Habituation Trials Research Articles

Dishabituation of the BOLD response to speech sounds

BackgroundNeural systems show habituation responses at multiple levels, including relatively abstract language categories. Dishabituation – responses to non-habituated stimuli – can provide a window into the structure of these categories, without requiring an overt task.MethodsWe used an event-related fMRI design with short interval habituation trials, in which trains of stimuli were presented passively during 1.5 second intervals of relative silence between clustered scans. Trains of four identical stimuli (standard trials) and trains of three identical stimuli followed by a stimulus from a different phonetic category (deviant trials) were presented. This paradigm allowed us to measure and compare the time course of overall responses to speech, and responses to phonetic change.ResultsComparisons between responses to speech and silence revealed strong responses throughout the extent of superior temporal gyrus (STG) bilaterally. Comparisons between deviant and standard trials revealed dishabituation responses in a restricted region of left posterior STG, near the border with supramarginal gyrus (SMG). Novelty responses to deviant trials were also observed in right frontal regions and hippocampus.ConclusionA passive, dishabituation paradigm provides results similar to studies requiring overt responses. This paradigm can readily be extended for the study of pre-attentive processing of speech in populations such as children and second-language learners whose overt behavior is often difficult to interpret because of ancillary task demands.

Pup exposure differentially enhances foraging ability in primiparous and nulliparous rats

The role of maternal experience (i.e., pregnancy and pup exposure) on rats' performance in a foraging task was assessed. Primiparous (P) and nulliparous (N) animals were either exposed to pups for 21 days (+) or received no pup exposure (−). Following habituation trials, all animals were tested in spatial and cued versions of the dry land maze (DLM) for three days (three trials per day). In the spatial DLM, the presence of pups decreased latencies in both N and P groups in Trial 5 and P+ rats exhibited shorter latencies to baited food wells than P− animals on Trial 6. In the subsequent probe trial, P+ animals spent significantly more time in proximity to the previously baited well than P− rats. Pups enhanced performance of both P+ and N+ groups in trial 6 of the cued test. Thus, in the spatial task, the individual components of the maternal experience (e.g., pregnancy, parturition, lactation, and pup exposure) converge to produce behavioral modifications in the DLM spatial and probe tasks that enable the female to care for her offspring, in this case, by enhancing foraging behavior. Further, in one trial of each version of the task, pup exposure enhanced performance in N animals suggesting that, in isolation, pup exposure may be a more important influence on ancillary maternal behavior than the pregnancy itself.

馴化‐脱馴化法を用いたメスラットによるオスの性的匂い弁別

The present study examined whether a new habituation-dishabituation paradigm using multiple habituation-donors can detect the ability to discriminate sexual activeness of males by female rats. All females were ovariectomized and chronically treated with estradiol benzoate. During the habituation trials, half of the females were exposed to a urine odor obtained from a single castrated male (the single donor group), and the other half were exposed to 4 different urine odors collected from 4 different castrated males (the multiple donor group). After the habituation trials, half of each group was tested with a urine odor of a novel intact male, and the other half with that of a novel castrated male. Females exposed to odor of single males showed a significant increase in investigation time to the test-donor odor, irrespective of donors' sexual activeness. In contrast, females habituated to odors of multiple males showed dishabituation specific to odor of intact test males. These results suggest that the habituation-dishabituation paradigm with multiple donors should be useful for evaluating the discrimination ability of sexual odors by rats.

Nine- and twelve-month-old infants relate emotions to people's actions

Under investigation was whether 9- to 12-month-olds appreciate that a person's expression of pleasure when gazing toward an object is consistent with that person's subsequent handling of the object. Infants were randomly assigned to an experimental and control group. In the experimental group infants during the pretrials saw a Happy or an Unhappy person saying either “Oh I like objects” or, “I don't like objects”, respectively, while looking at an abstract object. In the habituation phase, infants saw an actor holding the abstract object, but the emotional expression of the actor was obscured. In the posttrial, infants were alternately presented with either the Happy or the Unhappy actor holding the object. In the control group, infants received the same three phase procedure, except that no object was present during the pre- and habituation trials. Analyses comparing the between-subjects variables revealed that infants in the Experimental group looked significantly longer at the Unhappy actor than infants in the Control group but less long at the Happy actor. This study is the first to compare positive and negative emotions and to show that infants as young as 9 months use these emotions to make inferences about people's subsequent actions on objects.

