Repeated Photobiomodulation Induced Reduction of Bilateral Cortical Hemodynamic Activation during a Working Memory Task in Healthy Older Adults

Zhishan Hu, Xiujuan Qu, Lexuan Li, Xiaohan Zhou, Qin Yang, Qi Dong, Hesheng Liu, Xiaobo Li, Ying Han, Haijing Niu

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


Transcranial photobiomodulation (tPBM) is an emerging non-invasive light-based neuromodulation technique that shows promising potential for improving working memory (WM) performance in older adults. However, the neurophysiological mechanisms associated with tPBM that underlie the improvement of WM and the persistence of such improvement have not been investigated. Sixty-one healthy older adults were recruited to receive a baseline sham stimulation, followed by one-week active tPBM (12 min daily, 1064-nm laser, 250 mW/cm2) and three-week follow-ups. N-back WM task was conducted on post-stimulation of the baseline, the first (Day 1) and seventh (Day 7) days of the active treatment, and at the follow-ups. During the task, functional near-infrared spectroscopy (fNIRS) imaging was employed to record the cortical hemodynamic changes. Brain activations during the active and follow-up sessions were compared with the baseline to determine how tPBM had changed cortical hemodynamic activity and how long these changes persisted. We found that tPBM stimulation on Day 1 induced significantly decreased activation in the right hemisphere during the 3-back. The decreased activation expanded from only the right hemisphere on Day 1 to both hemispheres on Day 7. The decreased activation persisted for one week in the right supramarginal gyrus and the left angular gyrus and two weeks in the left somatosensory association cortex. These activation changes were accompanied by significantly improved task accuracy during the N-back. These findings provide important evidence for understanding neural mechanisms underlying cognitive enhancement after tPBM.

Original languageEnglish (US)
Pages (from-to)2876-2885
Number of pages10
JournalIEEE Journal of Biomedical and Health Informatics
Issue number6
StatePublished - Jun 1 2023
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Health Information Management
  • Health Informatics
  • Electrical and Electronic Engineering
  • Computer Science Applications


  • Functional near-infrared spectroscopy (fNIRS)
  • n-back
  • older adults
  • photobiomodulation
  • working memory


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