Influyen las características psicológicas y los estilos de aprendizaje en el rendimiento académico de los estudiantes de medicina? Un estudio retrospectivo / The influence of phychological features and learning styles on the academic performance of medical students

BACKGROUND: The degree of difficulty we experience while learning different concepts and skills depends, among other things, on our psychological features and learning style. This may be particularly true for medical students, whose formation involves the acquisition of multiple cognitive, affective and psychomotor skills. AIM: To assess whether the psychological features and learning styles of medical students are associated with their academic performance. SUBJECTS AND METHODS: The psychological preferences and learning styles of 66 students of the 2001-graduating cohort were determined with the Myers Briggs Type Inventory (MBTI) and the Kolb Learning Style Inventory (LSI), respectively. The academic performance was assessed by the Calificación Médica Nacional (CMN), Chile and by the marks obtained during the Basic (1st to 3rd), Preclinical (4th and 5th) and Clinical (6th and 7th) years of undergraduate training. RESULTS: The psychological features, together with the sex of students were found to be associated with the performance in the Preclinical and Clinical years, and to the CMN. In men, the interest and ability to communicate with people and the concern for harmony, and in women the tendency to function in a systematic and orderly way are the features associated to high academic performance. No associations were found between learning styles and academic performance. CONCLUSIONS: The finding that the psychological preferences of medical students are relevent to their academic performance opens a new perspective to analyze the medical education and to design programs aimed at improving learning.

Tipos psicológicos y estilos de aprendizaje de los estudiantes que ingresan a medicina en la Pontificia Universidad Católica de Chile / Psychological types and learning styles of students entering medical school at the Pontificia Universidad Católica de Chile

BACKGROUND: Psychological type and learning style influence the way students perceive and process information. However, research in medical education in Chile still does not put enough emphasis in the study of these variables. AIM: To characterize the psychological types and learning styles of the students admitted to a Medical School. SUBJECTS AND METHODS: The Myers Briggs Type Indicator (MBTI) and the Kolb's Learning Styles Inventory (IEA) were administered to the 270 students admitted from 2000 to 2002 to the medical school of the Pontificia Universidad Católica de Chile. RESULTS: Fifty five percent of our students are concentrated in 4 of the 16 psychological types described. These students are characterized by the ability to base their decisions upon logical and objective reasoning (Thinking [T]) and to face life in a structured and decided way (Judging [J]). Only 10 per cent of the students have preferences opposite to T and J. These students base their decisions on the preservation of harmony and teamwork (Feeling [F]) and have a flexible attitude towards life (Perceiving [P]). The remaining 35 per cent have types with pairs of preferences TP and FJ. With regard to learning styles, more than two thirds of our students are Assimilators or Convergers. These learners tend to assimilate large amounts of information and abstract the main concepts, rather than to pay attention to concrete details. In general, our students are more reflective than active; they evaluate thoroughly all alternatives before making a decision. CONCLUSIONS: The psychological types and learning styles of medical students cluster around specific patterns whose features may either favor or hamper a specific learning. Knowledge of the differences in psychological types and learning styles of students may provide teachers with a new and valuable tool for improving learning and contributing to the academic success of students.

Neuropeptide Y induced inhibition of noradrenaline release in rat hypothalamus: role of receptor subtype and nitric oxide.

We aimed at characterizing the receptor subtype and the signaling pathway involved in the inhibitory effect of neuropeptide Y on the release of endogenous noradrenaline from rat hypothalamus. Slices of hypothalamus were stimulated with two trains of electrical pulses, and the release of noradrenaline and nitric oxide was measured. The electrical stimulation of hypothalamic slices induced a consistent release of both endogenous noradrenaline and NO. Neuropeptide Y inhibited concentration dependently the stimulated noradrenaline release. Similarly, agonists for neuropeptide Y Y1, Y2 and Y5 receptors inhibited noradrenaline release, albeit with a potency lower than neuropeptide Y. GW1229, a selective neuropeptide Y Y1 receptor antagonist counteracted the effect of neuropeptide Y, but not that of PYY-(3-36), an agonist active at neuropeptide Y Y5 and Y2 receptors. These results indicate that the inhibitory effect of neuropeptide Y is likely mediated by several receptor subtypes, including neuropeptide Y Y1, Y5 and possibly Y2 receptors. One microM NPY significantly enhanced NO release induced by the electrical stimulation. NG-monomethyl-L-arginine, an inhibitor of nitric oxide synthase, abolished NO release and blocked the inhibitory effect of neuropeptide Y on noradrenaline release. We conclude that nitric oxide participates in the signaling pathway of neuropeptide Y in the rat hypothalamus.

