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Spatial attention triggered by unimodal, crossmodal, and bimodal exogenous cues: a comparison of reflexive orienting mechanisms.

The aim of this study was to establish whether spatial attention triggered by bimodal exogenous cues acts differently as compared to unimodal and crossmodal exogenous cues due to crossmodal integration. In order to investigate this issue, we examined cuing effects in discrimination tasks and compared these effects in a condition wherein a visual target was preceded by both visual and auditory exogenous cues delivered simultaneously at the same side (bimodal cue), with conditions wherein the visual target was preceded by either a visual (unimodal cue) or an auditory cue (crossmodal cue). The results of two experiments revealed that cuing effects on RTs in these three conditions with an SOA of 200 ms had comparable magnitudes. Differences at a longer SOA of 600 ms (inhibition of return for bimodal cues, Experiment 1) disappeared when catch trials were included (in Experiment 2). The current data do not support an additional influence of crossmodal integration on exogenous orienting, but are well in agreement with the existence of a supramodal spatial attention module that allocates attentional resources towards stimulated locations for different sensory modalities.

Acoustic Stimulation↗

Inhibitory and facilitatory effects of cue onset and offset.

The response speed to a visual target is modulated by the position of previous events (cues) even if their position is not predictive of the target position. The modulation has been considered biphasic, with an early facilitatory and a later inhibitory component. We conducted three experiments that investigated the importance of the onset and offset features of the cue for the facilitatory and inhibitory effects and estimated their separate and joint effects. The two possible target locations, one in the right and one in the left visual field, were indicated by two empty boxes, and the cue consisted of the onset and/or offset of an arrowhead located just under one of the two boxes. Different time intervals were used between cue and target. Subjects were instructed to ignore the cue and to respond to the target (a cross inside one of the two boxes). The data showed only consistent effects of inhibition (inhibition of return) with the long intervals, but the pattern was different depending on the cue type. The amount of inhibition was much greater when the onset of the cue was followed by its offset. Apparently, inhibition of return depended on the dynamic changes of the cue.

Adolescent↗

Preference for spatial cues in a non-storing songbird species.

Male mammals typically outperform their conspecific females on spatial tasks. A sex difference in cues used to solve the task could underlie this performance difference as spatial ability is reliant on appropriate cue use. Although comparative studies of memory in food-storing and non-storing birds have examined species differences in cue preference, few studies have investigated differences in cue use within a species. In this study, we used a one-trial associative food-finding task to test for sex differences in cue use in the great tit, Parus major. Birds were trained to locate a food reward hidden in a well covered by a coloured cloth. To determine whether the colour of the cloth or the location of the well was learned during training, the birds were presented with three wells in the test phase: one in the original location, but covered by a cloth of a novel colour, a second in a new location covered with the original cloth and a third in a new location covered by a differently coloured cloth. Both sexes preferentially visited the well in the training location rather than either alternative. As great tits prefer colour cues over spatial cues in one-trial associative conditioning tasks, cue preference appears to be related to the task type rather than being species dependent.

Animals↗

Visually guided attention is neutralized when informative cues are visible but unperceived.

The ability to voluntarily shift the focus of visual attention away from the focus of gaze was investigated in a novel paradigm designed to elaborate the stages of processing underlying this ability. A basic experimental method used to investigate guided visual attention involves measuring response times to targets presented at positions of which the observer has been informed by an orienting cue. Binocular rivalry was utilized to dissociate presentation of the orienting cue from visual awareness of that cue. The findings indicated that when an informative cue was presented to an eye during the dominance phase, thus reaching visual awareness, manual response times were significantly affected by cue validity. In contrast, when the same cue was presented to an eye during suppression, and thus was not seen by observers, response times were not influenced by cue validity. We conclude that to guide attention, neural signals registering informative visual cues must be processed at stages lying beyond the site of rivalry suppression. Implications for investigating the neural basis of visual attention are discussed.

Attention↗

A perturbation analysis of depth perception from combinations of texture and motion cues.

