Biomedical subjects

D P Kimble

Publications and source records attributed to D P Kimble.

At least 19 recordsLinked to original sources

PubMed1997

Didelphid behavior.

There are approximately 75 species of American opossums (didelphids). Systematic behavioral research has been reported for only a small number of species, namely, Monodelphis domestica and Didelphis virginiana. Observational studies and field reports on several other didelphid species have also been published. The current review covers behavioral studies on didelphids including research on territoriality, reproductive behaviors, parturition, maternal behaviors, nest-building, vocalizations, scent-marking, circadian rhythms, swimming, locomotion, discrimination learning, maze learning, operant learning, problem box learning, exploration, death-feigning, predatory behavior, and prey manipulation. Didelphid behavior is compared in several contexts with eutherian mammals. Other than death-feigning, which has only been reported for one or two didelphid species, the behaviors observed in didelphids are qualitatively similar to those of eutherian mammals. Nevertheless, differences can be seen in prey manipulation and spatial maze behavior. Social interactions appear to be sparser in opossums than in most eutherian mammals. However, the scarcity of systematic research on didelphid behavior still prevents firm conclusions regarding these ancient and interesting mammals. Futher research on didelphids is warranted, particularly since they provide a natural comparison group for small generalist eutherians.

Animals↗

PubMed1995

Restoration of circadian behavior by anterior hypothalamic heterografts.

The suprachiasmatic nucleus (SCN) of the anterior hypothalamus (AH) is a circadian oscillator and an important component of the mammalian circadian system. To determine whether the SCN is the dominant circadian pacemaker responsible for generating a species-typical characteristic of circadian rhythms [i.e., period length (tau)], neural transplantation was conducted using fetal AH donors of different species and SCN-lesioned (SCNx) hosts. The circadian behavior of each of the three donor species is clearly distinguishable by its species-typical tau. The extent of SCN pacemaker autonomy was assessed by noting whether the period of the restored circadian rhythm following heterograft transplantation was characteristic of the donor or the host, or whether an atypical circadian period was established. Hamsters rendered arhythmic by SCN ablation were implanted with AH tissue from fetal hamsters (E13-E14, homograft controls) or fetal mice or rats (E15-E17). The AH homografts restored circadian activity rhythms with a tau similar to that of intact hamsters, and fetal mouse AH heterografts restored circadian rhythmicity with a tau similar to that of the donor mouse strain. However, fetal rat AH tissue implanted into SCNx hamsters renewed circadian rhythmicity with a period significantly shorter than either the species-typical tau of the rat donor or the hamster host. In both the mouse and rat AH heterograft experiments, immunocytochemical analysis performed with species-specific monoclonal antibodies revealed extensive fiber outgrowth from the implant into the host hypothalamus, evident up to 7 months postimplantation. The rat implants were consistently larger, more fully vascularized and exhibited less necrosis than the implanted mouse tissue. The histological appearance of the grafts, thus, provides no explantation for the difference in efficacy of the grafts to restore species-typical behavior. However, several interpretations are considered that are consistent with the combined behavioral results observed.

Animals↗

PubMed1992

Insect cardioactive peptides: regulation of hindgut activity by cardioacceleratory peptide 2 (CAP2) during wandering behaviour in Manduca sexta larvae.

The functional relationship between cardioacceleratory peptide 2 (CAP2) and hindgut activity during wandering behaviour was investigated in fifth-instar larvae of the tobacco hawkmoth Manduca sexta. Inspection of the alimentary canal on the day prior to wandering showed that the gut, in preparation for metamorphosis, was voided of all contents by 18:00 h. Associated with this event, which we refer to as 'gut emptying', was an increase in the frequency of hindgut contractions measured in vivo. No change in heart activity was seen during this developmental period. Measurements of the amount of CAP2 in the central nervous system (CNS) of fifth-instar caterpillars revealed that CAP2 storage levels declined sharply on the day of gut emptying. The drop in CNS levels of CAP2 at gut emptying was temporally correlated with the appearance of CAP2 in the haemolymph. CAP2, when applied at physiological concentrations to an in vitro larval hindgut bioassay, caused changes in several parameters, including contraction frequency and amplitude, and basal tension. In vivo administration of CAP2 elicited hindgut responses that were qualitatively and quantitatively similar to those seen in vitro. Developmental studies on changes in CAP2 responsiveness during the last larval instar demonstrated that the hindgut is maximally sensitive to CAP2 on the day of gut emptying. Direct evidence in support of a role for CAP2 in fifth-instar larvae was provided by experiments in which the increase in gut activity in vivo seen at gut emptying was significantly reduced by injections of an anti-CAP antibody. Based on data from cobalt backfills and anti-CAP immunohistochemical staining, we propose that CAP2 exerts its effect on the larval hindgut at wandering via a local release from CAP-containing neurones in the terminal ganglion that project directly to the hindgut.

Animals↗

PubMed1990

Functional effects of neural grafting in the mammalian central nervous system.

Grafts of fetal and nonfetal brain tissues have been successfully implanted into the mammalian central nervous system (CNS). The functional effects of neural grafting in the CNS of rodents and nonhuman primates in a variety of situations are reviewed. Research areas discussed included the effects of dopamine-rich grafts in animal models of Parkinson's disease and acetylcholine-rich grafts in animals with lesions of the cholinergic pathways to the neocortex and hippocampus. Graft effects also are examined in aged animals and genetic mutants. In addition, the effects of neural grafts on circadian rhythmicity, reproductive functions, and conditioned taste aversion are discussed. The beneficial functional effects of neural grafts and the possible mechanisms and implications for these effects are discussed, including the possibility that the CNS exhibits a regional biochemical specificity that influences the outcome of neural graft procedures.

Animals↗

PubMed1986

Fetal brain implants improve maze performance in hippocampal-lesioned rats.

Hippocampal tissue from day 16 fetal rats was implanted into the damaged hippocampal formation of adults. Significant recovery of the lesion-induced deficit in spatial maze performance was observed, particularly in those animals which showed integration of the implanted fetal tissue with the host hippocampal formation. A two-stage procedure in which 2 weeks or more elapsed between the initial lesion and the implantation resulted in more successful tissue integration and better behavioral recovery.

Animals↗

PubMed1982

In utero taste/odor aversion conditioning in the rat.

Rat fetuses exposed to a taste-odor stimulus and an aversive stimulus in utero showed an aversion to the taste/odor stimulus when tested 16 days postnatally. Fetuses which received various control treatments in utero did not show an aversion. These data show that rat fetuses at 20 days of gestation are capable of associative learning which can be demonstrated more than two weeks postnatally.

Animals↗

PubMed1982

Further evidence for latent learning in hippocampal-lesioned rats.

Rats with substantial dorsolateral lesions to the hippocampal formation showed significant latent learning of a complex spatial maze. Their overall maze performance, however, was characteristically impaired. Behavior during the pre-exposure phase of the experiment was useful in predicting test maze behavior. Three measures in particular had predictive value: entrances into the maze alley leading to the final choice point, behavior at that choice point, and goal box entries.

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PubMed1981