Fetal rate of behavioral inhibition and preference for novelty during infancy

Background Correlations between infant measures of information processing and later IQ have been established, and a few studies have extended this continuum by examining links between various fetal measures and cognitive measures during infancy. Aims This study compared fetal rate of behavioral habituation among infants identified as at high or low cognitive risk. Study design This study was a retrospective examination of differences in fetal rate of behavioral habituation as a function of cognitive risk status at 6.5 and 9 months postpartum, using an independent two-group design. Subjects Participants were 32 infants who were born between 36 and 42 weeks gestational age at normal birth weight and had normal APGAR scores. Outcome measures The Fagan Test of Infant Intelligence (FTII) was used to obtain a measure of preference for novelty, which served as the basis for identification of infants at high or low risk for cognitive difficulty. These infants had undergone up to three habituation trials using a vibroacoustic stimulus during fetal development. Results Infants who were classified as being at high cognitive risk at 6 months had required more trials to habituation as fetuses. Conclusions Fetal rate of behavioral habituation is associated with information processing during the first 6 months of infancy. We suggest that fetal habituation may be influenced by early cognitive mechanisms and therefore represents an immature but real form of information processing.

14‐Month‐Old Infants Form Novel Word—Spatial Relation Associations

This study explored 14-month-old infants' ability to form novel word-spatial relation associations. During habituation, infants heard 1 novel word (e.g., teek) while viewing dynamic containment events (i.e., Big Bird placed in a box) and, on other habituation trials, a second novel word (e.g., blick) while viewing dynamic support events (i.e., Big Bird placed on the box). Each novel word was presented in a sentence (e.g., "She's putting Big Bird teek the box"). During the test, infants discriminated an event that maintained the habituation word-relation pairing from one that presented a switch in this pairing. The results indicate that 14-month-olds can learn to form word-relation associations quickly, requiring only a few minutes of experience with each word-relation pairing.

Multibehavioral analysis of fear and anxiety before, during, and after experimentally induced predatory stress in Callithrix penicillata

A detailed behavioral analysis of nine Callithrix penicillata was conducted in the Marmoset Predator Confrontation Test (MPCT) during (a) four habituation trials with no “predator,” (b) six confrontation trials with the predator (taxidermized oncilla cat, Felis tigrina), and (c) four trials with the predator removed. The marmosets habituated to the test apparatus with significant decreases in locomotion, exploration and long calls. Initial exposure to the predator elicited mainly fear-related behaviors (proximic avoidance, tsik-tsik vocalization, swaying/tongue in–out), whereas repeated confrontations attenuated these behaviors, concomitant to an increase in anxiety-associated responses (scratching/grooming/scent marking). The initial behavioral repertoire, observed before confrontations, was fully restored only upon removal of the predator. This easily discernable complex defensive behavioral repertoire is hoped to provide a comprehensive baseline for studying the biological substrates of fear/anxiety parameters in nonhuman primates.

Young infants' reasoning about hidden objects: evidence from violation-of-expectation tasks with test trials only

The present research examined alternative accounts of prior violation-of-expectation (VOE) reports that young infants can represent and reason about hidden objects. According to these accounts, young infants' apparent success in these VOE tasks reflects only novelty and familiarity preferences induced by the habituation or familiarization trials in the tasks. In two experiments, 4-month-old infants were tested in VOE tasks with test trials only. The infants still gave evidence that they could represent and reason about hidden objects: they were surprised, as indicated by greater attention, when a wide object became fully hidden behind a narrow occluder (Experiment 1) or inside a narrow container (Experiment 2). These and control results demonstrate that young infants can succeed at VOE tasks involving hidden objects even when given no habituation or familiarization trials. The present research thus provides additional support for the conclusion that young infants possess expectations about hidden objects. Methodological issues concerning the use of habituation or familiarization trials in VOE tasks are also discussed.

