Invariant visual representation by single neurons in the human brain

It takes a fraction of a second to recognize a person or an object even when seen under strikingly different conditions. How such a robust, high-level representation is achieved by neurons in the human brain is still unclear. In monkeys, neurons in the upper stages of the ventral visual pathway respond to complex images such as faces and objects and show some degree of invariance to metric properties such as the stimulus size, position and viewing angle. We have previously shown that neurons in the human medial temporal lobe (MTL) fire selectively to images of faces, animals, objects or scenes. Here we report on a remarkable subset of MTL neurons that are selectively activated by strikingly different pictures of given individuals, landmarks or objects and in some cases even by letter strings with their names. These results suggest an invariant, sparse and explicit code, which might be important in the transformation of complex visual percepts into long-term and more abstract memories.     

Correlation of ammonia liberation and calcium deposition by the avian egg and blood ammonia levels in the laying hen

Zusammenfassung Mittels biochemischer Daten wird der Nachweis erbracht, dass im Ovidukt des Huhnes während der Schalenbildung zwar vermehrt NH₄ ⁺ freigesetzt wird, jedoch eine negative Korrelation zwischen NH₄ ⁺-Produktion und Ca⁺⁺-Abscheidung besteht.

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Supported by a training grant from the U.S. Public Health Service No. 5-T1-DE-118. We thank Dr.P. R. Tramell for his help during the initial stage of this investigation.     

Circadian rhythmicity in phosphorylase activity and glycogen content in the heart muscle of the scorpion,Heterometrus fulvipes,C.L. Koch

Summary Maximal activity levels of phosphorylase A and AB at 20.00 h alternate with minimal levels at 08.00 h of the day, while the glycogen content exhibited a reverse trend in the heart of the scorpion,Heterometrus fulvipes.Acknowledgment. The authors thank Prof. K.S. Swami, for providing facilities. The financial assistance rendered by UGC (to VJ) and ICMR (to DCR) is gratefully acknowledged.     

Hepatopancreatic amylase activity as a function of warm-adaptation in a fresh-water field crab

Zusammenfassung Im Hepatopankreas der Krabben sind Fermentsysteme, die eine Wärmeadaptation besitzen. Diese lässt sich mit ähnlichen physiologischen Erscheinungen bei kaltblütigen Vertebraten vergleichen.     

Dial variations in the levels of blood glucose and hepatopancreatic glycogen in the slug,Laevicaulis alte (Ferussac 1821)

Summary InLaevicaulis alte maximal blood glucose level at 00.00 h alternates with minimal level at 12.00 h of the day, while hepatopancreatic glycogen showed an opposite trend. Variations in blood glucose levels are inversely proportional to the corresponding variations in hepatopancreatic glycogen content, while blood glucose level shoots up to a maximum, hepatopancreatic glycogen declines to a minimum and vice versa.Acknowledgment. The authors thank Prof. K.S. Swami for providing facilities. The financial assistance rendered by ICMR (DCR), UGC (VJ) and CSIR (KS), New Delhi, India is gratefully acknowledged.     

Hyperglycemic activity of crab and scorpion hormones in grasshopper (Poecilocerus pictus)

Summary Hyperglycemic hormones obtained from crab and scorpion both cause significant, dose-dependent elevations of hemolymph sugars in the grasshopperPoecilocerus pictus. These results suggest a highly conservative evolution of some mandibulate arthropod neuro-hormones.This work was supported by CSIR grant to PSR.