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PubMed2004

Improvement of visual acuity by spatial cueing: a comparative study in human and non-human primates.

This study investigated the influence of spatial cueing (valid/invalid/no cue) on visual discrimination in human and non-human primates. We employed a spatial resolution task which required the accurate discrimination of the orientation of a Landolt "C" ring. The C appeared as single target in specific retinal locations while subjects maintained fixation of a central fixation point. The minimal discernable size of the "C" (=acuity threshold) was determined as a function of cue condition, retinal eccentricity (3 degrees -15 degrees ), and stimulus onset asynchrony (SOA) (200-1100 ms). For both species, we found consistent benefits from spatial cueing with differences in absolute thresholds ranging from 6% to 25%. These differences increased with retinal eccentricity and decreased with longer SOAs. Further experiments performed with humans only, showed that the effect of spatial cueing on visual discrimination is independent of spatial uncertainty, i.e. the number of possible target locations (2 versus 4), but fades with longer target presentation times. From our results we draw the following conclusions. (i) Since sensory noise and spatial uncertainty was small in our tasks, spatial shifts of attention involve signal enhancement in both, human and non-human primates. (ii) The similarity of the results obtained for humans and macaque monkeys indicates that the latter may serve as a suitable model system in studies trying to tackle the neural underpinnings of attentional control. (iii) In order to elicit robust effects on visual discrimination by spatial shifts of attention, a paradigm comprising short SOAs (approximately 200 ms) and target presentation times (approximately 150 ms), and retinal eccentricities larger than approximately 9 degrees seems most promising.

Adult↗
PubMed2006

Spatial and feature-based effects of exogenous cueing on visual motion processing.

In two experiments, we investigated the effects of exogenous cueing on visual motion processing. The first experiment shows that the typical pattern of reaction time (RT) effects, namely early facilitation and later inhibition of return (IOR), can be obtained using a color change as exogenous cue and a direction change as target. In the second experiment, we manipulated the validity of the cue independently with respect to location and feature using transparent motion stimuli. Facilitation of RTs with short cue-target interstimulus-intervals (ISIs) was only evident for targets with both the valid location and the valid feature. Furthermore, at longer cue-target intervals, RTs were prolonged for targets at the cued location, irrespective of the cued feature. These results demonstrate spatial and feature-based components of early facilitation and purely spatial IOR.

Adult↗
PubMed2004

"Mind the gap": the size-distance dissociation in visual neglect is a cueing effect.

There is a growing body of evidence that the processes mediating the allocation of spatial attention within objects may be separable from those governing attentional distribution between objects. In the neglect literature, a related proposal has been made regarding the perception of (within-object) sizes and (between-object) distances. This proposal follows observations that, in size-matching and bisection tasks, neglect is more strongly expressed when patients are required to attend to the sizes of discrete objects than to the (unfilled) distances between objects. These findings are consistent with a partial dissociation between size and distance processing, but a simpler alternative must also be considered. Whilst a neglect patient may fail to explore the full extent of a solid stimulus, the estimation of an unfilled distance requires that both endpoints be inspected before the task can be attempted at all. The attentional cueing implicit in distance estimation tasks might thus account for their superior performance by neglect patients. We report two bisection studies that address this issue. The first confirmed, amongst patients with left visual neglect, a reliable reduction of rightward error for unfilled "gap" stimuli as compared with solid lines. The second study assessed the cause of this reduction, deconfounding the effects of stimulus type (lines vs. gaps) and attentional cueing, by applying an explicit cueing manipulation to line and gap bisection tasks. Under these matched cueing conditions, all patients performed similarly on line and gap bisection tasks, suggesting that the reduction of neglect typically observed for gap stimuli may be attributable entirely to cueing effects. We found no evidence that a spatial extent, once fully attended, is judged any differently according to whether it is filled or unfilled.

Adult↗
PubMed1999

Effects of temporal cueing on residual visual discrimination in blindsight.