The Impact of Prenatal Alcohol Exposure on Neurophysiological Encoding of Environmental Events at Six Months

Using methodologies from developmental studies on infant information-processing skills, early manifestations of later long-term neurocognitive effects of prenatal alcohol exposure can be explored by assessing primary cognitive processes, including attentional regulation and processing speed. One hundred eighteen 6-month-old infants (18 high risk, 100 low risk) from a longitudinal study of moderate prenatal alcohol exposure and intrauterine growth retardation were presented with both auditory (400 and 1000 Hz pure tones) and visual stimuli (chromatic Caucasian faces) in an information-processing paradigm with cardiac response as the dependent variable. The first three habituation trials were analyzed to assess neurophysiological encoding of environmental events in infants categorized as high and low risk based on status of maternal drinking. Specific indexes of the cardiac response were used to assess the infant's (1). speed of initiating attention, (2). sustained attention, and (3). shifting attention after stimulus offset. Infants identified as high risk based on a cumulative risk index for prenatal alcohol exposure responded more slowly to stimuli and were rated as significantly higher in arousal level across the three trials but did not display differences in their sustained deceleration responses or responses to stimulus-offset. Less efficient neurophysiological encoding was observed among high-risk infants, suggesting that prenatal alcohol exposure may disrupt fundamental components of the attentional system responsible for regulating the body's responses to environmental events. Slower neurophysiological responses involved in encoding environmental stimuli and initiating attention and higher levels of behavioral arousal suggest that these infants may have had difficulties with regulating the interactions between arousal level and the attentional system needed to provide optimal efficiency in processing environmental events. These outcomes suggest that prenatal alcohol exposure results in specific impairments in early attentional regulation, which may influence subsequent cognitive development and behavioral outcomes dependent on these primary cognitive processes.

CB1 cannabinoid receptor activation inhibits a neural correlate of song recognition in an auditory/perceptual region of the zebra finch telencephalon.

A notable consequence of CB1 cannabinoid receptor activation in vertebrates is an impairment of cognitive function related to learning and short-term memory. The mechanisms of this impairment remain unclear, but one possibility is that cannabinoids influence encoding of stimuli at sensory and/or perceptual levels. Here, by treating zebra finches with the cannabinoid agonist WIN55212-2 and then measuring expression of the transcription factor zenk following presentation of novel zebra finch song, we show that cannabinoid receptor activation differentially influences zenk expression in sensory versus perceptual regions of the songbird auditory telencephalon. That is, WIN55212-2 dose-dependently inhibited zenk expression in a region for auditory perception (NCM, the caudomedial neostriatum), but had no effect on zenk expression in the primary auditory area, the Field L complex. The inhibitory effects of WIN55212-2 on zenk expression in NCM were reversed by coadministration of the CB1-selective antagonist SR141716A. Moreover, we found that the habituation of the NCM zenk response to repeated presentation of the same song, a well-established neural correlate of song recognition, was blocked when birds were treated with WIN55212-2 during habituation trials. Our data suggest that activation of CB1 cannabinoid receptors can selectively influence perceptual and mnemonic aspects of auditory experience.

