening. Move any hair to ensure contact between the tip of the optode and scalp. Finally, after all of the optodes are in position, check for signal quality, using the fNIRS system built in software.
Adjust individual probes, as necessary, until sufficient signal quality is achieved. Begin by placing noise-canceling headphones on the participant's head, being careful not to interfere with fNIRS probe placement. Ensure that the headphones deliver auditory speech stimuli, if applicable to the participant, as well as block any ambient noise.
Instruct the participant to fixate on the cross, in the middle of the screen. Ask them to remain still during the experiment, while the experimental tasks are displayed. Dim the lights, and begin recording the participant on the built in video camera.
Begin fNIRS data recording, on the fNIRS command computer, and commence tasks on the stimulus presentation computer. Monitor participant performance, throughout all tasks, and provide breaks between tasks and runs. Ensure that triggering, from the experimental stimuli presentation computer is received by the fNIRS command computer.
Finally, at the end of all tasks, stop collecting video and fNIRS data. After the experiment is complete, remove each optode from the optode holder cap. Without disrupting the position of the optode holder cap on the participant's head, direct the participant to sit in a position, to obtain a second 3D digitizer measurement.
Repeat the 3D digitizer measurement, to ensure that any disruptions to the scalp probe positions during the experiment can be detected, by comparing the two position files. Finally, after the repeat measurement is complete, remove the optode holder cap from the participant's head. The 3D position data and experimental design data, were combined with fNIRS time series data, for analysis in order to map experiment related, significant neural activation patterns on a standard brain template.
This subject showed greater activation in the left hemisphere superior temporal gyrus, during rhyming trials compared with rest. Further, greater activation for nonrhyming verses rhyming trials, in the left hemisphere is shown. Such as Subject 1 showed greater activation in the left inferior frontal gyrus, and Subject 2 showed greater activation in the left superior temporal gyrus.
Following this procedure, other methods like assessments of cognitive and verbal skills can be performed in order to answer additional questions about the association between brain activity and children's abilities. After watching this video, you should have a good understanding of important considerations in field neuroimaging, such as local partnerships with communities and researchers, as well as a technical understanding of how to position the fNIRS cap, place the optodes, and collect data with this system. Don't forget that working in remote locations can be dangerous, with risks of illness, crime, and political instability.
And precautions such as medication, vaccinations, and monitoring travel advisories should always be taken while performing this procedure.
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