New insights into the regulation of synaptic plasticity from an unexpected place: Hippocampal area CA2

The search for molecules that restrict synaptic plasticity in the brain has focused primarily on sensory systems during early postnatal development, as critical periods for inducing plasticity in sensory regions are easily defined. The recent discovery that Schaffer collateral inputs to hippocampal area CA2 do not readily support canonical activity-dependent long-term potentiation (LTP) serves as a reminder that the capacity for synaptic modification is also regulated anatomically across different brain regions. Hippocampal CA2 shares features with other similarly "LTP-resistant" brain areas in that many of the genes linked to synaptic function and the associated proteins known to restrict synaptic plasticity are expressed there. Add to this a rich complement of receptors and signaling molecules permissive for induction of atypical forms of synaptic potentiation, and area CA2 becomes an ideal model system for studying specific modulators of brain plasticity. Additionally, recent evidence suggests that hippocampal CA2 is instrumental for certain forms of learning, memory, and social behavior, but the links between CA2-enriched molecules and putative CA2-dependent behaviors are only just beginning to be made. In this review, we offer a detailed look at what is currently known about the synaptic plasticity in this important, yet largely overlooked component of the hippocampus and consider how the study of CA2 may provide clues to understanding the molecular signals critical to the modulation of synaptic function in different brain regions and across different stages of development.     

The relationship between color–object associations and color preference: Further investigation of ecological valence theory

Ecological valence theory (EVT; Palmer & Schloss, Proceedings of the National Academy of Sciences 107:8877–8882, 2010) proposes that color preferences are due to affective responses to color-associated objects: That is, people generally like colors to the degree that they like the objects associated with those colors. Palmer and Schloss found that the average valence of objects associated with a color, when weighted by how well the objects matched the color (weighted affective valence estimates: WAVE) explained 80% of the variation in preference across colors. Here, we replicated and extended Palmer and Schloss’s investigation to establish whether color–object associations can account for sex differences in color preference and whether the relationship between associated objects and color preference is equally strong for males and females. We found some degree of sex specificity to the WAVEs, but the relationship between WAVE and color preference was significantly stronger for males than for females (74% shared variance for males, 45% for females). Furthermore, analyses identified a significant inverse relationship between the number of objects associated with a color and preference for the color. Participants generally liked colors associated with few objects and disliked colors associated with many objects. For the sample overall and for females alone, this association was not significantly weaker than the association of the WAVE and preference. The success of the WAVE at capturing color preference was partly due to the relationship between the number of associated objects and color preference. The findings identify constraints of EVT in its current form, but they also provide general support for the link between color preference and color–object associations.     

Midlife Sexuality Among Thai Adults: Adjustment to Aging in the Thai Family Context

The objective of the study is to assess views of age related changes in sexual behavior among married Thai adults age 53–57. Results are viewed in the context of life course theory. In-depth interviews were conducted with 44 Thai adults in Bangkok and the four regions of Thailand. Topics covered include changing sexual behavior with age, adjustment to this change, gender differences in behavior, attitudes toward commercial sex and other non-marital sexual partners, and condom use. Most respondents were aware of this change and saw a decrease in sexual activity and desire more often among women compared to men. At the same time, many respondents viewed sexuality as important to a marriage. Some respondents accepted the decrease in sexual activity and focused more on work, family and temple activities. Thai Buddhism was seen as an important resource for people who were dealing with changes due to aging. Other persons turned to other partners including both commercial and non-commercial partners. The influence of the HIV epidemic that began in the 1990s was seen in concerns about disease transmission with extramarital partners and consequent attitudes toward condom use. The acceptability of extramarital partners in the family and community ranged from acceptance to strong disapproval of extramarital relationships.     

Invisible “Others”: Sexual Health Vulnerabilities of Wives of Men who Have Sex with Men

The recent trend in the feminization of the HIV epidemic poses great risk to women, especially to the wives of men who have sex with men (MSM). The objective of the present study was to explore wives’ responses to their husbands’ sexual orientation as well as the factors that influence their sexual health in India. For this research, 15 wives who were aware of their husbands’ sexual orientation and their husbands were interviewed separately using semi-structured in-depth interviews and focus groups. The study explored the social and cultural structures that create gender inequality, which put women married to MSM at sexual health risk. These factors need to be addressed carefully through existing MSM targeted interventions, without breaching the confidentiality of either partner.     

