Rumination mediates the relationship between structural variations in ventrolateral prefrontal cortex and sensitivity to negative life events.

Individuals have different levels of stress sensitivity. An individual's predisposition to experience negative life events (NLEs) may make him/her more vulnerable to a series of psychopathological and physical diseases. However, the neuroanatomical correlates of individual differences in sensitivity to NLEs remain unknown. In this study, voxel-based morphometry was used to identify the gray matter (GM) associations of individual differences in sensitivity to NLEs measured by adolescent self-rating life events checklist. Results showed that there was a positive association between individual NLEs sensitivity and regional GM volume (rGMV) in the ventrolateral prefrontal cortex (VLPFC). GM was mostly evident in the left frontal operculum and a small part of the left middle frontal gyrus. This region was thought to play an important role in introception. Importantly, our study revealed that rumination served as a mediator between the rGMV of the VLPFC and individual NLEs sensitivity. These findings suggest that people with greater VLPFC might be more inclined to ruminate and the ruminative response style might make them more sensitive to NLEs.

Emotional arousal to negative information after traumatic experiences: an event-related brain potential study.

Event-related brain potentials (ERPs) during an emotional Stroop task were measured in two groups of participants: 14 participants who had experienced the great Sichuan earthquake (earthquake group) and 14 participants who did not experience the earthquake (control group). ERP data showed that negative words elicited a more negative P2 than positive words in the earthquake group. Moreover, negative words also elicited a more negative ERP deflection (N280-380 effect) than positive words in the earthquake group, while this effect was not found in the control group. We suggest that the N280-380 effect may reflect heightened emotional arousal to negative words due to personal experience of a traumatic event. Dipole analysis localized the N280-380 to the parahippocampal gyrus and the cuneus, which we suggest may be related to the automatic recollection of the traumatic experience.

Neural correlates of mental preparation for successful insight problem solving.

A distinct type of mental preparation (activity in medial frontal and temporal areas) had been found to facilitate insight problem solving independent of specific problems [25]. In order to explore whether neural activity during a preparatory interval (mental preparation) is associated with which insight problems would be solved or not, we developed a task that uses Chinese logogriphs (riddles) as materials. Blood oxygenation level-dependent fMRI contrasts between Successful and Unsuccessful mental preparation were measured. Results showed that mental preparation leading to successful problem solving involves heightened activity in the left middle/medial frontal gyrus, the left middle/superior temporal gyrus, the right cerebellum, the bilateral claustrum and the left postcentral gyrus. We discussed the role of these areas in mental preparation for successful insight problem solving.

Optimal design of a thermistor probe for surface measurement of cerebral blood flow.

Microthermistors are put on the surface of cerebral cortex to monitor local cerebral blood flow (CBF) continuously with minimal tissue damage and disturbance to the normal physiological state. Using a distributed, dynamic model of the measurement system, we simulated the effects of this flow measurement method under isothermal and adiabatic boundary conditions. Numerical results show that the adiabatic boundary condition can provide maximal sensitivity to perfusion changes at physiological perfusion levels. The constant power and constant temperature operating modes are compared in terms of output relation, sensitivity, and frequency response through analytical and numerical solutions. While the steady-state relations between thermistor measurements and perfusion for the two modes do not differ significantly, the constant temperature mode has better frequency response. Analytical results show that the relative sensitivity is the same for the two modes and is approximately proportional to the radius of thermistor. If there is an unperfused layer surrounding the thermistor, the sensitivity will decrease as the thickness of the layer increases. Simulations predict that the thermal measurement has a low-pass frequency response and the cutoff frequency is inversely proportional to the probe surface area. The results provide a theoretical foundation to the optimal design of thermistor probe for continuous CBF measurement from tissue surface.

High T(c) superconductor coating: superreflectance and surface waves.

For a high T(c) superconductor, a theory is derived that superreflectance (R = 100%) is due to EM field exclusion but is restricted by the energy gap to the far infrared and longer wavelengths. Presence of ohmic dissipation modifies but does not dramatically change the nature of the results. At oblique incidence, EM exclusion leads to surface waves. An ion beam sputtering method is proposed for coating superconductor on cyrstalline substrates. This method has consistently produced near perfect reflectance from optical interference coatings, and holds great potential in producing superreflectance.

Ion beam interference coating for ultralow optical loss.

Ion beam interference coating (IBIC) is a sputter-deposition process for multiple layers of optical thin films employing a Kaufman gun. It has achieved coatings of extremely low optical loss and high mechanical strength. It has many potential applications for a wide spectral range. This coating process is described in terms of principle, fabrication procedure, and optical measurements. Some discussions follow the history and outlooks of IBIC with emphasis on how to achieve low loss and on the throughput improvements.