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PubMed1985

Prazosin: effect on psychomotor-stimulant cues and locomotor activity in mice.

Mice trained to discriminate 1 mg/kg d-amphetamine from saline, or the selective norepinephrine uptake inhibitor, nisoxetine, from saline, cross-generalized to the alternate drug. They also generalized to 5.6 mg/kg cocaine. The cues produced by amphetamine were antagonized by the selective alpha 1-adrenoceptor antagonist, prazosin, and slightly potentiated by the selective alpha 2-adrenoceptor antagonist, yohimbine. The nisoxetine cue was also antagonized by prazosin. In contrast, the peripherally acting sympathomimetics, p-hydroxyamphetamine and phenylpropranolamine, failed to substitute for, and pimozide and propranolol failed to block, either drug cue. In addition, prazosin, at a dose that did not affect either saline-associated locomotor behavior in mice or the locomotor-activity increase produced by the dopamine uptake inhibitor, bupropion, also antagonized the locomotor stimulation produced by amphetamine and cocaine. Thus, in mice, both the cues and locomotor stimulation produced by amphetamine and cocaine appear to be at least partially mediated by central alpha 1-adrenoceptor activation secondary to increased central synaptic concentrations of norepinephrine.

Amphetamine↗
PubMed1985

Tolerance to morphine-induced analgesia in mice: magnetic fields function as environmental specific cues and reduce tolerance development.

Mice receiving daily injection of morphine (10 mg/kg) developed tolerance to morphine-induced analgesia, such that after 5-7 days of treatment their thermal response (paw licking) latencies in the hot plate test were indistinguishable from those of control animals. Exposure to a rotating magnetic field for thirty minutes before the daily morphine administrations significantly reduced the development of tolerance. These magnetic exposures also significantly increased over 7-10 days the basal nociceptive thresholds and paw licking response latencies of saline treated mice. Control and sham exposed mice that were fully tolerant to the analgesic effects of morphine failed to show any tolerance to morphine-induced analgesia when exposed to the magnetic stimuli prior to injection. Likewise, the partial tolerance to morphine shown by mice exposed to the rotating magnetic field pre-injection environmental cues was eliminated when control or sham pre-injection cues lacking the magnetic stimuli were provided. In all cases tolerance to morphine-induced analgesia was evident in the subsequent re-test with the original cues. These results indicate that magnetic field exposure can reduce the development of tolerance to the analgesic effects of morphine. They also show that magnetic stimuli function as significant environmental cues for the development of tolerance to morphine-induced analgesia. This suggests that magnetic stimuli affect both the associative (classical conditioning) and non-associative (physiological, pharmacological) mechanisms involved in the development of opiate tolerance.

Analgesia↗
PubMed1991

An investigation of naming errors following semantic and phonemic cueing.

This study investigated the types of verbal errors produced by aphasic patients following phonemic and semantic cueing. Twenty-eight aphasic patients--10 Broca's, 10 Wernicke's and 8 conduction aphasics--served as subjects. Semantic and phonemic cues were administered on object and action confrontation-naming tasks. When subjects did not respond correctly to phonemic cueing, a significantly greater number of phonemic errors were produced, with a concurrent decline in related words and extended circumlocutions. When subjects failed to respond to semantic cueing on the action task, there was an increase in a number of error categories.

Anomia↗
PubMed1977

Dietary-dependent cross-species similarities in maternal chemical cues.

Acomys cahirinus pups preferred chemical cues from conspecific lactating females maintained on the maternal diet as compared to such cues from females fed an unfamiliar diet. Likewise, chemical cues from maternal diet Mus musculus were preferred over those from unfamiliar diet conspecific females. Thus, the production of maternal chemical stimuli may be basically similar in Acomys and Mus, with maternal diet being more critical than genetically programmed species-specific characteristics in determining the properties of the chemical cues to which A. cahirinus pups respond.

Animals↗
PubMed1988

Shape similarity and distance disparity as apparent motion correspondence cues.

Apparent motion is perceived when two spots of light are presented successively in different locations. When more than one element is present in each frame, there is a correspondence problem in matching the elements in one frame with those in the other. We report the effects of shape similarity and distance disparity on the correspondence process. Twenty subjects were tested using a 2-AFC design. We found that both shape and distance cues are used by the correspondence process: when distance is the only cue the motion which is usually perceived is that involving the shorter distance; when shape is the only cue the motion involving two elements of the same shape is preferred. We also studied the interaction between the two cues when both were present. Quantitative measures of the relative strengths of these effects and of their interaction are reported. A Signal Detection Theory model is used to analyze these apparent motion correspondence effects.