Discrimination of individual odours by hamsters ( Mesocricetus auratus) varies with the location of those odours

When animals perceive social signals, information about the identity and the location of the signaller can be important determinants of a response by the perceiver. An unfamiliar individual often elicits a greater response than does a familiar individual. Similarly, a signal from an unexpected location may elicit a greater response than if it came from an expected location. For example, in field experiments on vocal communication in birds, an unexpected location has been many metres away from the expected one. Laboratory experiments on the responses of voles and hamsters to scent overmarks and on the habituation of hamsters to social scents suggest that much smaller differences in the location of odours may be salient. To explore this further, we examined the influence of changes in spatial location of familiar and novel male scents on responses of female golden hamsters, M. auratus . The spatial changes were about 9 cm, less than three-fourths of the body length of our subjects. The decline in females' investigation of the same male's flank odour across four habituation trials was not affected by changing the location of the odour. During test trials, however, changes in location did influence the results. The expected higher level of investigation of a novel scent versus that of a familiar one was observed primarily when the novel scent occupied a novel location. Such increases in investigation were usually not seen when only one of these variables was changed (individual or location). Thus, small changes in spatial location influence the salience of conspecific odours in this species. Copyright 2002 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved.

Anxiolytic-like effects of substance P fragment (SP 1–7) in non-human primates ( Callithrix penicillata)

The behavioral effects of the amino (N)-terminal fragment of substance P (SP 1–7) on the marmoset ( Callithrix penicillata) predator confrontation test of fear/anxiety were investigated. The test apparatus consisted of a figure-eight maze with three parallel arms interconnected at each extremity to a perpendicular arm. A taxidermized oncilla cat ( Felis tigrina) was placed outside the maze facing one of its corners. Subjects were submitted to seven 30 min maze habituation trials (HTs), in the absence of the ‘predator’, and then to six 30 min treatment trials (TTs), in the presence of the ‘predator’, consisting of four doses of SP 1–7 (5, 50, 250 and 500 μg/kg; IP), saline and sham injection. SP 1–7 treatment reversed, in a dose-dependent way, the fear-induced avoidance behavior due to the predator’s presence and increased the frequency of exploratory behaviors. Locomotor activity decreased during successive HTs, yet increased after all SP 1–7 treatments. These results indicate that systemic administration of SP 1–7 produces anxiolytic-like effects in marmosets tested in the predator confrontation model of fear/anxiety.

Dissociation of stress behaviors in the chick social-separation-stress procedure

Separation from conspecifics in chicks produces an increase in distress vocalizations and a decrease in response to a noxious stimulus (stress-induced analgesia). This study questioned the relative contributions of novelty to the test chamber and social separation in mediating these stress responses. Eight-day-old chicks were tested either in isolation or in the presence of two social companions for a 3-min observation period in which distress vocalizations were recorded as well as the frequency of footlifts in response to a 50-μl injection of 0.10% formalin into the plantar surface of the footpad. In Expt. 1, chicks received six, 3-min test chamber habituation trials (vs. no habituation) one per day before testing; in Expt. 2, chicks were tested with mirrors placed in the chambers (vs. no mirrors). In both studies, isolated chicks in control groups (i.e., no habituation or no mirror) exhibited increased distress vocalizations and decreased nociceptive responses. In Expt. 1, habituation to the test chamber attenuated stress-induced analgesia but did not affect distress vocalizations. In Expt. 2, placement of mirrors in the test chamber attenuated distress vocalizations but did not affect stress-induced analgesia. These findings demonstrate a dissociation of stress behaviors in the chick social-separation-stress procedure: the stress-induced analgesia response is primarily mediated by novelty to the test apparatus while the distress vocalizations response is mediated by separation from conspecifics.

Variability and its sources in infant categorization

Variability of infants’ categorization performance and potential sources of this variability were investigated. Using data from 13 categorization studies employing a habituation-of-looking paradigm with infants 3, 5, 6, and 9 months of age, a method for establishing a categorization criterion was developed and then used to classify individual infants as “categorizers” for particular tasks. Logistic regression analyses were then used to identify demographic and information-processing variables that predicted “categorizer” classification. Variables that increased the odds of being classified as a categorizer were gender, number of habituation trials, and duration of peak look during habituation; total looking time during habituation decreased the odds of categorizer classification. These findings are discussed in the context of individual differences in information processing.

