ADVANCES IN COGNITIVE SCIENCE
Year:2007 | Volume:9 | Issue:2 (34)|Papers Count:13

Objective: In this study, the effects of bilateral injections of nicotinic cholinergic agents into the hippocampal CA1 region of Wistar rats on morphine-induced conditioned place preference (CPP) was studied.Method: All animals were canulated in the CA1 area of dorsal hippocampus by stereotaxic instrument. Each animal was allowed to recover 1-week before CPP induction. We used a 5-day schedule for CPP with three distinct phases: first, the preconditioning phase, second, the conditioning phase and finally, the testing or the expression phase.Results: Subcutaneous administration of different doses of morphine sulphate (0.5-6mg/kg) produced a dose-dependent CPP. Using a 3-day schedule of conditioning, it was found that intra-CA1 administration of nicotine (0.5, 0.75, and 1mg/rat) with an ineffective dose of morphine (0.5mg/kg) elicited a significant CPP. Bilateral injections of different doses of the nicotinic receptor antagonist, mecamylamine (2, 4, and 8mg/rat) into the CA1 regions significantly inhibited the morphine (6mg/kg)-induced CPP. Moreover mecamylamine (8mg/rat, intra-CA1) decreased the effect of nicotine-induced potentiation of the morphine response.Conclusion: Intra-CA1 injections of nicotine or mecamylamine alone did not induce a significant place preference or place aversion. It may be concluded that the nicotinic receptors of the hippocampal CA1 regions play an important role in morphine reward.

Introduction: Cognitive dysfunction with a prevalence of about 50 to 60 percent is the most important factor causing vocational disability and unemployment in patients with multiple sclerosis (MS). The role of psychological assessments in the detection of these disorders is proven; and there has been especially an emphasis on the importance of computer tests regarding their precise time recording. In this study we used computerized Farsi neuropsychological assessment tasks to evaluate the functions of dorsolateral and ventromedial prefrontal cortex in MS patients.Method: 43 patients (27 females) and 40 healthy controls (25 females), who were matched according to age, sex, IQ, and the level of depression were included in a historical cohort study by convenient sampling. The subjects also underwent a complete neurological assessment, the evaluation of Estimated Disability Status Scale (EDSS), Wisconsin Card Sorting Task (WCST), Time Perception Task (TTP), Iowa Gambling Task (IGT), Delayed Discounting Task (DOT), and Balloon Analogue Risk Task (BART).Results: MS patients produced more perseverance errors in WCST and a longer time to choose from the disadvantageous deck in IGT. Also, there was a lower amount of decrease in reward value in DOT, lower amount of risk taking in BART and finally an over-estimation and over-reproduction of time intervals in TPT.Conclusion: The analysis of data in this study showed for the first time that despite a competent general intelligence, patients with MS show a high degree of conservatism in their cognitive functions. This particular cognitive strategy which is in contrast to what is seen in drug dependents, gamblers, criminals and other risk taking groups, could be explained by Multiple Disconnection Syndrome due to specific lesions in prefrontal white matter seen in these patients, slowing of information processing, or a social learning based on the consequences and personal experience of patients with MS.

Objective: to evaluate the effect of age differences and type of information (laboratory and everyday tasks) on explicit and implicit memory. In other words, to assess whether differences in the function of explicit and implicit memories are due to processing or structural (systemic) factors.Method: 240 subjects were randomly selected from two age groups, namely adults and children. The children and adult group consisted of schoolchildren and university students respectively. Instruments included everyday and laboratory tasks which were carried out to assess explicit and implicit memories through recognition and word stem completion respectively. Each everyday and laboratory task included 32 high and low frequency words. Data were analyzed through analysis of variance by SPSS.Results: Explicit and implicit memories were influenced by age difference and type of information. Also, there was an interaction effect between age differences and type of information.Conclusion: The difference between explicit and implicit memories is due to processing factors. And the difference is not solely due to the possession of different systems or structures by these memories.

Objective: The aim of the present research was to examine the role of identity styles and commitment on university students' psychological well-being.Method: Identity Styles Inventory and Scales of Psychological Well-being were completed by 376 subjects (158 male, 218 female). Using path analysis, the direct and indirect effects of identity styles on commitment and psychological well-being measures were evaluated.Results: Informational identity style has a significant positive effect on commitment, autonomy, environmental mastery, personal growth, positive relations with others, and purpose in life; normative identity style has a positive and significant effect on commitment and a negative and significant effect on autonomy; and diffuse/avoidant identity style has a negative and significant effect on commitment, autonomy, personal growth and purpose in life. The indirect effects of informational identity style through commitment, on autonomy, environmental mastery, personal growth, positive relations with others, purpose in life and self-acceptance were positively significant (p<0.05); and the indirect effects of diffuse/avoidant identity style through commitment on autonomy, environmental mastery, personal growth, positive relations with others, purpose in life and self-acceptance were negatively significant (p<0.05).Conclusion: In total, the results show that avoiding facing identity issues is negatively related to psychological well-being. Also, the results show that in addition to commitment, the manner of facing issues related to identity are important factors in the prediction of psychological well-being.

