Optical imaging (NIRS)

All of our experiments are reviewed and authorized by the Hungarian Egyesített Pszichológiai Kutatásetikai Bizottság (Unified Psychological Ethics Committee). Participation in all our studies in voluntary, and consent can be revoked at any stage of the experiment without justification.

Researchers use this fact to examine which particular brain region is active during different mental processes. As blood carrying more oxygen is redder compared to blood that is not carrying as much, the activity of the brain can be measured through examining the color of the blood in particular regions. While the flow of blood in the brain can’t be observed directly, with sensitive tools we are able to measure the reflection of light through the skull.

The optical imaging tool emits mild, invisible infrared light, and it analyses the composition of its reflection. This tool can be used with infants easily, as it only requires the wearing of a hat-like headband, but they are not required to remain motionless during the experiment. This technique is perfectly safe and harmless, and is widely used in infant research to measure brain activity. While the headband used during this procedure might appear to be a tool from science-fiction movies, its wearing is risk free. Just as natural light causes no alteration in an object, the mild infrared light has no influence on the activity of the brain.

Age range: 6-9 months

Question(s): What is the relationship between particular cognitive mechanisms and the activity of particular regions in the brain?

Assumption: Whenever a certain area of the brain is active, the blood stream carries more oxygen to that region. We use this fact to ascertain which area is active when performing a certain cognitive task.

Procedure: You can read about the detailed procedure of an optical imaging study below.
- The baby and the caregiver remain together through the whole procedure.
- First, we measure the head circumference of the baby with a soft tape measure.
- After this, we place the headband on the head of the baby, and secure it below the chin with a small strap. The babies are usually very calm during this process, however if they start to cry, we remove the headband immediately.
- Through glass fiber cables, the headband is connected to a computer, which controls light emission and measures its reflection.
- During the experiments, babies are observing movies and still images. The experiment itself rarely lasts longer than 5 minutes, but in case the baby gets tired or fussy, we stop the procedure before its end.

Example: For instance, using optical imaging, it is possible to find out which area of the brain is used by babies to retain objects in memory that have disappeared from the screen - in other words, the phenomenon is called object permanence. In order to measure this, you present an object on the screen, and then you make it disappear (either behind an occluder, or amongst other objects), and establish the activity of the brain during the presentation.

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