GW1229, a novel neuropeptide Y Y1 receptor antagonist, inhibits the vasoconstrictor effect on neuropeptide Y in the hamster microcirculation.

We studied the effect of GW1229, a novel neuropeptide Y Y1 receptor antagonists, on the vasoconstriction induced by neuropeptide Y and structurally related analogs in the hamster cheek pouch microcirculation. Changes in arteriolar diameter and microvascular conductance were assessed by intravital microscopy and measurement of sodium22 clearance. GW1229 did not affect basal vascular conductance but inhibited, concentration dependently, the reduction in arteriolar diameter and vascular conductance induced by 100 nM neuropeptide Y. GW1229 also counteracted the vasoconstrictor effect of 100 nM [Leu31,Pro34]neuropeptide Y, and that of 300 nM neuropeptide Y-[(13-36). In contrast, GW1229 had no effect on the vasoconstriction induced by noradrenaline. We conclude that the vasoconstrictor effect on neuropeptide Y in the hamster cheek pouch is mediated by neuropeptide Y Y1 receptors. The maintenance of physiological tone in this vascular bed does not involve the participation of endogenous neuropeptide Y.

Does the release of tritiated noradrenaline accurately reflect the release of endogenous noradrenaline from rat was deferens nerve terminals?

To determine whether the release of tritiated noradrenaline (NA) from the sympathetic nerve terminals of the rat vas deferens is an accurate reflection of the release of endogenous NA, we compared the electrically-evoked release of tritiated and endogenous NA from the prostatic sections of the vasa deferentia of male rats. We found that while the release of tritiated NA was completely dependent on the presence of calcium, the release of endogenous NA was not. The overflow of both, tritiated and endogenous NA, was virtually unaffected by blockade of the neuronal uptake mechanism by desipramine. In contrast, blockade of the extraneuronal uptake greatly increased the overflow of endogenous NA, while having no effect on the overflow of tritiated NA. Tritiated NA release, on the other hand, was sensitive to prejunctional regulation, while the release of endogenous NA was not. Increases in stimulus train duration induced a significant increase in the release of endogenous NA, but not in that of tritiated NA. In contrast, the later responded to lower stimulus train frequencies and reached a plateau at lower frequency values as compared to the endogenous NA release. Our results indicate the existence of marked differences between the release of tritiated and endogenous NA. We conclude that: 1) the assumption that tritiated NA release provides a good marker for endogenous NA release in the rat was deferens seems unwarranted; 2) the use of endogenous NA to study the release process in the vas deferens requires a re-examination of the experimental conditions used, in order to minimize possible artifacts that may obscure the study of neuronal release; 3) the choice between measuring the release of tritiated or endogenous NA must be evaluated for each tissue in particular, taking into account its cytoarchitecture, as well as the experimental conditions used.

Neuropeptide Y inhibits 3[H]noradrenaline release in the rat vas deferens independently of cAMP levels.

The purpose of the present investigation was to ascertain the functional significance of the reduction in cyclic AMP (cAMP) levels in the inhibitory action of neuropeptide Y (NPY) on [3H]noradrenaline ([3H]NA) release, as well as to further characterize the subtype(s) of NPY receptors involved in the peptide's actions in the rat vas deferens. We studied the effects of NPY, carboxyterminal fragments of this peptide and the NPY analog (Leu31,Pro34)-NPY on three functional responses, namely, the release of [3H]NA and the associated muscle contractions evoked by electrical stimulation, and the accumulation of cAMP stimulated by forskolin. NPY, a known inhibitor of the electrically-evoked [3H]NA release and neurogenic contractions is also a potent inhibitor of the forskolin-stimulated cAMP synthesis in the prostatic portion of the rat vas deferens. However, the ability of NPY to inhibit cAMP accumulation is lost upon tissue denervation, suggesting that this is likely to be a prejunctional effect. Elevation of cAMP levels by the use of the cell permeant analog of cAMP, 8-(p-chlorophenylthio)-cAMP (8pCPTcAMP) increases the electrically-evoked release of [3H]NA. However, the inhibition of [3H]NA release by NPY is not prevented by 8pCPTcAMP. Structure-activity relationship studies reveal that NPY and related peptides inhibit the release of [3H]NA, the muscle contractions and the synthesis of cAMP with a similar pharmacological profile. NPY is the most potent inhibitory agent, whereas [Leu31,Pro34]-NPY and NPY13-36, the respective Y1 and Y2 selective agonists, display similar potencies to inhibit the three responses. It is concluded that NPY inhibits neurotransmission in the rat vas deferens through the activation of a peptide receptor different from the known NPY-Y1 or NPY-Y2 receptor subtypes. NPY receptor activation in the vas deferens is negatively coupled to adenylyl cyclase activity. This intracellular signalling pathway is, however, not likely to mediate the peptide effects on the prejunctional regulation of noradrenaline release.

