Signal propagation in 2-dimensional threshold cellular space

Summary A two-dimensional network of uniformly connected McCulloch-Pitts neurons is considered and signal propagations in the network are analyzed. The problems are set up in the framework of cellular space such that each cell is a copy of any given McCulloch-Pitts neuron and is connected to the nearest neighboring cells. It is assumed that the threshold value is positive and that there exists only one firing cell at the beginning. Then it is shown that essentially there are only four signal propagation patterns and a firing pattern at any time t can be obtained by such a superposition of the propagation patterns that includes the newly defined concept of dominance and assimilation. The exact formulae representing firing patterns at any time t are obtained for any finite rectangle cell space with constant 0 (i.e., non-firing) boundary condition and for the entire two-dimensional cellular space.     

The active space of blue monkey and grey-cheeked mangabey vocalizations

The audible distance of 11 primate vocalizations uttered by blue monkeys, Cercopithecus mitis, and grey-cheeked mangabeys, Cercocebus albigena, and the human utterance ‘hey’ were determined experimentally. Calculations were based on measurements of (1) sound power of vocal signals (Brown: Bioacoustics, in press), (2) the attenuation rates of sound of different frequencies in East African forests (Waser & Brown: Am. J. Primatol., 1986, 10, 135–154), and (3) sensitivity of conspecific listeners to vocal signals presented in forest noise. Calculations were made of the active space, the area over which a call is audible, and the expected number of recipients of signals in nature. Masked thresholds for test vocalizations ranged from 21·1 dB for the mangabey ‘staccato bark’ call to 41·3 dB for the blue monkey ‘boom’ vocalization. The audible distance of the test signals ranged from 79 m for the blue monkey ‘chirp’ call to 1951 m for the mangabey ‘chorused grunt’ vocalization. Calls could be grouped into short- and long-range signals. The audible distance of primate long-range calls varied between 2·4 and nine times that of a typical yell given by human subjects. The active space of the test signals ranged from 1·4 to 1031·8 ha. The mean active space of monkey long-range calls (445·4 ha) was more than an order of magnitude greater than the loudest human yell. The average blue monkey long-range call was audible for 870 m, while the average mangabey long-range call was audible for 1800 m. The typical mangabey home range is four times that of the blue monkey, and in both species the average long-range call had an audible distance twice the diameter of the median home range of each species.     

The differentiation of color signals by the frog retina]

Multidimensional scaling of principal interstimulus chromatic differences, measured by the value of ERG reaction of the frog retina allowed to construct a model reflecting colour differentiating function of this level. It follows from this model that the frog retina has colour differentiating characteristics answering standard requirements of trichromatic vision. Colour-opponent system of frog is represented by the functions of red-green and blue-yellow opponentness compared with the analogous functions obtained for man.     

Kinematic study of reaching-grasping movements in the monkey]

Kinematics of reaching-grasping movement towards stimuli of three different sizes located at two different distances were studied in one monkey (Macaca nemestrina). Transport and manipulation components were analyzed using the ELITE system. Transport time, peak velocity and deceleration phase of velocity were influenced by stimulus size, whilst acceleration phase remained unmodified. Peak velocity clearly increased with distance, while transport time remained constant (isochrony ). The main parameters of manipulation component were all influenced by stimulus size but they did not vary with distance. A comparison with kinematic data obtained from human subjects was made.     

A 3-dimensional presentation of the functional liver unit]

The reconstruction of the liver parenchyma of a golden hamster after poisoning with allyl formate is described. Allyl formate primarily destroys the periportal areas and leads, following the microvascularisation of the liver parenchyma, to a necrosis of the hepatocytes progressing towards the terminal hepatic venule. The still intact parenchymal zones can be characterized by the positive PAS reaction. In this study the preterminal and the terminal portal branches as well as zone 3, situated in the vasculatory periphery, were reconstructed. By this method, a three-dimensional presentation of the acinar functional zones was possible for the first time.     

Orientation of attention in the visual space]

The display was composed of four boxes, horizontally aligned above the fixation point. In Experiment I, each box was cued by a digit shown at fixation. In Experiment II there were only two numeric cues, signalling the inner or the outer boxes, depending on the experimental condition. The subject was instructed to orient attention to the cued box, and to respond to the imperative stimulus as fast as possible, wherever it appeared. By using four time interval (SOAs), we tried to determine the route covered by attention movements. In Experiment I, with the shortest SOA (100 msec), it was shown that attention does not reach the cued box through a direct path. Rather it moves first on the inner boxes, thereafter focusing on the cued location. The same results were obtained in Experiment II, where the cue directed attention to the inner boxes. When the external boxes were cued, however, this trend was not observed.     

