Abstract
Microglia, the primary immune cells of the brain, play a key role in pathological and normal brain function. Growing efforts aim to reveal how these cells may be harnessed to treat both neurodegenerative diseases such as Alzheimer’s and developmental disorders such as schizophrenia and autism. We recently showed that using noninvasive exposure to 40-Hz white-light (4,000 K) flicker to drive 40-Hz neural activity transforms microglia into an engulfing state and reduces amyloid beta, a peptide thought to initiate neurotoxic events in Alzheimer’s disease (AD). This article describes how to construct an LED-based light-flicker apparatus, expose animals to 40-Hz flicker and control conditions, and perform downstream assays to study the effects of these stimuli. Light flicker is simple, faster to implement, and noninvasive, as compared with driving 40-Hz activity using optogenetics; however, it does not target specific cell types, as is achievable with optogenetics. This noninvasive approach to driving 40-Hz neural activity should enable further research into the interactions between neural activity, molecular pathology, and the brain’s immune system. Construction of the light-flicker system requires ~1 d and some electronics experience or available guidance. The flicker manipulation and assessment can be completed in a few days, depending on the experimental design.
This is a preview of subscription content, access via your institution
Relevant articles
Open Access articles citing this article.
-
Cognitive and Neuropathophysiological Outcomes of Gamma-tACS in Dementia: A Systematic Review
Neuropsychology Review Open Access 06 March 2023
-
Visuospatial alpha and gamma oscillations scale with the severity of cognitive dysfunction in patients on the Alzheimer’s disease spectrum
Alzheimer's Research & Therapy Open Access 17 August 2021
-
SSVEP phase synchronies and propagation during repetitive visual stimulation at high frequencies
Scientific Reports Open Access 02 March 2021
Access options
Access Nature and 54 other Nature Portfolio journals
Get Nature+, our best-value online-access subscription
$29.99 / 30 days
cancel any time
Subscribe to this journal
Receive 12 print issues and online access
$209.00 per year
only $17.42 per issue
Rent or buy this article
Get just this article for as long as you need it
$39.95
Prices may be subject to local taxes which are calculated during checkout







References
Kayed, R. et al. Common structure of soluble amyloid oligomers implies common mechanism of pathogenesis. Science 300, 486–489 (2003).
Murphy, M. P. & LeVine, H. III. Alzheimer’s disease and the amyloid-beta peptide. J. Alzheimers. Dis. 19, 311–323 (2010).
Masters, C. L. et al. Neuronal origin of a cerebral amyloid: neurofibrillary tangles of Alzheimer’s disease contain the same protein as the amyloid of plaque cores and blood vessels. EMBO J. 4, 2757–2763 (1985).
Masters, C. L. et al. Amyloid plaque core protein in Alzheimer disease and Down syndrome. Proc. Natl. Acad. Sci. USA 82, 4245–4249 (1985).
Glenner, G. G. & Wong, C. W. Alzheimer’s disease and Down’s syndrome: sharing of a unique cerebrovascular amyloid fibril protein. Biochem. Biophys. Res. Commun. 122, 1131–1135 (1984).
Karran, E., Mercken, M. & De Strooper, B. The amyloid cascade hypothesis for Alzheimer’s disease: an appraisal for the development of therapeutics. Nat. Rev. Drug Discov. 10, 698–712 (2011).
Salloway, S. et al. Two phase 3 trials of bapineuzumab in mild-to-moderate Alzheimer’s disease. N. Engl. J. Med. 370, 322–333 (2014).
Gjoneska, E. et al. Conserved epigenomic signals in mice and humans reveal immune basis of Alzheimer’s disease. Nature 518, 365–369 (2015).
Wu, Y., Dissing-Olesen, L., MacVicar, B. A. & Stevens, B. Microglia: dynamic mediators of synapse development and plasticity. Trends Immunol. 36, 605–613 (2015).
