Using Functional Near Infrared Spectroscopy (fNIRS) to Study Dynamic Stereoscopic Depth Perception.

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Visual Perception

Background:

• The parietal cortex is crucial for depth perception, but functional near-infrared spectroscopy (fNIRS) is underutilized for studying its role.
• Hemodynamic responses (HDR), specifically changes in oxy- ([HbO]) and de-oxyhaemoglobin ([HbR]), are key indicators of neural activity.

Purpose of the Study:

• To investigate the hemodynamic response (HDR) associated with depth perception using fNIRS.
• To examine the role of the parieto-occipital and occipital cortices in processing induced depth using dynamic random-dot-stereograms (RDS).

Main Methods:

• Utilized fNIRS to measure [HbO] and [HbR] in 13 healthy young adults.
• Employed a blocked design with dynamic RDS, contrasting stimuli with and without binocular disparity to induce depth perception.
• Recorded HDR across parieto-occipital and occipital cortices.

Main Results:

• A significant effect of depth stimulation was observed in the right parieto-occipital cortex (p < 0.01).
• Depth perception significantly increased [HbO] in the right parieto-occipital cortex compared to the control stimulus (p < 0.001).
• No significant HDR changes were detected in the occipital cortex, possibly due to stimulus similarity.

Conclusions:

• Cerebral oxygenation measures ([HbO]) confirm the strong association of the right parieto-occipital cortex with depth perception processing.
• fNIRS is a valid tool for investigating hemodynamic responses during high-level visual processing of complex stimuli like RDS.