Near-infrared Excitation
Near-infrared Excitation - Related Videos
08:11
Infrared Spectroscopy
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2023
Source: Vy M. Dong and Zhiwei Chen, Department of Chemistry, University of California, Irvine, CA This experiment will demonstrate the use of infrared (IR) spectroscopy (also known as vibrational spectroscopy) to elucidate the identity of an unknown compound by identifying the functional group(s) present. IR spectra will be obtained on an IR spectrometer using the attenuated total reflection (ATR) sampling technique with a neat sample of the unknown.
10:12
Near-infrared Fluorescence Imaging of Abdominal Aortic Aneurysms
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2023
Source: Arvin H. Soepriatna1, Kelsey A. Bullens2, and Craig J. Goergen1 1 Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana 2 Department of Biochemistry, Purdue University, West Lafayette, Indiana Near-infrared fluorescence (NIRF) imaging is an exciting optical technique that utilizes fluorescent probes to visualize complex biomolecular assemblies in tissues. NIRF imaging has many advantages over conventional imaging methods for noninvasive imaging of diseases.
01:45
Visualization of Mouse Cerebral Thrombi Using Near-Infrared Fluorescence Imaging
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2025
Source: Kim, D. E., et al. Combined Near-infrared Fluorescent Imaging and Micro-computed Tomography for Directly Visualizing Cerebral Thromboemboli. J. Vis. Exp. (2016)This video demonstrates near-infrared fluorescent (NIRF) imaging to visualize thrombi in excised brain tissue labeled with a fibrin-specific probe. Near-infrared light excites the probe, causing the thrombus to fluoresce, enabling high-contrast thrombi visualization in the major cerebral artery and small cortical blood vessels.
12:33
Corticospinal Excitability Modulation During Action Observation
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Cited by 22 •
2013
Single-pulse transcranial magnetic stimulation over the primary motor cortex, neuronavigation, and registration of electromyographic activity of hand muscles were used in this study to explore corticospinal excitability while participants were observing action sequences.
12:13
Assessing Primary Motor Cortex Excitability and Excitability Modulation by Pairing Transcranial Magnetic Stimulation with Electromyography
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2025
Here, we present a protocol outlining the methodology to assess primary motor cortex excitability and excitability modulation using transcranial magnetic stimulation (TMS) paired with electromyography (EMG).
FAQs
Direct absorption occurs when a light-sensitive molecule absorbs near-infrared light and reaches an excited state. In nonlinear two-photon excitation, two lower-energy photons are absorbed nearly simultaneously to achieve the same transition. These routes can lead to fluorescence, photochemical activity, or changes in neural activity, so the excitation mechanism helps determine the type of biological signal produced.
Longer wavelengths than visible red light can improve penetration through biological tissue, allowing optical energy to reach neural structures that may be less accessible to shorter-wavelength approaches. This property supports investigation of neural circuits while retaining the possibility of spatially selective activation or measurement, making wavelength choice important for balancing access to tissue with localized effects.
The outcome depends on the light-sensitive component being activated and the way it responds after absorbing light. A chromophore or probe may generate fluorescence, whereas another light-responsive system may undergo photochemical activity or influence neural activity. Identifying the relevant molecule, probe, or neural interface is therefore essential for interpreting what the observed response represents.
Direct absorption uses the energy of an individual near-infrared photon to activate a light-sensitive molecule. Two-photon excitation instead relies on the near-simultaneous absorption of two lower-energy photons. Because these mechanisms reach an excited state differently, they provide distinct ways to control where and how optical signals or neural responses are generated in tissue.
In neuroscience, investigators can use it for optical recording, targeted stimulation, or imaging. The selected light-sensitive molecule, probe, or neural interface determines whether the experiment emphasizes signal detection, photochemical action, or modulation of neural activity. These applications make the approach useful for examining neural responses and investigating the organization and function of neural circuits.
The resulting outcome may be a fluorescence signal, a photochemical response, or a change in neural activity. Fluorescence can support optical readouts, while photochemical or activity-related effects can indicate that the light-sensitive system has been functionally engaged. Interpreting the outcome requires distinguishing the optical signal itself from the biological response produced by excitation.
Spatial selectivity allows researchers to associate an optical effect with a more specifically targeted neural region or circuit rather than treating a broad tissue volume as one response. Combined with the potential for improved penetration, this selectivity supports experiments that examine neural circuits with greater precision while using optical recording, stimulation, or imaging strategies.