We tested the ability of a blindsight patient, GY, to identify in which of two locations a target was presented in a spatial two-alternative forced choice paradigm (spatial 2AFC). On each trial the subject was asked to make a second manual response indicating whether he had had any awareness of an event occurring during the trial. A cue, presented at the fixation location, could signal the 0.4 s period over which the target appeared within the 10 s duration of each trial. Targets of three contrasts, 93, 43 and 22% were used. We found that GY's ability to discriminate the location of targets in his blind field remained significantly above chance, with and without cueing, for each contrast. Cueing, did, however, significantly improve his performance for low contrast targets. When he performed a similar task with near threshold contrast targets in his spared visual field his discrimination was at chance unless the presentation of targets was cued, despite his reporting more awareness for these stimuli than he did for low-contrast stimuli in his blind field. These results are compared with those previously reported in monkeys who received lesions to their visual cortices as infants or adults. We conclude that (1) GY's blindsight is qualitatively different from near-threshold normal vision. (2) In common with infant-lesioned monkeys his blindsight remains even in the absence of temporal cues. (3) Residual vision is subject to modulation by attentional processes, or arousal, associated with temporal cueing.

Adult↗
PubMed2001

Cue interactions, border ownership and illusory contours.

When two retinally adjacent image regions both claim 'ownership' of their common boundary based on different visual cues, their perceptual competition could result in: (1) cue averaging, in which the common boundary is not strongly perceived as owned by either region, or (2) perceptual bistability, in which the competing interpretations alternate in conscious perception over time. We report that when the perception of one or another illusory surface depends on the outcome of such a competition, the alternative percepts primarily exhibit bistability rather than averaging (or mutual weakening). More generally, we suggest that mutually inconsistent perceptual interpretations of sensory data will tend to exhibit bistability to the extent that they require significant constructive activity by vision. When one interpretation is more 'literal' (i.e. less constructive), it will tend to block alternative percepts. Put somewhat differently, when competing visual cues specify different preferred (but not necessary) interpretations, then the likely perceptual outcome is bistability rather than cue averaging. However, inconsistent visual cues can also result in perceptual bistability if the interpretations they specify are so incommensurable that simply averaging them would not provide useful information for perception.

Analysis of Variance↗
PubMed2002

Voluntary saccadic eye movements in humans studied with a double-cue paradigm.

In the classic double-step paradigm, subjects are required to make a saccade to a visual target that is briefly presented at one location and then shifted to a new location before the subject has responded. The saccades in this situation are "reflexive" in that they are made in response to the appearance of the target itself. In the present experiments we adapted the double-step paradigm to study "voluntary" saccades. For this, several identical targets were always visible and subjects were given a cue to indicate that they should make a saccade to one of them. This cue was then changed to indicate another of the targets before the subject had responded: double-cue (DC) paradigm. The saccadic eye movements in our DC paradigm had many features in common with those in the double-step paradigm and we show that apparent differences can be attributed to the spatio-temporal arrangements of the cues/targets rather than to any intrinsic differences in the programming of these two kinds of eye movements. For example, a feature of our DC paradigm that is not seen in the usual double-step paradigm is that the second cue could cause transient delays of the initial saccade, and these delays still occurred when the second cue was reflexive--provided that it was at the fovea (as in our DC paradigm) and not in the periphery (as in the usual double-step paradigm). Thus, the critical factor for the delay was the retinal (foveal) location of the second cue/target--not whether it was cognitive or reflexive--and we argue that the second cue/target is here acting as a distractor. We conclude that the DC paradigm can be used to study the programming of voluntary saccades in the same way that the double-step paradigm can be used to study reflexive saccades.

Cognition↗
PubMed2001

Cue dependency of nicotine self-administration and smoking.

