Boosting Brain Metabolism in Spaceflight with Transcranial Photobiomodulation

[Ed. note May 2020: Report submitted by TRISH to Task Book in March 2020; covers reporting as of November 2019.]

(1) Original project aims/objectives.

The objective of this proposal is to develop a new technique for enhancing brain activity by applying safe levels of laser light to the forehead. It is known that near-infrared light is absorbed by an enzyme in the mitochondria and subsequently leads to greater energy availability in the stimulated cells. When stimulating the brain, this additional energy can be used by brain cells to carry out the necessary functions required to maintain high cognitive performance (for example, sustained attention, accurate memory recall). We will test the proposed technology by scanning participants' brain activity while they receive laser stimulation to the forehead and at the same time perform a challenging perceptual task. We will also perform experiments where Light Emitting Diodes (LEDs) are used to stimulate participants' brains while they are trained on a working memory task and simultaneously have their brain activity measured. Our expectation is that we will observe increased energy metabolism in the frontal part of the brain, as well as an improvement in the performance of both perceptual and memory tasks. We expect that this research will lead to a new, non-pharmacological technique for boosting the performance of the brain by delivering safe levels of near-infrared light to the brain.

(2) Key Findings.

We have demonstrated with magnetic resonance (MR) Thermometry that tPBM does not heat the brain tissue. To show this, we recruited n=20 healthy participants to receive both active and sham tPBM while recording their brain temperature with an MR imaging (MRI) technique that is sensitive to temperature changes. We did not detect any time points of significant deviation in temperature between active and sham, and temperature increases were limited to 0.15 degrees Celsius, which is well within the range of physiological fluctuation. Therefore, we are confident that the technique is safe, and its mechanism does not rely on heating of the brain. We have also demonstrated a robust effect on functional connectivity in the human brain during tPBM. We scanned n=20 healthy participants with blood oxygenation level dependent (BOLD)-functional MRI (fMRI), and then measured the functional connectivity among brain regions before, during, and after illumination. We found a 20-27% increase in connectivity during stimulation. This suggests that brain activity becomes synchronized during tBPM, pointing to its potential in improving cognitive performance. In collaboration with New York University (NYU) Radiology, we have designed a Phosphorus magnetic resonance spectroscopy (MRS) experiment with data collection beginning on December 18th. We have already collected pilot data without the tPBM to verify that we are able to resolve the important energy metabolites: Phosphocreatine (PCr), three ATP groups. We are confident that we will be able to resolve a potential effect on ATP concentration with the current MRS sequence. University of Texas Arlington (UTA) group: we have begun collecting data to test the hypothesis in Aim 2 (11 subjects in both sham and active groups). Subjects have been performing the Psychomotor Vigilance Task and 2-back Tasks as implemented by the NASA Cognition software (courtesy of Mathias Basner). Participants receive tPBM with an LED. As this is a 12-week experiment, results are not yet available.

(3) Impact of key findings on hypotheses, technology requirements, objectives, and specific aims of the original proposal.

Our findings have been positive and lend further credence to our central hypothesis that tPBM is capable of enhancing cognitive function during spaceflight. We will continue with our research activities as planned in the proposal. We have strong evidence for the safety of our intervention, and also for the ability of near-infrared light to stimulate mitochondrial function in the human brain. We are very encouraged by the findings from the first year.

(4) Proposed research plan for the coming year.

We will be scanning N=26 healthy participants between December 18th, 2019 and June 18th, 2020 at NYU with Phosphorus MRS. These experiments will produce data that will shed important light as to whether the mechanism of tPBM is indeed enhanced mitochondrial activity. We will continue the 12-week LED based study taking place at University of Texas Arlington. We will analyze data from both experiments, followed by dissemination of the findings in peer-reviewed journals.