Septal co-infusions of glucose with a GABAB agonist impair memory

Septal infusions of glucose exacerbate memory deficits produced by co-infusions of drugs that increase gamma-aminobutyric acid (GABA)(A) receptor activity. To further understand the interaction between glucose and GABA, this experiment tested whether glucose would also potentiate spatial working memory deficits produced by septal infusions of the GABA(B) receptor agonist baclofen. Fifteen minutes prior to assessing spontaneous alternation (SA), male Sprague-Dawley derived rats were given septal infusions of vehicle, glucose (33 nmol), baclofen (0.1 nmol), or glucose combined with baclofen in one solution. Septal co-infusions of glucose with baclofen, at doses that individually had no effect, significantly impaired SA. Thus, the memory-impairing effects of glucose are observed with either GABA(A) or GABA(B) receptor ligands. This raises the possibility that glucose may impair memory by increasing synaptic levels of GABA and subsequent activation of these different receptor subtypes. These effects of glucose could contribute to the memory-impairing effects of hyperglycemia.     

A typology of motor vehicle consumers using motives for leasing versus financing

• Previous consumer research suggests that individuals who finance high‐cost items tend to differ from those who lease the same items. Some differences are economic, such as income and wealth, while other dissimilarities involve non‐economic issues such as personal preferences. We employ non‐hierarchical cluster analysis to create consumer segments of motor vehicle lessees and financers based on motives for leasing versus financing and demographics. Five segments were uncovered. Lessees predominate in two categories: budget gourmets and automotive hedonists. Another two categories, utility seekers and basic transportation seekers, are mainly comprised of financers. The final group, mature luxury seekers, consists of a roughly equal mix of lessees and financers. Differences between the segments are addressed here, along with a discussion of findings and implications.

Copyright © 2006 John Wiley & Sons, Ltd.     

Further exploration of the Vedic Personality Inventory: validity, reliability and generalizability

The purpose of this study was to explore the validity, reliability, and generalizability of the Vedic Personality Inventory which consists of constructs derived from the Vedic literature of India. There were 57 participants (20 men, 37 women). The mean age was 44.3 yr. (SD= 15.1). The sample was predominantly older, well-educated women who volunteered to participate as respondees to invitations to participate posted in supermarkets, churches, colleges, and on the internet. Analysis yielded statistically significant correlations for scores on the Vedic Personality Inventory and on the Daily Spiritual Experiences Scale and the Brief Symptom Inventory, each of which measures domains of interest addressed by the first inventory.     

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.     

Modeling the antecedents of proactive behavior at work

Using a sample of U.K. wire makers (N = 282), the authors tested a model in which personality and work environment antecedents affect proactive work behavior via cognitive-motivational mechanisms. Self-reported proactive work behaviors (proactive idea implementation and proactive problem solving) were validated against rater assessments for a subsample (n = 60) of wire makers. With the exception of supportive supervision, each antecedent was important, albeit through different processes. Proactive personality was significantly associated with proactive work behavior via role breadth self-efficacy and flexible role orientation, job autonomy was also linked to proactive behavior via these processes, as well as directly; and coworker trust was associated with proactive behavior via flexible role orientation. In further support of the model, the cognitive-motivational processes for proactive work behavior differed from those for the more passive outcome of generalized compliance.     

The relationships between justice perceptions, trust, and employee attitudes in a downsized organization

The authors examined perceptions of distributive justice, procedural justice, trust, organizational commitment, organizational satisfaction, and turnover intentions among survivors in an organization that had recently completed an organizational downsizing. Results suggested that trust partially mediated the relationship between distributive justice and both organizational satisfaction and affective commitment. Additionally, the relationship between procedural justice and turnover intentions was mediated by trust perceptions.     

Modeling human performance in statistical word segmentation

The ability to discover groupings in continuous stimuli on the basis of distributional information is present across species and across perceptual modalities. We investigate the nature of the computations underlying this ability using statistical word segmentation experiments in which we vary the length of sentences, the amount of exposure, and the number of words in the languages being learned. Although the results are intuitive from the perspective of a language learner (longer sentences, less training, and a larger language all make learning more difficult), standard computational proposals fail to capture several of these results. We describe how probabilistic models of segmentation can be modified to take into account some notion of memory or resource limitations in order to provide a closer match to human performance.