A paradox exists regarding the reinforcing properties of nicotine. The abuse liability associated with smoking equals or exceeds that of other addictive drugs, yet the euphoric, reinforcing and other psychological effects of nicotine, compared to these other drugs, are more subtle, are manifest under more restricted conditions, and do not readily predict the difficulty most smokers experience in achieving abstinence. One possible resolution to this apparent inconsistency is that environmental cues associated with drug delivery become conditioned reinforcers and take on powerful incentive properties that are critically important for sustaining smoking in humans and nicotine self-administration in animals. We tested this hypothesis by using a widely employed self-administration paradigm in which rats press a lever at high rates for 1 h/day to obtain intravenous infusions of nicotine that are paired with two types of visual stimuli: a chamber light that when turned on signals drug availability and a 1-s cue light that signals drug delivery. We show that these visual cues are at least as important as nicotine in sustaining a high rate of responding once self-administration has been established, in the degree to which withdrawing nicotine extinguishes the behavior, and in the reinstatement of lever pressing after extinction. Additional studies demonstrated that the importance of these cues was manifest under both fixed ratio and progressive ratio (PR) schedules of reinforcement. The possibility that nicotine-paired cues are as important as nicotine in smoking behavior should refocus our attention on the psychology and neurobiology of conditioned reinforcers in order to stimulate the development of more effective treatment programs for smoking cessation.

Animals↗
PubMed1999

GTS-21, a mixed nicotinic receptor agonist/antagonist, does not affect the nicotine cue.

Identification of nicotinic receptor subtypes involved in nicotine dependence is required for guiding the design of more selective antagonists capable of blocking the nicotine cue and nicotine self-administration. Due to the multiplicity of nicotinic receptors in the mammalian brain, selective agonists and antagonists are needed to assess the functional involvement of a particular subtype in vivo. Only recently have a few nicotinic receptor subtype-selective antagonists and agonists been identified. GTS-21 (also known as DMBX-anabaseine) is the only agent so far reported that selectively stimulates the alpha7 nicotinic receptor. Here GTS-21 was used to assess the possible mediation of the nicotine cue by this receptor subtype. Long-Evans rats were trained to discriminate between presession administration of 0.10 or 0.40 mg/kg (-)-nicotine bitartrate and its vehicle. GTS-21 did not substitute for nicotine, as all subjects consistently chose the vehicle lever after GTS-21 substitution. In another experiment, different doses of GTS-21 were administered prior to nicotine administration to investigate whether GTS-21 would antagonize the nicotine cue. Such was not the case. The lack of effect of GTS-21 upon the nicotine cue is consistent with the notion that the cue is mediated by nicotinic receptors other than the alpha7 receptor.

Alkaloids↗
PubMed1989

Damage to the hippocampal formation in rats selectively impairs the ability to learn cue relationships.

We assessed the contribution of the hippocampal formation to performance in tasks that require rats to respond to a relationship between discriminative stimuli. The first experiment employed a nonmatching-to-sample procedure in a Y-maze. Three pairs of boxes were used which differed in brightness of the walls and in the odors that they contained. The rats were trained prior to receiving kainic acid and colchicine-induced damage to the hippocampal formation or electrolytic damage to the amygdala. After surgery all rats performed the nonmatching-to-sample task accurately if both brightness and odor cues were present in the sample and choice boxes or if the boxes contained either visual cues alone or odor cues alone. If the available cue modality was different in sample and choice boxes, then the amygdala-damaged, but not the hippocampal-damaged, rats performed accurately. In the second experiment control rats or rats with hippocampal formation damage were trained postoperatively in a conditional black/white discrimination task in a Y-maze. Only the control group successfully learned to select the white arm if the start box was illuminated and the black arm if the start box was dark. Subsequently, both groups learned a simple black/white discrimination. The same rats were tested in the hidden platform version of the Morris water task and only the control group learned to swim accurately to the goal. Both groups learned to swim accurately to a visible black platform. The results are consistent with the notion that the hippocampal formation is essential to learning that involves control exerted by a configural relationship among cues, independently of the spatial or conditional requirements of tasks.

