Brain heating induced by near-infrared lasers during multiphoton microscopy

Kaspar Podgorski; Gayathri Ranganathan

doi:10.1152/jn.00275.2016

Brain heating induced by near-infrared lasers during multiphoton microscopy

Journal of Neurophysiology ◽

10.1152/jn.00275.2016 ◽

2016 ◽

Vol 116 (3) ◽

pp. 1012-1023 ◽

Cited By ~ 96

Author(s):

Kaspar Podgorski ◽

Gayathri Ranganathan

Keyword(s):

High Power ◽

Heat Dissipation ◽

Near Infrared ◽

Multiphoton Microscopy ◽

Total Power ◽

Continuous Illumination ◽

Two Photon ◽

Cranial Window ◽

Shock Proteins ◽

The Brain

Two-photon imaging and optogenetic stimulation rely on high illumination powers, particularly for state-of-the-art applications that target deeper structures, achieve faster measurements, or probe larger brain areas. However, little information is available on heating and resulting damage induced by high-power illumination in the brain. In the current study we used thermocouple probes and quantum dot nanothermometers to measure temperature changes induced by two-photon microscopy in the neocortex of awake and anaesthetized mice. We characterized heating as a function of wavelength, exposure time, and distance from the center of illumination. Although total power is highest near the surface of the brain, heating was most severe hundreds of micrometers below the focal plane, due to heat dissipation through the cranial window. Continuous illumination of a 1-mm2 area produced a peak temperature increase of ∼1.8°C/100 mW. Continuous illumination with powers above 250 mW induced lasting damage, detected with immunohistochemistry against Iba1, glial fibrillary acidic protein, heat shock proteins, and activated caspase-3. Higher powers were usable in experiments with limited duty ratios, suggesting an approach to mitigate damage in high-power microscopy experiments.

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Brain heating induced by near infrared lasers during multi-photon microscopy

10.1101/057364 ◽

2016 ◽

Cited By ~ 3

Author(s):

Kaspar Podgorski ◽

Gayathri Ranganathan

Keyword(s):

High Power ◽

Heat Dissipation ◽

Near Infrared ◽

Total Power ◽

Continuous Illumination ◽

Two Photon Microscopy ◽

Two Photon ◽

Cranial Window ◽

Shock Proteins ◽

The Brain

AbstractTwo-photon imaging and optogenetic stimulation rely on high illumination powers, particularly for state-of-the-art applications that target deeper structures, achieve faster measurements, or probe larger brain areas. However, little information is available on heating and resulting damage induced by high-power illumination in the brain. Here we used thermocouple probes and quantum dot nanothermometers to measure temperature changes induced by two-photon microscopy in the neocortex of awake and anaesthetized mice. We characterized heating as a function of wavelength, exposure time, and distance from the center of illumination. Although total power is highest near the surface of the brain, heating was most severe hundreds of microns below the focal plane, due to heat dissipation through the cranial window. Continuous illumination of a 1mm2area produced a peak temperature increase of approximately 1.8°C/100mW. Continuous illumination with powers above 250 mW induced lasting damage, detected with immunohistochemistry against Iba1, GFAP, heat shock proteins, and activated Caspase-3. Higher powers were usable in experiments with limited duty ratios, suggesting an approach to mitigate damage in high-power microscopy experiments.

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Application of multiphoton microscopy in dermatological studies: A mini-review

Journal of Innovative Optical Health Sciences ◽

10.1142/s1793545813300103 ◽

2014 ◽

Vol 07 (05) ◽

pp. 1330010 ◽

Cited By ~ 38

Author(s):

Elijah Yew ◽

Christopher Rowlands ◽

Peter T. C. So

Keyword(s):

Near Infrared ◽

Second Harmonic ◽

Multiphoton Microscopy ◽

Infrared Light ◽

Future Research ◽

Two Photon ◽

Recent Developments ◽

Future Research Directions ◽

Microscopy Techniques ◽

Penetration Depths

This review summarizes the historical and more recent developments of multiphoton microscopy, as applied to dermatology. Multiphoton microscopy offers several advantages over competing microscopy techniques: there is an inherent axial sectioning, penetration depths that compete well with confocal microscopy on account of the use of near-infrared light, and many two-photon contrast mechanisms, such as second-harmonic generation, have no analogue in one-photon microscopy. While the penetration depths of photons into tissue are typically limited on the order of hundreds of microns, this is of less concern in dermatology, as the skin is thin and readily accessible. As a result, multiphoton microscopy in dermatology has generated a great deal of interest, much of which is summarized here. The review covers the interaction of light and tissue, as well as the various considerations that must be made when designing an instrument. The state of multiphoton microscopy in imaging skin cancer and various other diseases is also discussed, along with the investigation of aging and regeneration phenomena, and finally, the use of multiphoton microscopy to analyze the transdermal transport of drugs, cosmetics and other agents is summarized. The review concludes with a look at potential future research directions, especially those that are necessary to push these techniques into widespread clinical acceptance.

