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PubMed1978

The impact of stress experience on heart rate and task performance in the presence of a novel stressor.

The impact of prior stress experience on heart rate and task performance in the presence of a novel stressor was studied. During a training phase 42 female students were required to solve arithmetical problems under conditions of either no stressor, delayed auditory feedback, or distraction. Subsequently in a testing phase all subjects performed the same task in the presence of delayed auditory feedback. Training in the presence of stress resulted in decreased heart rate and better performance in the testing phase. These data were interpreted as supporting the hypothesis that training under stress-inducing conditions increases stress resistance which generalizes to a novel stressor and which leads subjects to experience the novel stressor as being less stressful.

Adolescent↗
PubMed1986

Intravenous self-administration of (-)-cathinone and 2-amino-1-(2,5-dimethoxy-4-methyl)phenylpropane in rhesus monkeys.

The reinforcing effects of (-)-cathinone, a pharmacologically active ingredient of khat, and 2-amino-1-(2,5-dimethoxy-4-methyl)phenylpropane ((STP) (DOM)), a hallucinogenic psychotomimetic, were studied by intravenous self-administration experiments in rhesus monkeys. Among the experiments described in this paper, the result of continuous self-administration of (-)-cathinone was briefly reported elsewhere. T. Yanagita, Studies on Cathinones, NIDA Research Monograph 27, Proceedings of 41st Annual Scientific Meeting of the Committee on Problems of Drug Dependence, 1979, pp. 326-327.

DOM 2,5-Dimethoxy-4-Methylamphetamine↗
PubMed1988

Ethanol and Ro 15-4513: behaviour maintained by operant procedures (DRL-72s and PTZ-drug discrimination) in rats.

The proposed amethystic imidazobenzodiazepine Ro 15-4513 and ethanol (ETOH) were examined in rats using two operant procedures, differential reinforcement of low rates of responding (DRL), and drug discrimination learning (DDL). In the first bar-pressing responses occurring 72 s or longer after the last reinforcement were rewarded; responses occurring earlier reset the time schedule. In the latter, animals were trained to discriminate between the effects of the analeptic pentylenetetrazole (PTZ) and the non-drug condition; the schedule of reinforcement was FR-10. Water was the reinforcer. A dose of 1000 mg/kg ETOH decreased the rate of bar pressing in the DRL experiment; doses of 300 and 560 mg/kg ETOH did not. The decrease was not attenuated by Ro 15-4513. No significant deviations from baseline responding occurred with Ro 15-4513 (1, 3 10 mg/kg). The number of reinforcements increased significantly after ETOH (1000 mg/kg), but not after Ro 15-4513. Combinations of the two agents produced increases in the number of reinforcements. Changes in DRL behaviour induced by diazepam (1 and 10 mg/kg) were normalized by 3 mg/kg Ro 15-4513. In DDL, Ro 15-4513 (10 mg/kg) substituted for PTZ; ETOH did not. Diazepam and Ro 15-1788 attenuated the response generalization from Ro 15-4513 to PTZ; ETOH did not. There was a dose-related increase in the time to complete the DDL tests after ETOH treatment; addition of Ro 15-4513 increased the time further. In conclusion, antagonism between Ro 15-4513 and ETOH did not occur in the present studies; data are furthermore consistent with the view that Ro 15-4513 acts as a partial inverse benzodiazepine agonist.

Animals↗
PubMedDate not supplied

Neural and behavioral responsivity to ethyl alcohol as a tastant.