Cues↗
PubMed1990

Cue summation in spatial discriminations.

We investigated the extent to which discrimination performance improves when more than a single cue distinguishes two patterns. When two simple gratings differ slightly in spatial frequency, orientation, and/or contrast, the performance of most observers is better in multiple-cue conditions than in single-cue conditions and by an amount indicating Euclidean summation of information. These results are shown to be consistent with discrimination models that integrate information over different, spatially selective pathways. However, little summation is found when the task requires integration of cues across widely separated spatial frequency bands. This result implies that information is integrated only over pathways tuned to a common region of the spatial frequency domain.

Contrast Sensitivity↗
PubMed1993

The cue for contour-curvature discrimination.

Seven potential geometric cues for contour-curvature discrimination were tested: curvature, turning-angle, arc-length, arc-length-divided-by-chord-length, maximum-deviation (sag), mean-deviation and area. Three experiments were performed, each requiring the discrimination of two simultaneously presented, 1-sec-duration, curved-line stimuli, whose chord-lengths ranged from 12 to 48 arcmin visual angle and whose curvatures ranged from 0 to 0.13 arcmin-1. Experiments 1 and 2 determined for each cue the smallest detectable increment (the increment threshold) as a function of cue value, for a set of spatial transformations of the stimulus (one- and two-dimensional scalings) equivalent to changes in viewing distance and direction. In accordance with statistical estimation theory, the "best" cue was defined as the most efficient one, that is, the one which best accounted for the variance in the data. As a control, Expt 3 compared increment-threshold functions for circular and elliptical arcs of constant chord-length and circular arcs of constant arc-length. Over all three experiments, only sag and its linear approximation, mean-deviation, accounted well for the variance in the data; sag provided the best predictor, and its increment-threshold function satisfied Weber's law over almost all of the stimulus range. Additionally, sag has a special theoretical property (shared only with mean-deviation and area): the relationship it defines (in proportional terms) between curved contours in an image of an object or a scene is constant and independent of viewing distance and direction.

Adult↗
PubMed1995

The use of egocentric and exocentric location cues in saccadic programming.

Theoretically, the location of a visual target can be encoded with respect to the locations of other stimuli in the visual image (exocentric cues), or with respect to the observer (egocentric cues). Egocentric localization in the oculomotor system has been shown to rely on an internal representation of eye position that inaccurately encodes the time-course of saccadic eye movements, resulting in the mislocalization of visual targets presented near the time of a saccade. In the present investigation, subjects were instructed to localize perisaccadic stimuli in the presence or absence of a visual stimulus that could provide exocentric location information. Saccadic localization was more accurate in the presence of the exocentric cue, suggesting that localization is based on a combination of exocentric and egocentric cues. These findings indicate the need to reassess previously reported neurophysiological studies of spatial accuracy and current models of oculomotor control, which have focused almost exclusively on the egocentric localization abilities of the brain.

Cues↗
PubMed1985

Scopolamine degrades spatial working memory but spares spatial reference memory: dissimilarity of anticholinergic effect and restriction of distal visual cues.

The influence of the centrally active anticholinergic, scopolamine hydrobromide, on working and reference memory was studied in rats tested in a 12-arm radial maze. Both 0.25 and 0.5 mg/kg doses of the drug increased the number of working memory (WM) errors but had no effect on reference memory (RM) errors. A lower dose (0.125 mg/kg) was ineffective, as was the peripherally active anticholinergic, scopolamine methylbromide (0.5 mg/kg). Some of the behavioral effects of anticholinergics on spatial memory are mimicked by blindness or eliminating distal visual cues. If distal visual cues were more important for maintaining accurate WM than for RM, the selective effect of scopolamine on WM could be easily explained. But surrounding the maze with a curtain to eliminate extramaze cues increased RM errors without significantly increasing WM errors. Thus, the selective effect of anticholinergies on spatial memory in the radial maze is qualitatively different from the effect of restricting distal visual cues and must arise from some other action of the drug.

Animals↗
PubMed1987

Differential effects of physostigmine on cues produced by electrical stimulation of the ventral tegmental area using two discrimination procedures.