We examined how depth information from two different cue types (object motion and texture gradient) is integrated into a single estimate in human vision. Two critical assumptions of a recent model of depth cue combination (termed modified weak fusion) were tested. The first assumption is that the overall depth estimate is a weighted linear combination of the estimates derived from the individual cues, after initial processing needed to bring them to a common format. The second assumption is that the weight assigned to a cue reflects the apparent reliability of that cue in a particular scene. By this account, the depth combination rule is linear and dynamic, changing in a predictable fashion in response to the particular scene and viewing conditions. A novel procedure was used to measure the weights assigned to the texture and motion cues across experimental conditions. This procedure uses a type of perturbation analysis. The results are consistent with the weighted linear combination rule. In addition, when either cue is corrupted by added noise, the weighted linear combination rule shifts in favor of the uncontaminated cue.

Cues↗

The effects of scopolamine and cues to forget on pigeons' memory for time.

Pigeons were trained with a 0-s delayed symbolic matching-to-sample procedure to indicate whether a houselight sample stimulus was short (2 s) or long (8 s) by pecking a red or a green comparison stimulus. In Experiment 1, the pigeons received injections of scopolamine hydrobromide (0.015 mg/kg), or saline, and the delay interval was manipulated (0, 1, 3, and 9 s). Memory for time was significantly poorer following scopolamine injections than following saline injections. A significant choose-short bias was observed under scopolamine at delays as brief as 3 s, but not under saline. In Experiment 2, a brief postsample cue (a vertical or horizontal line) signaled whether the comparison stimuli would be presented or omitted on each trial. During training, comparison stimuli were always presented following the remember (R) cue, but never following the forget (F) cue. During testing, memory for time was significantly poorer on F-cue trials than on R-cue trials. A significant choose-short bias was observed on F-cue trials at the 5- and 10-s delays, but not on R-cue trials. The results suggest that anticholinergic blockade accelerates the rate at which memory for temporal events is foreshortened in working memory. This effect is similar to that produced by an explicit cue to forget the temporal sample.

Animals↗

Effects of extraneous stimuli on social cue perception in schizophrenia.

Competing hypotheses that explain the effects of emotionally arousing, extraneous auditory stimuli on the social cue perception of schizophrenic patients were examined in this study: (1) extraneous arousing stimuli enhance patients' cue perception; (2) extraneous stimuli distract patients, and cue perception is diminished. Twenty-five patients with DSM-III-R diagnoses of schizophrenia completed a cue-perception task in which half of the videotaped vignettes included in the task were presented with simultaneous extraneous stimuli and half were not. Item difficulty and consistency across extraneous stimuli conditions were matched on standardization and cross-validation samples. Results showed that schizophrenic subjects were significantly more sensitive to cues when exposed to extraneous stimuli, thereby supporting the first hypothesis. This effect was also observed in a subgroup of schizophrenic subjects who demonstrated a distraction decrement on another test of short-term recall. The presence of extraneous stimuli interacted with perception of abstract cues; that is, schizophrenic subjects were particularly better at perceiving abstract cues when extraneous stimuli were presented simultaneously. Future research needs to determine characteristics of extraneous stimuli that enhance cue perception.

Adult↗

Covert orienting to non-informative cues: reaction time studies.

Lateralized, non-informative visual cues lengthen reaction time (RT) to successive targets flashed in the same hemified. Early ipsilateral RT facilitation is limited to the co-occurrence of cues and targets. Inhibition from visual cues has sensory components which do not depend on orienting, as well as attentional components which are limited to one side of the vertical meridian. An inhibition of RT to targets ipsilateral to the cues has been found with somatic or auditory cues and targets, and also when somatic targets follow visual cues or visual targets follow somatic cues. The results reviewed in this paper (1) are best accounted for by directional constraints in motor readiness which are induced by the voluntary suppression of an overt orienting toward the location of the cue; (2) indicate that similar mechanisms of covert orienting operate in the whole peripersonal and near extrapersonal space; and (3) point to a common neural substrate mediating both intramodal and cross-modal effects.

Animals↗

Social cue perception and intelligence in schizophrenia.