Three experiments were designed to study the sensory properties of ethyl alcohol (EtOH) in the rat. In Experiment 1, a conditioned taste aversion (CTA) was produced to 3%, 6% or 9% EtOH. None of these aversions generalized to any of the 4 basic tastants. However, rats in the 6% and 9% EtOH groups did generalize the CTA to a mixture of sucrose-QHCl but not to a mixture of NaCl-HCl. In Experiment 2, a CTA was produced to 6% EtOH and animals were then tested with all 6 combinations of the basic tastants. The CTA was found to generalize significantly to sucrose-QHCl and marginally to sucrose-HCl. In Experiment 3, single unit responses to gustatory stimuli were recorded in the nucleus of the tractus solitarius. Solutions of NaCl, HCl, sucrose, QHCl, 6% and 9% EtOH were bathed over the rostral tongue through a plastic flow chamber. Approximately half of the units responded to 9% EtOH. Analysis of the across-unit patterns of response revealed a weak relationship between responses to EtOh and sucrose in the first 1.0 sec of response.

Animals↗
PubMedDate not supplied

MDMA (Ecstasy) substitutes for the ethanol discriminative cue in HAD but not LAD rats.

Selectively bred high- and low-alcohol-drinking (HAD/LAD) rats were trained to discriminate the interoceptive stimuli produced by IP-administered 600 mg/kg ethanol (10% w/v in a two-lever, food-motivated operant task. Once criterion discrimination was attained, animals were tested with 3.0, 1.5, 1.0, and 0.5 mg/kg MDMA. Although no differences in alcohol discrimination were observed between the HAD and LAD animals, the HAD line was significantly more sensitive than the LAD line to the effects of MDMA. These results provide additional information to the growing body of evidence suggesting serotonergic mediation of some of the behavioral effects of ethanol.

Alcohol Drinking↗
PubMed1987

Increasing positive social interactions by handicapped individuals during a recreational activity using a multicomponent treatment package.

A multicomponent treatment package increased the rate of positive statements among handicapped youth during a social/leisure activity at a work training setting. The package of role playing, graphic feedback, contingent reinforcement, and self-monitoring was directly replicated across three experiments in producing normative rates of positive verbal statements. There was no evidence of generalization to other stimulus activities. There was limited response generalization to a class of negative verbal statements. The study further examined the critical components of the maintenance package through a withdrawal design. It was found that contingent reinforcement and self-monitoring could maintain substantial rates of positive behaviors. In the third experiment it was further demonstrated that self-monitoring alone could maintain positive statements in three of the four students in the group.

Adolescent↗
PubMed1990

A comparison of the Task Demonstration Model and the Standard Prompting Hierarchy in teaching word identification to persons with moderate retardation.

Six persons with moderate mental retardation were taught to identify three words by each of two different procedures. One, the Task Demonstration Model, was a fading procedure which relied on presenting many examples of both the correct and incorrect words while systematically increasing their similarity. The other, the Standard Prompting Hierarchy, is one of the most common procedures for teaching persons with mental retardation, and relied on a least-to-most intrusive prompting hierarchy. Data were presented in three phases and show that the Task Demonstration Model produced fewer errors in (a) acquisition (4% to 14%), (b) generalization (9% to 14%), and (c) maintenance (8% to 14%). Results were discussed in terms of the fading procedure and how the Task Demonstration Model provides a simple means for teachers to improve their students' responding in acquisition, generalization, and maintenance.

Adolescent↗
PubMedDate not supplied

Generalized identity matching to sample of two-dimensional forms in individuals with intellectual disabilities.

An assessment of identity matching to sample with two-dimensional forms was conducted with 44 subjects with moderate and severe intellectual disabilities. Identity matching that did not require conditional discriminative functions was tested first; subjects who passed that test were then tested on a conditional identity matching task. Tests for generalized identity matching were passed by 30 of the 44 subjects. The 14 individuals who did not pass were given a further teaching assessment that sought to teach identity matching directly via standard teaching methods. Some subjects also received training on a series of simple discriminations taught by the same methods. Four additional subjects passed identity matching tests. Overall, generalized identity matching was demonstrated in 34 of 44 subjects, including 7 of 16 individuals with mental age (MA) scores of 3.0 years and below and 14 of 15 individuals with MA scores between 3.0 and 5.0 years. Results with these two groups are much superior to those typically reported for individuals with comparable MA scores. The capacity for generalized performances requiring same/different judgments appears to have been substantially underestimated in this population, perhaps especially when the stimuli are two-dimensional, relatively abstract forms.

