Biomedical subjects

D Costa-Miserachs

Publications and source records attributed to D Costa-Miserachs.

7 recordsLinked to original sources

PubMed1999

Presumed 'prefrontal cortex' lesions in pigeons: effects on visual discrimination performance.

The posterodorsolateral neostriatum (PDLNS) in pigeons may be an equivalent of the prefrontal cortex (PFC) in mammals. Here we report that lesions of this brain region in pigeons have a detrimental effect on various learned visual discriminations. Pigeons with lesions of the overlying area corticoidea dorsolateralis (CDL) served as controls. Both the postoperative re-learning to criterion of a preoperatively learned simultaneous double visual mirror pattern discrimination and the learning of a simple successive go, no-go discrimination were impaired by the PDLNS lesions. The PDLNS and CDL groups did not differ significantly in the postoperative learning of a reversal of the simultaneous discrimination. The results are discussed in relation to the presumed equivalence between the avian PDNLS and the mammalian PFC.

Animals↗

PubMed1998

Posttraining epinephrine and memory consolidation in rats with different basic learning capacities. The role of the stria terminalis.

Rats received bilateral stria terminalis (ST) lesions or were sham-operated. Five days later, the animals were trained in a two-way active avoidance task (one session, 30 trials) and, immediately after the training session, received 0.01 mg/kg i.p. epinephrine or distilled water. Retention was tested 20 days after the acquisition session. In sham-operated groups, epinephrine improved retention in rats that were poor learners and impaired it in rats that were good learners. In poor learners with posttraining epinephrine, lesions of the ST not only blocked the facilitatory effect of epinephrine but also disrupted performance throughout the retention session. In good learners, ST lesions attenuated the disruptive effect of epinephrine. Lesions per se did not affect either acquisition or retention. We conclude that ST is involved in the modulatory effect of posttraining epinephrine on memory consolidation. In addition and considering the results observed in rats that were poor learners, we suggest that emotional factors and/or other amygdaloid pathways different from the ST could participate in the effects of posttraining epinephrine, along with the ST.

Amygdala↗

PubMed1997

Facilitation of a distributed shuttle-box conditioning with posttraining intracranial self-stimulation in old rats.

Old Wistar rats (16-17 months) were trained in a two-way active avoidance task for 5 consecutive days (10 trials/day). Immediately after each training session a lateral hypothalamic intracranial self-stimulation session (ICSS group) or a sham-treatment session (Control group) was given to the animals. Long-term retention was tested 7 days after the last acquisition session. ICSS treatment led to a significant improvement in acquisition. In the long-term retention session the level of avoidance in both groups was similar to that achieved in the last acquisition session, although differences among groups failed to reach statistical significance. These results are compared with those obtained in previous experiments with young adult rats. While ICSS facilitated the process of acquisition in both young and old rats (however, it was much more powerful in young animals), further experiments are needed to elucidate whether this effect is long-lasting in old rats, as occurs in young adult subjects.

Animals↗

PubMed1997

Long-term memory modulation by posttraining epinephrine in rats: differential effects depending on the basic learning capacity.

Effects of posttraining epinephrine on retention of a massed (1 session, 30 trials) 2-way active avoidance task were studied in rats. Immediately after the training session rats received an injection of 0.05 or 0.01 mg/kg ip epinephrine, or distilled water. Retention was tested 11, 20, or 45 days after training, in independent groups of rats. The 20- and 45-day retention was improved in poor-learning rats and disrupted in good-learning rats. It was concluded that the effect (facilitatory or disruptive) of posttraining epinephrine on memory consolidation depends on the basic learning capacity of rats for this task and needs a long time to be expressed.

Animals↗

PubMed1996

Shuttle-box memory facilitation by posttraining intracranial self-stimulation: differential effects in rats with high and low basic conditioning levels.

The effects of intracranial self-stimulation (ICSS) on retention (after 24 hr, 7, 15, or 60 days) of a massed 2-way active avoidance task were studied in independent groups of rats. All groups showed a higher performance on the retention session than on the acquisition one. In the control subjects, the higher retention performances were observed in the 7- and 15-day groups. However, the ICSS treatment facilitated the 24-hr retention compared with its control group, allowing the treated subjects to achieve the same level of performance on the 24-hr retention session than that achieved by the control rats at the 7-day retention test. In the 24-hr groups, the facilitatory ICSS effect was stronger in the subjects with a low level of conditioning and weaker in those with a high level. Results suggest that posttraining ICSS accelerates memory consolidation and equalizes the performance of poor and good learners.

Animals↗

PubMed1994

Long-term memory facilitation in rats by posttraining epinephrine.

Effects of posttraining epinephrine (EPI) on retention of a massed (1 session, 30 trials) 2-way active avoidance task in rats were studied. The rats received an injection (ip) of 0.05 mg/kg EPI, 0.01 mg/kg EPI, or distilled water immediately after the training session. EPI did not improve retention 24 hr after the training session (Experiment 1) but enhanced retention 20 days after the training session (Experiment 2). The group receiving the smaller dose of EPI had better retention than the group receiving the larger dose, indicating dose dependency. The authors suggest that the process of consolidation of massed 2-way active avoidance conditioning is long and elaborative. Posttraining EPI would facilitate this active process of consolidation, improving performance as consolidation goes on. This facilitation needs, at least under certain conditions, more than 24 hr to be expressed as a higher level of performance on the retention test.

Animals↗

PubMed1993

Facilitation of a distributed shuttlebox conditioning with post-training epinephrine in rats.

Forty-two male Wistar rats were trained in a two-way active avoidance task during 5 consecutive days (10 trails/session). Immediately after each training session animals were given an injection, ip, of 0.1 mg/kg (EPI 0.1 group) or 0.05 mg/kg (EPI 0.05 group) of epinephrine, or vehicle (Vehicle group). Long-term retention was tested 20 days after the last acquisition session. Our results showed that the lower dose of epinephrine (0.05 mg/kg) led to a significant improvement of acquisition, compared with both the Vehicle and the EPI 0.1 group. On the long-term retention session the level of avoidances in both EPI 0.05 and Vehicle groups was similar to that achieved on the last acquisition session, although differences between groups failed to reach statistical significance. Concerning the EPI 0.1 group, a significant increase in the number of avoidances was observed between the last acquisition session and the long-term retention session. This later result might suggest that the higher dose of epinephrine would need a longer period to manifest its effectiveness. We conclude that the facilitatory effects of epinephrine are dose-dependent, and that under a distributed paradigm epinephrine modulates memory consolidation processes leading to an improvement of the magnitude of learning rather than merely speeding up learning.

Animals↗