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Near-infrared photonic energy penetration: can infrared phototherapy effectively reach the human brain?

Henderson TA, Morries LD - Neuropsychiatr Dis Treat (2015)

Bottom Line: Traumatic brain injury (TBI) is a growing health concern effecting civilians and military personnel.Yet, it remains unclear if sufficient photonic energy can be delivered to the human brain to yield a beneficial effect.Pulsing at 10 Hz reduced the dose of light delivered to the surface by 50%, but 2.4% of the surface energy reached the depth of 3 cm.

View Article: PubMed Central - PubMed

Affiliation: The Synaptic Space, Centennial, CO, USA ; Neuro-Laser Foundation, Lakewood, CO, USA.

ABSTRACT
Traumatic brain injury (TBI) is a growing health concern effecting civilians and military personnel. Research has yielded a better understanding of the pathophysiology of TBI, but effective treatments have not been forthcoming. Near-infrared light (NIR) has shown promise in animal models of both TBI and stroke. Yet, it remains unclear if sufficient photonic energy can be delivered to the human brain to yield a beneficial effect. This paper reviews the pathophysiology of TBI and elaborates the physiological effects of NIR in the context of this pathophysiology. Pertinent aspects of the physical properties of NIR, particularly in regards to its interactions with tissue, provide the background for understanding this critical issue of light penetration through tissue. Our recent tissue studies demonstrate no penetration of low level NIR energy through 2 mm of skin or 3 cm of skull and brain. However, at 10-15 W, 0.45%-2.90% of 810 nm light penetrated 3 cm of tissue. A 15 W 810 nm device (continuous or non-pulsed) NIR delivered 2.9% of the surface power density. Pulsing at 10 Hz reduced the dose of light delivered to the surface by 50%, but 2.4% of the surface energy reached the depth of 3 cm. Approximately 1.22% of the energy of 980 nm light at 10-15 W penetrated to 3 cm. These data are reviewed in the context of the literature on low-power NIR penetration, wherein less than half of 1% of the surface energy could reach a depth of 1 cm. NIR in the power range of 10-15 W at 810 and 980 nm can provide fluence within the range shown to be biologically beneficial at 3 cm depth. A companion paper reviews the clinical data on the treatment of patients with chronic TBI in the context of the current literature.

No MeSH data available.


Related in: MedlinePlus

Hypothesized mechanism of action of near-infrared light (NIR) photobiomodulation.Notes: NIR (600–980 nm) penetrates tissue to variable depth depending on wavelength, coherence, time, and the tissue involved. A portion of the photonic energy reaches the mitochondria and is absorbed by cytochrome c oxidase. In addition to inducing increased adenosine triphosphate (ATP) production, NIR appears to initiate increased production of reactive oxygen species (ROS), reactive nitrogen species (RNS), and possibly (?) nitric oxide (NO). Downstream events include increased early response genes – c-fos, c-jun – and activation of nuclear factor kappa-B (NF-κB), which in turn induces increased transcription of gene products leading to neurogenesis, synaptogenesis, and increased production of growth factors and inflammatory mediators.Abbreviation: ↑, increase.
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f1-ndt-11-2191: Hypothesized mechanism of action of near-infrared light (NIR) photobiomodulation.Notes: NIR (600–980 nm) penetrates tissue to variable depth depending on wavelength, coherence, time, and the tissue involved. A portion of the photonic energy reaches the mitochondria and is absorbed by cytochrome c oxidase. In addition to inducing increased adenosine triphosphate (ATP) production, NIR appears to initiate increased production of reactive oxygen species (ROS), reactive nitrogen species (RNS), and possibly (?) nitric oxide (NO). Downstream events include increased early response genes – c-fos, c-jun – and activation of nuclear factor kappa-B (NF-κB), which in turn induces increased transcription of gene products leading to neurogenesis, synaptogenesis, and increased production of growth factors and inflammatory mediators.Abbreviation: ↑, increase.

Mentions: The precise mechanisms underlying photobiomodulation and its therapeutic benefits are not fully understood. The purported effects of NIR are illustrated in Figure 1. Light in the wavelength range of 600–1,200 nm has significant photobiomodulation capability.56 Current data most strongly support that absorption of NIR photons by cytochrome c oxidase (COX) in the mitochondrial respiratory chain is the key initiating event in photobiomodulation.4,54,56 COX is a large transmembrane protein of the inner mitochondrial membrane. It contains two copper (Cu) centers and two heme-iron centers. These metal centers have different light absorption peaks. Reduction of CuA occurs with 620 nm, oxidation of CuA occurs with 825 nm, reduction of CuB occurs with 760 nm, and oxidation of CuB occurs at 680 nm.54 These peaks correspond to the “optical window” associated with the biological effects of NIR. Irradiation of COX increases the activity of the entire electron transport chain producing more adenosine triphosphate (ATP). In addition, COX is auto-inducible and its gene expression is activity dependent, such that NIR irradiation may increase the amount of available COX over time.57


Near-infrared photonic energy penetration: can infrared phototherapy effectively reach the human brain?