Previous research has shown that both acutely ill and remitted schizophrenic patients are more sensitive to the concrete, than the abstract, cues of a social situation. The purpose of this study is to determine whether this difference is attributable to a generalized performance deficit by determining whether difference in concrete and abstract cue recognition correlates with verbal intelligence. A second goal of this study is to determine whether differences in the cue perception of schizophrenic and normal control samples is also attributable to differences in verbal intelligence. Samples of inpatients (n = 23) and outpatients (n = 20) with DSM-III-R diagnosis of schizophrenia or schizoaffective disorder completed the Social Cue Recognition Test, the Vocabulary Subtest of the WAIS-R, and the Brief Psychiatric Rating Scale. Standardized residual scores representing differences in sensitivity across abstract and concrete cue recognition were not found to correlate significantly with verbal IQ in either sample. However, overall sensitivity was significantly associated with intelligence in both samples and standardized residual scores were significantly associated with thinking disturbance in the inpatients. Differences in cue perception across schizophrenic and normal control samples remained significant after adjusting cue perception scores by scores on the Vocabulary Subtest. These findings suggest that the differential deficit in cue recognition may not be attributable to generalized performance deficit.

Adult↗

A comparison of cue competition in a simple and a complex design.

Recent evidence suggests that controlled reasoning processes play an important role in cue competition in human causal learning (see De Houwer, J., Beckers, T., & Vandorpe, S. (2005). Evidence for the role of higher-order reasoning processes in cue competition and other learning phenomena. Learning &Behavior, 33(2), 239-249, for a review). Until now, this evidence comes almost exclusively from studies with simple designs that involved only a limited number of cues. Little is known about the role of controlled reasoning processes when the design is more complex. It is important to examine this issue because the complexity of the design could determine the resources that are available for reasoning and thus the role that reasoning plays in cue competition. We directly compared cue competition in a simple and a complex design. The results showed that complexity of the design affected retrospective cue competition but not forward cue competition. More fine grained analyses with respect to retrospective cue competition showed that unovershadowing but not backward blocking differed significantly between complexity conditions.

Adult↗

Alcohol seeking in C57BL/6 mice induced by conditioned cues and contexts in the extinction-reinstatement model.

We have recently shown that the alcohol self-administration context can reinstate extinguished responding for alcohol when that extinction occurs in a different context [Burattini, C., Gill, T. M., Aicardi, G., & Janak, P. H. (2006)]. The ethanol self-administration context as a reinstatement cue: acute effects of naltrexone. Neuroscience, in press; Zironi, I., Burattini, C., Aicardi, G., & Janak, P. H. (2006). Context is a trigger for relapse to alcohol. Behav Brain Res 167, 150-155). Here, we test whether the C57BL/6 mice will also show context-induced reinstatement for alcohol, and whether presentation of an alcohol-associated cue will alter the observed responding. Male C57BL/6 mice were trained to lever press on a fixed ratio-3 schedule for a 10% ethanol solution in a context made distinctive using visual, tactile, and olfactory stimuli. Each ethanol delivery was paired with a compound tone-light stimulus. After training, extinction sessions were given in a distinct context, comprised of different visual, tactile, and olfactory stimuli; the compound cue and the alcohol were not available during these sessions. In Experiment 1, after response extinction, subjects were tested by placement into both the alcohol self-administration context and, on a subsequent test, by response-contingent presentation of the cue following placement into the alcohol self-administration context. In Experiment 2, after response extinction, subjects were tested in both of these conditions, with the addition of a test of the effects of response-contingent presentation of the cue in the extinction context. The results indicate that the alcohol self-administration context produces a mild increase in responding at the alcohol lever, and that presentation of the alcohol-associated cue in the alcohol context, but not the extinction context, strongly increases responding on the alcohol lever. These findings suggest that the power of an alcohol-associated cue can be modulated by the context. The observed effects of alcohol contexts and cues on alcohol-seeking behavior in the C57BL/6 mouse suggest that this reinstatement model may be useful for understanding the neurobiological and genetic mechanisms of relapse triggered by conditioned environmental stimuli.

Alcohol Drinking↗

Cues used by male and female hooded rats for locating a brightness change.

Entries of and time spent in a novel Y-maze arm that had changed from white (during acquisition trials) to black (during retention trials) were investigated in male and female Long-Evans hooded rats after the apparatus had been horizontally rotated through 180 degrees or left undisturbed. Maze rotation reduced responsiveness to this arm in males but not in females. When each arm was associated with a different set of visual cues, males significantly chose the novel arm only in the presence of intra- and extra-maze cues either alone or in combination. Females significantly selected the novel arm only in the absence of either type of cue, and in the presence of intra-maze cues alone. However, when the duration of acquisition trials was increased from 6 to 12min, females also selected the novel arm in the presence of both intra- and extra-maze cues. It was concluded that, while female rats appeared able to use egocentric (or response-related) cues for locating the novel arm, males were more dependent on allocentric (or place-related) cues following shorter acquisition trials. Because of the importance of such cues, it seemed that the task of recognizing which maze arm had changed in brightness defined the test as one of spatial memory.

