Home About us Contact
|
Home About us Contact | ||
|
|
||
Rat Fetus (rat + fetus)
Selected AbstractsPrenatal Development of Interlimb Motor Learning in the Rat FetusINFANCY, Issue 3 2008Scott R. Robinson The role of sensory feedback in the early ontogeny of motor coordination remains a topic of speculation and debate. On E20 of gestation (the 20th day after conception, 2 days before birth), rat fetuses can alter interlimb coordination after a period of training with an interlimb yoke, which constrains limb movement and promotes synchronized, conjugate movement of the yoked limbs. The aim of this study was to determine how the ability to express this form of motor learning may change during prenatal development. Fetal rats were prepared for in vivo study at 4 ages (E18,21) and tested in a 65-min training-and-testing session examining hind limb motor learning. A significant increase in conjugate hind limb activity was expressed by El9, but not El 8 fetuses, with further increases in conjugate hind limb activity on E20 and E21. These findings suggest substantial development of the ability of fetal rats to modify patterns of interlimb coordination in response to kinesthetic feedback during motor training before birth. [source] Conjugate limb coordination after experience with an interlimb yoke: Evidence for motor learning in the rat fetusDEVELOPMENTAL PSYCHOBIOLOGY, Issue 4 2005Scott R. Robinson Abstract This study investigated the capacity of the E20 rat fetus to adaptively alter patterns of interlimb coordination in a prenatal model of motor learning. Fetal limb movement was manipulated with an interlimb yoke, consisting of a fine thread attached at the ankles, which created a physical linkage between two limbs. Exposure to the yoke resulted in a gradual increase in conjugate movements of the yoked limbs during a 30-min training period, which persisted after removal of the yoke. Training effects were evident when the yoke was applied to two hindlimbs, two forelimbs, or a homolateral forelimb,hindlimb pair. A savings in the rate of acquisition also was observed when fetuses experienced yoke training in a second session. These data argue that the rat fetus can respond to kinesthetic feedback resulting from variation in motor performance, which suggests that experience contributes to the development of coordinated motor behavior before birth. © 2005 Wiley Periodicals, Inc. Dev Psychobiol 47: 328,344, 2005. [source] Emergence of long-term memory for conditioned aversion in the rat fetusDEVELOPMENTAL PSYCHOBIOLOGY, Issue 3 2004Nadège Gruest Abstract Pregnant rats were subjected to garlic essential oil as the conditioned stimulus and 45 min later to LiCl as the unconditioned stimulus either on embryonic Days 15 and 16 (E15 and E16) or on 18 and 19 (E18 and E19). Control dams received only garlic, LiCl, or water. Progenies were tested on garlic drinking 6 weeks after the exposure to the stimuli via the mothers. In the E18 to 19 group, rats that were exposed to paired garlic,LiCl expressed a significant aversion for garlic. In the E15 to 16 group, no significant differences appeared between subgroups. These results confirm that an associative memory can be established before birth and suggests that this ability potentially emerges in a short time window of 3 days at the end of gestation. Moreover, it appears that a long-term memory can be acquired in utero and retained to be expressed postnatally when animals are autonomous. © 2004 Wiley Periodicals, Inc. Dev Psychobiol 44: 189,198, 2004. [source] Classical conditioning in the rat fetus: Involvement of mu and kappa opioid systems in the conditioned responseDEVELOPMENTAL PSYCHOBIOLOGY, Issue 2 2002William P. Smotherman Abstract When the Embryonic Day 20 (E20) rat fetus is given a conditioning trial involving a paired presentation of an artificial nipple (the conditioned stimulus; CS) with an intraoral infusion of milk (the unconditioned stimulus; US), it shows evidence of classical conditioning when again exposed to the CS during a test trial. Specifically, the fetus shows fewer oral grasp responses (the conditioned response; CR) when continuously presented with the artificial nipple. The present study further investigated this classically conditioned reduction in oral grasping. Separate experiments (a) examined the time course of the reduction in oral grasping (Experiment 1), (b) characterized the time course of mu opioid (Experiment 2) and kappa opioid (Experiment 3) involvement in the CR, and (c) described changes in fetal behavior (Experiment 4) associated with mu and kappa opioid effects on responding to the artificial nipple. The results are discussed in terms of opioid involvement in establishing and maintaining early suckling behavior. © 2002 Wiley Periodicals, Inc. Dev Psychobiol 40: 104,115, 2002. DOI 10.1002/dev.10016 [source] Classical conditioning in the rat fetus: Temporal characteristics and behavioral correlates of the conditioned responseDEVELOPMENTAL PSYCHOBIOLOGY, Issue 2 2002William P. Smotherman Abstract This study examined the temporal characteristics and behavioral correlates of the conditioned response (CR) following classical conditioning of the embryonic Day 20 (E20 rat fetus). The conditioning procedure involved pairing of an artificial nipple (the CS) with an infusion of milk (the US) to establish classical conditioning. The test for classical conditioning involved measurement of a stimulus-evoked facial wiping response in a classical conditioning test. Experiment 1 compared the effectiveness of one- and three-trial procedures to establish classical conditioning. Experiment 2, 3, and 4 described the time course for the CR following one- and three-trial conditioning procedures. Experiments 3b and 4b describe the behavioral responses to (a) presentation of the CS at the time of conditioning, (b) infusion of the milk US at the time of conditioning, and (c) reexposure to the CS before the test for classical conditioning. Experiments 5 and 6 exposed the fetus to manipulations that either increased or decreased stretching (a behavior found to be associated with the CR). The results are discussed in terms of the temporal characteristics and behavioral correlates of conditioned and unconditioned responses and their mediation by activity in endogenous mu and kappa opioid systems. © 2002 Wiley Periodicals, Inc. Dev Psychobiol 40: 116,130, 2002. DOI 10.1002/dev.10017 [source] Staining methods for magnetic resonance microscopy of the rat fetusJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 6 2007Alexandra Petiet MS Abstract Purpose To develop a magnetic resonance histology (MRH) staining and fixation method by immersion to enhance the signal-to-noise ratio (SNR) with a paramagnetic contrast agent permitting microscopic acquisition within a 3-hour scan time. Materials and Methods Methods were optimized for embryonic day 18.5 (E18.5) rat fetuses and imaging at 9.4T with an RF refocused spin-echo pulse sequence (TR/TE = 75 msec/5.2 msec). Fixation/staining was performed by immersion in Bouin's fixative containing varied concentrations of ProHance (from 10:1 to 500:1 Bouin's:ProHance) and for varied immersion durations (up to 24 hours). Results The results showed a significant change in T1 and T2 relaxation times as a function of concentration of contrast agent and immersion duration. As the contrast agent penetrated the tissues, T1 was reduced as desired (typically by 10×), but at the same time T2 was profoundly reduced (typically by 3×) due to both protein cross-linking from the fixative and the high concentration of contrast agent. A systematic assessment of this staining protocol showed an increased SNR (by 5×) over that in unstained specimens. Conclusion This staining protocol reduced scan time for very-high-resolution images (19.5 ,m) to only 3 hours, making MRH a routine tool for evaluating fetal development. J. Magn. Reson. Imaging 2007;25:1192,1198. © 2007 Wiley-Liss, Inc. [source] | ||||||||||