The influence of the hypophysis upon the calorigenic action of catecholamines

Zusammenfassung Durch Hypophysektomie wird die kalorigene Wirkung von Noradrenalin bei 23–28 sowie 63 Tage alten Ratten fast vollständig aufgehoben, während die Wirkung von 2,4-Dinitrophenol kaum beeinflusst wird.     

Roles of PPARs in health and disease

In developed societies, chronic diseases such as diabetes, obesity, atherosclerosis and cancer are responsible for most deaths. These ailments have complex causes involving genetic, environmental and nutritional factors. There is evidence that a group of closely related nuclear receptors, called peroxisome proliferator-activated receptors (PPARs), may be involved in these diseases. This, together with the fact that PPAR activity can be modulated by drugs such as thiazolidinediones and fibrates, has instigated a huge research effort into PPARs. Here we present the latest developments in the PPAR field, with particular emphasis on the physiological function of PPARs during various nutritional states, and the possible role of PPARs in several chronic diseases.     

Perception of three-dimensional shape influences colour perception through mutual illumination

Objects in the natural world possess different visual attributes, including shape, colour, surface texture and motion. Previous perceptual studies have assumed that the brain analyses the colour of a surface independently of its three-dimensional shape and viewing geometry, although there are neural connections between colour and two-dimensional form processing early in the visual pathway. Here we show that colour perception is strongly influenced by three-dimensional shape perception in a novel, chromatic version of the Mach Card--a concave folded card with one side made of magenta paper and the other of white paper. The light reflected from the magenta paper casts a pinkish glow on the white side. The perceived colour of the white side changes from pale pink to deep magenta when the perceived shape of the card flips from concave to convex. The effect demonstrates that the human visual system incorporates knowledge of mutual illumination-the physics of light reflection between surfaces--at an early stage in colour perception.     

The calorigenic action of norepinephrine in rats after hypophysectomy

Zusammenfassung 2–4 h nach Hypophysektomie erhöht Noradrenalin den Sauerstoffverbrauch wie bei Kontrollratten, 7 Tage nach der Entfernung der Hypophyse ist jedoch diese Wirkung des Noradrenalin aufgehoben. Die CO₂-Abgabe verhält sich qualitativ wie der Sauerstoffverbrauch.     

Apparent surface curvature affects lightness perception

The human visual system has the remarkable capacity to perceive accurately the lightness, or relative reflectance, of surfaces, even though much of the variation in image luminance may be caused by other scene attributes, such as shape and illumination. Most physiological, and computational models of lightness perception invoke early sensory mechanisms that act independently of, or before, the estimation of other scene attributes. In contrast to the modularity of lightness perception assumed in these models are experiments that show that supposedly 'higher-order' percepts of planar surface attributes, such as orientation, depth and transparency, can influence perceived lightness. Here we show that perceived surface curvature can also affect perceived lightness. The results of the earlier experiments indicate that perceiving luminance edges as changes in surface attributes other than reflectance can influence lightness. These results suggest that the interpretation of smooth variations in luminance can also affect lightness percepts.     

人类早期视皮层对边缘所有权的选择性以及注意的调节作用

自然场景中的物体通常是互相遮挡的,识别这些物体的关键在于确定不同图像区域之间的边缘属于哪一个物体。然而,对于人类视皮层如何编码边缘所有权这个问题,我们知之甚少。在本研究中,我们设计了两个简单有效的视觉刺激作为实验材料。在这些刺激中,对情境信息的微小变动就可以导致边缘所有权的彻底改变。利用功能性核磁共振适应的方法,我们发现次级视皮层对边缘所有权显示了稳定可靠的选择性,而且这种选择性依赖于注意过程。本研究提供了第一个以人类被试为研究对象的实验证据,结果表明次级视皮层是对边缘所有权进行加工的关键区,而且该加工依赖于高级皮层区的调节反馈。