Understanding brain structure and function, and the complex relationships between them, is one of the grand challenges of contemporary sciences. Thanks to their flexibility, optical techniques could be the key to explore this complex network. In this manuscript, we briefly review recent advancements in optical methods applied to three main issues: anatomy, plasticity and functionality. We describe novel implementations of light-sheet microscopy to resolve neuronal anatomy in whole fixed brains with cellular resolution. Moving to living samples, we show how real-time dynamics of brain rewiring can be visualized through two-photon microscopy with the spatial resolution of single synaptic contacts. The plasticity of the injured brain can also be dissected through cutting-edge optical methods that specifically ablate single neuronal processes. Finally, we report how nonlinear microscopy in combination with novel voltage sensitive dyes allow optical registrations of action potential across a population of neurons opening promising prospective in understanding brain functionality. The knowledge acquired from these complementary optical methods may provide a deeper comprehension of the brain and of its unique features.

Cellular pathways are ordinarily diagnosed with pathway inhibitors, related gene regulation, or fluorescent protein markers. They are also suggested to be diagnosed with pathway activation modulation of photobiomodulation (PBM) in this paper. A PBM on a biosystem function depends on whether the biosystem is in its function-specific homeostasis (FSH).An FSH, a negative feedback response for the function to be performed perfectly, is maintained by its FSH-essential subfunctions and its FSH-non-essential subfunctions (FNSs). A function in its FSH or far from its FSH is called a normal or dysfunctional function. A direct PBM may self-adaptatively modulate a dysfunctional function until it is normal so that it can be used to discover the optimum pathways for an FSH to be established. An indirect PBM may self-adaptatively modulate a dysfunctional FNS of a normal function until the FNS is normal, and the normal function is then upgraded so that it can be used to discover the redundant pathways for a normal function to be upgraded.

Singlet oxygen (¹O₂) is a highly reactive oxygen species involved in numerous chemical and photochemical reactions in different biological systems and in particular, in photodynamic therapy (PDT). However, the quantification of ¹O₂ generation during in vitro and in vivo photosensitization is still technically challenging. To address this problem, indirect and direct methods for ¹O₂ detection have been intensively studied. This review presents the available methods currently in use or under development for detecting and quantifying ¹O₂ generation during photosensitization. The advantages and limitations of each method will be presented. Moreover, the future trends in developing PDT-¹O₂ dosimetry will be briefly discussed.

Microwave-induced thermoacoustic tomography (TAT) is a noninvasive, nonionizing modality based on the inherent differences in microwave absorption of malignant breast tissues and normal adipose-dominated breast tissues. In this paper, a TAT system based on multielement acquisition system was built to receive signals. Slices from different layers in the sample were composed into a three-dimensional (3D) volume. Based on the 3D volume, inherent differences in microwave absorption between different biological tissues can be converted into structure information. Our experimental results of some mimicked and human tumors indicate that TAT may potentially be used to detect early-stage breast cancers with high contrast.

sparse coding method, which can effectively reduce the dimension of the neuronal activity and express neural coding. Multichannel spike trains were recorded in rat prefrontal cortex during a work memory task in Y-maze. As discrete signals, spikes were transferred into continuous signals by estimating entropy. Then the normalized continuous signals were decomposed via non-negative sparse method. The non-negative components were extracted to reconstruct a low-dimensional ensemble, while none of the feature components were missed. The results showed that, for welltrained rats, neuronal ensemble activities in the prefrontal cortex changed dynamically during the working memory task. And the neuronal ensemble is more explicit via using non-negative sparse coding. Our results indicate that the neuronal ensemble sparse coding method can effectively reduce the dimension of neuronal activity and it is a useful tool to express neural coding.

Our research has identified a couple of near-infrared (NIR) heptamethine indocyanine dyes exhibiting preferential tumor accumulation property for in vivo imaging. On the basis of our foregoing work, we describe here a preliminary structure-activity relationship (SAR) study of 11 related heptamethine indocyanine dyes and several essential requirements of these structures for in vivo tumor-targeted imaging.

Multiphoton microscopy (MPM), based on two-photon excited fluorescence and second harmonic generation, enables direct noninvasive visualization of tissue architecture and cell morphology in live tissues without the administration of exogenous contrast agents. In this paper, we used MPM to image the microstructures of the mucosa in fresh, unfixed, and unstained intestinal tissue of mouse. The morphology and distribution of the main components in mucosa layer such as columnar cells, goblet cells, intestinal glands, and a little collagen fibers were clearly observed in MPM images, and then compared with standard H&E images from paired specimens. Our results indicate that MPM combined with endoscopy and miniaturization probes has the potential application in the clinical diagnosis and in vivo monitoring of early intestinal cancer.

The reflectance spectrum has been widely adopted to extract diagnosis information of human tissue because it possesses the advantages of noninvasive and rapidity. The external pressure brought by fiber optic probe may influence the accuracy of measurement. In this paper, a systematic study is focused on the effects of probe pressure on intrinsic changes of water and scattering particles in tissue. According to the biphasic nonlinear mixture model, the pressure modulated reflectance spectrum of both in vitro and in vivo tissue is measured and processed with second-derivation. The results indicate that the variations of bulk and bonded water in tissue have a nonlinear relationship with the pressure. Differences in tissue structure and morphology contribute to site-specific probe pressure effects. Then the finite element (FEM) and Monte Carlo (MC) method is employed to simulate the deformation and reflectance spectrum variations of tissue before and after compression. The simulation results show that as the pressure of fiber optic probe applied to the detected skin increased to 80 kPa, the effective photon proportion form dermis decreases significantly from 86% to 76%. Future designs might benefit from the research of change of water volume inside the tissue to mitigate the pressure applied to skin.

trachea stenosis. Microwave tissue coagulation (MTC) and diathermy (MD) therapy via bronchofiberscope were performed on 37 patients with severe trachea stenosis diseases at least two times. The effective rate immediately after treatment was 100% in all cases. After one month, the rate remained 100% in the patients with benign diseases, but it dropped to 67% in the patients with malignant tumors. We have demonstrated that the microwave thermotherapy via bronchofiberscope is an effective method to treat patients with benign trachea stenosis noninvasively. For cancer patients with trachea soakage and blockage, it can be performed to improve their life quality by alleviating their agonies.