Amygdala↗
PubMed1998

Factors that affect social cue recognition in schizophrenia.

Earlier research (Corrigan and Green, Am. J. Psychiatry, 150 (1993) 589-594) showed fairly symptomatic persons with schizophrenia give more false-positive responses when answering questions about abstract cues in a social situation (i.e. affect, rules, and goals inferred about an interpersonal situation) than concrete cues (i.e. actions and dialogue observed in a situation). It is unclear, however, whether differential cue recognition is due to schizophrenia per se, or some aspect of the illness commensurate with significant symptoms and in-patient care. Moreover, the abstract and concrete dimension in the earlier study had not been independently validated. In this study, the 288 items of the Social Cue Recognition Test (SCRT) were divided into three sets based on abstraction ratings provided by 38 college students. The SCRT was then completed by 48 participants with DSM-III-R diagnoses of schizophrenia or schizoaffective disorder. Participants with schizophrenia were divided into low and high symptom groups using scores from the Brief Psychiatric Rating Scale. Results showed both low symptom and high symptom groups exhibited a differential deficit in cue recognition. False positives were greater for items rated as more abstract. Implications for understanding the social cognitive deficits of persons with schizophrenia are discussed.

Adult↗
PubMed2001

Sex differences in the dynamics of cue utilization and exploratory behavior.

The purpose of the present study was to investigate the effects of sex and estrous cycle on exploratory behavior, as well as the degree to which reliance on environmental cues changes with training. Fischer 344 rats were placed three times in an open field box that contained three objects (two identical bottles and a cylinder). During the initial exposure to the environment all females showed higher activity levels and explored a larger region of the environment compared to males. However, upon subsequent exposure to the same environment, these sex differences disappeared. During the third and final session, the locations of the bottle and the cylinder were switched. The estrous females and to a lesser degree male rats, responded to the relocation of objects with a renewal of exploration and activity; proestrous females did not show this response. The rats were then trained on a four-arm radial maze reference memory task. The correct arm could be located by its relation to extra-room cues, a large distal white panel, or to local inserts on the maze. Once the animals consistently chose the goal arm, a probe session was conducted to determine which cues the animals were using to solve the task. During the probe trial both the white panel and the local inserts were rotated 90 degrees clockwise and counterclockwise respectively and the animals' choice of arm recorded. During the first probe, females tended to rely on all three types of cues in solving the task. With additional training there was a shift towards predominantly using the distal visual information. In contrast, male rats did not show this shift; by the first probe session the males were predominantly using the distal visual information to solve the task. The findings indicate: (1) sex differences in the initial use of environmental cues; (2) the usage of environmental information is dynamic and changes with additional exposures to the environment. The results are related to previous findings on sex differences and estrous cycle effects, with an emphasis on the implications for hippocampal processing.

Animals↗
PubMed1991

Evidence that dopamine in the nucleus accumbens is involved in the ability of rats to switch to cue-directed behaviours.

Recently we have reported that injections of d-amphetamine into the nucleus accumbens enhanced the number of switches to cue-directed behaviours without an effect on the number of switches to non-cue-directed behaviours in a swimming test. In the present study we investigated to what extent this effect is mediated via the dopaminergic system in the nucleus accumbens. For that purpose drugs selective for D1- and D2-receptors were studied in this swimming test. It was found that the selective D2-agonist LY 171 555 (50 ng/0.5 microliters) enhanced the number of different cue-directed behaviours. The selective D2-antagonist raclopride (50 ng/0.5 microliters) decreased it. Furthermore an ineffective dose of raclopride attenuated the effect of LY 171 555. Both the selective D1-antagonist SCH 23390 (400 ng/0.5 microliters) and the selective D1-agonist SKF 38393 (50-400 ng/0.5 microliters) decreased the number of different cue-directed behaviours. The effect induced by SCH 23390 could not be blocked by SKF 38393. Similarly the effect induced by SKF could not be attenuated by SCH 23390. These data point to a role for dopamine D2-receptors in the ability to switch to cue-directed behaviours. The present findings do not yet allow the conclusion that D1-receptors are involved.

