Development of eye-movement control

Cognitive control of behavior continues to improve through adolescence in parallel with important brain maturational processes including synaptic pruning and myelination, which allow for efficient neuronal computations and the functional integration of widely distributed circuitries supporting top-down control of behavior. This is also a time when psychiatric disorders, such as schizophrenia and mood disorders, emerge reflecting a particularly vulnerability to impairments in development during adolescence. Oculomotor studies provide a unique neuroscientific approach to make precise associations between cognitive control and brain circuitry during development that can inform us of impaired systems in psychopathology. In this review, we first describe the development of pursuit, fixation, and visually-guided saccadic eye movements, which collectively indicate early maturation of basic sensorimotor processes supporting reflexive, exogenously-driven eye movements. We then describe the literature on the development of the cognitive control of eye movements as reflected in the ability to inhibit a prepotent eye movement in the antisaccade task, as well as making an eye movement guided by on-line spatial information in working memory in the oculomotor delayed response task. Results indicate that the ability to make eye movements in a voluntary fashion driven by endogenous plans shows a protracted development into adolescence. Characterizing the transition through adolescence to adult-level cognitive control of behavior can inform models aimed at understanding the neurodevelopmental basis of psychiatric disorders.     

Effects of moderate chronic ethanol consumption on hippocampal nicotinic receptors and associative learning

A number of studies have reported that ethanol exposure induces changes in different brain systems. The hippocampus is a brain region that is very vulnerable to ethanol exposition, which functionally results in impairment of learning and memory processes reported in heavy drinkers. Hippocampal nicotinic receptors are involved in learning and memory. In this study, we determined the effects of ethanol on the main hippocampal subtypes of neural nicotinic receptors (α7 and α4β2) in rats non-selected for alcohol consumption, in order to check for possible changes on these receptors that could be linked with alterations in learning acquisition. Binding assays were carried out with [³H]methyllycaconitine ([³H]MLA) to study the α7 and [³H]nicotine to study α4β2 receptors. Auto-shaping, continuous ratio and extinction procedures were used as behavioral tests. The results show that moderate chronic ethanol consumption for 10 weeks produces: (a) a decrease of both hippocampal nicotinic receptor subtypes without alterations in affinity; (b) no differences in behavioral performance between control rats and ethanol-drinking rats in auto-shaping and continuous ratio; (c) an improvement of performance of extinction paradigm. These results indicate that chronic ethanol consumption, at moderate levels, induces changes in hippocampal nicotinic receptors but does not impair acquisition and performance of new associative learning and even improves some kind of paradigms. These results may have implications in the biochemical basis of interactions between alcohol and nicotine and the effects of these drugs on behavior.     

Frequency versus magnitude of reinforcement: New data with a different procedure

Two pigeons, with previous exposure to concurrent schedules, were submitted to 29 sessions of 8 hours each with concurrent variable-interval variable-interval schedules in which reinforcement parameters changed from session to session. In the first nine sessions reinforcement durations were equal in both schedules while reinforcement frequencies varied; in Sessions 10 through 18, both frequency and duration of reinforcement were varied; in Sessions 19 through 29, only reinforcement duration was varied. Results with this different procedure confirm previous findings that behavior is more sensitive to changes in reinforcement frequency than to reinforcement magnitude.     

Low platelet monoamine oxidase activity in sensation-seeking bullfighters

In this study, we attempt to demonstrate an association between low platelet monoamine oxidase (MAO) activity, as assessed by isotopic methods, and the stable behavioral pattern of sensation- and risk-seeking of professional bullfighters. Sixteen professional bullfighters were studied and compared with a control group of 46 healthy control subjects who did not engage in risky jobs or activities. The group of bullfighters had significantly reduced platelet MAO activity compared with the control group (P<0.05). Bullfighters were shown to be significantly more extroverted and sensation-seeking than controls on various temperament scales. A predisposition to engage in risky activities (eg, bullfighting) and sensation-seeking could be partly conditioned by the presence of biological components of personality manifested by a significantly decreased platelet MAO activity.     

Schizotypy and verbal memory in the adolescent general population

The following study examines the relationship between verbal memory deficits and schizotypal traits measured psychometrically from a non- clinical adolescent population. In this transversal analytical study participated 139 subjects. They were secondary school students, with ages ranging from 13 to 16 years old (mean= 14, 35; Sta.Dev.= 0, 548). After administrating the scales O-LIFE (psychometrical schizotypy), CVLT (verbal memory), and Letters and Numbers subtest of WAIS-III (working memory), data was analyzed utilizing Pearson correlations and mean comparison test. Results showed lack of relations between schizotypy measures and working memory. Nonetheless, some of the O-LIFE dimensions correlated with verbal memory. These findings support partly the literature reviewed. Yet, more work focused on schizotypy and cognitive deficits as risk factors are suggested.     

Fragment difficulty in priming on word-completion tests

Word-fragment completion is a frequently used test in implicit memory research. In this test priming is the relevant variable. Priming is obtained by subtracting the proportion of nonstudied word fragments correctly completed (called "completion difficulty baseline") from the studied word fragments correctly completed. Since completion difficulty can spuriously vary greatly between experimental conditions, its effect on magnitude of priming is studied. Normative frequency of occurrence of target words was considered because their influence over performance is known. In an experiment using a word-fragment completion test, participants' completion of fragments at three levels of completion difficulty and two levels of frequency was tested. Analysis showed that completion difficulty had a significant effect on global priming. The priming magnitude was higher for Difficult and Moderately Difficult fragments than for Easy ones. An interaction between fragment difficulty and normative word frequency was observed. When the fragments were easy to complete, the expected effect of higher priming for low-frequency words than for high-frequency words was not observed.     

Education and conspiracy beliefs: A replication of van Prooijen (2017)

The main aim of the study was to replicate and extend van Prooijen's findings on how education and its outcomes (cognitive complexity, subjective social standing, self-esteem, a feeling of control and powerlessness, cognitive reflection, epistemic curiosity and scientific reasoning) predict conspiracy beliefs. In two studies (Study 1: N = 497, M_age = 49.06, SD_age = 14.92; Study 2: N = 482, M_age = 47.45, SD_age = 15.87), subjective socioeconomic status and cognitive reflection (Study 1) and a feeling of powerlessness and scientific reasoning (Study 2) contributed to the negative relationship between education level and belief in conspiracy theories. These results showed the connection of education to socioeconomic status, a feeling of control and analytic thinking (cognitive reflection, scientific reasoning) and their power to reduce conspiracy beliefs.     

Predicting interest in liposuction among women with eating problems: a population-based study

The purpose of this paper was to examine predictors of an interest in liposuction among women with eating problems. A questionnaire was sent to 3500 women aged 18-35 years, whereof 378 of 1861 responders screened positively on eating problems. Assessments included sociodemographic status, social network, physical exercise, attitudes towards cosmetic surgery, teasing history, body dysmorphic disorder-like symptoms, body image, self-esteem, personality, interpersonal attachment and emotional distress. Fifty-two percent reported an interest in liposuction, which was independently predicted by appearance orientation, appearance evaluation, being critical/quarrelsome, teasing history, wish for a better relationship with father, low education and being unmarried. Predictors differed somewhat from those previously found in the general population. Considering that our sample consisted of women with self-reported eating problems, the association between liposuction and eating behaviors should be further examined in a sample of patients with a formal eating disorder diagnosis.