Iaccarino, H. F. et al. Gamma frequency entrainment attenuates amyloid load and modifies microglia. Nature 540, 230–235 (2016).
Wang, Y. et al. TREM2 lipid sensing sustains the microglial response in an Alzheimer’s disease model. Cell 160, 1061–1071 (2015).
Kreutzberg, G. W. Microglia: a sensor for pathological events in the CNS. Trends Neurosci. 19, 312–318 (1996).
Raivich, G. et al. Neuroglial activation repertoire in the injured brain: graded response, molecular mechanisms and cues to physiological function. Brain Res. Rev. 30, 77–105 (1999).
Eckhorn, R. et al. Coherent oscillations: a mechanism of feature linking in the visual cortex? Biol. Cybern. 60, 121–130 (1988).
Oakley, H. et al. Intraneuronal NL-amyloid aggregates, neurodegeneration, and neuron loss in transgenic mice with five familial Alzheimer’s disease mutations: potential factors in amyloid plaque formation. J. Neurosci. 26, 10129–10140 (2006).
Jankowsky, J. L. et al. Mutant presenilins specifically elevate the levels of the 42 residue beta amyloid peptide in vivo: evidence for augmentation of a 42-specific gamma secretase. Hum. Mol. Genet. 13, 159–170 (2004).
Chung, K. et al. Structural and molecular interrogation of intact biological systems. Nature 497, 332–337 (2013).
Murray, E. et al. Simple, scalable proteomic imaging for high-dimensional profiling of intact systems. Cell 163, 1500–1514 (2015).
Cardin, J. A. et al. Driving fast-spiking cells induces gamma rhythm and controls sensory responses. Nature 459, 663–667 (2009).
Allen, B. D., Singer, A. C. & Boyden, E. S. Principles of designing interpretable optogenetic behavior experiments. Learn. Mem. 22, 232–238 (2015).
Teng, F. et al. Square or sine: finding a waveform with high success rate of eliciting SSVEP. Comput. Intell. Neurosci. 2011, 1–5 (2011).
Treuting, P. M. & Snyder, J. M. Mouse necropsy. Curr. Protoc. Mouse Biol. 5, 223–233 (2015).
Chung, K. & Deisseroth, K. CLARITY for mapping the nervous system. Nat. Methods 10, 508–513 (2013).
Tomer, R., Ye, L., Hsueh, B. & Deisseroth, K. Advanced CLARITY for rapid and high-resolution imaging of intact tissues. Nat. Protoc. 9, 1682–1697 (2014).
Helwig, M. et al. The neuroendocrine protein 7B2 suppresses the aggregation of neurodegenerative disease-related proteins. J. Biol. Chem. 288, 1114–1124 (2013).
Ohmi, K., Zhao, H.-Z. & Neufeld, E. F. Defects in the medial entorhinal cortex and dentate gyrus in the mouse model of Sanfilippo syndrome type B. PLoS ONE 6, e27461 (2011).
Mastrangelo, M. A. et al. Detailed immunohistochemical characterization of temporal and spatial progression of Alzheimer’s disease-related pathologies in male triple-transgenic mice. BMC Neurosci. 9, 81 (2008).
Sudol, K. L. et al. Generating differentially targeted amyloid-β specific intrabodies as a passive vaccination strategy for Alzheimer’s disease. Mol. Ther. 17, 2031–2040 (2009).
Garcia, J. A. et al. Isolation and analysis of mouse microglial cells. Curr. Protoc. Immunol. 104, 14.35.1–14.35.15 (2014).
Yoshiyama, Y. et al. Synapse loss and microglial activation precede tangles in a P301S tauopathy mouse model. Neuron 53, 337–351 (2007).
Beck, S. J. et al. Deregulation of mitochondrial F1FO-ATP synthase via OSCP in Alzheimer’s disease. Nat. Commun. 7, 11483 (2016).