Animals↗
PubMed2000

The time course of spatial orienting elicited by central and peripheral cues: evidence from event-related brain potentials.

To study differences in the time course of attentional orienting triggered by salient peripheral events and by central symbolic precues, event-related brain potentials (ERPs) were recorded in response to letter stimuli following spatially informative symbolic or peripheral precues after a cue-target interval (CTI) of either 200 or 700 ms. Stimuli at cued (attended) locations elicited an enhanced negativity relative to stimuli at uncued locations. With short CTIs, these effects started around 150 ms post-stimulus for peripheral cues. They were delayed by about 100 ms for central cues. This latency difference is assumed to reflect fast exogenous orienting elicited by peripheral, but not by central cues. Beyond 200 ms post-stimulus, attentional negativities were larger with long CTIs than with short CTIs for both cue types, presumably related to the gradual build-up of endogenous orienting triggered by spatially predictive events.

Adolescent↗
PubMed2003

On-line feedback control of human visually guided slow ramp tracking: effects of spatial separation of visual cues.

Visual feedback control of tracking movements is dependent upon a visual comparison of the guiding target and moving limb positions but the human fovea greatly restricts the area of high acuity vision. The effect of vertically separating the target and movement cues in a slow movement task is investigated. Subjects track a slow constant velocity target in the horizontal plane with wrist flexion controlled cursor movements. The effects of changes in the vertical distance between the two cues upon tracking performance were observed. When both cursors were at the same level, tracking was most accurate but showed significant intermittency around 2 Hz in frequency. Increased separation of cues reduced significantly both accuracy and intermittency; tracking was smoother but less accurate. Thus, feedback control is dependent upon the efficiency of positional comparison and hence becomes less effective as the cue separation increases. These results also support previous studies suggesting each cue makes an equal contribution to visuomotor feedback control, each acting as a reference to the other.

Adult↗
PubMed2001

Position sensitivity in phasically discharging nucleus accumbens neurons of rats alternating between tasks requiring complementary types of spatial cues.

To determine how hippocampal location-selective discharges might influence downstream structures for navigation, nucleus accumbens neurons were recorded in rats alternating between two tasks guided respectively by lit cues in the maze or by extramaze room cues. Of 144 phasically active neurons, 80 showed significant behavioral correlates including displacements, immobility prior to, or after reward delivery, as well as turning, similar to previous reports. Nine neurons were position-selective, 22 were sensitive to task and platform changes and 40 others were both. Although the accumbens neurons showed the same behavioral correlate in two or four functionally equivalent locations, these responses were stronger at some of these places, evidence for position sensitivity. To test whether position responses were selective for room versus platform cues, the experimental platform was rotated while the rat performed each of the two tasks. This revealed responses to changes in position relative to both platform and room cues, despite the fact that previous studies had shown that place responses of hippocampal neurons recorded in the same task are anchored to room cues only. After these manipulations and shifts between the two tasks, the responses varied among simultaneously recorded neurons, and even in single neurons in alternating visits to reward sites. Again this contrasts with the uniformity of place responses of hippocampal neurons recorded in this same task. Thus accumbens position responses may derive from hippocampal inputs, while responses to context changes are more likely to derive from other signals or intrinsic processing. Considering the accumbens as a limbic-motor interface, we conclude that position-modulated behavioral responses in the accumbens may be intermediate between the allocentric reference frame of position-selective discharges in the hippocampus and the egocentric coding required to organize movement control. The conflicting responses among simultaneously recorded neurons could reflect competition processes serving as substrates for action selection and learning.

Animals↗
PubMed2003

Basolateral amygdala lesions impair both cue- and cocaine-induced reinstatement in animals trained on a discriminative stimulus task.