Henderson TA, Morries LD - Neuropsychiatr Dis Treat (2015)

Hypothesized mechanism of action of near-infrared light (NIR) photobiomodulation.Notes: NIR (600–980 nm) penetrates tissue to variable depth depending on wavelength, coherence, time, and the tissue involved. A portion of the photonic energy reaches the mitochondria and is absorbed by cytochrome c oxidase. In addition to inducing increased adenosine triphosphate (ATP) production, NIR appears to initiate increased production of reactive oxygen species (ROS), reactive nitrogen species (RNS), and possibly (?) nitric oxide (NO). Downstream events include increased early response genes – c-fos, c-jun – and activation of nuclear factor kappa-B (NF-κB), which in turn induces increased transcription of gene products leading to neurogenesis, synaptogenesis, and increased production of growth factors and inflammatory mediators.Abbreviation: ↑, increase.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4552256&req=5

f1-ndt-11-2191: Hypothesized mechanism of action of near-infrared light (NIR) photobiomodulation.Notes: NIR (600–980 nm) penetrates tissue to variable depth depending on wavelength, coherence, time, and the tissue involved. A portion of the photonic energy reaches the mitochondria and is absorbed by cytochrome c oxidase. In addition to inducing increased adenosine triphosphate (ATP) production, NIR appears to initiate increased production of reactive oxygen species (ROS), reactive nitrogen species (RNS), and possibly (?) nitric oxide (NO). Downstream events include increased early response genes – c-fos, c-jun – and activation of nuclear factor kappa-B (NF-κB), which in turn induces increased transcription of gene products leading to neurogenesis, synaptogenesis, and increased production of growth factors and inflammatory mediators.Abbreviation: ↑, increase.
Mentions: The precise mechanisms underlying photobiomodulation and its therapeutic benefits are not fully understood. The purported effects of NIR are illustrated in Figure 1. Light in the wavelength range of 600–1,200 nm has significant photobiomodulation capability.56 Current data most strongly support that absorption of NIR photons by cytochrome c oxidase (COX) in the mitochondrial respiratory chain is the key initiating event in photobiomodulation.4,54,56 COX is a large transmembrane protein of the inner mitochondrial membrane. It contains two copper (Cu) centers and two heme-iron centers. These metal centers have different light absorption peaks. Reduction of CuA occurs with 620 nm, oxidation of CuA occurs with 825 nm, reduction of CuB occurs with 760 nm, and oxidation of CuB occurs at 680 nm.54 These peaks correspond to the “optical window” associated with the biological effects of NIR. Irradiation of COX increases the activity of the entire electron transport chain producing more adenosine triphosphate (ATP). In addition, COX is auto-inducible and its gene expression is activity dependent, such that NIR irradiation may increase the amount of available COX over time.57

Bottom Line: Traumatic brain injury (TBI) is a growing health concern effecting civilians and military personnel.Yet, it remains unclear if sufficient photonic energy can be delivered to the human brain to yield a beneficial effect.Pulsing at 10 Hz reduced the dose of light delivered to the surface by 50%, but 2.4% of the surface energy reached the depth of 3 cm.

View Article: PubMed Central - PubMed

Affiliation: The Synaptic Space, Centennial, CO, USA ; Neuro-Laser Foundation, Lakewood, CO, USA.

ABSTRACT
Traumatic brain injury (TBI) is a growing health concern effecting civilians and military personnel. Research has yielded a better understanding of the pathophysiology of TBI, but effective treatments have not been forthcoming. Near-infrared light (NIR) has shown promise in animal models of both TBI and stroke. Yet, it remains unclear if sufficient photonic energy can be delivered to the human brain to yield a beneficial effect. This paper reviews the pathophysiology of TBI and elaborates the physiological effects of NIR in the context of this pathophysiology. Pertinent aspects of the physical properties of NIR, particularly in regards to its interactions with tissue, provide the background for understanding this critical issue of light penetration through tissue. Our recent tissue studies demonstrate no penetration of low level NIR energy through 2 mm of skin or 3 cm of skull and brain. However, at 10-15 W, 0.45%-2.90% of 810 nm light penetrated 3 cm of tissue. A 15 W 810 nm device (continuous or non-pulsed) NIR delivered 2.9% of the surface power density. Pulsing at 10 Hz reduced the dose of light delivered to the surface by 50%, but 2.4% of the surface energy reached the depth of 3 cm. Approximately 1.22% of the energy of 980 nm light at 10-15 W penetrated to 3 cm. These data are reviewed in the context of the literature on low-power NIR penetration, wherein less than half of 1% of the surface energy could reach a depth of 1 cm. NIR in the power range of 10-15 W at 810 and 980 nm can provide fluence within the range shown to be biologically beneficial at 3 cm depth. A companion paper reviews the clinical data on the treatment of patients with chronic TBI in the context of the current literature.

No MeSH data available.


Related in: MedlinePlus