Effect of anisomycin on the development of rapid tolerance to ethanol-induced motor impairment.

Male Wistar rats given a single moderate dose (1.7 g/kg, IP) of ethanol (EtOH), followed by six trials on the moving belt apparatus during the next hour, showed functional tolerance to the motor-impairing effects of a second dose given 24 h later if the first EtOH was preceded and followed by an injection of saline. The same EtOH dose and intoxicated practice did not produce tolerance if the saline injections were replaced by two doses of anisomycin (60 mg/kg each, SC) 15 min before and 105 min after the first dose of EtOH. This finding suggests that rapid tolerance, like chronic tolerance, requires de novo synthesis of protein during a short period immediately related to the test experience.

Development of rapid tolerance to pentobarbital and cross-tolerance to ethanol on a motor performance test with intoxicated practice.

Male Wistar rats given a single moderate dose (1.7 mg/kg, IP) of pentobarbital (PB), followed by six trials on the moving belt apparatus during the next hour, showed tolerance to the motor-impairing effects of a second dose of 17 mg/kg given 24 h later. A control group that received saline before the first test showed the usual initial sensitivity when tested with PB 24 h later. Three weeks later, the first group showed cross-tolerance to the effects of ethanol (1.7 g/kg, IP) on the same test, while the second group did not. These findings support the suggestion that rapid tolerance is closely similar to chronic tolerance and that the contribution of intoxicated practice results in a long-lasting component that applies to cross-tolerance to ethanol on the same test.

Co-release of neuropeptide Y (NPY) and noradrenaline from the sympathetic nerve terminals supplying the rat vas deferens; influence of calcium and the stimulation intensity.

Epididymal (E) and prostatic (P) segments of the rat vas deferens were incubated with tritium-labeled noradrenaline (NA); upon transmural electrical stimulation for 20 or 60 s (70 V, 1 ms, 3-35 Hz), the outflow of immunoreactive neuropeptide Y (ir-NPY) and NA was detected in the superfusion media. Ir-NPY was detected only following trains of 35 Hz for 60 s in both E and P. In contrast, tritium was released in a graded fashion following trains of 3, 15 or 35 Hz stimulation for 60 s in E, whereas in P it reached a plateau at frequencies larger than 15 Hz. The outflow of tritium, under present conditions, was dependent on the duration of the stimuli, while the release of ir-NPY was only evoked with stimuli of 60 s duration. In the absence of external Ca2+, neurotransmission was blocked and co-release of ir-NPY and NA was prevented.

Age and castration modulate the inhibitory action of neuropeptide Y on neurotransmission in the rat vas deferens.

The potency of neuropeptide Y (NPY) to inhibit the electrically induced contractions of the epididymal half of the vas deferens diminishes markedly with age, being at least 20 times lower in the adult than in the 26-day-old rat. Castration sensitizes the epididymal segment to NPY in a testosterone-reversible manner. [Pro34]NPY was 3 times less potent than NPY in prepubertal rats and inactive in castrated adults, while NPY-(13-36) had no effect in either group. In the prostatic half, NPY and its analogs were active in rats from all ages studied; the order of potency being NPY greater than [Pro34]NPY greater than NPY-(13-36). The sensitivity of the prostatic segment from adult rats to NPY was unchanged by castration or testosterone replacement therapy. The NPY content of the ductus increases during development being higher in the prostatic than in the epididymal half at all ages studied. Castration decreases the peptide content in the two segments and the effect is prevented by testosterone administration. The present investigation demonstrated that the effect of NPY on vas deferens neurotransmission is subject to regulation by sex steroids, which affects differently the response of the two segments of the ductus.

Learning factor in rapid tolerance to ethanol-induced motor impairment.

Exposure of male Wistar rats to a single moderate dose (1.7 g/kg, IP) of ethanol (EtOH), followed by intensive intoxicated practice on the moving belt apparatus (a total of 12 min during the first hour after EtOH injection), results in functional tolerance to the motor-impairing effects of a second dose given either 8 or 24 h later. In the absence of intoxicated practice, or after a considerably reduced opportunity for it (a total of 4 min during the first hour after EtOH injection), the same dose of EtOH fails to produce tolerance. Thus, not only the opportunity to practice, but also its extent and possibly its quality are important determinants in the rapid development of intersessional tolerance. In contrast to its rapidity of development, no significant loss of this tolerance is evident three weeks after the tolerance acquisition sessions.