Sources of information controlling motor patterns in arthropod local search orientation

Search orientation is controlled by information that is stored genetically, idiothetically or through learning and that is gained from internal and external sensory systems. Sources of variation in motor patterns could derive from any of the types of information, or could originate during the execution of the instructions derived from orientation information. Local search after resource utilization in the flies Musca demestica and Drosophila melanogaster can be addressed as an initial increase in turning rate and decrease in locomotory rate, followed by a transition in both measures to a lower turning rate and a higher locomotory rate characteristic of ranging. The search tactic of flies promotes accrual of discrete resources in a patch. A forward-moving tendency, combined with a “noisy” looping motor pattern, enhances resource-finding in both linear and non-linear resource patterns. The period before a fly leaves a patch—its giving-up-time—is a function of current resource density and the slope of the transition from local search to ranging: once a fly switches to the relatively straight path characteristic of ranging, the chances of it leaving the patch depends on whether or not another resource is encountered. Duration of local search is dependent on the genotype of an individual, level of starvation or satiation, resource quality (sucrose concentration) and quantity (patch size) and presence of resource-specific sensory information.     

The menotactic orientation of the prosobranch mollusc Littorina littorea

The menotactic orientation of the prosobranch mollusc Littorina littorea to a one stripe pattern (Fig. 2) has been investigated under open-loop and closed-loop conditions. Results: 1) Under open-loop conditions the animals try to compensate for an angular deviation of the pattern from the menotactic angular position by turning movements of, on the average, constant angular velocity (Fig. 4). 2) The angular velocity depends on this deviation according to the -characteristic (Fig. 5). The orientation behaviour under closed-loop conditions can be directly derived from the -characteristic. Within experimental limits the snail does not show an optomotor response. 3) To patterns of wedge-shaped intensity distribution the snails orientate at a small angle relative to the edge of the pattern (Fig. 3). The orientation angle of the animals to this pattern is much less variable than the orientation angle to a single light source. The orientation behaviour shows that the intensity gradient of the pattern is important for the orientation of the animal. 4) A normally distributed noise process is superimposed on the average orientation direction. The variance of this noise process is the same for the orientation under open-loop and under closed-loop conditions (Fig. 7). In both cases the power spectrum of the noise process contains pronounced maxima at equally spaced frequencies (Fig. 8).     

Zur Bedeutung der Antennen für die Wahrnehmung der Schwerkraftrichtung bei der Stabheuschrecke Carausius morosus

Summary The result of the following presentation is that antennal receptors affect only the sign of the geotactic turning tendency, but not its amount.     

Mechanisms of gravity processing by leg and abdominal gravity receptors in bees

In Apis florea, the strength of the geotactic turning tendency depends on the inclination γ of the walking plane, from γ = 15° to γ = 90° (vertical). In contrast to Bombus terrestris, pedal proprioreceptors are not involved in gravity reception in A. florea, whereas the petiole organ, as in Bombus, is a gravity receptor. Stimulation of this sense organ, by loading the abdomen of the bee, causes a decrease of the standard deviation of the walking directions from the negative and positive geotactic basic direction.The processing of gravity in Apis cerana is similar to that in Apis mellifera. The metageotactic reaction is controlled by bristle fields of the petiole and by pedal proprioreceptors. Loading the thorax, as well as eliminating the petiole organ, alters the type of geotactic reaction. On the contrary, a simultaneous change of stimulus for the leg organs and the petiolus organ by loading the abdomen does not affect the metageotactic reaction.     

Nest-box choice in the laboratory mouse: Preferences for nest-boxes differing in design (size and/or shape) and composition

The purpose of this paper is to introduce two experimental paradigms used for a laboratory approach to spatial choice behaviour in the mouse. The experimental procedure involves a free-choice spatial situation which allows the development of a long-term behavioural process. The animal is placed in an arena containing two or more nest-boxes to be chosen as nest-sites. These may differ in certain characteristics, such as size, shape, or composition. The experimental procedures are: (1) a series of independent successive choice tests, or “paired comparisons”; (2) a dependent successive choice test, or “forced progressive elimination ranking”. Both procedures have been used to study nest-box choice in mice according to spatial parameters. In Experiment I, “paired comparisons” were used to evaluate the strength of individual preferences for nest-boxes differing in design (size and/or shape), according to whether nest-boxes were open or closed. In Experiment II, the second method was used to analyse individual preferential ranking patterns with series of nest-boxes differing in design or composition. The results of the two types of experiment were complementary regarding the design (size and shape) of the nest-boxes: highest in order of preference were small narrow-sided nest-boxes, followed by small square ones, then the small circular one, and last the big circular ones. Experiment I proved in particular the role of closure in reinforcing the strength of preferences. In Experiment II, on the other hand, the constituent materials did not appear to have any clear influence on preferential ranking patterns for the nest-boxes differing in design; nevertheless, a positive correlation was noted between the classification of objects made of different materials, and the degree of darkness afforded by these materials.     

