Ethics,Changing Populations,and the Dental Profession

This review emphasizes the worldwide and U.S. evolving population demographics and the need for the dental profession to exercise its professional and ethical duty to expand its traditional patient base to provide needed services.     

The neurobiology of substance and behavioral addictions

Behavioral addictions, such as pathological gambling, kleptomania, pyromania, compulsive buying, and compulsive sexual behavior, represent significant public health concerns and are associated with high rates of psychiatric comorbidity and mortality. Although research into the biology of these behaviors is still in the early stages, recent advances in the understanding of motivation, reward, and addiction have provided insight into the possible pathophysiology of these disorders. Biochemical, functional neuroimaging, genetic studies, and treatment research have suggested a strong neurobiological link between behavioral addictions and substance use disorders. Given the substantial co-occurrence of these groups of disorders, improved understanding of their relationship has important implications not only for further understanding the neurobiology of both categories of disorders but also for improving prevention and treatment strategies.     

Specific phonological impairments in dyslexia revealed by eyetracking

Phonological deficits in dyslexia are typically assessed using metalinguistic tasks vulnerable to extraneous factors such as attention and memory. The present work takes the novel approach of measuring phonology using eyetracking. Eye movements of dyslexic children were monitored during an auditory word recognition task in which target items in a display (e.g., candle) were accompanied by distractors sharing a cohort (candy) or rhyme (sandal). Like controls, dyslexics showed slower recognition times when a cohort distractor was present than in a baseline condition with only phonologically unrelated distractors. However, unlike controls, dyslexic children did not show slowed recognition of targets with a rhyme distractor, suggesting they had not encoded rhyme relationships. This was further explored in an overt phonological awareness test of cohort and rhyme. Surprisingly, dyslexics showed normal rhyme performance but poorer judgment of initial sounds on these overt tests. The results implicate impaired knowledge of rhyme information in dyslexia; however they also indicate that testing methodology plays a critical role in how such problems are identified.     

Anterior medial temporal lobe activation during encoding of words: FMRI methods to optimize sensitivity

The existence of a rostrocaudal gradient of medial temporal lobe (MTL) activation during memory encoding has historically received support from positron emission tomography studies, but less so from functional MRI (FMRI) studies. More recently, FMRI studies have demonstrated that characteristics of the stimuli can affect the location of activation seen in the MTL when those stimuli are encoded. The current study tested the hypothesis that MTL activation during memory encoding is related to the modality of stimulus presentation. Subjects encoded auditorily or visually presented words in an FMRI novelty paradigm. Imaging and analysis parameters were optimized to minimize susceptibility artifact in the anterior MTL. Greater activation was observed in the anterior than posterior MTL for both modalities of stimulus presentation. The results indicate that anterior MTL activation occurred during encoding, independent of stimulus modality and provide support for the hypothesis that verbal-semantic memory processing occurs in anterior MTL. The authors suggest that technical factors are critical for observing the rostrocaudal gradient in MTL memory activation.     

Transformations of mathematical and stimulus functions

Following a pretest, 8 participants who were unfamiliar with algebraic and trigonometric functions received a brief presentation on the rectangular coordinate system. Next, they participated in a computer-interactive matching-to-sample procedure that trained formula-to-formula and formula-to-graph relations. Then, they were exposed to 40 novel formula-to-graph tests and 10 novel graph-to-formula tests. Seven of the 8 participants showed substantial improvement in identifying formula-to-graph relations; however, in the test of novel graph-to-formula relations, participants tended to select equations in their factored form. Next, we manipulated contextual cues in the form of rules regarding mathematical preferences. First, we informed participants that standard forms of equations were preferred over factored forms. In a subsequent test of 10 additional novel graph-to-formula relations, participants shifted their selections to favor equations in their standard form. This preference reversed during 10 more tests when financial reward was made contingent on correct identification of formulas in factored form. Formula preferences and transformation of novel mathematical and stimulus functions are discussed.     

Warning signs for suicide: theory, research, and clinical applications

The current article addresses the issue of warning signs for suicide, attempting to differentiate the construct from risk factors. In accordance with the characteristic features discussed, a consensus set of warning signs identified by the American Association of Suicidology working group are presented, along with a discussion of relevant clinical and research applications.     

Stability of pigeon body weight under free-feeding conditions

Increases in regulatory oversight of animal research require verification of effects of standard practices. There are no formal guidelines for establishing free-feeding weights in adult pigeons. In the present study, pigeons were obtained from a commercial supplier, weighed upon arrival, and then held in quarantine for 7 days with free access to food. Subsequently, still with continuous access to food, they were weighed daily for 30 days. No significant changes in weights occurred over the 30-day period for male pigeons, indicating that seven days is sufficient for establishing a baseline body weight. A secondary finding of higher day-to-day variability in the weights of female pigeons may serve as a method of sexing pigeons.     

The day of the week when you were born in 700 ms: calendar computation in an Autistic savant

Some individuals are able to determine the weekday of a given date in a few seconds (finding for instance that June 12, 1900, was a Tuesday). This ability has fascinated scientists for many years because it is predominantly observed in people with limited intelligence and may appear very early in life. Exceptional visual memory, exceptional concentration abilities, or privileged access to lower levels of information not normally available through introspection have been advanced to explain such phenomena. In the present article, the authors show that a simple cognitive model can explain all aspects of the performance of Donny, a young autistic savant who is possibly the fastest and most accurate calendar prodigy ever described.     

Stability in cognition across early childhood. A developmental cascade

Children confront the formidable task of assimilating information in the environment and accommodating their cognitive structures to that information. Developmental science is concerned equally with two distinctive features of these processes: children's group mean level of performance through time and the standing of individual children through time. Prevailing opinion since the inception of the mental-measurement movement has been that individual development is unstable-that individual children change unpredictably in their abilities. We report results of a large-scale controlled, multivariate, prospective, microgenetic, 4-year longitudinal study that reveals a statistically significant cascade of species-typical cognitive abilities from infancy to childhood. Infancy is a recognizable starting point of life; we find that to a small but significant degree, infancy also represents a setting point in the life of the individual.