We utilized Near-Infrared (NIR) spectroscopy to closely investigate the activation change in anterior prefrontal cortex (aPFC) during verbal anagram problem-solving and learning. We used a parametric design of anagram-solving with three difficulty levels and evaluated anagram skill with two sets of subjects and protocols. The first protocol was a one-time evaluation of untrained subjects (n = 10) and the second protocol evaluated subjects over 6 weeks of training (n = 6). The untrained subjects in the first protocol demonstrated blood oxygenation corresponding to neuronal activation in the aPFC in response to medium and hard difficulty levels of the stimuli, while the easy anagram task deoxygenated the aPFC bilaterally, corresponding to deactivation. Higher performers have more aPFC activation than lower performers in the medium difficulty level anagram-solving task. Six weeks of training in the second protocol showed that training reduced oxygenation in aPFC. In particular, subjects with lower baseline skill in anagram production showed a larger reduction in oxygenation where true performance gains occurred (medium difficulty) and smaller reduction where the performance gains were limited (hard anagrams). Association of the aPFC activation with the difficulty of the complex task suggests that aPFC is a part of a circuit for execution of task performance. In addition, more use of aPFC by untrained high performers suggests that the role of the aPFC is to increase efficiency of a problem-solving task. Thus, the NIR spectroscopy showed that the aPFC is a key structure in the circuit implementing the development of anagram skill.

Severe body stress induced by hypoxemia and hypotension may lead to total body energy state deterioration. The perfusion of the most vital organs is maintained at the expense of “less vital” organs. In the present study, we used a multi-site multiparametric (MSMP) monitoring system for real-time evaluation of tissue blood flow (TBF) and mitochondrial NADH fluorescence of the brain and the small intestine following hemorrhage. In Group 1, uncontrolled hemorrhage, mean arterial pressure (MAP) was decreased to 40mmHg within 2 minutes and shed blood was re-infused after 30minutes. In Group 2, controlled hemorrhage, during the 30minutes of hemorrhage, MAP was kept at 40mmHg. During hemorrhage, in both groups, the intestinal TBF and NADH deteriorated, while the brain remained relatively well protected. In Group 1, all parameters partly recovered within the hemorrhage phase, while in Group 2, complete recovery occurred only after resuscitation. At the end of the experiment, both models showed a decrease in intestinal viability (TBF decreased, NADH increased), while the brain metabolic state in Group 2 declined slightly. Our unique multi-parametric monitoring device demonstrated that, under hemorrhage, the small intestine responded entirely differently from the brain. This may suggest the potential usefulness of the monitoring of less vital organs, as proxy organs, in critical conditions such as massive hemorrhage. The present study also highlights the importance of mitochondrial function monitoring in similar conditions in the clinical environment.

Hyperbaric oxygenation (HBO) treatment protocols utilize low pressures up to 3ATA. Higher pressures may induce side effects such as convulsions due to brain toxicity. The optimal HBO pressure allowing for maximal therapy and minimal toxicity is under controversy. However, it can be evaluated by monitoring oxygen delivery, saturation, and consumption. In this study, the monitoring system fixed on the rats’ brain cortex included a time-sharing fluorometer-reflectometer for monitoring mitochondrial NADH and hemoglobin oxygenation (HbO2) combined with Laser Doppler Flowmetry (LDF) for blood-flow monitoring. Rats were located in a hyperbaric chamber and exposed to different pressures. The HBO pressure caused an increase in HbO2 and a decrease in NADH in proportion to the increase in hyperbaric pressure, up to a nearly maximum effect at 2.5ATA. At 6ATA, 15 minutes before convulsions started, blood volume and NADH started to increase, while tissue O2 supply by hemoglobin remained stable. Oxygen pool includes oxygen dissolved in the plasma and also bounded to hemoglobin. Above 2.5ATA, hemoglobin is fully saturated and the oxygen pool nourishment derives only from the oxygen dissolved in the plasma, exceeding the physiological ability for autoregulation; hence, homeostasis is disturbed and convulsions appear. This information is vital because pressures around 2.5ATA–3ATA are standard clinically applied pressures used to treat most of the pathophysiological problems considering the potential benefit which must be balanced against the potential toxicity. This study enables, for the first time, to evaluate the oxygenation level of hemoglobin in the microcirculation. Furthermore, our study showed that additional oxygen pressure (above 2.5ATA) caused brain oxygen toxicity within a short variable period of time after the pressure elevation.

Compared with event-related potential (ERP) which is widely used in psychology research, functional near-infrared imaging (fNIRI) is a new technique providing hemodynamic information related to brain activity, except for electrophysiological signals. Here, we use both these techniques to study ocular attention. We conducted a series of experiments with a classic paradigm of ocular nonselective attention, and monitored responses with fNIRI and ERP respectively. The results showed that fNIRI measured brain activations in the left prefrontal lobe, while ERPs showed activation in frontal lobe. More importantly, only with the combination measurements of fNIRI and ERP, we were then able to find the pinpoint source of ocular nonselective attention, which is in the left and upper corner in Brodmann area 10. These results demonstrated that fNIRI is a reliable technique in psychology, and the combination of fNIRI and ERP can be promising to reveal more information in the research of brain mechanism.

