Large-scale functional connectivity in associative learning: interrelations of the rat auditory, visual, and limbic systems

Large-scale functional connectivity in associative learning: interrelations of the rat auditory, visual, and limbic systems. J. Neurophysiol. 80: 3148-3162, 1998. Functional relations between specialized parts of the brain may be important determinants of learned behaviors. To study this, we examined the interrelations of the auditory system with several extraauditory structures in two groups of rats having different behavioral histories. Both groups were trained to associate a tone conditional stimulus (CS) with an aversive unconditional stimulus (US). For one group, a light presented with the tone predicted the absence of the US (group TL-). In the other group, the light was a neutral stimulus (group TL0). Fluorodeoxyglucose (FDG) incorporation was measured in the presence of the tone-light compound. Because the tone-light compound was physically identical for both groups, neural differences between groups reflected differences in the learned associative properties of the stimuli. Covariances of FDG uptake in the auditory system and extraauditory structures were examined using partial least squares. Three strong covariance or functional connectivity patterns were identified. The first pattern mainly reflected similarities between groups, with strong interrelations between the subcortical auditory system and the thalamocortical visual system, cerebellum, deep cerebellar nuclei, and midline thalamus. This pattern of interactions may represent part of a common circuit for relaying the associative value of the tone CS to the cerebellum and the midline thalamus. The external nucleus of the inferior colliculus and medial division of the medial geniculate nucleus were associated more strongly with this pattern for group TL-, which was interpreted as representing the change of the associative value of the tone by the light, mediated through extraauditory influences on these two regions. A second pattern involved midbrain auditory regions, superior colliculus, zona incerta, and subiculum and was stronger for group TL0. The relations between midbrain structures may represent the excitatory conditioned response (CR) evoked by the tone in this group. The final pattern was strongest in group TL- and involved interrelations of the thalamocortical auditory system with hippocampus, basolateral amygdala, and hypothalamus. This pattern may represent the learned inhibition of the CR to the tone in the presence of the light. These findings are consistent with behavioral studies suggesting that at least two types of associations are formed during associative learning. One is the sensory relation of the stimuli and another is the relation between the CS and the affective components of the US. These behavioral associations are mapped to the patterns of functional connectivity between auditory and extraauditory regions.     

Childhood cancer incidence and trends in Minnesota, 1988-1994

Childhood cancer incidence patterns for Minnesota, obtained from the Minnesota Cancer Surveillance System, were compared with national rates as well as with historic data from eight Minnesota counties. In total, 1,140 neoplasms were diagnosed in children (ages 0 to 14) between 1988 and 1994. Leukemias were the most common diagnosis for boys (30.3%) and girls (29.6%), followed by central nervous system tumors. The average annual age-adjusted incidence rates for all cancer sites were 167.2 and 136.2 per million for boys and girls, respectively. These rates were somewhat higher than national rates. In particular, the incidence rate for astrocytoma in boys was significantly elevated. Childhood cancer incidence, particularly brain tumors, has increased in the eight-county region from 1969 to 1994. This analysis demonstrated the Minnesota's childhood cancer incidence patterns are similar to national patterns.     

Mortality in a cohort of men expressing the glucose-6-phosphate dehydrogenase deficiency

The objective of this study was to test the hypothesis of a lower mortality from cancer and cardiovascular diseases among men expressing glucose-6-phosphate dehydrogenase (G6PD) deficiency. We designed a mortality study based on death certificates from January 1, 1982 through December 31, 1992 in a cohort of G6PD-deficient men. Cohort members were 1,756 men, identified as expressing the G6PD-deficient phenotype during a 1981 population screening of the G6PD polymorphism. The setting was the island of Sardinia, Italy. Outcome measures were cause-specific standardized mortality ratios (SMRs), which were computed as 100 times the observed/expected ratio, with the general Sardinian male population as the reference. Deaths from all causes were significantly less than expected due to decreased SMRs for ischemic heart disease (SMR, 28; 95% confidence interval [CI], 10 to 62), cerebrovascular disease (SMR, 22; 95% CI, 6 to 55), and liver cirrhosis (SMR, 12; 95% CI, 0 to 66), which explained 95.6% of the deficit in total mortality. All cancer mortality was close to the expectation, with a significant increase in the SMR for non-Hodgkin's lymphoma (SMR, 545; 95% CI, 147 to 1,395). A decrease in mortality from cardiovascular diseases was one of the study hypotheses, based on an earlier human report and experimental evidence. However, selection bias is also a likely explanation. Further analytic studies are warranted to confirm whether subjects expressing the G6PD-deficient phenotype are protected against ischemic heart disease and cerebrovascular disease. This cohort study is consistent with more recent case-control studies in rejecting the hypothesis of a decreased cancer risk among G6PD-deficient subjects. The observed increase in mortality from non-Hodgkin's lymphoma and decrease in mortality from liver cirrhosis were not previously reported.     

