Deficits in water escape performance and alterations in hippocampal cholinergic mechanisms associated with neonatal monosodium glutamate treatment in mice.

Mice treated neonatally with monosodium glutamate (MSG) were found to have learning and memory deficits in performing a non-spatial water escape task. Scopolamine impaired the water-escape performance of the control mice but not that of the MSG-treated mice. It was suggested that the water-escape performance deficit in the MSG-treated mice was a result of impaired central cholinergic mechanisms. As such, scopolamine was unable to further incapacitate an already impaired cholinergic system. This is strongly supported by the decreased affinity of the sodium-dependent high-affinity choline uptake observed in the hippocampus. D-Cycloserine, a partial agonist at the glycine site of the NMDA receptor, did not affect the water-escape performance of the MSG-treated and control mice; nor did it alter the effects of scopolamine. This lack of effect of D-Cycloserine may imply that the NMDA receptors are not involved in non-spatial learning, in contrast to their reported involvement in spatial learning.

Effects of caffeine on mood and memory.

The effects of caffeine on mood and memory tasks were investigated in a double-blind study of 95 healthy young adults who were randomly assigned to three doses: 0, 200, and 400 mg of oral administration of caffeine. Subjects completed a battery of tasks once predrug and several times postdrug. Caffeine, in general, showed nonsignificant effects on cognitive, learning, and memory performance. The exception is that 200 mg caffeine facilitated performance on the relatively more difficult cancellation (addition and multiplication) tasks than the digit cancellation task. In addition caffeine decreased boredom and relaxation, and increased other ratings of subjective moods--anxiousness, tenseness, and nervousness. The reduction in boredom or fatigue is associated with the repetitive nature of the task and the period of time during which the tasks were repeated. In general, high-to-moderate users of caffeine recalled more words than low users, particularly at the beginning of the lists. Results are discussed in terms of the effects of caffeine on task difficulty and sensitivity and the relative potency of caffeine doses on behavior. User effect is suggested as an important consideration of memory assessment.

Pharmacokinetic and pharmacodynamic interactions between caffeine and diazepam.

The pharmacokinetic and dynamic interactions of caffeine and diazepam after single doses were investigated in six young healthy adults. Subjects received 6 mg/kg of caffeine, 0.3 mg/kg of diazepam, and their combination at 2-week intervals according to a Latin square design and a double-blind procedure. Subjects had blood samples withdrawn at 0, 5, 10, 20, 30, 45, 60 minutes and every 30 minutes thereafter until 210 minutes after treatment. A battery of behavioral tests were administered before treatment and after each blood sampling, starting with the 20-minute period. The coadministration of caffeine with diazepam resulted in a 22% reduction in diazepam plasma levels. Caffeine produced hand tremors and diazepam produced sedation and impaired memory and cognition. The two drugs did not antagonize the effects of each other except in the symbol cancellation task. There were significant correlations between the caffeine and diazepam plasma levels and performance on several tasks and evidence for the development of acute tolerance to both drugs.

Improved localization of moving targets with prior knowledge of direction of target motion.

In dynamic environments in which many stimulus elements are in motion, visual search may depend upon specific characteristics of target motion that are known in advance. When stimulus elements move in various directions but each element can move in only one direction, prior knowledge of the target's direction of motion reduces search time.

Caffeine effects: interaction of drug and wheelrunning experience.

Male Sprague-Dawley rats were tested for wheelrunning following repeated injections of caffeine or distilled water after varying amounts of experience with caffeine and wheelrunning. Rats experienced with caffeine in combination with wheelrunning ran significantly more than rats experienced only with caffeine or wheelrunning alone. Results suggest that caffeine's stimulant effects are greater when subjects are experienced with wheelrunning while under the influence of the drug.

Caffeine and diazepam: separate and combined effects on mood, memory, and psychomotor performance.

The effects of caffeine and diazepam on several mood, cognitive, learning, memory, and psychomotor tasks were investigated in a double-blind study of 108 young healthy adults who were randomly assigned to nine treatments; oral administration of caffeine (0, 3 and 6 mg/kg), diazepam (0, 0.15, and 0.30 mg/kg) and their combinations. Subjects completed a battery of tasks once before and twice after administration of the drugs. Caffeine alone showed no effects on cognitive, learning, and memory performance, but impaired fine motor coordination and increased anxiety and tenseness. Diazepam alone produced sedation, lowered other ratings of subjective moods, and impaired cognitive, learning, and memory performance. The two drugs did not antagonize the effects of each other, except in the symbol cancellation task.