Adolescent↗
PubMed1995

Learning a new visuomotor transformation: error correction and generalization.

The use of an aiming tool requires learning a new transformation between visual and proprioceptive information and motor command. We have examined this question by quantifying the kinematics of the movement during the transitory phase of adaptation to a rotational bias (60 degrees counterclockwise, then clockwise) added to a standard mouse-cursor device in the plane of the screen. Control-aiming movements were almost linear with a bell-shaped velocity profile. The bias induced an equivalent initial directional error which was usually corrected within 20 trials. The learning trajectories were combinations of spirals and fast or slow straight movements. The posture of the hand was slightly (less than 10 degrees) modified by the bias. These features suggest three corrective processes: on-line continuous correction based on evaluation of the relative cursor-to-target position, discrete correction based on assessment of the discrepancy angle between the cursor-to-target direction and the effective cursor direction, and memorization of trial-to-trial correction. These results are interpreted in the light of neurophysiological data and neural net modeling, which suggest that the visuomotor transformation performed by cortical areas for reaching is effected by projecting the visual information on a reference frame that rotates with the arm. The initial directional error reappeared when the direction of the target was changed and increased with degree of change. The limited generalization suggests that bias correction is stored in relation to the coding of the target direction and that movement towards a new direction is computed as a projection of the previously learned bias on the new visual direction.

Feedback↗
PubMed2006

A developmental dissociation of view-dependent and view-invariant object recognition in adolescence.

Spatial generalization skills in school children aged 8-16 were studied with regard to unfamiliar objects that had been previously learned in a cross-modal priming and learning paradigm. We observed a developmental dissociation with younger children recognizing objects only from previously learnt perspectives whereas older children generalized acquired object knowledge to new viewpoints as well. Haptic and--to a lesser extent--visual priming improved spatial generalization in all but the youngest children. The data supports the idea of dissociable, view-dependent and view-invariant object representations with different developmental trajectories that are subject to modulatory effects of priming. Late-developing areas in the parietal or the prefrontal cortex may account for the retarded onset of view-invariant object recognition.

Adolescent↗
PubMed2006

Evidence that pigeons represent both time and number on a logarithmic scale.

Pigeons were presented with trials that always began with presentation of a houselight that lasted for 1-16s. Red and green side keys were presented immediately after the houselight went off. A peck on the red key was reinforced if the houselight duration was 8s or shorter, and a peck on the green key was reinforced if the houselight duration was 9s or longer. Plots of asymptotic performance as a function of houselight duration showed bow-shaped curves with higher accuracy at the ends of the scale than in the middle. Training to bisect a scale containing houselight durations of 2-32s yielded a performance curve that superimposed on the 1-16s curve. Both curves showed two important asymmetries around the midpoint: pigeons were more accurate at 9 and 10s than at 7 and 8s but were more accurate at 1-4s than at 13-16s. These findings closely resembled those found in a similar study of number scale bisection [Roberts, W.A., 2005. How do pigeons represent numbers? Studies of number scale bisection. Behav. Process. 69, 33-43]. Theoretical predictions from associative and confusion models showed a good match to the obtained data if it was assumed that time and number scales were logarithmic and that generalization or confusion curves were constant but not if it was assumed that scales were linear and that generalization or confusion curves were scalar.

Animals↗
PubMed2006

Mechanisms of same/different concept learning in primates and avians.

Mechanisms of same/different concept learning by rhesus monkeys, capuchin monkeys, and pigeons were studied in terms of how these species learned the task (e.g., item-specific learning versus relational learning) and how rapidly they learned the abstract concept, as the training set size was doubled. They had similar displays, training stimuli, test stimuli, and contingencies. The monkey species learned the abstract concept at similar rates and more rapidly than pigeons, thus showing a quantitative difference across species. All species eventually showed full concept learning (novel-stimulus transfer equivalent to baseline: 128-item set size for monkeys; 256-item set for pigeons), thus showing a qualitative similarity across species. Issues of stimulus regularity/symmetry, generalization from item pairs, and familiarity processing were not considered to be major factors in the final performances, converging on the conclusion that these species were increasingly controlled by the sample-test relationship (i.e., relational processing) leading to full abstract-concept learning.

