Decisions require careful weighing of the risks and benefits associated with a choice. Some people need to be offered large rewards to balance even minimal risks, whereas others take great risks in the hope for an only minimal benefit. We show here that risk-taking is a modifiable behavior that depends on right hemisphere prefrontal activity. We used low-frequency, repetitive transcranial magnetic stimulation to transiently disrupt left or right dorsolateral prefrontal cortex (DLPFC) function before applying a well known gambling paradigm that provides a measure of decision-making under risk. Individuals displayed significantly riskier decision-making after disruption of the right, but not the left, DLPFC. Our findings suggest that the right DLPFC plays a crucial role in the suppression of superficially seductive options. This confirms the asymmetric role of the prefrontal cortex in decision-making and reveals that this fundamental human capacity can be manipulated in normal subjects through cortical stimulation. The ability to modify risk-taking behavior may be translated into therapeutic interventions for disorders such as drug abuse or pathological gambling.

Reputation formation pervades human social life. In fact, many people go to great lengths to acquire a good reputation, even though building a good reputation is costly in many cases. Little is known about the neural underpinnings of this important social mechanism, however. In the present study, we show that disruption of the right, but not the left, lateral prefrontal cortex (PFC) with low-frequency repetitive transcranial magnetic stimulation (rTMS) diminishes subjects' ability to build a favorable reputation. This effect occurs even though subjects' ability to behave altruistically in the absence of reputation incentives remains intact, and even though they are still able to recognize both the fairness standards necessary for acquiring and the future benefits of a good reputation. Thus, subjects with a disrupted right lateral PFC no longer seem to be able to resist the temptation to defect, even though they know that this has detrimental effects on their future reputation. This suggests an important dissociation between the knowledge about one's own best interests and the ability to act accordingly in social contexts. These results link findings on the neural underpinnings of self-control and temptation with the study of human social behavior, and they may help explain why reputation formation remains less prominent in most other species with less developed prefrontal cortices.decision making ͉ social interaction ͉ transcranial magnetic stimulation

For in‐vivo diagnostics of cancer and pre‐cancer in the stomach, there is no endoscopic procedure offering both high sensitivity and high specificity. Our data suggest that multispectral or hyperspectral imaging may be helpful to solve this problem. It is successfully applied to the detection and analysis of easily reachable carcinomas, ex‐vivo samples of hollow organ mucosal carcinomas and also histological samples. An endoscopy system which allows flexible multispectral videoendoscopy for in‐vivo diagnostics has so far been unavailable. To overcome this problem, we modified a standard Olympus endoscopy system to conduct in‐vivo multispectral imaging of the upper GI tract. The pilot study is performed on 14 patients with adeno carcinomas in the stomach. For analysis, Support Vector Machine with linear and Gaussian Kernel, AdaBoost, RobustBoost and Random‐Forest‐walk are used and compared for the data classification with a leave‐one‐out strategy. The margin of the carcinoma for the training of the classifier is drawn by expert‐labeling. The cancer findings are cross‐checked by biopsies. We expect that the present study will help to improve the further development of hyperspectral endoscopy and to overcome some of the problems to be faced in this process.

Laser surgery is a rising surgical technique, which offers several advantages compared to the traditional scalpel. However, laser surgery lacks a contact-free feedback system which offers high imaging contrast to identify the tissue type ablated and also a high penetration depth. Photoacoustic imaging has the potential to fill this gap. Since photoacoustic detection is commonly contact based, a new non-interferometric detection technique based on speckle-analysis for remote detection is presented in this work. Phantom and ex-vivo experiments are carried out in transmission and reflection-mode for proof of concept. In summary, the potential of the remote speckle sensing technique for photoacoustic detection is demonstrated. In future, this technique might be applied for usage as a remote feedback system for laser surgery, which could help to broaden the applications of lasers as smart surgical tools.

Due to significant advantages, the trend in the field of medical technology is moving towards minimally or even non-invasive examination methods. In this respect, optical methods offer inherent benefits, as does diffuse reflectance imaging (DRI). The present study attempts to prove the suitability of DRI—when implemented alongside a suitable setup and data evaluation algorithm—to derive information from anatomically correctly scaled human capillaries (diameter: $$10\,\upmu \hbox {m}$$ 10 μ m , length: $$45\,\upmu \hbox {m}$$ 45 μ m ) by conducting extensive Monte–Carlo simulations and by verifying the findings through laboratory experiments. As a result, the method of shifted position-diffuse reflectance imaging (SP-DRI) is established by which average signal modulations of up to 5% could be generated with an illumination wavelength of $$\lambda =424\,\hbox {nm}$$ λ = 424 nm and a core diameter of the illumination fiber of $$50\,\upmu \hbox {m}$$ 50 μ m . No reference image is needed for this technique. The present study reveals that the diffuse reflectance data in combination with the SP-DRI normalization are suitable to localize human capillaries within turbid media.