Caffeine and nicotine: differential effects on ambulation, rearing and wheelrunning.

Male Sprague Dawley rats were tested for open field ambulation and rearing, and for wheelrunning, following repeated injections of either caffeine or nicotine, given according to a Latin Square design. Caffeine enhanced ambulation and rearing at 5 and 15 mg/kg, IP, and increased wheelrunning with 15 and 45 mg/kg. Nicotine (0.63 mg/kg) also enhanced ambulation, but not rearing, and depressed wheelrunning during the first 20 min of testing. Caffeine's enhancement of wheelrunning was not significant during the first two drug administrations. Results suggest that caffeine and nicotine affect activity via different neuropharmacological mechanisms. Previous experience with these drugs may modulate animals' reactivity to them.

Effects of caffeine use and ingestion on a protracted visual vigilance task.

College students (12 female, 12 male) were assigned to either higher caffeine user (HCU) or lower caffeine user (LCU) groups based on a caffeine usage survey. Prior to testing, subjects ingested either placebo or 195 or 325 mg caffeine. They then performed a visual vigilance task measuring response blocks, discrete responses (hits and false alarms), reaction times, and a Mood Check List using a double-blind design. HCU made significantly fewer hits, more false alarms, and also responded faster than LCU. No significant main effects of caffeine administration were found. In the mood analyses, male subjects were more anxious at the end of the experiment. Overall, the user factor (HCU versus LCU) was the most potent experimental variable.

Potential uses of kairomones for behavioral manipulation ofCotesia marginiventris (Cresson).

The effects of kairomone pattern and preconditioning on parasitization rates of fall armyworm larvae,Spodoptera frugiperda (J.E. Smith) byCotesia (=Apanteles)marginiventris (Cresson) were investigated in the laboratory and greenhouse using a hexane extract of frass and actual fall armyworm frass. Parasitization rates increased 55 and 26% in Petri dishes and on corn seedlings, respectively, when the entire experimental area was sprayed with the frass extract. Applying the extract in spots resulted in a 20-30% reduction in parasitization compared to treating the entire area. However, spot application produced significantly better parasitization rates compared to the control treatment. Exposing the parasitoids to actual fall armyworm frass resulted in ca. 50% greater retention in the release area and an increase of ca. 60-75% in the number of parasitoids searching.C. marginiventris parasitized factitious hosts topically treated with an extract of fall armyworm frass.

Behavioral and biological responses ofCotesia marginiventris to kairomones of the fall armyworm,Spodoptera frugiperda.

Potential kairomone sources of the fall armyworm (FAW),Spodoptera frugiperda (J.E. Smith), were bioassayed with females ofCotesia marginiventris (Cresson) in Petri dishes (10 cm diam). MatedC. marginiventris females, ranging in age from 1 to 3 days exhibited the most intense bioassay responses to potential sources of kairomone. Contacting a FAW-damaged corn leaf modified the pattern of movement inC. marginiventris from random to one exhibiting a significant increase in klinokinesis. No significant differences were present in kairomone responses of nonconditioned and conditioned parasitoids and parasitoid response to kairomones did not change throughout the photophase (0800-1800 hr). Removal of one, both, or the first eight antennal segments reduced or eliminated the response of the parasitoid to kairomones. Female parasitoids did not exhibit a preference for corn leaves damaged by a particular fall armyworm instar and parasitization rates were highest in larvae 48 hr old.

Sources of fall armyworm,Spodoptera frugiperda (Lepidoptera: Noctuidae), kairomones eliciting host-finding behavior inCotesia (=Apanteles) marginivenitris (Hymenoptera: Braconidae).

Bioassay responses inCotesia marginiventris (Cresson) females to materials derived from fall armyworm (FAW) larvae,Spodoptera frugiperda (J. E. Smith), were most intense for frass and somewhat less intense for larval and pupal cutical materials, scales, exuviae, silk, and oral secretion, with FAW larval hemolymph eliciting only a slight response. The highest percentage of ovipositor probing was caused by frass (100%) and moth scales (90%). Various types of corn-leaf damage when assayed alone did not produce responses as intense as when assayed in combination with frass, cuticle material, and oral secretion. Parasitoid response was somewhat better to frass derived from FAW larvae feeding on corn and peanut leaves than from larvae feeding on the foliage of soybeans, Bermuda grass, cowpeas, or laboratory diet. Hexane and chloroform were better than methanol and water for extracting active material from FAW frass, and chloroform was the best of these solvents for extracting corn leaves. Serial dilutions of frass extracts resulted in a reduction in parasitoid response.