Ultrafast two-photon fluorescence imaging of cerebral blood circulation in the mouse brain in vivo.

Characterizing blood flow dynamics in vivo is critical to understanding the function of the vascular network under physiological and pathological conditions. Existing methods for hemodynamic imaging have insufficient spatial and temporal resolution to monitor blood flow at the cellular level in large blood vessels. By using an ultrafast line-scanning module based on free-space angular chirped enhanced delay, we achieved two-photon fluorescence imaging of cortical blood flow at 1,000 two-dimensional (2D) frames and 1,000,000 one-dimensional line scans per second in the awake mouse. This orders-of-magnitude increase in temporal resolution allowed us to measure cerebral blood flow at up to 49 mm/s and observe pulsatile blood flow at harmonics of heart rate. Directly visualizing red blood cell (RBC) flow through vessels down to >800 µm in depth, we characterized cortical layer­dependent flow velocity distributions of capillaries, obtained radial velocity profiles and kilohertz 2D velocity mapping of multifile blood flow, and performed RBC flux measurements from penetrating blood vessels.

BiPMAP: a toolbox for predicting perceived motion artifacts on modern displays.

Viewers of digital displays often experience motion artifacts (e.g., flicker, judder, edge banding, motion blur, color breakup, depth distortion) when presented with dynamic scenes. We developed an interactive software tool for display designers that predicts how a viewer perceives motion artifacts for a variety of stimulus, display, and viewing parameters: the Binocular Perceived Motion Artifact Predictor (BiPMAP). The tool enables the user to specify numerous stimulus, display, and viewing parameters. It implements a model of human spatiotemporal contrast sensitivity in order to determine which artifacts will be seen by a viewer and which will not. The tool visualizes the perceptual effects of discrete space-time sampling on the display by presenting side by side the expected perception when the stimulus is continuous compared to when the same stimulus is presented with the spatial and temporal parameters of a prototype display.

Rapid mesoscale volumetric imaging of neural activity with synaptic resolution.

Imaging neurons and neural circuits over large volumes at high speed and subcellular resolution is a difficult task. Incorporating a Bessel focus module into a two-photon fluorescence mesoscope, we achieved rapid volumetric imaging of neural activity over the mesoscale with synaptic resolution. We applied the technology to calcium imaging of entire dendritic spans of neurons as well as neural ensembles within multiple cortical regions over two hemispheres of the awake mouse brain.

[Diagnosis Significance of the Levels of Cytokines IL-6, IL-10 and CXCL-13 in Cerebrospinal Fluid for Central Nervous System Infiltration of Lymphoma].

OBJECTIVE: To evaluate the diagnostic value of the expression levels of cytokines interleukin-6(IL-6), interleukin-10 (IL-10) and chemokine （C-X-C motif） ligand-13 (CXCL-13) in cerebrospinal fluid (CSF) for central nervous system infiltration of lymphoma. METHODS: Forty patients diagnosed as lymphoma or acute lymphoblastic leukemia in General Hospital of Northern Theater Command from July 2020 to July 2021 were collected and recorded their CSF indexes, including pressure, protein, Pandy test, nucleated cell count, glucose and chlorine content in CSF. The levels of cytokines IL-6, IL-10 and CXCL-13 were detected by Enzyme-linked immunosorbent assay. RESULTS: The patients were divided into CNSI (central nervous system infiltration) group and non-CNSI group, the average levels of IL-6, IL-10, CXCL-13 and IL-10/IL-6 ratio in CNSI group were higher than those in non-CNS group, but the difference of IL-10/IL-6 ratio between the two groups was statistically significant (P<0.05). Then the patients were divided into protein elevated(n=14) group and protein normal group(n=26), the levels of IL-6 ï¼» (5.78±2.69) pg/ mlï¼½ and CXCL-13 ï¼»(0.83±0.59) pg/mlï¼½ in protein elevated group were significantly higher than those in the protein normal group ï¼»IL-6: (2.41±1.16) pg/ml; CXCL-13: (0.38±0.18) pg/mlï¼½ (P<0.05). Further analysis of the expression levels of the cytokines in non-CNSI group (n=32), IL-6, IL-10, CXCL-13 level and IL-10/IL-6 ratio in the protein elevated group (n=12) were higher than those in the protein normal group (n=20), but the difference was not statistically significant. CONCLUSION: The levels of IL-6, IL-10 and CXCL-13 in CSF of lymphoma patients with CNS infiltration were higher than those in non-CNS infiltration group, and those in patients with protein elevated group are higher than those in the protein normal group.

High-throughput synapse-resolving two-photon fluorescence microendoscopy for deep-brain volumetric imaging in vivo.

Optical imaging has become a powerful tool for studying brains in vivo. The opacity of adult brains makes microendoscopy, with an optical probe such as a gradient index (GRIN) lens embedded into brain tissue to provide optical relay, the method of choice for imaging neurons and neural activity in deeply buried brain structures. Incorporating a Bessel focus scanning module into two-photon fluorescence microendoscopy, we extended the excitation focus axially and improved its lateral resolution. Scanning the Bessel focus in 2D, we imaged volumes of neurons at high-throughput while resolving fine structures such as synaptic terminals. We applied this approach to the volumetric anatomical imaging of dendritic spines and axonal boutons in the mouse hippocampus, and functional imaging of GABAergic neurons in the mouse lateral hypothalamus in vivo.

In vivo measurement of afferent activity with axon-specific calcium imaging.

In vivo calcium imaging from axons provides direct interrogation of afferent neural activity, informing the neural representations that a local circuit receives. Unlike in somata and dendrites, axonal recording of neural activity-both electrically and optically-has been difficult to achieve, thus preventing comprehensive understanding of neuronal circuit function. Here we developed an active transportation strategy to enrich GCaMP6, a genetically encoded calcium indicator, uniformly in axons with sufficient brightness, signal-to-noise ratio, and photostability to allow robust, structure-specific imaging of presynaptic activity in awake mice. Axon-targeted GCaMP6 enables frame-to-frame correlation for motion correction in axons and permits subcellular-resolution recording of axonal activity in previously inaccessible deep-brain areas. We used axon-targeted GCaMP6 to record layer-specific local afferents without contamination from somata or from intermingled dendrites in the cortex. We expect that axon-targeted GCaMP6 will facilitate new applications in investigating afferent signals relayed by genetically defined neuronal populations within and across specific brain regions.