Researchers from Beijing Normal University and the University of Birmingham in the UK and China showed that non-invasive therapy can increase working memory in persons by up to 25 per cent.
The right prefrontal cortex of the brain receives the treatment, known as transcranial photobiomodulation (tPBM). It is generally acknowledged that this region is crucial for working memory. The team’s experiment demonstrated how, following several minutes of treatment, the research participants’ working memory improved. Electroencephalogram (EEG) monitoring during therapy and assessment allowed them to keep tabs on changes in brain activity.
Previous studies have shown that laser light treatment will improve working memory in mice, and human studies have shown that tPBM treatment can improve accuracy, speed up reaction time and improve high-order functions such as attention and emotion.
This is the first study, however, to confirm a link between tPBM and working memory in humans.
Dongwei Li, a visiting PhD student at the University of Birmingham’s Centre for Human Brain Health, is a co-author of the paper. He said: “People with conditions like ADHD (attention deficit hyperactivity disorder) or other attention-related conditions could benefit from this type of treatment, which is safe, simple and non-invasive, with no side-effects.”
Ninety male and female individuals between the ages of 18 and 25 participated in the study’s experiments, which were conducted at Beijing Normal University. While some participants received treatment at a longer wavelength or to the left prefrontal brain, others received treatment with laser light at wavelengths of 1064 nm to the right prefrontal cortex. To eliminate the placebo effect, each subject was also given a sham, or inactive, tPBM.
The subjects were asked to recall the orientations or colours of a series of objects exhibited on a screen after receiving tPBM treatment for more than 12 minutes. When compared to those who received the other treatments, the subjects who received laser light at 1064 nm to the right prefrontal cortex displayed definite memory gains.
Participants who received the targeted treatment were able to recall between 4 and 5 of the test objects, but those getting other treatment variations were only able to remember between 3 and 4.
At the University of Birmingham, analysis of the experiment’s data, including electroencephalogram (EEG) monitoring, revealed alterations in brain activity that also foretold the gains in memory function.
The exact cause of the treatment’s beneficial benefits on working memory and the duration of those effects are still unknown to the researchers. The investigation of these topics will continue through more research.
Professor Ole Jensen, also at the Centre for Human Brain Health, said: “We need further research to understand exactly why the tPBM is having this positive effect, but it’s possible that the light is stimulating the astrocytes – the powerplants – in the nerve cells within the prefrontal cortex, and this has a positive effect on the cells’ efficiency. We will also be investigating how long the effects might last. Clearly, if these experiments are to lead to clinical intervention, we will need to see long-lasting benefits.”