Temporal Specificity of Extinction in Autoshaping.

Three experiments investigated the effects of varying the conditioned stimulus (CS) duration between training and extinction. Ring doves (Streptopelia risoria) were autoshaped on a fixed CS-unconditioned stimulus (US) interval and extinguished with CS presentations that were longer, shorter, or the same as the training duration. During a subsequent test session, the training CS duration was reintroduced. Results suggest that the cessation of responding during an extinction session is controlled by generalization of excitation between the training and extinction CSs and by the number of nonreinforced CS presentations. Transfer of extinction to the training CS is controlled by the similarity between the extinction and training CSs. Extinction learning is temporally specific. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Mental Health of Lesbian, Gay, Bisexual, and Heterosexual Siblings: Effects of Gender, Sexual Orientation, and Family.

Self-identified lesbian, gay male, and bisexual (LGB) individuals were recruited via convenience sampling, and they in turn recruited their siblings (79% heterosexual, 19% LGB). The resulting sample of 533 heterosexual, 558 lesbian or gay male, and 163 bisexual participants was compared on mental health variables and their use of mental health services. Multilevel modeling analyses revealed that sexual orientation predicted suicidal ideation, suicide attempts, self-injurious behavior, use of psychotherapy, and use of psychiatric medications over and above the effects of family adjustment. Sexual orientation was unrelated to current psychological distress, psychiatric hospitalizations, and self-esteem. This is the 1st study to model family effects on the mental health of LGB participants and their siblings. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Impaired timing precision produced by striatal D2 receptor overexpression is mediated by cognitive and motivational deficits.

Increased striatal dopamine D2 receptor activity is thought to contribute to the pathophysiology of schizophrenia. To model this condition in mice, Kellendonk et al. (2006) generated transgenic mice that selectively overexpress the D2 receptor in striatum (D2OE). Drew et al. (2007) reported that D2OE mice display deficits in interval timing and motivation. The present study further explored the impaired timing in D2OE mice. Experiment 1 assessed the role of motivation in producing timing deficits in the peak procedure and found that performance in D2OE mice was improved by increasing motivation. In addition, performance was impaired in control mice when motivation was decreased. In Experiment 2, we found that D2OE mice have no timing impairment when tested using the bisection task, a procedure in which the measure of timing performance is less influenced by motivation to respond. In Experiment 3, we also used the bisection task and found selective impairment in timing of long durations in D2OE mice. These results suggest that striatal D2 overexpression impairs timing by decreasing motivation and through its impact on working memory and/or sustained attention. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Pioneers in Partnership: Lesbian and Gay Male Couples in Civil Unions Compared With Those Not in Civil Unions and Married Heterosexual Siblings.

This study compared 212 lesbians and 123 gay men who had civil unions in Vermont (during the first year legislation made this available) with 166 lesbians and 72 gay men in their friendship network who had not had civil unions, and also with 219 heterosexual married women and 193 heterosexual married men consisting of civil union couples' siblings and their spouses. Married heterosexual couples had been together longer and had more traditional division of labor and child care than did lesbians and gay men in both types of couples. Lesbians in civil unions were more open about their sexual orientation than those not in civil unions, and gay men in civil unions were closer to their family of origin than gay men not in civil unions. This is the first study on same-sex couples with civil unions, and the first to compare lesbians and gay men with their married siblings. At a time of legal changes for same-sex couples, these results indicate that legalized same-sex relationships are related to visibility of same-sex couples to their family and the general public. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Form of early pecking in the ring dove squab (Streptoplia risoria): An examination of the preformation hypothesis.

Investigated the components of pecking in adult and squab ring doves. A very precise gape transduction system was used to collect normative data and examine the hypothesis that food pecking develops prefunctionally, that is, without related experience. In Exp 1, adult gapes were characterized as a function of pellet size. In Exp 2, squab's gapes during early attempts to feed were examined. These gapes were not very similar to the adult form and were poorly coordinated with head thrusts. In Exp 3, contributions of maturation to the development of the food peck were assessed. Squab raised on powdered grain received Pavlovian pairings of the sight of whole grain with feedings. Induced pecks had gapes that were not similar to the adult form and displayed poor coordination with thrust. It is concluded that task-specific experience is needed for the development of the adult food peck. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Pavlovian contingencies and temporal information.