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Cancer Imaging and Thermal Therapy Facilitated by Nanoparticles and Multiphoton Microscopy

ASME 2010 First Global Congress on NanoEngineering for Medicine and Biology ◽

10.1115/nemb2010-13180 ◽

2010 ◽

Author(s):

Emily S. Day ◽

Lissett R. Bickford ◽

Rebekah A. Drezek ◽

Jennifer L. West

Keyword(s):

Cancer Cells ◽

Causes Of Death ◽

Near Infrared ◽

Multiphoton Microscopy ◽

Therapeutic Agents ◽

Thermal Therapy ◽

Infrared Light ◽

Two Photon ◽

Cancer Management ◽

Gold Sulfide

Despite use of currently available technologies, cancer remains one of the leading causes of death worldwide. Gold-based nanoparticles that strongly absorb near-infrared light, such as nanoshells and nanorods, have shown potential as both diagnostic and therapeutic agents for cancer management (1–3). In this work we explored the use of gold-gold sulfide nanoparticles (mean diameter = 37 nm) with peak plasmon resonance at 800 nm for combined imaging and therapy of breast cancer. Upon excitation with a pulsed laser, these particles exhibit two-photon induced luminescence which may be used to image cancer cells. In addition, by increasing the power output of the laser, cancer cells can be thermally ablated as the gold-gold sulfide nanoparticles convert the light energy into heat.

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All-near-infrared multiphoton microscopy interrogates intact tissues at deeper imaging depths than conventional single- and two-photon near-infrared excitation microscopes

Journal of Biomedical Optics ◽

10.1117/1.jbo.18.10.106012 ◽

2013 ◽

Vol 18 (10) ◽

pp. 106012 ◽

Cited By ~ 12

Author(s):

Pinaki Sarder ◽

Siavash Yazdanfar ◽

Walter J. Akers ◽

Rui Tang ◽

Gail P. Sudlow ◽

...

Keyword(s):

Near Infrared ◽

Multiphoton Microscopy ◽

Two Photon ◽

Infrared Excitation

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Two-photon imaging induces brain heating and calcium microdomain hyperactivity in cortical astrocytes

10.1101/321091 ◽

2018 ◽

Cited By ~ 1

Author(s):

Elke Schmidt ◽

Martin Oheim

Keyword(s):

Laser Power ◽

Near Infrared ◽

Continuous Wave ◽

Average Power ◽

Infrared Light ◽

Near Infrared Light ◽

Two Photon Microscopy ◽

Two Photon ◽

Cortical Astrocytes ◽

The Brain

ABSTRACTUnraveling how neural networks process and represent sensory information and how this cellular dynamics instructs behavioral output is a main goal in current neuroscience. Two-photon activation of optogenetic actuators and fluorescence calcium (Ca2+) imaging with genetically encoded Ca2+ indicators allow, respectively, the all-optical stimulation and readout of activity from genetically identified cell populations. However, these techniques expose the brain to high near-infrared light doses raising the concern of light-induced adverse effects on the biological phenomena being studied. Combing Ca2+ imaging of GCaMP6f-expressing cortical astrocytes as a sensitive readout for photodamage and an unbiased machine-based event detection, we demonstrate the subtle build-up of aberrant microdomain Ca2+ signals in fine astroglial processes. Illumination conditions routinely being used in biological two-photon microscopy (920-nm excitation, 100-fs regime, ten mW average power) increased the frequency of microdomain Ca2+ events, but left their amplitude, area and duration rather unchanged. This increase in local Ca2+ activity was followed by Ca2+ transients in the otherwise silent soma. Ca2+ hyperactivity occurred without overt morphological damage. Surprisingly, at the same average power, continuous-wave 920-nm illumination was as damaging as fs pulses, indicating a linear, heating-mediated (rather than a highly non-linear) damage mechanism. In an astrocyte-specific IP3-receptor knock-out mouse (IP3R2-KO), Near-infrared light-induced Ca2+ microdomains signals persisted in the small processes, underpinning their resemblance to physiological IP3R2-independent Ca2+ signals, while somatic activity was abolished. Contrary to what has generally been believed in the field, shorter pulses and lower average power are advantageous to alleviate photodamage and allow for longer useful recording windows.SIGNIFICANCE STATEMENTImaging the fine structure and function of the brain has become possible with two-photon microscopy that uses ultrashort-pulsed infrared laser light for better tissue penetration. The high peak energy of these light pulses has raised concerns about photodamage resulting from multi-photon processes. Here, we show that the time-averaged rather than the peak laser power matters. At wavelengths and with laser powers now commonly used in neuroscience brain damage occurs as a consequence of direct infrared light absorption, i.e., heating. To counteract brain heating we explore a strategy that uses even shorter, more energetic pulses but a lower time-averaged laser power to produce the same image quality while making two-photon microscopy less invasive.