Animals↗

Task-set switching under cue-based versus memory-based switching conditions in younger and older adults.

Adult age differences in task switching and advance preparation were examined by comparing cue-based and memory-based switching conditions. Task switching was assessed by determining two types of costs that occur at the general (mixing costs) and specific (switching costs) level of switching. Advance preparation was investigated by varying the time interval until the next task (short, middle, very long). Results indicated that the implementation of task sets was different for cue-based switching with random task sequences and memory-based switching with predictable task sequences. Switching costs were strongly reduced under cue-based switching conditions, indicating that task-set cues facilitate the retrieval of the next task. Age differences were found for mixing costs and for switching costs only under cue-based conditions in which older adults showed smaller switching costs than younger adults. It is suggested that older adults adopt a less extreme bias between two tasks than younger adults in situations associated with uncertainty. For cue-based switching with random task sequences, older adults are less engaged in a complete reconfiguration of task sets because of the probability of a further task change. Furthermore, the reduction of switching costs was more pronounced for cue- than memory-based switching for short preparation intervals, whereas the reduction of switch costs was more pronounced for memory- than cue-based switching for longer preparation intervals at least for older adults. Together these findings suggest that the implementation of task sets is functionally different for the two types of task-switching conditions.

Adult↗

Contextual taste cues modulate olfactory learning in C. elegans by an occasion-setting mechanism.

Manipulations of context can affect learning and memory performance across species in many associative learning paradigms. Using taste cues to create distinct contexts for olfactory adaptation assays in the nematode Caenorhabditis elegans, we now show that performance in this associative learning paradigm is sensitive to context manipulations, and we investigate the mechanism(s) used for the integration of context cues in learning. One possibility is that the taste and olfactory stimuli are perceived as a combined, blended cue that the animals then associate with the unconditioned stimulus (US) in the same manner as with any other unitary conditioned stimuli (CS). Alternatively, an occasion-setting model suggests that the taste cues only define the appropriate context for olfactory memory retrieval without directly entering into the primary association. Analysis of genetic mutants demonstrated that the olfactory and context cues are sensed by distinct primary sensory neurons and that the animals' ability to use taste cues to modulate olfactory learning is independent from their ability to utilize these same taste cues for adaptation. We interpret these results as evidence for the occasion-setting mechanism in which context cues modulate primary Pavlovian association by functioning in a hierarchical manner to define the appropriate setting for memory recall.

Adaptation, Physiological↗

Processing of conflicting cues in an attention-shift paradigm studied with fMRI.

We investigated the effects of conflicting cues in visual attention on brain function, based on a modified version of the Posner cue-target paradigm. The classic paradigm utilizes either a peripheral or centrally placed cue that involuntary or voluntary results in a shift of attention to the cued side. The modified paradigm involves presenting both a peripheral and central cue at the same time, but where the two cues convey conflicting information regarding direction of attention. Functional magnetic resonance imaging (fMRI) were used to record neuronal activation in localized brain areas and networks when the subjects performed the attention task. We hypothesized that the 'exogenous invalid/endogenous valid' condition would activate the anterior attention system to a larger extent than the 'exogenous valid/endogenous invalid' condition, reflecting a need for top-down information processing in this condition. The results for performance data showed that the peripheral cue took precedence over the centrally placed cue when the two cues were in conflict, since reaction times were significantly longer in the "exogenous invalid/endogenous valid" condition. The fMRI data showed an increase in activation in the visual cortex, the left parietal lobule, and in the left cingulate gyrus in both the exogenous valid/endogenous invalid and exogenous invalid/endogenous valid conditions. For the exogenous invalid/endogenous valid condition, there were, in addition, significant activations also in the inferior and middle frontal gyri, and in the precentral gyrus. We interpret these findings as reflecting that these brain areas particularly involved in top-down modulation of attention that interferes with a bottom-up, exogenous-driven effect.

Adult↗

Correspondence of cue activity to reward activity in the macaque orbitofrontal cortex.

