Response cost,reinforcement, and children's porteus maze qualitative performance

Sixty fourth-grade children were given two different series of the Porteus Maze Test. The first series was given as a baseline, and the second series was administered under one of four different experimental conditions: control, response cost, positive reinforcement, or negative verbal feedback. Response cost and positive reinforcement, but not negative verbal feedback, led to significant decreases in the number of all types of qualitative errors in relation to the control group. The reduction of nontargeted as well as targeted errors provides evidence for the generalized effects of response cost and positive reinforcement.     

Effects of ketamine on tunnel maze and water maze performance in the rat

The NMDA receptor, which has been implicated in memory formation, is noncompetitively blocked by ketamine. The present study examines the effect of ketamine (0, 3, 6, 12, and 25 mg/kg body wt; ip) on tunnel maze and water maze performance in Wistar rats. In the hexagonal tunnel maze (HTM) high doses of ketamine (12 and 25 mg/kg) decreased locomotor activity. Moreover, ketamine induced perimeter walking (6, 12, and 25 mg/kg) and attenuated exploratory efficiency (25 mg/kg). When the HTM was converted into a modified six-arm radial maze, ketamine impaired short-term but not long-term memory. In the Morris water maze, rats injected with ketamine (12 and 25 mg/kg) acquired a spatial navigation task more slowly than controls. When the escape platform was removed, the drug-treated rats did not preferentially search for it in the area where the platform had been during the acquisition phase. However, when the escape platform was visible, no differences in the performance of ketamine-treated and control rats could be found. In summary, ketamine seems to attenuate some but not all forms of learning in the tunnel maze and it impairs the acquisition of a spatial navigation task.     

Cholinergic-dopaminergic interactions in radial-arm maze performance

Although acetylcholine and dopamine are believed to play complementary roles in motor function, a comparable neurochemical interaction has not been established for cognitive function. The muscarinic receptor blocker scopolamine and the dopaminergic antagonist haloperidol have been found to impair choice accuracy of rats in the radial-arm maze. In the present study, low doses of these two drugs were administered intraperitoneally either alone or in combination to rats trained on a working memory task (food reward) in an eight-arm radial maze. Scopolamine, 0.125 mg/kg, produced a significant decrease in choice accuracy (i.e., arm entries until an error). Haloperidol, 0.0625 mg/kg, did not cause a significant decrease in accuracy, but there was a trend in that direction. The combination of haloperidol with scopolamine attenuated significantly the amnestic effect of scopolamine. These results suggest that, like motor behavior, cognitive function may be influenced by the balance between acetylcholine and dopamine.     

Gerbils in space: performance on the 17-arm radial maze.

In Experiment 1 six hungry gerbils received six trials per day on a 17-arm radial maze. During each trial the subjects were allowed to choose freely among the arms, each of which contained a food pellet, until each arm had been visited once or until eight minutes had elapsed. An error was recorded when the subject entered a previously visited arm. The gerbils quickly learned not to re-enter previously visited arms and generally made errors on fewer than 15% of entries, performance comparable to that of the rat and superior to that of other species tested in the radial arm maze. The intertrial-interval duration did not affect accuracy of arm choices during acquisition but did influence asymptotic accuracy. Accuracy did not change systematically over the six trials. A high proportion of arm entries were to nearby arms. Errors occurred most often towards the end of a trial. Odor cues were not important. When the number of trials per day was reduced from six to one, accuracy deteriorated slightly. In Experiment 2 neither the transposition of extramaze cues nor the placement of the maze in a different room had large disruptive effects on accuracy. In Experiment 3 the addition of three explicit intramaze brightness cues aided accuracy, perhaps by permitting the subjects to decompose the large maze into three smaller mazes, although there was no direct evidence that this was the case. Implications of a number of these results for models of spatial maze performance were discussed.     

Effects of the nicotinic receptor blocker mecamylamine on radial-arm maze performance in rats

Lesions of cholinergic neurons have been found by many investigators to impair choice accuracy in the radial arm maze. Because muscarinic receptor blockers, such as scopolamine, have also repeatedly been found to impair choice accuracy in the radial-arm maze, it has generally been thought that the critical effect of cholinergic lesions is the deafferentation of muscarinic receptors. The possible involvement of nicotinic receptors in the cholinergic bases of cognitive performance in the radial-arm maze has not been as well investigated. The present study examined the effects of the blockade of nicotinic receptors on performance of female Sprague-Dawley rats in the radial-arm maze. Acute administration of the the nicotinic receptor blocker, mecamylamine (10 mg/kg) was found to significantly impair radial-arm maze choice accuracy. This dose also caused a significant increase in response latency in the maze. The effect on choice behavior but not locomotor speed seemed to be due to the central effects of mecamylamine, because administration of the peripheral nicotine receptor blocker, hexamethonium (20 mg/kg), did not impair choice accuracy, even though it did increase response latency to a similar degree as the 10-mg/kg dose of mecamylamine. Lower doses of mecamylamine (2.5 and 5 mg/kg) did not impair choice accuracy. These results indicate that central nicotinic as well as muscarinic cholinergic receptors are involved with cognitive functioning.