Objective: The main purpose of this study was to investigate the relationship between circadian typology and reaction time in the morning and evening. The other aim of this I research was to study the differences of reaction times in the morning and the evening I among students.Method: In a cross-sectional study 65 students of Isfahan University (36 females, 29 males) were randomly selected. Data were collected using Morningness- Eveningness Questionnaire and Visual Reaction Time Task. For evaluating the day time effect on subject performance, reaction time was tested twice (9 A.M. and 3 P.M.).Results: There was no relation between Morningness-Eveningness scores and reaction time. Also, there was no difference between reaction time scores at two performances (morning and evening). Multivariate analysis showed a significant difference between males and females in Morningness-Eveningness scores (p<0.006). However, there was no significant difference between the two sexes in reaction time.Conclusion: There is no significant difference between reaction time and circadian typology. Since the Morningness-Eveningness scores of subjects in this study belonged to neither type in circadian typology, there is a possibility I that this has affected the reaction time test results. Different results might be obtained if the. Subjects are selected from two ends of the continuum (morningness and eveningness).

Objective: The present study aims at providing a clearer image of antisocial personality disorder through the evaluation of different dimensions of temperament and character factors in individuals with this disorder, and comparing them with normal subjects.Method: 24 male subjects with antisocial personality disorder were chosen using Structured Clinical Interview for DSM-IV Axis II Personality Disorders (SCID-II). Rate of depression and anxiety were measured as covariates using Beck Depression and Anxiety Inventory. Also, dimensions of temperament and character were assessed by Cloninger's Temperament Character Inventory.Results: People with antisocial personality disorder scored higher on novelty seeking and harm avoidance and lower in persistence, self directedness, and cooperativeness in comparison with normal population. Scores of reward dependence and self transcendence were in the range of normal population. There was a positive correlation between harm avoidance and Beck anxiety score.Conclusions: Lower scores on character factors indicate weaker development of character and the presence of personality disorder. Higher scores on novelty seeking and lower scores on persistence (among character factors) are associated with personality traits of Cluster B. High scores of harm avoidance and normal scores of reward dependence are incompatible with previous studies, the most probable cause of which - in addition to the small number of subjects - can be the presence of people with secondary psychopathy traits and anxiety among the clinical subjects, which in turn affects the harm avoidance dimension.

Objective: To evaluate the effect of stress management training on Iranian students preparing for university entry exam.Method: In this study 217 participants were randomly assigned to four experimental and four control groups of two sexes. An eight-session training package was used for training the experimental group. The subjects were assessed by Beck Depression and Anxiety Inventory.Results: The result of the second experiment indicates a significant efficacy of stress management training on lowering the level of anxiety and depression of the subjects.Conclusion: It seems that policy-makers should consider applying stress management training along with planning university entry exam programs in order to lower the level of anxiety and depression of individuals.

Objective: To study the effect of negative and positive induced emotions on anxiety and ruminating thoughts caused by previously induced negative emotions.Method: In a semi experimental study (pretest-post test with control group), 32 female first year high school students in the city of Isfahan were randomly divided into two control and two experimental groups, each comprised of eight subjects. The subject completed questionnaires of ruminating thoughts, anxiety, MMPI2 (Minnesota Multiphasic Personality Inventory), and two scales of the Big Five Factorial Questionnaire (Introversion-Neuroticism). After induction of anxiety, sad, cheerful and neutral films were shown to the first, second and third groups respectively, and the fourth group remained without intervention. In the following day, all groups completed the questionnaires of ruminating thoughts and anxiety. Results were analyzed using analysis of covariance and multivariate analysis of variance.Results: There were significant differences among the groups with regard to ruminating thoughts and anxiety. The level of anxiety and ruminating thoughts in the second group (cheerful film) decreased and showed a significant difference from the first (sad film) and the control groups. The effect of positive emotions on decreasing the effects of negative emotions such as anxiety and thought rumination was also significant.Conclusion: The level and severity of negative emotions can be reduced with the induction of positive emotions.