Involvement of the rat anterior cingulate cortex in control of instrumental responses guided by reward expectancy

The anterior cingulate cortex (ACC) plays a critical role in stimulus-reinforcement learning and reward-guided selection of actions. Here we conducted a series of experiments to further elucidate the role of the ACC in instrumental behavior involving effort-based decision-making and instrumental learning guided by reward-predictive stimuli. In Experiment 1, rats were trained on a cost-benefit T-maze task in which they could either choose to climb a barrier to obtain a high reward (four pellets) in one arm or a low reward (two pellets) in the other with no barrier present. In line with previous studies, our data reveal that rats with quinolinic acid lesions of the ACC selected the response involving less work and smaller reward. Experiment 2 demonstrates that breaking points of instrumental performance under a progressive ratio schedule were similar in sham-lesioned and ACC-lesioned rats. Thus, lesions of the ACC did not interfere with the effort a rat is willing to expend to obtain a specific reward in this test. In a subsequent task, we examined effort-based decision-making in a lever-press task where rats had the choice between pressing a lever to receive preferred food pellets under a progressive ratio schedule, or free feeding on a less preferred food, i.e. lab chow. Results show that sham- and ACC-lesioned animals had similar breaking points and ingested comparable amounts of less-preferred food. Together, the results of Experiment 1 and 2 suggest that the ACC plays a role in evaluating how much effort to expend for reward; however, the ACC is not necessary in all situations requiring an assessment of costs and benefits. In Experiment 3 we investigated learning and reversal learning of instrumental responses guided by reward predictive stimuli. A reaction time (RT) task demanding conditioned lever release was used in which the upcoming reward magnitude (five vs. one food pellet) was signalled in advance by discriminative visual stimuli. Results revealed that rats with ACC lesions were able to discriminate reward magnitude-predictive stimuli and to adapt instrumental behavior to reversed stimulus-reward magnitude contingencies. Thus, in a simple discrimination task as used here, the ACC appears not to be required to discriminate reward magnitude-predictive stimuli and to use the learned significance of the stimuli to guide instrumental behavior.     

Cognitive neural prosthetics

Research on neural prosthetics has focused largely on using activity related to hand trajectories recorded from motor cortical areas. An interesting question revolves around what other signals might be read out from the brain and used for neural prosthetic applications. Recent studies indicate that goals and expected value are among the high-level cognitive signals that can be used and will potentially enhance the ability of paralyzed patients to communicate with the outside world. Other new findings show that local field potentials provide an excellent source of information about the cognitive state of the subject and are much easier to record and maintain than spike activity. Finally, new movable probe technologies will enable recording electrodes to seek out automatically the best signals for decoding cognitive variables.     

Identifying environmental contributions to autism: provocative clues and false leads

The potential role of environmental factors in autism spectrum disorders (ASD) is an area of emerging interest within the public and scientific communities. The high degree of heritability of ASD suggests that environmental influences are likely to operate through their interaction with genetic susceptibility during vulnerable periods of development. Evaluation of the plausibility of specific neurotoxicants as etiological agents in ASD should be guided by toxicological principles, including dose-effect dependency and pharmacokinetic parameters. Clinical and epidemiological investigations require the use of sufficiently powered study designs with appropriate control groups and unbiased case ascertainment and exposure assessment. Although much of the existing data that have been used to implicate environmental agents in ASD are limited by methodological shortcomings, a number of efforts are underway that will allow more rigorous evaluation of the role of environmental exposures in the etiology and/or phenotypic expression of the disorder. Surveillance systems are now in place that will provide reliable prevalence estimates going forward in time. Anticipated discoveries in genetics, brain pathology, and the molecular/cellular basis of functional impairment in ASD are likely to provide new opportunities to explore environmental aspects of this disorder.     

