Structural and functional imaging of brains

Analyzing the complex structures and functions of brain is the key issue to understanding the physiological and pathological processes.Although neuronal morphology and local distribution of neurons/blood vessels in the brain have been known,the subcellular structures of cells remain challenging,especially in the live brain.In addition,the complicated brain functions involve numerous functional molecules,but the concentrations,distributions and interactions of these molecules in the brain are still poorly understood.In this review,frontier techniques available for multiscale structure imaging from organelles to the whole brain are first overviewed,including magnetic resonance imaging(MRI),computed tomography(CT),positron emission tomography(PET),serial-section electron microscopy(ss EM),light microscopy(LM)and synchrotron-based X-ray microscopy(XRM).Specially,XRM for three-dimensional(3D)imaging of large-scale brain tissue with high resolution and fast imaging speed is highlighted.Additionally,the development of elegant methods for acquisition of brain functions from electrical/chemical signals in the brain is outlined.In particular,the new electrophysiology technologies for neural recordings at the single-neuron level and in the brain are also summarized.We also focus on the construction of electrochemical probes based on dual-recognition strategy and surface/interface chemistry for determination of chemical species in the brain with high selectivity and long-term stability,as well as electrochemophysiological microarray for simultaneously recording of electrochemical and electrophysiological signals in the brain.Moreover,the recent development of brain MRI probes with high contrast-to-noise ratio(CNR)and sensitivity based on hyperpolarized techniques and multi-nuclear chemistry is introduced.Furthermore,multiple optical probes and instruments,especially the optophysiological Raman probes and fiber Raman photometry,for imaging and biosensing in live brain are emphasized.Finally,a brief perspective on existing challenges and further research development is provided.

Recent advances in development of devices and probes for sensing and imaging in the brain

As the most important part of the central nervous system,the brain is extremely complex in structure and function.In vivo analysis of chemical signals is an essential way to investigate brain activity and function.Although functional magnetic resonance imaging(fMRI)or electrophysiology can be used to record brain activity,they are usually limited by low spatiotemporal fidelity or the difficulty of distinguishing the contributions of various neurochemicals.In addition,the development of in vivo biosensors with high selectivity and accuracy is essential to understand the roles that neurochemicals play in the brain.In this review,we focus on the development of instruments and devices for recording chemical signals in the live brain.Meanwhile,the strategies for development of electrochemical and fluorescent probes with high selectivity,high accuracy and good stability are also summarized.In particular,this review highlighted the contributions of our research group to this field.The development of techniques and probes enable us to understand the brain structure and function,and the mechanism of brain diseases,providing the solution for preventing and treating brain diseases.