Optimization of behavior by minimization of displeasure in a 2-dimensional sensory space

Three healthy young adult males were placed on a treadmill geared to five speeds and five slopes in combination. At minute 16 they gave estimates of displeasure for sensations aroused in their chest and lower limbs. These estimates were compared to the operant choice of the subjects when they were given the task, in other sessions, of climbing up 300 m on the treadmill at varying speeds and slopes. When speed was imposed, they could adjust slope and reciprocally. The were instructed that the session would end when they had reached the 300 m elevation. The results showed that the subjects adjusted slope and speed inversally; time for climbing up 300 m was almost constant, i.e. they tended to work at constant power in various conditions. Such performance could be predicted from the sum of ratings of displeasure aroused in the lower limbs and in the chest. These results suggest that optimalization of behaviour was obtained by minimization of bidimensional displeasure.     

Allelic variation in the squirrel monkey x-linked color vision gene: biogeographical and behavioral correlates

Most Neotropical primate species possess a polymorphic X-linked and a monomorphic autosomal color vision gene. Consequently, populations are composed of both dichromatics and trichromatics. Most theories on the maintenance of this genetic system revolve around possible advantages for foraging ecology. To examine the issue from a different angle, we compared the numbers and relative frequencies of alleles at the X-linked locus among three species of Saimiri representing a wide range of geographical and behavioral variation in the genus. Exons 3, 4, and 5 of the X-linked opsin gene were sequenced for a large number of X chromosomes for all three species. Several synonymous mutations were detected in exons 4 and 5 for the originally reported alleles but only a single nonsynonymous change was detected. Two alleles were found that appeared to be the result of recombination events. The low occurrence of recombinant alleles and absence of mutations in the amino acids critical for spectral tuning indicates that stabilizing selection acts to maintain the combinations of critical sites specific to each allele. Allele frequencies were approximately the same for all Saimiri species, with a slight but significant difference between S. boliviensis and S. oerstedii. No apparent correlation exists between allele frequencies and behavioral or biogeographical differences between species, casting doubt on the speculation that the spectral sensitivities of the alleles have been maintained because they are specifically well-tuned to Saimiri visual ecology. Rather, the spectral tuning peaks might have been maintained because they are as widely spaced as possible within the limited range of middlewave to longwave spectra useful to all primates. This arrangement creates a balance between maximizing the distance between spectral tuning peaks (allowing the color opponency of the visual system to distinguish between peaks) and maximizing the number of alleles within a limited range (yielding the greatest possible frequency of heterozygotes).     

Assignment of alpha-Fuc to1p in man and the chimpanzee and to chromosome 4 in the African green monkey]

Analysis of cellular hybrids confirms the assignment of alpha-L-fucosidase (alpha-FUC) to 1p in man. Discordant results are in favour of the following gene order: 1pter (ENO-1, alpha-FUC,AK2) PGM1 centromere Pep-C but give no information on the relative positions of ENO-1,alpha-FUC, and AK2. The assignments of alpha-FUC to chromosome 1 in the chimpanzee and to chromosome 4 in the African green monkey are demonstrated (chromosome nomenclature by Finaz et al, 1976). These results confirm the homology of chromosome 4 of the African green monkey and 1p of man and the chimpanzee.     

3-dimensional characterization of the synoviocytes of the human synovial intima]

The intimal synovial surface in normal conditions, using a scanning electron microscope, has been studied. The three synovial membrane types are clearly recognizable: fibrous (Fig. 8), adipose (Figs. 9 and 10) and areolar (Figs. 1 and 2); but only in the areolar type, the characterization of the main two cellular types: synoviocytes B and A, is possible. Synoviocyte B represents the constitutive element which characterizes the synovial intima; it has a cellular body of irregular shape and long cytoplasmic processes directed towards the joint cavity (Figs. 3, 4 and 5). The cellular body and the cytoplasmic processes are covered by small blebs (Fig. 6). and similar vesicles, probably of the same cellular origin, are scattered throughout the extracellular matrix. These cells are likely responsible for the specific structure of the interstitial tissue adapted to the exchanges and to the regulation of the composition of the synovial fluid (Okada et. al. 1981; Linck and Porte, 1978, 1981). Synoviocyte A is a small minority; it has many long and irregular membrane infoldings which define a complicated system of intracellular canaliculi of various depth (Fig. 7). The ultrastructural characteristics of their surface and the peculiarity of their organelle apparatus, described by other AA. (Fell et. al., 1976), demonstrate that these elements carry out a macrophagic function. The clear majority of the synoviocytes B in the intimal surface suggests that in normal conditions, the synthesizing processes prevail over the phagocytosis ones.     

Vector mathematical model for the analysis of complex movements in 3-dimensional space exemplified by the divided symphysis

For the analysis of complex movements in the divided pubic symphysis of cadavers a vector-mathematical model was developed. Overall movements is analysed in components, as translations in the three dimensions of space and rotations around the three axes of space, as error-free and as simply as possible by measuring the distances to different defined points. Experimental conditions, the development of a vector-mathematical system of analysis, error analysis and interpretation of results are shown. With this method it also possible to analyse similar problems in the same way.