Determinants of Electoral Support for Anti-Gay Marriage Constitutional Amendments: An Examination of Ballot Issues in California and Florida

Between 1998 and 2006, twenty-seven states amended their constitutions to prohibit same sex marriage. The 2008 elections again saw three states with ballot measures aimed at banning gay marriage. This study examines the determinants of support for those measures in California and Florida, and includes a similar measure placed on the primary election ballot in California in 2000. Support is measured as the county-wide vote in favor of each gay marriage ban. A number of hypotheses are explored that examine the urban/rural nature of each county, as well as the political and demographic characteristics of county residents. It is suggested that states may be best viewed as relatively independent groupings of diverse subcultures, rather than as homogenous populations with a single political culture. The findings reported here indicate that a host of demographic, political and religious differences within each state influence residents’ votes on gay marriage bans.     

A Randomized, Double-Blind, Crossover Comparison of MK-0929 and Placebo in the Treatment of Adults With ADHD

Objective: Preclinical models, receptor localization, and genetic linkage data support the role of D4 receptors in the etiology of ADHD. This proof-of-concept study was designed to evaluate MK-0929, a selective D4 receptor antagonist as treatment for adult ADHD. Method: A randomized, double-blind, placebo-controlled, crossover study was conducted in adults with primary ADHD. The primary end point was changed from baseline in total score on the Adult ADHD Investigator Symptom Rating Scale following a 4-week treatment regimen. Additional measures included Clinical Global Impression-Severity Scale, Hospital Anxiety and Depression Scale, and Brown Attention Deficit Disorder Scale and D4 genotype analysis. Results: No statistically significant treatment differences were found between MK-0929 and placebo in any of the primary or secondary assessments. Conclusion: Results from this study suggest that blockade of the D4 receptor alone is not efficacious in the treatment of adult ADHD.     

Online Responsibility: Bad Samaritanism and the Influence of Internet Mediation

In 2008 a young man committed suicide while his webcam was running. 1,500 people apparently watched as the young man lay dying: when people finally made an effort to call the police, it was too late. This closely resembles the case of Kitty Genovese in 1964, where 39 neighbours supposedly watched an attacker assault and did not call until it was too late. This paper examines the role of internet mediation in cases where people may or may not have been good Samaritans and what their responsibilities were. The method is an intuitive one: intuitions on the various potentially morally relevant differences when it comes to responsibility between offline and online situations are examined. The number of onlookers, their physical nearness and their anonymity have no moral relevance when it comes to holding them responsible. Their perceived reality of the situation and ability to act do have an effect on whether we can hold people responsible, but this doesn’t seem to be unique to internet mediation. However the way in which those factors are intrinsically connected to internet mediation does seem to have a diminishing effect on responsibility in online situations.     

Associative memory or algorithmic search: a comparative study on learning strategies of bats and shrews

Two common strategies for successful foraging are learning to associate specific sensory cues with patches of prey ("associative learning") and using set decision-making rules to systematically scan for prey ("algorithmic search"). We investigated whether an animal's life history affects which of these two foraging strategies it is likely to use. Natterer's bats (Myotis nattereri) have slow life-history traits and we predicted they would be more likely to use associative learning. Common shrews (Sorex araneus) have fast life-history traits and we predicted that they would rely more heavily on routine-based search. Apart from their marked differences in life-history traits, these two mammals are similar in body size, brain weight, habitat, and diet. We assessed foraging strategy, associative learning ability, and retention time with a four-arm maze; one arm contained a food reward and was marked with four sensory stimuli. Bats and shrews differed significantly in their foraging strategies. Most bats learned to associate the sensory stimuli with the reward and remembered this association over time. Most shrews searched the maze using consistent decision-making rules, but did not learn or remember the association. We discuss these results in terms of life-history traits and other key differences between these species. Our results suggest a link between an animal's life-history strategy and its use of associative learning.     

Sequential learning and rule abstraction in Bengalese finches

The Bengalese finch (Lonchura striata var. domestica) is a species of songbird. Males sing courtship songs with complex note-to-note transition rules, while females discriminate these songs when choosing their mate. The present study uses serial reaction time (RT) to examine the characteristics of the Bengalese finches’ sequential behaviours beyond song production. The birds were trained to produce the sequence with an “A–B–A” structure. After the RT to each key position was determined to be stable, we tested the acquisition of the trained sequential response by presenting novel and random three-term sequences (random test). We also examined whether they could abstract the embedded rule in the trained sequence and apply it to the novel test sequence (abstract test). Additionally, we examined rule abstraction through example training by increasing the number of examples in baseline training from 1 to 5. When considered as (gender) groups, training with 5 examples resulted in no statistically significant differences in the abstract tests, while statistically significant differences were observed in the random tests, suggesting that the male birds learned the trained sequences and transferred the abstract structure they had learned during the training trials. Individual data indicated that males, as opposed to females, were likely to learn the motor pattern of the sequence. The results are consistent with observations that males learn to produce songs with complex sequential rules, whereas females do not.