Functional Near-Infrared Spectroscopy for Recording Brain Activity During Social Interactions

Begin with a parent-child dyad fitted with probe grids of a functional near-infrared spectroscopy, or fNIRS, system and positioned in front of a shared display.

Emitter probes in the grid emit near-infrared light, which penetrates brain tissue.

As a baseline, when no stimulus is present, the blood in the cerebral vessels maintains normal metabolic oxygen levels.

Record the baseline activity by measuring the reflected light detected by the detector probes.

Introduce a visual stimulus that requires the participants to respond by pressing buttons in either cooperation or competition, resulting in increased activity in the prefrontal cortex, a brain region crucial for social interaction.

Increased neuronal activity elevates the metabolic oxygen demand, triggering the flow of oxygenated blood carrying oxyhemoglobin.

A change in light absorption by the increased oxyhemoglobin reflects the increased activity.

Analyze the co-occurrence of increased activity between the participants during the task to assess brain-to-brain synchrony.