Animals↗
PubMed2005

EEG phase synchrony differences across visual perception conditions may depend on recording and analysis methods.

OBJECTIVE: (1) To investigate the neural synchrony hypothesis by examining if there was more synchrony for upright than inverted Mooney faces, replicating a previous study; (2) to investigate whether inverted stimuli evoke neural synchrony by comparing them to a new scrambled control condition, less likely to produce face perception. METHODS: Multichannel EEG was recorded via nose reference while participants viewed upright, inverted, and scrambled Mooney face stimuli. Gamma-range spectral power and inter-electrode phase synchrony were calculated via a wavelet-based method for upright stimuli perceived as faces and inverted/scrambled stimuli perceived as non-faces. RESULTS: When the frequency of interest was selected from the upright condition exhibiting maximal spectral power responses (as in the previous study) greater phase synchrony was found in the upright than inverted/scrambled conditions. However, substantial synchrony was present in all conditions, suggesting that choosing the frequency of interest from the upright condition only may have been biased. In addition, artifacts related to nose reference contamination by micro-saccades were found to be differentially present across experimental conditions in the raw EEG. When frequency of interest was selected instead from each experimental condition and the data were transformed to a laplacian 'reference free' derivation, the between-condition phase synchrony differences disappeared. Spectral power differences were robust to the change in reference, but not the combined changes in reference and frequency selection criteria. CONCLUSIONS: Synchrony differences between face/non-face perceptions depend upon frequency selection and recording reference. Optimal selection of these parameters abolishes differential synchrony between conditions. SIGNIFICANCE: Neural synchrony is present not just for face percepts for upright stimuli, but also for non-face percepts achieved for inverted/scrambled Mooney stimuli.

Adult↗
PubMed2006

Depth electrode recorded cerebral responses with deep brain stimulation of the anterior thalamus for epilepsy.

OBJECTIVE: We investigated the relation between anterior thalamic stimulation and the morphology of the evoked cerebral responses (CRs) using intracerebral depth electrodes in patients with intractable epilepsy undergoing deep brain stimulation (DBS) of the thalamus. METHODS: Monopolar cathodic and bipolar stimuli were delivered at a rate of 2 or 1 Hz to the anterior nucleus (AN) and the dorsomedian nucleus (DM) of two patients using the programmable stimulation device (Medtronic ITREL II) or a GRASS stimulation device (S12). CRs were recorded from depth or DBS electrodes, situated bilaterally in mesial temporal (hippocampus, both patients), lateral temporal (one patient), orbitofrontal (Brodmann area 11, one patient) and anterior thalamic sites (one patient). RESULTS: The distribution and morphology of the CRs depended primarily on the site of stimulation within the anterior thalamic region. Overall, monopolar cathodic and bipolar stimulation of the AN elicited CRs mainly in ipsilateral mesial temporal cortical areas, whereas stimulation of the DM evoked high-amplitude CRs predominantly in ipsilateral orbitofrontal areas. The amplitude of the CR was positively related to the strength of the stimulus and generally higher with monopolar than with bipolar stimulation. The differences between CRs elicited during wakefulness or slow wave sleep were minimal. CONCLUSIONS: The distribution of the CRs corresponded with the intracerebral pathways of the involved structures and the findings are in good accordance with those of our previous study investigating the sources of CRs using statistical non-parametric mapping of low resolution electromagnetic tomography (LORETA) values. SIGNIFICANCE: Our findings indicate a certain degree of point-to-point specificity within the thalamocortical circuitry, which may make optimal localization of DBS electrodes important in patients with epilepsy.