Expression screening of a yeast artificial chromosome contig refines the location of the mouse H3a minor histocompatibility antigen gene

The H3 complex, on mouse Chromosome 2, is an important model locus for understanding mechanisms underlying non-self Ag recognition during tissue transplantation rejection between MHC-matched mouse strains. H3a is a minor histocompatibility Ag gene, located within H3, that encodes a polymorphic peptide alloantigen recognized by cytolytic T cells. Other genes within the complex include beta2-microglobulin and H3b. A yeast artificial chromosome (YAC) contig is described that spans the interval between D2Mit444 and D2Mit17, a region known to contain H3a. This contig refines the position of many genes and anonymous loci. In addition, 23 new sequence-tagged sites are described that further increase the genetic resolution surrounding H3a. A novel assay was developed to determine the location of H3a within the contig. Representative YACs were modified by retrofitting with a mammalian selectable marker, and then introduced by spheroplast fusion into mouse L cells. YAC-containing L cells were screened for the expression of the YAC-encoded H3a(a) Ag by using them as targets in a cell-mediated lympholysis assay with H3a(a)-specific CTLs. A single YAC carrying H3a was identified. Based on the location of this YAC within the contig, many candidate genes can be eliminated. The data position H3a between Tyro3 and Epb4.2, in close proximity to Capn3. These studies illustrate how genetic and genomic information can be exploited toward identifying genes encoding not only histocompatibility Ags, but also any autoantigen recognized by T cells.     

Space charge analysis in doped zinc phthalocyanine thin films

We present an improved method for the determination of the space charge density in organic semiconductors used as active layers in Schottky barriers. These measurements provide a powerful tool for the interpretation of basic properties such as the rectifying effect, doping process and carrier trapping mechanisms of films together with a way to assess the potential for sensor applications. Metal/molecular semiconductor Schottky junctions were prepared on zinc phthalocyanine layers doped by a controlled exposure to the ambient air. The organic material is deposited on aluminium or heavily doped silicon substrates, in order to make a Schottky barrier (film thickness around 1 μm). An ohmic contact is obtained by a gold deposition on the strongly doped side of the molecular material. We have investigated the current-voltage and capacitance-voltage characteristics. The results are interpreted in terms of a space charge region at the interface with the substrate, followed by an extended semi-insulating layer.The contribution of these two regions to the total impedance is analyzed in well improved conditions of measurements.     