Two procedures were employed to assess the effects of physostigmine on the discrimination of cues produced by either high or low intensity electrical brain stimulation (EBS) of the ventral tegmental area in rats. When the procedure involved frequent presentation of brief trials, physostigmine enhanced the perceived intensities of the cues, causing the rats to respond to low intensities as though they had higher values. In contrast, physostigmine had no effects on the discrimination when the trials were less frequent and extended in duration. These results confirm the existence of multiple substrates for cues produced by stimulation of the ventral tegmental area in rats and implicate cholinergic neurons as substrates for the non-dopaminergic cues identified in the companion paper.

Animals↗
PubMed1989

Characteristics of radiation-induced performance changes in bar-press avoidance with and without a preshock warning cue.

Rats were trained to perform one of three tasks in which responses on a lever delayed the onset of footshock for 20 sec. One task provided a warning tone beginning 15 sec after the last response on the lever and lasting for 5 sec just prior to the presentation of a shock (fixed-interval signalled avoidance), while a second task provided no external cues (unsignalled avoidance). The third task was similar to the fixed-interval signalled avoidance task, except that the warning tone preceding shock began at varying intervals after the last response on the lever (variable-interval signalled avoidance). Animals trained on the signalled avoidance paradigms received fewer shocks than those on the unsignalled avoidance paradigm. After 10 krads of gamma radiation, animals performing on either task with cues were less able to avoid shock, although they recovered somewhat over a 90-min period. The animals not provided cues also experienced more shocks during the first 10 min after irradiation but were relatively less affected in performing the task. Response rates on the bar and the patterns of responding on these tasks were not significantly different after irradiation, except that animals responded after the onset of shock more often after irradiation than before. These results suggest that rats will continue to effectively use task related cues after irradiation, but that the relative degree of behavioral decrement may depend on the initial level of performance or possibly the complexity of the task.

Animals↗
PubMed1991

The pentylenetetrazole-cue antagonist actions of bretazenil (Ro 16-6028) as compared to midazolam.

In order to compare the potencies of bretazenil (Ro 16-6028) and midazolam (MDZ) to antagonize the pentylenetetrazole (PTZ) cue, rats were trained to discriminate between 15 mg/kg IP PTZ and saline (FR10, food reinforced). Additionally, other rats were trained to discriminate between 1.0 mg/kg IP MDZ and saline in order to investigate the degree of generalization of bretazenil to MDZ, and to test for the antagonizing effects of PTZ. Both bretazenil and MDZ were able to block the PTZ cue. Bretazenil was about 60 times more potent than MDZ in this respect. In tests for response generalization, bretazenil substituted for MDZ cue. Bretazenil did not show MDZ-antagonist actions. PTZ did block the MDZ cue and the generalization of bretazenil in the MDZ-trained animals. Assuming that the drug discriminative stimulus functions of PTZ are closely related to its anxiogenic effects, it was concluded that bretazenil may possess powerful anxiolytic properties. Bretazenil did not suppress the response rates which is consistent with previous studies reporting a lack of sedative and muscle-relaxant effects of bretazenil.

Animals↗
PubMed1994

Tobacco abstinence, smoking cues, and the reinforcing value of smoking.

One definition of the reinforcing value of a drug is the degree to which an organism will work to obtain it. Male and female smokers (n = 8 each) engaged in a task involving concurrent schedules of reinforcement for responding to receive cigarette puffs versus money on four occasions, following overnight abstinence versus no abstinence and in the presence of a lit cigarette (smoking "cue") or with no cigarette (2 x 2 design). Reinforcement schedule for puffs ranged from variable ratio 4 (VR4) to VR32, with schedule order during the first five trials (VR4 first, VR32 first) counterbalanced and repeated in reverse sequence during the second five trials. Schedule for money remained at VR4 during all trials. Results indicated significantly greater responding for puffs after overnight abstinence and in the presence of the smoking cue, although effect of the cue was specific to the "leaner" VR schedules (VR16, VR32). Unexpectedly, not only was reinforcement schedule for puffs a significant determinant of responding, but the order of these schedules (i.e., VR4 first vs. VR32 first) produced a significant overall difference in responding for puffs, especially in the presence of the cue. There was no difference in responding between males and females. These findings indicate that the reinforcing value of smoking is increased by overnight abstinence, the presence of a lit cigarette under lean reinforcement conditions, and the order in which reinforcement schedules are presented.

Adult↗
PubMed1994

Drug effects in a radial maze designed for dissociation of cues used by mice.

