The intensity of a fetal taste aversion is modulated by the anesthesia used during conditioning

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.

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Emergence of long‐term memory for conditioned aversion in the rat fetus

Gruest

Richer

Hars

2004

“…Infants and fetuses are now recognized as having a diverse behavioral repertoire and intellectual abilities to perceive and interact with their environment (Smotherman & Robinson, 1988b). Because the gustatory and olfactory systems are somewhat functional late in gestation (Teicher & Blass, 1977), our laboratory has been studying conditioned taste aversion (CTA) formation, taste recognition memory formation, and other gustatory memory phenomena in fetal and neonatal rats (Mickley, Lovelace, Farrell, & Chang, 1995;Mickley, Remmers-Roeber, Crouse, & Peluso, 2000a, 2000bMickley, Remmers-Roeber, Crouse, Walker, & Dengler, 2000;Mickley, Remmers-Roeber, Dengler, Kenmuir, & Crouse, 2001;Mickley et al, 1998). The studies reported here extend this work to a different behavioral paradigm designed to assess behavioral indicators of gustatory positive contrast and long-term habituation in fetal and neonatal rats.…”

Section: Introductionmentioning

confidence: 87%

“…Administration of the NMDA receptor-blocking drug ketamine before CS to US pairings potentiated CTA formation and conditioned motor responses in E18 fetuses (Mickley et al, 1995;Mickley et al, 2001). However, when injected with equivalent doses of ketamine at the time of conditioning, E19 and older rats later failed to exhibit a CTA or conditioned motor responses (Mickley et al, 1998;Mickley et al, 2001).…”

Section: Figurementioning

confidence: 94%

Repeated exposures to gustatory stimuli produce habituation or positive contrast effects in perinatal rats

Mickley

Kenmuir

Crish

et al. 2004

Self Cite

Adult rats exhibit a decrease in consummatory responses following repeated presentations of a taste (habituation) and an increase in consummatory responses if they experience an upward shift in the magnitude or intensity of a gustatory stimulus (e.g., sucrose or saccharin). These responses do not represent a direct sensorimotor reaction to a gustatory cue, but rather reflect a change in responding based on the memory of a previous taste. Here, we sought to determine if fetal rats could (like adults) adjust their orofacial motor responses based on a memory of recent gustatory experience. Embryonic Day 18 (E18) or Day 19 (E19) rat fetuses received oral lavage with either 0.15 or 0.30% saccharin (SAC). Subsequently, observations of orofacial movements (mouthing and licking) following oral lavage with 0.30% SAC were made 50 min later, 24 hr later, or on postnatal Day 3 (P3). Thus, some animals were in a "shifted" condition in which they first experienced a relatively low concentration of SAC and then a higher one while control rats ("nonshifted") received 0.30% SAC during both taste exposures. Fetuses exhibited evidence of both habituation (with repeated presentation of the 0.30% SAC) and positive contrast effects (PCEs) (following an upward shift in SAC concentration) when retested 50 min after their first exposure to SAC on E19. However, these animals did not exhibit PCEs 24 hr later or 5 days later (on P3). Contrast effects were not observed when the initial SAC exposure was on E18, and habituation responses were variable depending on the time interval between the taste presentations to these animals. Rats with a 5- to 6-day latency between the two taste presentations showed neither PCEs nor habituation. Our data indicate that PCEs and habituation effects emerge at different ages, and their demonstration is dependent upon the latency between the taste presentations.

Latent inhibition of a conditioned taste aversion in fetal rats

Mickley

Hoxha

DiSorbo

et al. 2013

Self Cite

The etiology of schizophrenia's cognitive symptoms may have its basis in prenatal alterations of glutamate N-methyl-D-aspartate (NMDA) receptor functioning. Therefore, the current study investigated the effects of ketamine (an NMDA receptor blocking drug) on both a conditioned taste aversion (CTA) and latent inhibition (LI; a model of attentional capacity) in rat fetuses. We first sought to determine if a CTA could be diminished by nonreinforced preexposure to a CS in fetal rats (i.e., LI). We injected E18 pregnant Sprague-Dawley rats with 100% allicin (garlic taste) or an equal volume of saline. Some of the pregnant dams also received ketamine (100 mg/kg, i.p.). One day later (E19), the dams received a second injection of the CS, followed by either lithium chloride (the US) or saline. Finally, on E21 pups received oral lavage with allicin and observations of ingestive orofacial motor responses were recorded. When allicin had been paired with LiCl in utero, E21 fetuses exhibited a conditioned suppression of orofacial movements, indicative of an aversion to this taste. Preexposure to the garlic taste on E18 produced a LI of this CTA. Ketamine significantly disrupted the formation of the CTA and had some impact on LI. However, the direct effect of ketamine on LI is less certain since the drug also blocked the original CTA.