Abstract: About 2-3% of all children are affected by mental retardation, and genetic conditions rank among the leading causes of mental retardation. Alterations in the information encoded by genes that regulate critical steps of brain development can disrupt the normal course of development, and have profound consequences on mental processes. Genetically modified mouse models have helped to elucidate the contribution of specific gene alterations and gene-environment interactions to the phenotype of several forms of mental retardation. Mouse models of several neurodevelopmental pathologies, such as Down and Rett syndromes and X-linked forms of mental retardation, have been developed. Because behavior is the ultimate output of brain, behavioral phenotyping of these models provides functional information that may not be detectable using molecular, cellular or histological evaluations. In particular, the study of ontogeny of behavior is recommended in mouse models of disorders having a developmental onset. Identifying the role of specific genes in neuropathologies provides a framework in which to understand key stages of human brain development, and provides a target for potential therapeutic intervention.

Abstract: The process of domestication involves adaptation, usually to a captive environment. Domestication is attained by some combination of genetic changes occurring over generations and developmental mechanisms (e.g., physical maturation, learning) triggered by recurring environmental events or management practices in captivity that influence specific biological traits. The transition from free-living to captive status is often accompanied by changes in availability and/or accessibility of shelter, space, food and water, and by changes in predation and the social environment. These changes set the stage for the development of the domestic phenotype. Behavioral development in animals undergoing domestication is characterized by changes in the quantitative rather than qualitative nature of responses. The hypothesized loss of certain behavior patterns under domestication can usually be explained by the heightening of response thresholds. Increases in response frequency accompanying domestication can often be explained by atypical rates of exposure to certain forms of perceptual and locomotor stimulation. Genetic changes influencing the development of the domestic phenotype result from inbreeding, genetic drift, artificial selection, natural selection in captivity, and relaxed selection. Experiential contributions to the domestic phenotype include the presence or absence of key stimuli, changes in intraspecific aggressive interactions and interactions with humans. Man's role as a buffer between the animal and its environment is also believed to have an important effect on the development of the domestic phenotype. The domestication process has frequently reduced the sensitivity of animals to changes in their environment, perhaps the single-most important change accompanying domestication. It has also resulted in modified rates of behavioral and physical development. Interest in breeding animals in captivity for release in nature has flourished in recent decades. The capacity of domestic animals to survive and reproduce in nature may depend on the extent to which the gene pool of the population has been altered during the domestication process and flexibility in behavioral development. “Natural” gene pools should be protected when breeding wild animals in captivity for the purpose of reestablishing free-living natural populations. In some cases, captive-reared animals must be conditioned to live in nature prior to their release.

Abstract: Three-year-old children were tested on three categorization tasks of increasing levels of abstraction (used with adult baboons in an earlier study): the first was a conceptual categorization task (food vs toys), the second a perceptual matching task (same vs different objects), and the third a relational matching task in which the children had to sort pairs according to whether or not the two items belonged to the same or different categories. The children were tested using two different procedures, the first a replication of the procedure used with the baboons (pulling one rope for a category or a relationship between two objects, and another rope for the other category or relationship), the second a task based upon children's prior experiences with sorting objects (putting in the same box objects belonging to the same category or a pair of objects exemplifying the same relation). The children were able to solve the first task (conceptual categorization) when tested with the sorting into boxes procedure, and the second task (perceptual matching) when tested with both procedures. The children were able to master the third task (relational matching) only when the rules were clearly explained to them, but not when they could only watch sorting examples. In fact, the relational matching task without explanation requires analogy abilities that do not seem to be fully developed at 3 years of age. The discrepancies in performances between children tested with the two procedures, with the task explained or not, and the discrepancies observed between children and baboons are discussed in relation to differences between species and/or problem-solving strategies.

Abstract: The purpose of this study was to determine the effects of early experience (rearing conditions) on the central nervous system (CNS) and behavior of spiderlings of Hogna carolinensis (Lycosidae). We were interested in whether or not spiderlings that were allowed to remain in contact with their maternal parent and siblings (enriched condition, EC) would exhibit differences in CNS development or subsequent behavior when compared with those reared in isolation (improverished condition, IC). Spiderlings emerged from their egg sacs and climbed onto the dorsal surface of their mother's abdomen where they remained until their yolk supply was depleted (5 days). They dispersed on day 6 after emergence. We compared the ability of 16-day-old EC and IC spiderlings to capture prey in a linear runway and to learn a complex maze (spatial learning). We also compared certain aspects of CNS development (brain weight, total number of brain cells, volume of central body and protocerebral neuropil) in EC and IC spiderlings. Results indicated that EC subjects are more efficient at capturing moving prey (crickets) and exhibited improved performance (significantly fewer blind alley errors) in the maze. The volume of the protocerebral neuropil in 6-day-old EC animals increased 30% over a 5-day period after emergence as compared to IC animals of the same age. The volume of the central body of EC animals increased 34.8% over the same time period. On day 6 after emergence, the weight of the protocerebrum was significantly greater in EC versus IC subjects. There were no significant effects of rearing condition (EC vs IC) or age (1- and 6-day-old spiderlings) on the total number of nerve cells in the protocerebrum, suggesting that the difference in protocerebral weight was due primarily to differences in supporting glial tissues and neuropil matrix. In conclusion, the data suggest that early contact with the maternal parent and siblings is of vital importance to CNS development in lycosid spiderlings and can influence the capacity for spatial learning as well as the ability to capture prey.

Abstract: We studied the development of infant baboons' (Papio cynocephalus ursinus) responses to conspecific 'barks' in a free-ranging population in the Okavango Delta, Botswana. These barks grade from tonal, harmonically rich calls into calls with a more noisy, harsh structure. Typically, tonal variants are given when the signaller is at risk of losing contact with the group or a particular individual ('contact barks'), whereas harsh variants are given in response to predators ('alarm barks'). We conducted focal observations and playback experiments in which we presented variants of barks recorded from resident adult females. By six months of age, infants reliably discriminated between typical alarm and contact barks and they responded more strongly to intermediate alarm calls than to typical contact barks. Infants of six months and older also recognized their mothers by voice. The ability to discriminate between different call variants developed with increasing age. At two and a half months of age, infants failed to respond at all, whereas at four months they responded irrespective of the call type that was presented. At six months, infants showed adult-like responses by responding strongly to alarm barks but ignoring contact barks. We concluded that infants gradually learn to attach the appropriate meaning to alarm and contact barks.