Adult↗
PubMedDate not supplied

Recognition invariance obtained by extended and invariant features.

In performing recognition, the visual system shows a remarkable capacity to distinguish between significant and immaterial image changes, to learn from examples to recognize new classes of objects, and to generalize from known to novel objects. Here we focus on one aspect of this problem, the ability to recognize novel objects from different viewing directions. This problem of view-invariant recognition is difficult because the image of an object seen from a novel viewing direction can be substantially different from all previously seen images of the same object. We describe an approach to view-invariant recognition that uses extended features to generalize across changes in viewing directions. Extended features are equivalence classes of informative image fragments, which represent object parts under different viewing conditions. This representation is extracted during learning from images of moving objects, and it allows the visual system to generalize from a single view of a novel object, and to compensate for large changes in the viewing direction, without using three-dimensional information. We describe the model, its implementation and performance on natural face images, compare it to alternative approaches, discuss its biological plausibility, and its extension to other aspects of visual recognition. The results of the study suggest that the capacity of the recognition system to generalize to novel conditions in an efficient and flexible manner depends on the ongoing extraction of different families of informative features, acquired for different tasks and different object classes.

Computer Simulation↗
PubMed2006

Multimodal similarity and categorization of novel, three-dimensional objects.

Similarity has been proposed as a fundamental principle underlying mental object representations and capable of supporting cognitive-level tasks such as categorization. However, much of the research has considered connections between similarity and categorization for tasks performed using a single perceptual modality. Considering similarity and categorization within a multimodal context opens up a number of important questions: Are the similarities between objects the same when they are perceived using different modalities or using more than one modality at a time? Is similarity still able to explain categorization performance when objects are experienced multimodally? In this study, we addressed these questions by having subjects explore novel, 3D objects which varied parametrically in shape and texture using vision alone, touch alone, or touch and vision together. Subjects then performed a pair-wise similarity rating task and a free sorting categorization task. Multidimensional scaling (MDS) analysis of similarity data revealed that a single underlying perceptual map whose dimensions corresponded to shape and texture could explain visual, haptic, and bimodal similarity ratings. However, the relative dimension weights varied according to modality: shape dominated texture when objects were seen, whereas shape and texture were roughly equally important in the haptic and bimodal conditions. Some evidence was found for a multimodal connection between similarity and categorization: the probability of category membership increased with similarity while the probability of a category boundary being placed between two stimuli decreased with similarity. In addition, dimension weights varied according to modality in the same way for both tasks. The study also demonstrates the usefulness of 3D printing technology and MDS techniques in the study of visuohaptic object processing.

Concept Formation↗
PubMed2006

Detection of free fatty acids following a conditioned taste aversion in rats.

A gustatory transduction mechanism for free fatty acids (FFAs) has been described in isolated rat taste receptor cells; however, the ability of behaving rats to detect FFAs has not been characterized. Through conditioned taste aversion (CTA) methodology, this study defines the ability of rats to detect and avoid the two principal FFA components of corn oil, linoleic and oleic acid. Following taste aversion conditioning, rats avoided both linoleic and oleic acid at greater than or equal to 66 muM and failed to avoid either 44 muM linoleic or oleic acid. Rats demonstrated generalized avoidances between 88 muM linoleic and oleic acid irrespective of presenting the FFAs as either unesterified acids dissolved in 5 mM ethanol or aqueous sodium salts, sodium linoleate and sodium oleate. Following a CTA to linoleic acid, rats did not show generalized avoidance of NaCl or ethanol, two potentially concomitant tastants in the oral cavity. A CTA to linoleic or oleic acid did produce a generalized avoidance to the other FFA. These results support the ability of rats to detect linoleic and oleic acid (>44 muM) and suggest that the two FFAs share common orosensory properties. Furthermore, it is unlikely that the detection of the FFAs is due to an enhancement of other concomitant tastants such as saliva or the delivery solution.

Animals↗