Effects of Transcranial Photobiomodulation and Attention Bias Modification on Anxiety Symptoms and Brain Hemodynamics

Composite cognitive score in the dot-probe task

时间窗: Visit 1 (baseline), Visit 2 (three days after Visit 1), Visit 3 (1 week after Visit 2)

The participant pays attention to a fixation cross in the center of the screen, which is followed by the presentation of two images on the left and right of the screen. One of these new images is a "threat" image, while the other is neutral. Following each trial of stimuli presentation, a probe type ("\<" vs. "\>") will randomly appear in the same location previously occupied by either the threatening or neutral image and remain on the screen until the participant has responded. Participants respond to the probe type by pressing the "←" or the "→" arrow key, respectively, on the keyboard, as quickly but as accurately as possible. The probe randomly replaces the neutral or the negative stimulus with equal frequency (50/50). The single primary outcome is the composite cognitive score which is calculated on the basis of performance in this task.

Change in concentration of oxygenated hemoglobin as measured by functional near-infrared spectroscopy

时间窗: Visit 1 (baseline), Visit 2 (three days after Visit 1), Visit 3 (1 week after Visit 2)

Hemodynamic activity is assessed non-invasively using near-infrared spectroscopy. In this procedure, a participant wears an apparatus on the head which contains an array of light sources and detectors. Light is applied to the surface of the skin, and a small fraction of the light passes through the underlying tissue and reflects back to the surface, where it is detected and the number of photons at specific light wavelengths are counted by a computer. This photon count can be converted to changes in concentration of metabolic indices, such as oxygenated/deoxygenated hemoglobin.