It has been reported that neurons in the orbitofrontal cortex (OFC) respond to emotionally significant events such as reward-predicting cues and/or the reward itself. The responses to reward-predicting cues are considered to carry the information of the predicted reward. However, few studies have focused on the relationship of the neuronal activity during a cue period with that during a reward period. We can infer that the cue responses of OFC neurons are correlated to the reward responses if they carry the information of the predicted reward. In this study, we focused on neurons that showed responses during both the cue and reward periods, and compared the response characteristics between these periods. We found 94 of 369 OFC neurons showed significant responses during both the cue and reward periods, and 43 of which preserved their selectivity between these periods. Furthermore, population analysis showed that stronger cue responses corresponded to stronger reward responses, and stronger reward responses corresponded to stronger cue responses. These results suggest that individual neurons in the OFC associate visual information with reward information, and contribute to the prediction of future rewards by forming reward representations.

Animals↗

An fMRI study of the cerebral macro network involved in 'cue invariant' form perception and how it is influenced by stimulus complexity.

We investigated the influence of stimulus complexity on the macro network of visual areas involved in 'cue invariant' form perception. Functional MRI imaging on 14 healthy, adult volunteers was performed during a two alternative forced choice (2-AFC) form discrimination task. The functional load imposed onto the visual system was varied by using simple and complex shapes. The figures were defined using a luminance, a chromatic or a motion contrast cue. The three cues activated the same visual areas in the ventral pathway, including area 'LO'. Activation of visual area 'V3v' but not area 'KO' in the dorsal pathway was observed to the motion contrast cue. The simple shapes induced a larger BOLD response in BA18 than the complex shapes, reflecting the selectivity of this region for the features in the stimuli such as edges and vertices. The brain regions yielding a larger BOLD signal to the complex shapes were areas know to be selective to the orthographic content of our complex stimuli. The processing requirement was assessed by comparing the subjects' reaction time. We found no significant difference in the reaction times to the simple and complex shapes. The reaction times to the luminance contrast cue and the chromatic contrast cue were identical but that to the motion contrast cue were 200 ms longer. This finding concurs with neurophysiological studies, reporting a longer onset latency for motion contrast stimuli. It further lends support to the idea that the motion contrast cue requires auxiliary processing by the visual areas of the dorsal pathway before entry into the ventral pathway.

Adult↗

Evidence for bidirectional cues as a function of time following treatment with amphetamine: implications for understanding tolerance and withdrawal.

RATIONALE: Previous drug-discrimination studies have focused on characterizing the cue properties associated with amphetamine's (AMPH) primary effect. Results from recent experiments indicate that equally prominent cues are associated with AMPH withdrawal. OBJECTIVES: The purpose of the present study was to investigate the extent to which AMPH-induced withdrawal cues, opposite to those associated with AMPH's primary effect are observed. METHODS: Since dopamine (DA) has been implicated in mediating the AMPH cue, rats were trained to discriminate between 0.25 mg/kg AMPH, an indirect DA agonist, and 0.033 mg/kg haloperidol (HAL), a DA antagonist at the D2 receptor site. Training doses were chosen so that rats responded about equally on both levers when tested on saline (SAL) providing a behavioral baseline sensitive to assessing AMPH-related bidirectional changes in cue state. Following acquisition of the discrimination, rats were tested for choice of responding on the AMPH and HAL levers at intervals from 6 to 72 h following treatment with a single dose of 3.0 mg/AMPH. Also, in order to investigate the relationship between withdrawal and tolerance to AMPH's cue properties, AMPH dose-response curves were determined 24 h following treatment with SAL, 1.5 and 3.0 mg/kg AMPH. RESULTS: At short intervals after treatment with 3.0 mg/kg AMPH, rats responded primarily on the AMPH lever followed by a shift to predominant responding on the HAL lever 16-30 h post-treatment, before returning to predrug levels. Treatment with 1.5 and 3.0 mg/kg AMPH produced parallel dose-response curve shifts to the right. CONCLUSIONS: Following a single dose of AMPH, robust cues associated with AMPH withdrawal were observed that lasted approximately three times longer than the cues associated with the drug's primary effects. Furthermore, results from the tolerance tests indicate that tolerance reflects a baseline shift rather than a loss in drug efficacy.

Amphetamine↗