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Probing neuropeptide volume transmission in vivo by a novel all-optical approach

10.1101/2021.09.10.459853 ◽

2021 ◽

Author(s):

Hejian Xiong ◽

Emre Lacin ◽

Hui Ouyang ◽

Aditi Naik ◽

Xueqi Xu ◽

...

Keyword(s):

Near Infrared ◽

Infrared Light ◽

Volume Transmission ◽

Two Photon ◽

All Optical ◽

And Behavior ◽

G Protein Coupled ◽

The Brain ◽

Somatostatin 14

AbstractNeuropeptides are essential signaling molecules in the nervous system involved in modulating neural circuits and behavior. Although hypothesized to signal via volume transmission through G-protein coupled receptors (GPCR), remarkably little is known about their extrasynaptic diffusion. Here, we developed an all-optical approach to probe neuropeptide volume transmission in mouse neocortex. To control neuropeptide release, we engineered photosensitive nanovesicles with somatostatin-14 (SST) that is released with near-infrared light stimulation. To detect SST, we created a new cell-based neurotransmitter fluorescent engineered reporter (CNiFER) using the SST2 GPCR. Under two-photon imaging, we determined the time to activate SST2R at defined distances as well as the maximal distance and loss rate for SST volume transmission in neocortex. Importantly, we determined that SST transmission is significantly faster in neocortex with a chemically degraded extracellular matrix, a diseased condition indicated in neuroinflammation and Parkinson’s disease. These new neurotechnologies can reveal important biological signaling processes previously not possible, and provide new opportunities to investigate volume transmission in the brain.

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Faculty Opinions recommendation of Combined non-linear laser imaging (two-photon excitation fluorescence microscopy, fluorescence lifetime imaging microscopy, multispectral multiphoton microscopy) in cutaneous tumours: first experiences.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1166974.629075 ◽

2009 ◽

Author(s):

Harvey Lui

Keyword(s):

Fluorescence Microscopy ◽

Fluorescence Lifetime ◽

Multiphoton Microscopy ◽

Fluorescence Lifetime Imaging Microscopy ◽

Fluorescence Lifetime Imaging ◽

Laser Imaging ◽

Two Photon ◽

Lifetime Imaging ◽

Photon Excitation ◽

Linear Laser

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Changes in the Total Power of Beta and Theta Bands When Using EEG Biofeedback in Primary School-Age Children Having Difficulties with Voluntary Regulation

Journal of Medical and Biological Research ◽

10.37482/2687-1491-z025 ◽

2020 ◽

pp. 331-340

Author(s):

Yuliya S. Dzhos ◽

◽

Irina A. Men’shikova ◽

Keyword(s):

Left Hemisphere ◽

Spectral Characteristics ◽

Low Frequency ◽

School Age Children ◽

Total Power ◽

Eeg Biofeedback ◽

Beta Band ◽

Bioelectric Activity ◽

Voluntary Regulation ◽

The Brain

This article presents the results of the study on spectral electroencephalogram (EEG) characteristics in 7–10-year-old children (8 girls and 22 boys) having difficulties with voluntary regulation of activity after 10 and 20 neurofeedback sessions using beta-activating training. Brain bioelectric activity was recorded in 16 standard leads using the Neuron-Spectrum-4/VPM complex. The dynamics was assessed by EEG beta and theta bands during neurofeedback. An increase in the total power of beta band oscillations was established both after 10 and after 20 sessions of EEG biofeedback in the frontal (p ≤ 0.001), left parietal (p ≤ 0.036), and temporal (p ≤ 0.003) areas of the brain. A decrease in the spectral characteristics of theta band oscillations was detected: after 10 neurofeedback sessions in the frontal (p ≤ 0.008) and temporal (p ≤ 0.006) areas of both hemispheres, as well as in the parietal area of the left hemisphere (p ≤ 0.005); after 20 sessions, in the central (p ≤ 0.004), frontal (p ≤ 0.001) and temporal (p ≤ 0.001) areas of both hemispheres, as well as in the occipital (p ≤ 0.047) and parietal (p ≤ 0.001) areas of the left hemisphere. The study into the dynamics of bioelectric activity during biofeedback using EEG parameters in 7–10-year-old children with impaired voluntary regulation of higher mental functions allowed us to prove the advisability of 20 sessions, as the increase in high-frequency activity and decrease in low-frequency activity do not stop with the 10th session. Changes in these parameters after 10 EEG biofeedback sessions are expressed mainly in the frontotemporal areas of both hemispheres, while after a course of 20 sessions, in both the frontotemporal and central parietal areas of the brain.

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