Behavioral effects of buspirone in the marmoset employing a predator confrontation test of fear and anxiety

In order to further validate the recently developed marmoset ( Callithrix penicillata) predator confrontation model of fear and anxiety, we investigated the behavioral effects of buspirone with this method. The apparatus consisted of three parallel arms connected at each end to a perpendicular arm, forming a figure-eight continuous maze. A taxidermized wild oncilla cat ( Felis tigrina) was positioned facing a corner of the parallel arms, alternating between the left or right side of the maze among animals tested. All subjects were first submitted to seven 30-min maze habituation trials (HTs) in the absence of the predator, and then to five randomly assigned treatment trials (TTs) in the presence of the predator: three buspirone sessions (0.1, 0.5 and 1.0 mg/kg), saline and sham injection controls. Twenty minutes after treatment administration, the animal was released into the maze and had free access to the apparatus for 30 min. All trials were taped for later behavioral analysis. Buspirone significantly decreased the frequency of scent marking, while increasing the time spent in proximity to the ‘predator’ stimulus, indicating an anxiolytic effect. Neither locomotor activity, exposure to a novel environment, stimulus location and habituation, nor gender influenced the effects of the drug treatments. These results further validate this method and demonstrate the potential usefulness of this ethologically based paradigm to test anxiety and fear-induced avoidance in nonhuman primates and its susceptibility to anxiolytic pharmacological manipulations.

Progestins influence performance on cognitive tasks independent of changes in affective behavior

In this study, the effects of progestins on various cognitive and affective tasks were investigated. Ovariectomized rats (N = 72) received subcutaneously 0.0, 4.0, or 8.0 mg/kg of progesterone (P), dihydroprogesterone (DHP), or 5α-pregnan-3α-ol-20-one (3α,5α-THP) suspended in 10% ethanol/sesame oil v/v. For the cognitive tasks (Y-maze, inhibitory avoidance, and object recognition), the subjects were injected after habituation and training trials and were tested 24 h later. For the nociception and affective tasks (open field, elevated plus-maze, and tailflick), the subjects were injected 1 or 24 h before testing. P reduced latencies to the goal arm in the Y-maze, enhanced latencies to the shock-associated side of the inhibitory avoidance chamber, and increased the percentage of time with a novel object. DHP reduced latencies to the goal arm, increased the percentage of correct choices in the Y-maze, and increased crossover latencies in the inhibitory avoidance task. 3α,5α-THP administration enhanced performance in the inhibitory avoidance task. P, DHP, and 3α,5α-THP increased the number of entries into the central squares of a brightly lit open field, open arm time in the elevated plus-maze, and tailflick latencies, when administered 1 h, but not 24 h, prior to testing. These data suggest that some progestins, when administered following habituation and training and 24 h prior to testing, produce changes in cognitive performance that do not coincide with overt changes in the affective behaviors examined.

Giant pandas discriminate individual differences in conspecific scent

The functions and mechanisms of chemical communication are well established for many species of small mammal amenable to investigation, but systematic research is virtually absent for large, rare species. The present study marks the first systematic investigation of chemical communication in the endangered giant panda,Ailuropoda melanoleuca. Using a habituation–discrimination paradigm, we sought to determine whether giant pandas can discriminate between scents from different individuals on the basis of chemical cues afforded by female urine and male anogenital gland secretions. Pandas habituated to successive presentations of scent stimuli from a single individual, as evidenced by diminished responsiveness across five habituation trials. In the discrimination test for male anogenital gland secretions, subjects of both sexes investigated a new individual’s scent significantly more than a familiar scent to which they were previously habituated. Neither sex significantly discriminated novel from habituated female urine, although a strong tendency to differentiate the stimuli was evident. We also found that the sex of the subject affected patterns of response. Females showed a significant preference for male anogenital gland secretions, whereas males investigated both types of scent stimuli equally. In general, male subjects were more responsive than females to conspecific scent, especially female urine. This study provides clear evidence that giant pandas distinguish individual odours emanating from male anogenital secretions, and implies that these odours contain individually distinctive chemical signatures. These results have implications that can be applied to the conservation and management of this species.

