Self-control in male and female rats

Eight male and 8 female Wistar rats were exposed to a discrete-trial procedure in which they chose between the presentation of a small (one pellet) or a large (three pellets) reinforcer. The delay to the small and large reinforcer was 6.0 s in the first condition of Experiment 1. Subjects consistently chose the large reinforcer. When the delay to the small reinforcer was decreased to 0.1 s in the next experimental condition, all subjects continued to choose the large 6.0-s delayed reinforcer. When the contingencies correlated with the two levers were reversed in the next experimental condition, the majority of subjects (5 males and 6 females) still chose the large delayed reinforcer over the small immediately presented reinforcer. The delay to the small reinforcer was maintained at 6.0 s, but the delay to the large reinforcer was varied among 9.0, 15.0, 24.0, and 36.0 s in Experiment 2, in which 4 males and 4 females participated. Most subjects consistently chose the large increasingly delayed reinforcer, although choice for the small 6.0-s delayed reinforcer developed in some females when the large reinforcer was delayed for 24.0 or 36.0 s. These choice patterns were not predicted from a literal application of a model that says choice should favor the alternative correlated with the higher (amount/delay) ratio.     

Mecamylamine prevents the enhancement of retention induced by lysine vasopressin in mice

Lysine vasopressin (0.03 microgram/kg, sc) enhanced retention of a one-trial, step-through inhibitory avoidance task when injected into male Swiss mice immediately post-training, as indicated by retention performance 48 h later. A low dose of the vasopressin antagonist, AAVP (0.01 microgram/kg, sc), did not significantly affect retention, whereas a higher dose (0.03 microgram/kg, sc) impaired retention. Neither lysine vasopressin nor AAVP modified latencies to step-through of mice that had not received a footshock during training. The simultaneous injection of AAVP (0.01 microgram/kg, sc) prevented the enhancement of retention induced by lysine vasopressin. The influence of lysine vasopressin on retention was antagonized by the simultaneous administration of mecamylamine (5 mg/kg, sc) but not by hexamethonium (5 mg/kg, sc), atropine (0.5 mg/kg, sc), or methylatropine (0.5 mg/kg, sc). A modulatory role of vasopressin on the activity of central cholinergic nicotinic mechanisms which participate in memory formation is suggested.     

Differences in hemispheric functional asymmetry between athletes and nonathletes: evidence from a Unilateral Tactile Matching Task

To study the hemispheric specialization for spatial information processing in athletes and nonathletes a Unilateral Tactile Matching Task was administered. Athletes showed more marked hemispheric specialization than nonathletes. The right hemisphere of the former, in fact, indicated a more pronounced accuracy than those of the latter in perceiving rod orientations.     

The effects of self-management of school attendance by problem adolescents.

Self-management of attendance by problem adolescents was shown to improve attendance in an alternative school. The use of biased measures to investigate change is discussed as well as the utility of frequent measures. The effect of improved attendance on academics is presented and future research in this area is suggested.     

Hemispheric equality in reaction times to emotional and non-emotional nouns

Twenty presentations of 6 emotional and 6 non-emotional words in mixed random orders were monaurally presented to the right or left ear. Using the left hand, subjects pushed one of two response buttons indicating type of word heard. Performance improved in later trials and emotional words were recognized more quickly regardless of ear presentation. No differences were associated with the separate ear presentations. Equivalent hemispheric performance indicates equal processing sensitivity to four-letter emotional and non-emotional nouns and substantiates the right hemisphere's verbal processing capability for simple nouns.