Odor tracking flight of male Manduca sexta moths along plumes of different cross-sectional area

Males of the hawkmoth, Manduca sexta, track wind-borne plumes of female sex pheromone by flying upwind, while continuously turning from side-to-side and changing altitude. Their characteristic “zigzagging” trajectory has long been thought to result from the interaction of two mechanisms, an odor-modulated orientation to wind and a built-in central nervous system turning program. An interesting and as of yet unanswered question about this tracking behavior is how the cross-section of an odor plume or its clean-air “edges” affects moths’ odor tracking behavior. This study attempts to address this question by video recording and analyzing the behavior of freely flying M. sexta males tracking plumes from pheromone sources of different lengths and orientations with equal odor concentration per unit area. Our results showed that moths generated significantly wider tracks in wide plumes from the longest horizontally-oriented sources as compared to narrower point-source plumes, but had relatively unaltered tracks when orienting to plumes from the same length sources oriented vertically. This suggests that in addition to wind and the presence of pheromones, the area of the plume’s cross section or its edges may also play an important role in the plume tracking mechanisms of M. sexta.     

A Darwinian evolutionary system. 3. Experiments on the evolution of feeding patterns

Another application of the Darwinian evolutionary system introduced earlier is presented. The evolution of spiraling and meandering feeding patterns, as exemplified by the marine polychaete Paraonis fulgens, was simulated by constructing an artificial “worm”, called Rectangulus, because it was capable of turning around 90 ° only. The behavioural program of Rectangulus contained six parameters, which controlled the following properties: (i) turning spontaneously after a given number of steps, (ii) turning before a former track, (iii) avoiding entering a “channel”, i.e. a path flanked by former tracks, (iv) keeping contact with former tracks, (v) performing a turn at the beginning (which in combination with contact-keeping leads to a spiral), and (vi) switching from spiraling to meandering behaviour after a given number of steps. These parameters were binary-coded in the “genomes” of Rectangulus, and were capable of mutating and recombining.Evolutionary experiments were performed with populations consisting of 50 individuals, inhabiting an area of 100 × 100 “unit steps”. Each individual had to “forage” for 140 steps, and the number of successful (uncovered area) and unsuccessful (area covered previously) steps were recorded. Individuals with greater “yield” (successful minus unsuccessful steps, divided by the total number of steps) had a greater probability of being reproduced (selection). It was found that Rectangulus soon “learned” to turn in front of a former track and a channel, and to keep contact, both if one starts with individuals who at the beginning could only go straight ahead, or with ones turning after every step. Evolution from this stage onward proceeded more variably. Different types of meandering, spiraling, and a combination of both emerged; however, in two out of six cases, evolution did not proceed beyond the turning and contact-keeping stage. It is suggested that the different outcomes represent separate adaptive peaks. The highest yield was obtained by the combination of spiraling and meandering, as used by Paraonis fulgens, followed by pure spiraling and meandering. This was confirmed by calculations made for populations with fixed parameters. The results further show that selection for non-crossing could only have been effective in producing these patterns for population densities much higher than the ones found for P. fulgens at the present time.     

The ability to solve elementary logic tasks in mice with the knockout of sodium–calcium exchanger gene 2 (<Emphasis Type="Italic">NCX2</Emphasis>)

Mice with a knockout of the sodium–calcium exchanger 2 (NCX2) gene were statistically significantly more successful than wild-type controls in the solution of two cognitive tasks, the test for the capacity to extrapolate the direction of the stimulus movement and the “puzzle-box” test for the capacity to find a hidden route to safe environment, which were based on food and aversive motivations, respectively. In both tests, the success of task solution was based on the animal’s ability to use the object’s “permanence” rule (according to J. Piaget). The data confirm that the knockout of this gene, which is accompanied by modulation of the temporal pattern of calcium membrane flux, also induces changes in mouse CNS plasticity.     