Red nucleus stimulation inhibits within the inferior olive

Red nucleus stimulation inhibits within the inferior olive. J. Neurophysiol. 80: 3127-3136, 1998. In the anesthetized cat, electrical stimulation of the magnocellular red nucleus (RNm) inhibits responses of rostral dorsal accessory olive (rDAO) neurons to cutaneous stimulation. We tested the hypothesis that RNm-mediated inhibition occurs within the inferior olive by using stimulation of the ventral funiculus (VF) of the spinal cord in place of cutaneous stimulation of the hindlimb. Fibers in the VF terminate on hindlimb rDAO neurons, so inhibition of this input would have to occur within the olive. rDAO responses elicited by VF stimulation were inhibited by prior stimulation of the RNm, indicating that inhibition occurs within the olive. In contrast, evoked potentials recorded from the VF or dorsal columns following hindlimb stimulation were not affected by prior stimulation of RNm, indicating that stimulation of the RNm does not inhibit olivary afferents at spinal levels. RNm stimulation that inhibited rDAO responses had little effect on evoked somatosensory responses in thalamus, indicating that inhibition generated by activity in RNm may be specific to rDAO. To test limb specificity of RNm-mediated inhibition, conditioning stimulation was applied to the dorsolateral funiculus at thoracic levels, which selectively activates RNm neurons projecting to the lumbar cord. Stimulation at thoracic levels inhibited evoked responses from hindlimb but not forelimb regions of rDAO, suggesting that inhibitory effects of RNm activity are limb specific. Several studies have reported that olivary neurons have reduced sensitivity to peripheral stimulation during movement; it is likely that RNm-mediated inhibition occurring within the olive contributes to this reduction of sensitivity. Inhibition of rDAO responses by descending motor pathways appears to be a salient feature of olivary function.     

Gastrointestinal tract symptoms and self-reported abuse: a population-based study

BACKGROUND/AIMS: A link between abuse and irritable bowel syndrome (IBS) has been reported in outpatients but remains controversial. No population-based studies have investigated this issue. The aim of this study was to determine the prevalence of abuse and its association with symptoms in a representative community sample. METHODS: An age- and sex-stratified random sample of residents of Olmsted County, Minnesota ranging in age from 30 to 49 years was mailed a valid self-report symptom questionnaire. Abuse was assessed by standard published criteria. RESULTS: Of the 919 responders (74%), the age-adjusted prevalence of any abuse was 41% in women and 11% in men, resulting in an age- and sex-adjusted prevalence of 26%. Symptoms of IBS, dyspepsia, and frequent heartburn were reported by 14%, 23%, and 12%, respectively. There was a significant association between IBS and sexual abuse, emotional or verbal abuse, and abuse in childhood and adulthood. Similarly, dyspepsia and heartburn were both significantly associated with abuse. In the population, 31% had visited a physician for gastrointestinal symptoms; the odds of visiting a physician were highest in those reporting abuse in adulthood and childhood. CONCLUSIONS: Self-reported abuse is common in middle-aged subjects; those who report abuse are more likely to have symptoms consistent with IBS, dyspepsia, or heartburn and to visit a physician for bowel symptoms.     

Standing up to the big squeeze

Consumer confidence is at its lowest ebb since 1980. Economic growth is at a standstill & unemployment & inflation are both rising. Here's a front-line report from more than three dozen operators who are fending off the recession's dual pressures of slow sales & rising costs. They are using discount pricing, partnering with vendors, setting pay for performance standards & a variety of other recession-beating practices.     

Psychometric Evaluation of the EMO and the SUS in the Context of a Large-Sample Unmoderated Usability Study

This article describes the psychometric properties of the Emotional Metric Outcomes (EMO) questionnaire and the System Usability Scale (SUS) using data collected as part of a large-sample unmoderated usability study (n = 471). The EMO is a concise multifactor standardized questionnaire that provides an assessment of transaction-driven personal and relationship emotional outcomes, both positive and negative. The SUS is a well-known standardized usability questionnaire designed to assess perceived usability. In previous research, psychometric evaluation using data from a series of online surveys showed that the EMO and its component scales had high reliability and concurrent validity with loyalty and overall experience metrics but did not find the expected four-factor structure. Previous structural analyses of the SUS have had mixed results. Analysis of the EMO data from the usability study revealed the expected four-factor structure. The factor structure of the SUS appeared to be driven by item tone. The estimated reliability of the SUS (.90) was consistent with previous estimates. The EMO and its subscales were also quite reliable, with the estimates of reliability for the various EMO scales ranging from .86 to .96. Regression analysis using SUS, EMO, and Effort as predictors revealed different key drivers for the outcome metrics of Satisfaction and Likelihood-to-Recommend. The key recommendations are to include the EMO as part of the battery of poststudy standardized questionnaires, along with the SUS (or similar questionnaire), but to be cautious in reporting SUS subscales such as Usable and Learnable.