Generalization of convex shapes by bees: what are shapes made of?

For about 70 years, bees were assumed not to possess the capacity to discriminate among convex shapes, such as a disc, a square or a triangle, based on results of early studies conducted by presenting shapes on horizontal planes. Using shapes presented on a vertical plane, we recently demonstrated that bees do discriminate among a variety of convex shapes. Several findings, summarized here, provide indirect evidence that discrimination is based on a cue located at the shapes' boundaries.

Importance of learning in the response of ewes to male odor.

Exposure of anestrous ewes to a ram or its odor results in the activation of the luteinizing hormone (LH) secretion leading to reinstatement of cyclicity in most females. Sexual experience and learning have been suggested as important factors to explain the variability of the female responses. In experiment 1, we compared the behavioral and endocrine responses of four groups of anestrous females that differed in age (young or adult) and previous exposure to males [naive (no exposure) or experienced (courtship behavior for young and numerous mating for adults)].

Shape discrimination by wasps (Paravespula germanica) at the food source: generalization among various types of contrast.

Wasps ( Paravespula germanica) were trained and tested at an artificial feeding site, using convex shapes that produced colour contrast, luminance contrast, or motion contrast against the background. With each of the three types of contrast, we tested the wasps' capacity to discriminate the learned shape from novel shapes. In addition, in each experiment we tested the wasps' capability to recognize the learned shape when it offered a different type of contrast than that it had during the training.

Discrimination of closed shapes by two species of bee, Apis mellifera and Megachile rotundata.

In the present study, the performance of two bee species, the honeybee Apis mellifera and the leaf-cutter bee Megachile rotundata, in discriminating among various closed (convex) shapes was examined systematically for the first time. Bees were trained to each of five different shapes, a disc, a square, a diamond and two different triangles, all of the same area, using fresh bees in each experiment. In subsequent tests, the trained bees were given a choice between the learned shape and each of the other four shapes.

Visual localization within single geometric planes of a space habitat.

Background: The present study investigated how human subjects capture and restore visual information within a line representation drawing the three-dimensional configuration of a space module.

Methods: Nine subjects were asked to perform a visual localization task within this geometric model. The task consisted of localizing a light point appearing during 3 s in 40 different spatial positions and for 8 tilt angles of the model in the following random order: 0 degree, 45 degrees, 180 degrees, 225 degrees, 90 degrees, 315 degrees, 135 degrees, and 270 degrees.

Tactic components in orientation.

In the first half of this century, taxes were considered the best models for working out the rules of stimulus-response systems. The interest for tactic behaviours suddenly disappeared in the mid-1960s, out of reasons specified in the present review. However, results of several recent studies reviewed in the present article suggest that tactic behaviours constitute, from an ontogenetic as well as phylogenetic point of view, a first step towards more complex oriented behaviours that have received much attention in recent years.

Unexplained sexual segregation in polygamous ungulates: a defense of an ontogenetic approach.

Two processes are generally mixed when considering ungulate sexual segregation: the social segregation which appears to be a rule in polygamous ungulate species and the spatial segregation which is facultative. Early in life, there is evidence that males and females exhibit different levels of activity and patterns of interaction which could lead to behavioural incompatibility. It is proposed that juvenile females, differently motivated than males to interact socially, may soon avoid the pseudo-sexual and agonistic male behavioural components.

Dynamic MRI in the congenital agenesis of the neural pituitary stalk syndrome: the role of the vascular pituitary stalk in predicting residual anterior pituitary function.

Objective: Magnetic resonance imaging (MRI) without contrast medium is unable to give detailed information on the hypothalamic-pituitary structures. MRI using gadopentetate dimeglumine (Gd-DTPA), and dynamic MRI, were performed in patients with hypopituitarism previously diagnosed as having anterior pituitary hypoplasia, ectopic posterior pituitary and unidentified pituitary stalk (1) to determine whether Gd-DTPA improves the delineation of hypothalamic-pituitary structures; (2) to verify whether, if so, such improvement can be correlated with residual pituitary function in patients subjected to long-term follow-up; and (3) to identify the hypothalamic-pituitary vascular network in such cases.

Patients: Eighteen patients (13 males, 5 females) aged 10-26.

Ethological experiments on human orientation behavior within a three-dimensional space--in microgravity.

In weightlessness situation the subject has to realize domestic and professional tasks comparable to those performed under normal gravity, whereas the "body tool" available to him has been placed in new conditions which require significant behavioral changes. The loss of weight, the disappearance or modification of some ideothetic and allothetic cues, notably the absence of gravity for the body's referential verticality have the most obvious effect of diversifying the astronaut's orientations. The vertical position is thus no longer the only one possible.

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Visually guided orientation is studied during ontogeny in field crickets (Gryllus bimaculatus) bred into complete darkness from egg stage. It is compared to control animals bred in normal 12L 12D light cycle conditions. Control animals are strongly scototactic: whatever their age, 85% of them step towards low reflecting targets.

Astronaut behavior in an orbital flight situation: preliminary ethological observations.

Following the ethological approach, astronaut behavior is divided into "observable" motor acts which make possible its quantitative description. Frame-by-frame analysis of current videotape recordings shows that the behavioral adaptation to weightlessness is achieved through various processes. Among these are new motor acts and stereotyped movements (successive movements of head, eye, arm, and hand), reversal and reorganization of the sequence of the motor acts to form new patterns (head and eye movements upward or downward), construction of a particular cognitive image of the astronaut's own world (more compensatory regulations than anticipatory processes), and the relationship between postures and orientations according to the proximate visual environment.

Social tendencies of the Corsican Mouflon Ovis ammon musimon in the caroux-espinouse massif (South of France).

Mouflons, according to their age and sex, show particular social tendencies during the annual cycle. During its life, each individual builds on its own "ontogenetic social trajectory" whose annual variations are representative of its social tendencies. Males and females present major differences from the beginning of their second year of life.

Ontogenese de certains aspects de l'orientation du grillon des bois Nemobius sylvestris (Bosc), dans son milieu naturel.

The ontogeny of the orientation of the wood-cricket, Nemobius sylvestris, was studied experimentally in a variety of biotopes. In each experimental situation, the straightness of the routes taken by crickets improves with age. These results demonstrate that, depending on the variety of the constraints within each living area, various local individual solutions to the problem of orientation develop during ontogeny.