Laser Beam Brain Stimulation Could Boost Short-Term Memory by 25%

Shining a laser light at a targeted region of the human brain can boost short-term memory function by up to 25%, suggests a new study. The non-invasive technique could one day help improve attention deficits in people with ADHD (attention deficit hyperactivity disorder), say the paper’s authors.

The study, a collaboration between researchers at the University of Birmingham in the UK and Beijing Normal University in China, is published in Science Advances.

Safe laser levels

The team used a technique called transcranial photobiomodulation (tPBM), where a solid-state laser beam is shone at the head above the area of the brain being targeted. The laser energy used was low, and no tissue damage or even perceptions of heat were reported by participants.

The 90 study volunteers – healthy college students aged between 18 and 25 – were exposed to roughly 6 minutes of laser stimulation. In the first experimental group (n=27), 1064 nm laser light was aimed at an area of the brain called the right prefrontal cortex, which is thought to be important for working memory. Two subsequent experiments (both n=21) investigated whether memory benefits were produced when the laser was aimed at the left prefrontal cortex or when a shorter wavelength beam was used. In each experiment, participants went through two rounds of testing, one with an active tPBM procedure, and one with a control laser stimulation to rule out potential placebo effects.  

After the stimulation, participants were asked to remember the color or orientations of items displayed on a screen. The participants who received the laser beam on their right prefrontal cortex showed notably enhanced memory. While participants receiving the other variations were able to recall between three and four test objects, those with the targeted treatment were able to recall between four and five objects. This difference was statistically significant.

The team also used electroencephalogram (EEG) monitoring during the study, showing that changes in brain activity during the tPBM were linked to the memory enhancements.

A multifunctional technique

This is the first study to show a connection between tPBM and short-term working memory in humans, following up on previous studies that showed similar improvements in mice. Other research has shown that tPBM can enhance reaction times, emotional function and accuracy in humans.

The researchers are yet to work out the mechanism that explains their findings, or how long the effects last but have planned further experiments to tease out the brain circuits involved. They are hopeful, nevertheless, that the technique will have significant translational potential. “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,” says Dongwei Li, a visiting PhD student in the University of Birmingham’s Centre for Human Brain Health and a co-author of the paper.

“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,” says Professor Ole Jensen, also at the Centre for Human Brain Health. “We will also be investigating how long the effects might last. Clearly if these experiments are to lead to a clinical intervention, we will need to see long-lasting benefits,” Jensen concludes.

Reference:  Zhao C, Li D, Kong Y, et al. Transcranial photobiomodulation enhances visual working memory capacity in humans. Sci. Adv. 2022;8(48). doi:10.1126/sciadv.abq3211

This article is a rework of a press release issued by the University of Birmingham. Material has been edited for length and content.