Photoacoustic molecular imaging, combined with the reporter-gene technique, can provide a valuable tool for cancer research. The expression of the lacZ reporter gene can be imaged using photoacoustic imaging following the injection of X-gal, a colorimetric assay for the lacZ-encoded enzyme β-galactosidase. Dual-wavelength photoacoustic microscopy was used to non-invasively image the detailed morphology of a lacZ-marked 9L gliosarcoma and its surrounding microvasculature simultaneously in vivo, with a superior resolution on the order of 10 μm. Tumor-feeding vessels were found, and the expression level of lacZ in tumor was estimated. With future development of new absorption-enhancing reporter-gene systems, we anticipate this strategy can lead to a better understanding of the role of tumor metabolism in cancer initiation, progression, and metastasis, and in its response to therapy.

The collateral circulation is crucial for the pathophysiology and outcome of acute cortical ischemia. Current understanding of collateral circulation still remains sparse, largely due to prior limitations of spatial or/and temporal resolution in methods to evaluate these diminutive redistributive routes of cerebral blood flow (CBF) especially in leptomeningeal anastomoses that connected cortical arteries. In the study, based on a mini-stroke model, laser speckle imaging with high spatiotemporal resolution was used to assess the dynamic evolution of the collateral circulation around a mini-ischemia in the rat cortex. We found that the blood flow and diameter in the intra-arterial anastomoses were enhanced immediately after the ligation of one branch of middle cerebral artery and recovered to baseline level as arterial recirculation was performed. Whereas the communicative flow-through of the posterior cerebral artery and the middle cerebral artery anastomoses was not significant enough to be determined. This is the evidence that intra-arterial anastomoses were the primary routes to restore blood flow into the ischemic territory during the acute phase of ischemia, and laser speckle imaging method was proven as a powerful tool to be potential for subserving further investigation of the collateral circulation.

We have applied functional near-infrared spectroscopy (fNIRS) to the human forehead to distinguish different levels of mental workload on the basis of hemodynamic changes occurring in the prefrontal cortex. We report data on 3 subjects from a protocol involving 3 mental workload levels based on to working memory tasks. To quantify the potential of fNIRS for mental workload discrimination, we have applied a 3-nearest neighbor classification algorithm based on the amplitude of oxyhemoglobin (HbO2) and deoxyhemoglobin (HbR) concentration changes associated with the working memory tasks. We have found classification success rates in the range of 44%–72%, which are significantly higher than the corresponding chance level (for random data) of 19.1%. This work shows the potential of fNIRS for mental workload classification, especially when more parameters (rather than just the amplitude of concentration changes used here) and more sophisticated classification algorithms (rather than the simple 3-nearest neighbor algorithm used here) are considered and optimized for this application.

The fundamental limitations of most vascular-based functional neuroimaging techniques are placed by the fact how fine the brain regulates the blood supply system. In vivo mapping of the cerebral microcirculation with high resolution and sensitivity hence becomes unprecedentedly compelling. This paper reviews the theoretical background of the laser speckle contrast imaging (LSCI) technique and attempts to present a complete framework stemming from a simple biophysical model. Through the sensitivity analysis, more insights into the tool optimization are attained for in vivo applications. Open questions of the technical aspects are discussed within this unified framework. Finally, it concludes with a brief perspective of future research in a way analogous to the magnetic resonance imaging (MRI) technique. Such exploration could catalyze their development and initiate a technological fusion for precise assessment of blood flow across various spatial scales.

Loop-mediated isothermal amplification (LAMP) is a novel nucleic acid amplification method. Compared with the widely utilized polymerase chain reaction (PCR), LAMP has higher speed and efficiency as well as lower requirement for system temperature control because the whole amplification process is isothermal and no efforts are needed to switch between different temperatures. In this paper, we designed and fabricated different kinds of polycarbonate (PC) microfluid chips, explored appropriate reaction condition for LAMP in microenvironment (1 nL→10 μL), and developed a microfluidic isothermal amplification detection system. The DNA optimal amplification temperature is obtained; the starting time of exponential amplification of DNA is put forward farther. The optimal condition of DNA amplification in microenvironment, with a little reaction materials and early starting exponential amplification time of DNA are very important for clinic DNA detection and the application of Lab-on-a-Chip.

This article gives an overview of the development and applications of the surfaceenhanced Raman scattering (SERS) techniques in biomedicine. We first introduce the fundamental principles of the SERS mechanisms. We also present the different fabrication techniques of SERS nanostructures and substrates. Finally, the importance and potential roles of the SERS nanostructures and substrates in biomedical applications are summarized.

Photobiomodulation (PBM) has been reported to have effects on respiratory burst of polymorphonuclear neutrophils (PMNs), but little focus was on the individual differences of human PMNs. The latter was investigated in this study. The PMNs were isolated from peripheral blood of 13 volunteers (10 ordinary persons, 3 athletes) and treated by red light (640 ± 15 nm) from light emitting diodes (RLED) at 50, 100, 300, 500 and 1000 J/m2 for 100 seconds, respectively. Blood samples of athletes were extracted at different running stages in 10 km non-interrupted long-distance running, before running, 1 hour after running began, just finishing the running, resting for 1 hour and 2 hours after running. The PMN respiratory burst was assessed by the nitroblue tetrazolium test. It was found that there were three types of RLED PBM on the respiratory burst of 3 types of PMNs, respectively, inducing for the subactivated PMNs, inhibiting for the overactivated PMNs and none for the PMNs in homeostasis. It was then concluded that there may be RLED PBM on dysfunctional human PMNs while none on those in homeostasis, and RLED at 300 J/m2 for 100 seconds may have bi-direction modulation on PMN respiratory burst.