Young infants’ expectations about hidden objects: a reply to three challenges

In this article, I address three broad challenges that have been directed at claims that even young infants are able to represent and to reason about hidden objects. The first challenge is that such claims are static and non‐developmental and as such represent an unproductive approach to the study of infant cognition. The second challenge is that claims that even young infants represent hidden objects typically go hand in hand with assertions that infants are born with a belief that objects exist continuously in time and move continuously through space, and there is no evidence to date to support such assertions. Finally, the third challenge is that reports that young infants represent hidden objects can all be explained more parsimoniously in terms of low level perceptual biases in infants’ encoding and processing of events, or in terms of transient expectations formed during habituation trials and later extended to test trials.

Reindeer (Rangifer tarandus) response to feces and urine from sheep (Ovis aries) and reindeer

<p>In many Norwegian alpine and tundra areas sheep and reindeer graze sympatrically. Areas covered with dung or urine may have consequences for reindeer pasture utilization. Experiments were conducted on 5 stall fed male reindeer calves where animals were individually presenred with two troughs (experimental and control) containing 200 g of concentrate. Fresh and dry sheep and reindeer pellets (50 g wet weight) were mixed with the concentrate in the experimental trough and the aversive response was tested against the control. Both fresh sheep (P < 0.0001) and reindeer (P < 0.0001) pellets were associated with aversive response by reindeer. A similar response was found for dry sheep (P = 0.006) and dry reindeer (P = 0.0009) pellets. Similar trials were conducted using sheep and reindeer urine (20 g sprayed evenly on the food) and the aversive response by reindeer was tested against the control (sprayed with 20 g of water). Both sheep and reindeer urine stimulated an aversive response by reindeer {P = 0.03 for both tests). The differences in the aversive response of reindeer ro fresh sheep and reindeer pellets, dry sheep and reindeer pellets and sheep and reindeer urine were also tested. No differences by reindeer were found between sheep and reindeer pellets, either for fresh (P = 0.28) or dry (P = 0.07), or between food treated with sheep and reindeer urine (P = 0.28). Possible habituation to sheep and reindeer pellets was tested using 8 consecutive trials with dry pellets, followed by 2 additional trials when dry pellets were soaked in water. This was done to simulate natural dry periods followed by rain showers. Habituation effects were found in trials with dry sheep and reindeer pellets. Subsequent trials with fecal pellets soaked in water significantly reduced food intake when compared with the last habituation trial with dry pellets (P < 0.05).</p>

Subcortical correlates of differential classical conditioning of aversive emotional reactions in social phobia

Background: Conditioning processes have been proposed to play a role in the development of anxiety disorders. As yet, the neurobiologic correlates of emotional learning have not been fully understood in these patients. Accordingly, brain activity was studied in subcortical and cortical regions involved in the processing of negative affect during differential aversive classical conditioning. Methods: Twelve patients with social phobia and 12 healthy control subjects were presented with paired conditioned (CS; neutral facial expressions) and unconditioned stimuli (US; negative odor vs unmanipulated air). Functional magnetic resonance imaging (fMRI) was utilized to examine regional cerebral activity during habituation, acquisition, and extinction trials. Activity was measured with echo-planar-imaging (EPI), and signal intensity in individually defined anatomic regions were analyzed. Results: Subjective ratings of emotional valence to the CS indicated that behavioral conditioning occurred in both groups. The presentation of CS associated with negative odor led to signal decreases in the amygdala and hippocampus of normal subjects, whereas an opposite increased activation in both regions was observed in patients. Regional differences were not found during habituation and extinction. Conclusions: Results suggest that conditioned aversive stimuli are processed in subcortical regions, with phobic patients differing from control subjects.