Scopolamine and amphetamine effects were investigated in a new radial maze. Three distinct procedures were designed to dissociate the use, by C57BL/6 mice, of the different cues available: a procedure where only spatial information was available, a procedure in which both spatial cues and olfactory trials were present, and a nonconfinement procedure where mice could use spatial cues, olfactory trials, and/or algorithmic strategies. We found that while scopolamine impaired performance on the maze in all three procedures, amphetamine tended to improve solving of the maze problem, but only in the procedure where spatial cues alone were available. The results are discussed in relation to hypotheses concerning these drug effects.

Algorithms↗
PubMed1991

The effects of semantic and phonemic prestimulation cues on picture naming in aphasia.

In this study of auditory prestimulation cues, picture naming performances under phonemic and semantic conditions were compared to picture naming performance under a neutral condition. Twenty aphasic subjects named 324 pictures (108 pictures x 3 conditions) each. Responses were scored using a coding system adapted by the investigator from classification systems used by Williams and Canter (1982) and Kohn and Goodglass (1985). Results indicated that naming accuracy was facilitated by phonemic and semantic cues. An examination of the distribution of errors under the three conditions revealed systematic effects of phonemic and semantic cues on the frequency of occurrence of specific error types. Increases in semantic paraphasia proportion scores and decreases in unrelated word error proportion scores were associated with the semantic condition, while increases in phonemic paraphasia proportion scores were associated with the phonemic condition. The finding that naming performance of aphasic adults varies as a function of the type of information provided by the cue is discussed in relation to cascade visual confrontation naming models.

Adult↗
PubMed1996

Locating reward cue at response manipulandum (CAM) induces symptoms of drug abuse.

Appetitive instrumental discrimination learning procedures provide for CAM (cue and manipulandum) when the reward cue (discriminative stimulus positively correlated with positive reinforcement) is located at the response manipulandum (object that when contacted or manipulated defines the performance of the instrumental response). Evidence reviewed shows that CAM induces excessive and compulsive instrumental responding relative to otherwise comparable non-CAM control procedures. In humans, symptoms of drug abuse are particularly likely when the drug-taking implement (response manipulandum at which instrumental drug-taking is directed) is also predictive of the drug's rewarding effects (reward cue). Evidence that the predictive relationship between a drug-taking implement and drug reward relates to drug abuse is reviewed, and implications for treatment and prevention are considered. CAM is related to neurobiological models of drug abuse that emphasize the role of the neurotransmitter dopamine (DA). CAM produces convergence of DA-mediated responding for conditioned reinforcement with DA mediation of psychomotor activation and incentive-motivational processes to yield reflexive cue-directed responding not observed in non-CAM controls.

Animals↗
PubMed1994

Spatial water maze learning using celestial cues by the meadow vole, Microtus pennsylvanicus.

The Morris water maze is widely used to evaluate to evaluate the spatial learning ability of rodents under laboratory settings. The present study demonstrates that reproductive male meadow voles, Microtus pennsylvanicus, are able to acquire and retain a spatial water maze task using celestial cues. Voles were able to acquire a modified outdoor Morris water maze task over 4 trials per day, whereby they had to learn and remember the location of a submerged hidden platform, using the position of the sun and associated celestial cues. Their proficiency on this task was related to the availability of the celestial cues, with voles displaying significantly poorer spatial navigation on overcast than clear days and when the testing time (and position of the sun and associated celestial cues) was shifted from morning to afternoon. These findings with meadow voles support the ecological relevance of the water maze task.

Animals↗
PubMedDate not supplied

Spatial cueing, sensory gating and selective response preparation: an ERP study on visuo-spatial orienting.

Event-related brain potentials (ERPs) were recorded in a visuo-spatial attention task where the position of an imperative stimulus was indicated either validly or invalidly by a central arrow (trial-by-trial cueing). Subjects had to perform choice RT tasks with the response being dependent either on the identity of the target stimulus or on its position. When target identity was relevant for response selection, validly cued stimuli elicited amplitude enhancements of the early, sensory-evoked P1 and N1 components at lateral posterior sites. The N1 validity effect was limited to scalp sites ipsilateral to the visual field of stimulus presentation. Although these effects were found only when the sensory discrimination task was considerably difficult, they are in line with models assuming that modulations of sensory-perceptual processing ("sensory gating") are induced by spatial cueing. However, when target location was response-relevant, N1 amplitude enhancements were consistently elicited by invalidly cued letters. CNV and LRP measures indicated that the arrow elicited response-related processing in the cue-target interval. Such processes occurred even when the cue contained no information about an upcoming response. Two consecutive lateralization phases were distinguishable in the LRP, with experimentally induced response assignments becoming effective only during the second phase.

Adult↗