Psychological research online: report of Board of Scientific Affairs' Advisory Group on the Conduct of Research on the Internet

As the Internet has changed communication, commerce, and the distribution of information, so too it is changing psychological research. Psychologists can observe new or rare phenomena online and can do research on traditional psychological topics more efficiently, enabling them to expand the scale and scope of their research. Yet these opportunities entail risk both to research quality and to human subjects. Internet research is inherently no more risky than traditional observational, survey, or experimental methods. Yet the risks and safeguards against them will differ from those characterizing traditional research and will themselves change over time. This article describes some benefits and challenges of conducting psychological research via the Internet and offers recommendations to both researchers and institutional review boards for dealing with them. ((c) 2004 APA, all rights reserved)     

A comparative study of values and attitudes of inner-city and middle-class postpartum women

This study compared postpartum women from the inner city (n = 94) and postpartum women from the urban middle class (n = 80) on values and goals for themselves and their newborn children. Terminal values of inner-city women for themselves related more to social and religious goals in contrast to the more intrapersonal and personal goals of middle-class women. Instrumental values of inner-city women for their newborn children demonstrated concern with conformity and control, whereas for the middle class there was more concern with competence. Goals for the near future of the inner-city mothers were based on a desire for jobs and education.     

Multimodal classical conditioning of fear: contributions of direct, observational, and verbal experiences to current fears

The authors propose that a multimodal classical conditioning model be considered when clinicians or clinical researchers study the etiology of fears and anxieties learned by human beings. They argue that fears can be built through the combined effects of direct, observed, and verbally presented classical conditioning trials. Multimodal classical conditioning is offered as an alternative to the three pathways to fear argument prominent in the human fear literature. In contrast to the three pathways position, the authors present theoretical arguments for why "learning by observation" and "learning through the receipt of verbal information" should be considered classical conditioning through observational and verbal modes. The paper includes a demonstration of how data, commonly collected in research on the three pathways to fear, would be studied differently using a multimodal classical conditioning perspective. Finally, the authors discuss implications for assessment, treatment, and prevention of learned fears in humans.     

Framing social information and generalized social phobia

Patients with generalized social phobia (GSP, N=33) and matched community controls (N=31) engaged in a social interaction that was constructed to go well, and then received feedback that framed social cues reflecting either the absence of negative outcomes or the presence of positive outcomes. Following feedback that framed positive social cues, the GSP group predicted they would experience more anxiety in a subsequent interaction than did non-phobic controls. In contrast, following feedback framing the absence of negative outcomes, the GSP group did not differ from controls in their anxiety predictions. The results demonstrated that framing paradigms and methods can be usefully applied to the study of cognitive processes in social phobia and indicated that research to examine how GSP patients process specific types of social information is needed.     

Illicit drug use and risky sexual behavior among African American and Puerto Rican urban adolescents: the longitudinal links

The authors assessed whether (a) early illicit drug use predicted later risky sexual activity, (b) early risky sex predicted later illicit drug use, and (c) common factors affected both risky sexual behavior and illicit drug use. African American and Puerto Rican youth completed questionnaires in their classrooms at Time 1 (T1) and face-to-face interviews with the authors in their homes 5 years later at Time 2 (T2). Logistic regression analyses showed the association between T1 illicit drug use and T2 risky sexual activity and between T1 risky sexual behavior and T2 illicit drug use. With few exceptions, T1 illicit drug use was associated with all of the T2 risky sexual behaviors. After controlling for demographic factors, the authors found that multiple sex partners at T1 was not related to illicit drug use at T2. Condom use at T1 was related to illicit drug use at T2, whereas sexually transmitted diseases and adolescent pregnancy were not related to this drug use. The findings indicated that assessments of and treatments for substance use should focus on the risky sexual behaviors that seem to accompany illicit drug use.     

Correlates of aggression in African American and Puerto Rican children

The authors examined a cross-sectional interrelationship of psychosocial domains as they relate to aggression in a group of African American and English-speaking Puerto Rican children living in New York City. The population included 80 biological children of African American and Puerto Rican young adults who had been participating in the authors' ongoing longitudinal study, and 77 mothers or mother substitutes (rearing mothers) of those children. The authors performed hierarchical multiple regression analysis. The results indicated that (a) the child's personality and maternal attributes were significantly related to the child's aggression, despite control on all of the other domains and (b) the ethnic identification and discrimination domain was no longer related to the child's aggression with control on the mother-child relationship domain or on the child's personality domain. The findings have implications for clinical practice and public policy.