Morphological and genetic characteristics of genetic tumor in Nicotiana glauca

It is well understood that genetic tumors develop in certain interspecific Nicotiana hybrids. Nicotiana species are divided into “plus” and “minus” groups and crosses between “plus” and “minus” species give rise to tumorous hybrids. However, it has been proposed that parents and hybrids derived from crosses among members within the same group do not produce tumors. In this study, genetic tumors were only obtained in Nicotiana glauca, which exhibited tumor features similar to those of N. glauca × N. langsdorffii. Our results suggest that genetic factors may control tumor formation independent of tumor induction dependent on the specific interspecific cross. Genetic tumor formation exhibited high B-type and D-type cyclin expression levels, indicating tumor cells are characterized by an uncontrolled cell cycle.     

Inhibitory and stimulatory effects of a synthetic glycopeptide (MDP) on the in vitro PFC response: factors affecting the response.

A synthetic adjuvant active glycopeptide, N-acetyl-muramyl-l-alanyl-d-isoglutamine (MDP), has been previously shown to enhance the in vitro immune response of mouse spleen cells to T-dependent or independent antigens. Data presented here show that the net activity of MDP on the in vitro immune response is closely related to the cell culture conditions: Two distinct patterns of MDP activities could actually be detected. Marked stimulation of the PFC response was observed at “low density” cell cultures. In contrast, suppression could be seen at “high density” cell cultures. Moreover, the culture conditions which permitted characterization of either the enhancement or suppression of the immune response by MDP were strongly dependent on the strain of mouse used. However, these activities were not dependent on antigen concentration, on kinetics of responses, or on cytotoxic effects.     

PHOTOTROPIC CIRCUS MOVEMENTS OF LIMAX AS AFFECTED BY TEMPERATURE

1. The theory of animal phototropism requires for particular instances a knowledge of the action of light as exerted through each of two bilaterally located receptors functioning singly. The measurement of "circus movements" which this involves must be concerned with such aspects of the reaction as are demonstrably dependent upon the effect of light. 2. The negatively phototropic slug Limax maximus exhibits very definite and continuous circus movement under vertical illumination when one eye-tentacle has been removed. The amplitude of the circling movement, measured in degrees deflection per cm. of path as an index of maintained differential tonus, is intimately related to the concurrent velocity of creeping. Analysis of the orienting mechanism is facilitated by the fact that in gasteropods such as Limax the animal creeps by means of the pedal organ, but orients (turns) by a totally distinct set of muscles in the dorsal and lateral regions of the body wall. 3. The expression of the phototropic orienting tendency, with illumination constant, is greatly influenced by the temperature. Above a zone centering at 15°, the amplitude of turning (degrees per cm. of path) is determined by the temperature in accurate agreement with Arrhenius'' equation for chemical reaction velocity, with the critical increment µ = 16,820; and the rate of creeping is progressively less as the temperature rises, µ for its reciprocal being 10,900. Below 15°, the velocity of creeping becomes less the the lower the temperature, µ being again 16,800; while the amplitude of orientation is limited merely by the velocity of creeping, its reciprocal being directly proportional thereto. 4. Measurements of Limax circus movements in terms of turning deflection as function of light intensity must therefore be carried out at a temperature well above 15°. 5. The analysis provides a gross physical model of how an end-result may be influenced by temperature according to the effect of temperature upon each of several interconnected processes when the "temperature vs. effect" curves for these processes dynamically intersect. 6. It is pointed out that a certain type of unpredictability (quantative variability) in animal behavior under "normal" natural conditions probably results from dynamic equilibrium there obtaining between diverse mechanisms competing for effector control (in the present case, the creeping mechanism and that for turning, in the range 14–16°C.). It follows that the unraveling of the elements of conduct necessitates experimentation under diverse abnormal conditions favoring individual mechanism of response.     

A theory of the pattern induced flight orientation of the fly Musca domestica II

In a preceding paper, Poggio and Reichardt (1973a), a phenomenological theory describing the visual orientation behaviour of fixed flying flies (Musca domestica) towards elementary patterns was presented. Some of the problems raised in this first paper are treated here in more detail. The mapping between the position dependent torque distribution — D(ψ) characteristics — associated with a given pattern and the stationary orientation distribution p(ψ), is studied taking into account that the fluctuation process (generated by the fly) is coloured gaussian noise. Under certain critical conditions this may lead to an “early symmetry breaking” in the mean values of the p(ψ) distribution. The validity of the “superposition principle” has also been examined. Although shift and superposition give the main qualitative features of the “attractiveness profile” D(ψ), associated with a 2-stripe pattern, superposition does not hold quantitatively for stripe separations up to about 80°. Evidence is presented suggesting that such an effect is due to inhibitory interactions between input channels of the fly's eye. Implications of this finding with respect to the problem of spontaneous pattern preference are also discussed.     