Drug-associated environmental cues can maintain drug use and contribute to relapse even after long periods of abstinence. We investigated the ability of sensory stimuli that signaled periods of reward availability to sustain cocaine self-administration and trigger the reinstatement of reward-seeking behavior. We demonstrate that lesions of the basolateral amygdala (BLA), a structure strongly implicated in attributing salience to environmental stimuli, significantly reduced the power of predictive cues to elicit reward-seeking behavior. In daily training sessions, a 20 s discriminative stimulus (DS) was presented to rats on a variable interval schedule. If five lever presses were recorded during the DS-on period, then cocaine (0.5 mg/kg) and a conditioned stimulus (CS) were simultaneously delivered. After training, half the animals received excitotoxic lesions of the BLA with quinolinic acid; the other half received saline. Compared with sham-lesioned animals, rats with BLA lesions earned fewer cocaine injections and were less accurate in responding to the DS in the first few days following the lesion. However, they maintained the same cocaine intake as sham-lesioned animals when the DS requirement was lifted. Finally, after seven extinction sessions, reinstatement was measured in response to: 1) i.v. cocaine infusion, 2) DS, 3) CS, 4) a familiar, but non-rewarded cue (S-) or 5) no stimulus. In sham-lesioned animals, cocaine and the DS, but not the CS or the S-, triggered reinstatement. BLA lesions abolished DS-induced reinstatement and significantly attenuated cocaine-induced reinstatement. These results demonstrate 1) that when tested under the same conditions, a discriminative cue which signals reward availability is a more robust trigger of reward-seeking than a Pavlovian CS which signals reward delivery and 2) that the BLA contributes to reinstatement in response to these discriminative cues.

Amygdala↗
PubMed1997

Cues to action in the process of changing lifestyle.

This research has been carried out in order to evaluate cues to action in health behavior. Which cues produce changes and how does the process of change proceed? In-depth qualitative interviews based on the Grounded Theory Method were made with 21 40-year-old men. Ten men were interviewed three times during a 1-year period to trace the process of change. In total 40 interviews were carried out during 1989-1990. All the interviewees were randomly selected from the population registers in the municipalities of Aarhus and Vejle. The main themes of the interviews are changes in previous health behavior, motivation for intentions to change in health behavior, and the role of health education in the process of change. Health behavior determinants seem to be knowledge, attitude, confidence, social influence, experiences and possibilities for change. Individuals typically exhibit a wide range of these determinants which makes it difficult to affect behavioral change through health education. Cues to action seem to arise from social influence, experiences, or underlying shifts in the possibilities of change. Experiences and social influence due to the health behavior in question seem to initiate changes in confidence, attitude and thereby motivation to change. Cues to action arising from these determinants are categorized as own illness or illness among friends and relatives, changes in self-perception, exceeded limits determined by the behavior in question, and social pressure. Shifts in the possibilities for change, such as change of partner or other life events, produce changes also affecting health behavior. A strategy to initiate changes in health behavior could be to create cues to action through personal experiences in the context of a specific health behavior or to establish contact to people when they are experiencing new life circumstances.

Adult↗
PubMedDate not supplied

Laboratory exposure to cocaine cues does not increase cocaine use by outpatient subjects.

Sixty-nine cocaine-dependent outpatients were exposed to cocaine-related stimuli and to non-drug events on separate days. Cocaine cue sessions were always followed by a meeting with a trained clinician designed to eliminate any craving that remained following cue presentations. Urine samples were collected before each laboratory session and 1 to 3 days later. Neither rates of cocaine use nor average urine metabolite values differed following the two sessions. Nearly 90% of subjects had the same urine test result both before and after the cocaine cue session. Thus, laboratory presentation of cocaine cues to outpatient subjects did not increase their risk of subsequent drug-taking. These results suggest that with proper clinical protections, cue exposure can be used as a treatment outcome measure and a behavioral intervention in outpatient settings without increasing the risk of drug use.

Adult↗