Brai, E., Alina Raio, N. & Alberi, L. Notch1 hallmarks fibrillary depositions in sporadic Alzheimer’s disease. Acta Neuropathol. Commun. 4, 64 (2016).
Hanisch, U.-K. & Kettenmann, H. Microglia: active sensor and versatile effector cells in the normal and pathologic brain. Nat. Neurosci. 10, 1387–1394 (2007).
Ransohoff, R. M. A polarizing question: do M1 and M2 microglia exist? Nat. Neurosci. 19, 987–991 (2016).
Bessis, A., Béchade, C., Bernard, D. & Roumier, A. Microglial control of neuronal death and synaptic properties. Glia 55, 233–238 (2007).
Acknowledgements
We are grateful to H. Iaccarino, S. Kale, and members of the Tsai, Singer, and Boyden laboratories for methods development, technical assistance, and comments on the paper. A.C.S. acknowledges the Lane family and the Packard Foundation; A.J.M. was supported by T32 GM007484 Integrative Neuronal Systems, MIT Champions of the Brain (Alder) Fellowship, and MIT Henry E. Singleton Fellowship; L.-H.T. acknowledges the JPB Foundation, Belfer Neurodegeneration Consortium, Halis Family Foundation, and NIH grant RF1 AG047661.
Author information
Authors and Affiliations
Contributions
A.C.S. developed the light-flicker methods; A.C.S., J.M.D., A.J.M., F.A., H.M., and C.A. performed the experiments; A.C.S., J.M.D., M.K.A., and J.T. constructed and tested the flicker circuitry; and A.C.S., J.M.D., A.J.M., F.A., and L.-H.T. wrote the manuscript.
Corresponding authors
Ethics declarations
Competing interests
L.-H.T. is the scientific founder and serves on the scientific advisory board of Cognito Therapeutics, and A.C.S. owns shares of Cognito Therapeutics. The remaining authors declare no competing interests.
Additional information
Publisher's note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Related links
Key references using this protocol
1. Iaccarino, H. F. et al. Nature 540, 230–235 (2016) https://doi.org/10.1038/nature20587
2. Mathys, H. et al. Cell Rep. 21, 366–380 (2017) https://doi.org/10.1016/j.celrep.2017.09.0393
3. Seo, J. et al. Cell 157, 486–498 (2014) https://doi.org/10.1016/j.cell.2014.01.065
Supplementary information
Supplementary Data
Example code to control the Arduino.
Supplementary Video
Mouse exposed to light flicker.
Rights and permissions
About this article
Cite this article
Singer, A.C., Martorell, A.J., Douglas, J.M. et al. Noninvasive 40-Hz light flicker to recruit microglia and reduce amyloid beta load. Nat Protoc 13, 1850–1868 (2018). https://doi.org/10.1038/s41596-018-0021-x
Published:
Issue Date:
DOI: https://doi.org/10.1038/s41596-018-0021-x
This article is cited by
-
Forty-hertz light stimulation does not entrain native gamma oscillations in Alzheimer’s disease model mice
Nature Neuroscience (2023)
-
Cognitive and Neuropathophysiological Outcomes of Gamma-tACS in Dementia: A Systematic Review
Neuropsychology Review (2023)
-
The Effect of 40-Hz White LED Therapy on Structure–Function of Brain Mitochondrial ATP-Sensitive Ca-Activated Large-Conductance Potassium Channel in Amyloid Beta Toxicity
Neurotoxicity Research (2022)
-
The 40-Hz White Light-Emitting Diode (LED) Improves the Structure–Function of the Brain Mitochondrial KATP Channel and Respiratory Chain Activities in Amyloid Beta Toxicity
Molecular Neurobiology (2022)
-
Visuospatial alpha and gamma oscillations scale with the severity of cognitive dysfunction in patients on the Alzheimer’s disease spectrum
Alzheimer's Research & Therapy (2021)
Comments
By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.