Association of the Asp298Asn polymorphism in the mc4r gene with back fat thickness in pigs of the large white breed

The association of the Asp298Asn polymorphism in the mc4r gene with the development of traites such as spinal fat thickness in pigs of the Large White breed from AF “Orzhitska” population was investigated. A tendency towards the development of thinner spinal fat was found in animals with the AG genotype. No significant difference was detected in the spinal fat thickness between animal groups with different genotypes of the mc4r gene caused by Asp298Asn polymorphism. The heterogeneous origin of the studied animals can be a possible cause of the absence of any statistically significant difference. A conclusion was reached that it was not expedient to use Asp298Asn polymorphism of the mc4r gene in the selection of pigs of the Large White breed from AF “Orzhitska” population.     

Letting the Air Out: <Emphasis Type="Italic">Aire</Emphasis> as an Empty Signifier in Oaxacan Understandings of Illness

“Air (aire, also aigre) in the body” is a frequent explanation of illness according to the traditional medical beliefs in Mexico. Anthropologists have generally scrutinized aire in the context of other common folk illnesses treated by traditional healers (curanderas). However, drawing on my research in the communities of Northern Oaxaca I suggest that aire occupies a more distinct position in the folk medical cosmology than it has usually been credited with. This distinction rests on the notion’s exceptional ambivalence and openness to multiple interpretations. “Air” is recurred to as the cause of illness mainly in situations where every other explanation, either “traditional” or “biomedical,” seems to be inadequate. The physical properties of air—its transparency, invisibility, apparent immateriality, near omnipresence, and virtual “nothingness”—render it a suitable explanation of the last resort. Local understandings of what aire “is” are often vague and elusive, and in many respects the term functions in folk medical discourse as an “empty signifier.”     

Sunset and the orientation of European robins (Erithacus rubecula)

The migratory orientation of European robins (Erithacus rubecula) in autumn was tested immediately after sunset and also after the beginning of astronomical darkness. In twilight tests under clear skies, the birds selected an appropriate migratory direction. During the course of autumn, along with the shift of sunset azimuth, the orientation of birds also shifted, always in a counter-clockwise direction. Although this shift of orientation was not statistically significant, the difference between the mean direction and the sunset was the same for each autumn period. This suggests that the migratory direction was selected on the basis of menotactic orientation re the setting sun. Random directions were observed under solid overcast skies as well as during tests under starry skies, begun after all trace of the sunset position had disappeared.     

Genotypic diversity,molecular markers and spatial distribution of genets in clonal plants,a literature survey

We present a literature survey of studies using molecular markers to investigate genet diversity and structure in clonal plants. The data from 40 studies comprised 45 species of which only two were studied by DNA methods, the rest by isozyme markers. Less than one third of the studies provided information about the spatial distribution of individual genets within populations, and only 12.5% of the studies used mapping of all ramets within plots or part of the population in combination with identification of multilocus genotypes. We also present two case studies. InGlechoma hederacea morphological criteria were used to select clones. Multi-samples of ramets within these “clones” turned out to be variable using isozymes indicating that these “clones” in most cases consisted of several genets. One individual multilocus genotype covered tens of square metres. InHylocomium splendens samples from 10×10 cm plots usually consisted of a mixture of multilocus genotypes, but occasionally the whole plot consisted of one genet.     

Collaborative and competitive motivations uniquely impact infants' racial categorization

Human history has been plagued by violent inter-group conflicts. Such conflicts are arguably grounded on group biases – particularly, a tendency to favor “ingroups” over “outgroups” – manifested in adults, children, and infants. A question these findings prompt is what motivates social categorization? Here it is shown that priming 14-month-old infants (N?=?144) with collaborative or competitive interactions affects their capacity to form racial categories, and that this effect varies according to the gender of the exemplars being categorized. Specifically, whereas racial categorization of women was facilitated by collaboration, racial categorization of men was facilitated by competition. The presence of these differential effects in infancy is consistent with the idea that social categorization is driven by fundamental functions of group relations.     