The effects of altering the contingency between the conditioned stimulus (CS) and the unconditioned stimulus (US) on the acquisition of autoshaped responding was investigated by changing the frequency of unsignaled USs during the intertrial interval. The addition of the unsignaled USs had an effect on acquisition speed comparable with that of massing trials. The effects of these manipulations can be understood in terms of their effect on the amount of information (number of bits) that the average CS conveys to the subject about the timing of the next US. The number of reinforced CSs prior to acquisition is inversely related to the information content of the CS. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Aqua regia extractable selenium concentrations of some Scottish topsoils measured by ICP‐MS and the relationship with mineral and organic soil components

BACKGROUND: To provide information concerning the geographical distribution of selenium (Se) in the soils of Scotland, we analysed 47 arable soils selected on the basis of their parent rock, which were expected to have relatively high, low or unclassified Se concentrations. To investigate relationships between the actual minerals in the soils and the aqua regia extractable Se concentration of the soil, soil minerals were quantified by X‐ray diffraction. RESULTS: The aqua regia extractable Se concentrations of the soils were between 0.19 and 1.46 mg kg^?1. No simple correlation between the aqua regia extractable Se concentrations of the soil and the parent rock classification estimated by soil survey was evident. Partial least squares analysis revealed that the aqua regia extractable Se concentration of the soils was positively related to loss on ignition (LOI) or C concentration and negatively related to the K‐feldspar concentration, with other minerals being less important. CONCLUSION: The Se concentration of arable topsoils from Scotland is more related to LOI or carbon concentration, with parent material being less important. Copyright © 2010 Society of Chemical Industry     

Temporal Control of Conditioned Responding in Goldfish.

The peak procedure was used to characterize response timing during acquisition and maintenance of conditioned responding in goldfish. Subjects received light-shock pairings with a 5- or 15-s interstimulus interval. On interspersed peak trials, the conditioned stimulus light was presented for 45 s and no shock was delivered. Peaks in the conditioned response, general activity, occurred at about the time of the expected unconditioned stimulus, and variability in the activity distribution was scalar. Modeling of the changes in the activity distributions over sessions revealed that the temporal features of the conditioned response changed very little during acquisition. The data suggest that times are learned early in training, and, contrary to I. P. Pavlov's (1927/1960) concept of "inhibition of delay," that timing is learning when to respond rather than learning when not to respond. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dopamine receptor blockade and extinction differentially affect behavioral variability.

Dopamine (DA) neurons respond to unexpected food delivery and are inhibited during the omission of expected reward. DA receptor blockade mimics some, but not all, aspects of nonreward (extinction) conditions. It was therefore of interest to ask whether DA receptor blockade produces extinction-like increases in behavioral variability in addition to its well-known operant response-suppressing effects. In the current experiment, rats were trained drug-free on an operant task in which they pressed on a keyboard. Two of the keys led to food on a continuous reinforcement schedule. Both response rates and behavioral variability were measured. Test day administration of D? and D? antagonists SCH23390 and raclopride, like extinction, suppressed responding but, unlike extinction, did not lead to an increase in variability. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of cortical and striatal dopamine D1 receptor blockade on cued versus noncued behavioral responses.

Various lines of evidence suggest that disruptions in brain dopamine (DA) transmission produce behavioral impairments that can be overcome by salient response-eliciting environmental stimuli. We examined here whether D1 receptor blockade within striatal or frontal cortical DA target regions would differentially affect head entry responses elicited by an auditory cue compared with those occurring during noncued intertrial intervals. Rats received 2 drug-free 28-trial daily sessions in which an auditory cue was immediately followed by food delivery. On the following day, separate groups of rats received bilateral infusions of D1 antagonist SCH23390 to the dorsomedial striatum (DMS), nucleus accumbens (NAcc) core, or the medial prefrontal cortex (mPFC). SCH23390 infused into the DMS and NAcc core suppressed noncued head entries but had no effect on head entries in response to the auditory cue. SCH23390 infused to the mPFC did not reduce either cued or noncued approach responses. Systemic administration of the drug, in contrast, reduced the frequency of both cued and noncued approaches. The results are consistent with the notion that has emerged from the Parkinson's literature that reduced DA transmission produces behavioral suppression that can be overcome by salient environmental response elicitors, and extends this notion by showing that D1 receptor transmission within the striatum strongly suppresses noncued responses while leaving the identical behavior intact when cued by an environmental stimulus. (PsycINFO Database Record (c) 2011 APA, all rights reserved)