Selective photobiomodulation for emotion regulation: model-based dosimetry study

Abstract

The transcranial photobiomodulation (t-PBM) technique is a promising approach for the treatment of a wide range of neuropsychiatric disorders, including disorders characterized by poor regulation of emotion such as major depressive disorder (MDD). We examine various approaches to deliver red and near-infrared light to the dorsolateral prefrontal cortex (dlPFC) and ventromedial prefrontal cortex (vmPFC) in the human brain, both of which have shown strong relevance to the treatment of MDD. We apply our hardware-accelerated Monte Carlo simulations to systematically investigate the light penetration profiles using a standard adult brain atlas. To better deliver light to these regions-of-interest, we study, in particular, intranasal and transcranial illumination approaches. We find that transcranial illumination at the F3-F4 location (based on 10-20 system) provides excellent light delivery to the dlPFC, while a light source located in close proximity to the cribriform plate is well-suited for reaching the vmPFC, despite the fact that accessing the latter location may require a minimally invasive approach. Alternative noninvasive illumination strategies for reaching vmPFC are also studied and both transcranial illumination at the Fp1-FpZ-Fp2 location and intranasal illumination in the mid-nose region are shown to be valid. Different illumination wavelengths, ranging from 670 to 1064 nm, are studied and the amounts of light energy deposited to a wide range of brain regions are quantitatively compared. We find that 810 nm provided the overall highest energy delivery to the targeted regions. Although our simulations carried out on locations and wavelengths are not designed to be exhaustive, the proposed illumination strategies inform the design of t-PBM systems likely to improve brain emotion regulation, both in clinical research and practice.

Transcranial Photobiomodulation with Near-Infrared Light from Childhood to Elderliness: Simulation of Dosimetry

“…We used the MarsAtlas parcellation in our previous study. 18,42 This parcellation of the vmPFC region includes the frontal pole (Brodmann Area 10) while several other studies did not . [43][44][45][46] This may potentially cause a discrepancy in calculations of energy deposition in vmPFC.…”

“…Similar to our previous study, 18 our primary interest here is to develop effective PBM treatment approaches for emotion regulation and depression. Thus, our main focuses in this dosimetry study are the dlPFC and vmPFC regions ( Fig.…”

“…In our study, a total of 15 simulations, a combination of 3 source positions and 5 wavelengths (670 nm, 810 nm, 850 nm, 980 nm and 1064 nm), are performed for each segmented brain atlas using our GPU-accelerated photon transport simulator (MCX). 32,33 The optical properties of each layer (WM, GM and CSF) are identical to those from our earlier study, 18 with the exception that the optical properties of the ECT layer (Table 1) are derived using the weighted average of the properties for fat, muscle, skin tissue and skull; the weights are derived from volume fractions of the respective tissue types in the Colin27 atlas. 54,55 For simplicity, we assume the optical properties for each tissue type are independent of age.…”

“…A pair of transcranial source configurations 18 are investigated: 1) F3-F4: two light-emitting-diode (LED) array sources are placed above and centered, respectively, at the F3 and F4 (10-20 EEG positions); 2) Fp1-Fpz-Fp2: one LED-array is placed on the forehead and between the Fp1-Fpz- Fp2 positions (referred to as the Fpz position hereinafter). The definitions of these source positions and orientations are similar to, 18 with the exception that the F3-F4 source arrays are rotated around 90 degrees, as shown in Fig. 3, to better align with the dlPFC region and maximize light delivery.…”

“…10,16,17 Although MDD has a broad age of onset, 2,4 most previously published studies have focused on t-PBM treatments in only middle-aged adult brain models. 18 However, personalization of treatments is key to increasing success rate and tolerability; therefore our interest is in developing precise PBM treatment strategies adapted for individual patients. One of the main factors impacting t-PBM light dosage is the thickness of extra-cerebral tissues (ECT), including both skull and scalp.…”