Patterns of turning in courtship orientation of the male German cockroach

Courtship turning of the male German cockroach, Blattella germanica, was analysed with respect to rotational and translational movements. Three different sources of orientation information are postulated for the control of this behaviour: external sensory information (perception of sex pheromone) releases courtship, proprioception from the legs is required to curtail turning when the specified turn angle is reached, and internally stored information determines the sign of turning and patterns the courtship actions.     

On the existence and the role of chaotic processes in the nervous system

Chaos theory is a rapidly growing field. As a technical term, “chaos” refers to deterministic but unpredictable processes being sensitively dependent upon initial conditions. Neurobiological models and experimental results are very complicated and some research groups have tried to pursue the “neuronal chaos”. Babloyantz's group has studied the fractal dimension (d) of electroencephalograms (EEG) in various physiological and pathological states. From deep sleep (d=4) to full awakening (d>8), a hierarchy of “strange” attractors paralles the hierarchy of states of consciousness. In epilepsy (petit mal), despite the turbulent aspect of a seizure, the attractor dimension was near to 2. In Creutzfeld-Jacob disease, the regular EEG activity corresponded to an attractor dimension less than the one measured in deep sleep. Is it healthy to be chaotic? An “active desynchronisation” could be favourable to a physiological system. Rapp's group reported variations of fractal dimension according to particular tasks. During a mental arithmetic task, this dimension increased. In another task, a P300 fractal index decreased when a target was identified. It is clear that the EEG is not representing noise. Its underlying dynamics depends on only a few degrees of freedom despite yet it is difficult to compute accurately the relevant parameters. What is the cognitive role of such a chaotic dynamics? Freeman has studied the olfactory bulb in rabbits and rats for 15 years. Multi-electrode recordings of a few mm² showed a chaotic hierarchy from deep anaesthesia to alert state. When an animal identified a previously learned odour, the fractal dimension of the dynamics dropped off (near limit cycles). The chaotic activity corresponding to an alert-and-waiting state seems to be a field of all possibilities and a focused activity corresponds to a reduction of the attractor in state space. For a couple of years, Freeman has developed a model of the olfactory bulb-cortex system. The behaviour of the simple model “without learning” was quite similar to the real behaviour and a model “with learning” is developed. Recently, more and more authors insisted on the importance of the dynamic aspect of nervous functioning in cognitive modelling. Most of the models in the neural-network field are designed to converge to a stable state (fixed point) because such behaviour is easy to understand and to control. However, some theoretical studies in physics try to understand how a chaotic behaviour can emerge from neural networks. Sompolinsky's group showed that a sharp transition from a stable state to a chaotic state occurred in totally interconnected networks depending on the value of one control parameter. Learning in such systems is an open field. In conclusion, chaos does exist in neurophysiological processes. It is neither a kind of noise nor a pathological sign. Its main role could be to provide diversity and flexibility to physiological processes. Could “strange” attractors in nervous system embody mental forms? This is a difficult but fascinating question.     

Interaction Between “Safe Sites” and “Safe Sides” for Germination of Neurada procumbens (Neuradaceae) in the Middle East

The seed bank of Neurada procumbens, a prostrate annual common in sandy desert habitats, is vulnerable to surface disturbances. Moreover, its seeds are highly heteromorphic, having both spinose and non-spinose sides, which affects both the vertical distribution of seeds and diaspores, and the precise position in which they lie in the soil. Here we explore the ecological implications of two factors, “safe sites” within habitats and seed orientation or “safe sides”, on seedling establishment and the seed bank. In three natural populations, the vertical distribution of buried, germinable diaspores decreased with soil depth. Most diaspores occurred at the surface (0–1 cm below the surface), while none were observed below 10 cm. Seedling emergence decreased with depth and reached zero in diaspores below 5 cm. Seedling emergence also proved highly sensitive to the orientation of diaspores in soil. Diaspores lying on their smooth side with the spinose upper side directed upwards reached the highest seedling emergence of 61 %. Root length ranged from 10 to 16 cm, and the root to shoot ratio varied between 22.8 and 30.3 cm, depending on diaspore size. Diaspores near the surface may constitute a more transient component of the seed bank, as few of these remained viable for more than a year. Persistence of Neurada seed banks seems to depend not only on vertical movement of diaspores among habitat “safe sites” but also on different seed position alternatives.