No abstract

Letter contrast sensitivity function depends on surround luminance and this influence should be considered in future standardized directives.

The effects of idazoxan, an alpha-2 noradrenergic antagonist, on play and open field behavior were assessed in juvenile rats. Play was assessed in two separate paradigms. Initially, juvenile rats were housed individually and given a daily 5 min opportunity to play with a responsive partner. Idazoxan (1-8 mg/kg) increased pinning, an indicator variable of play, but did not affect the frequency of dorsal contacts, an index of play solicitation. When rats were tested in a separate test for play solicitation using an unresponsive play partner, idazoxan increased all three measures of play solicitation. Idazoxan increased activity and exploration when rats were tested in an open field, suggesting that the effects of idazoxan on play may be due to an increase in behavioral arousal and/or attention. These data are consistent with a modulatory role for norepinephrine in the control of behavior.

While the fovea shows higher sensitivity than the areas of peripheral retina investigated in this study, the speed of adaptation, measured from the visibility loss, is greater for retinal regions between 6° and 9° than for the fovea or retinal eccentricities beyond 9°.

No abstract