Secondary task and risky driving behavior: a test of the mediating effect of situation awareness

A theoretical model is developed by using a contingency perspective to hypothesize the relationship between a secondary task and risky driving behavior. It is conjectured that the relationship between the two variables is mediated by situation awareness (SA). An experiment is designed and administered to provide empirical evidence. Thirty Indonesian students as subjects were required to carry out a driving assignment in a simulated environment. Empirical evidence suggests that SA provides a partial mediation effect towards the relationship between a secondary task and risky driving behavior. It is also found that a secondary task has a significant effect on risky driving behavior. The secondary task also becomes a significant explanation of SA. In addition, working memory capacity, experience and gender are found to have no significant impact towards SA.

Involvement of neuropeptide Y in glucose sensing in the dorsal hypothalamus of streptozotocin diabetic rats - in vitro and in vivo studies of transmitter release

AIMS

Within the brain, subgroups of neurons respond differently to altered glucose concentrations. Identification of neuropeptide Y in hypothalamic neurons that sense glucose suggests a role for neuropeptide Y in glucose sensing. Using in vitro and in vivo techniques to monitor transmitter release, we investigated whether lowering glucose concentration affects the release of neuropeptide Y from the brain, and whether this process is altered in Type I (insulin-dependent) diabetes mellitus.

METHODS

Male Sprague-Dawley rats were treated with 48 mg/kg streptozotocin or vehicle intravenously. The effect of reduced glucose on endogenous neuropeptide Y overflow from slices of hypothalamus and medulla incubated in Krebs solution was examined 4 weeks later. The hypothalamus was separated into a dorsal region containing the paraventricular nucleus and a ventral region containing the arcuate nucleus.

RESULTS

Streptozotocin-induced diabetes increased basal neuropeptide Y overflow in the dorsal and ventral hypothalamus ( p<0.05) but not the medulla. In vitro neuropeptide Y overflow was reduced by low glucose in the dorsal hypothalamus in diabetic, but not in control rats. No effect of reduced glucose was observed in the ventral hypothalamus or medulla. In vivo push-pull studies in the paraventricular nucleus also showed greater neuropeptide Y overflow in diabetic rats relative to control rats ( p<0.05). Insulin-induced hypoglycaemia induced a decrease in neuropeptide Y overflow in diabetic rats, while an increase was observed in control rats ( p<0.05).

CONCLUSION

These region-specific effects of low glucose on neuropeptide Y overflow in diabetic rats support a part for neuropeptide Y in altered glucose sensing in Type I diabetes.