Differential Effect of TEA on Long-Term Synaptic Modification in Hippocampal CA1 and Dentate Gyrus in vitro

The effectiveness of tetraethylammonium (TEA) and high-frequency stimulation (HFS) in inducing long-term synaptic modification is compared in CA1 and dentate gyrus (DG) in vitro. High-frequency stimulation induces long-term potentiation (LTP) at synapses of both perforant path-DG granule cell and Schaffer collateral-CA1 pyramidal cell pathways. By contrast, TEA (25 mM) induces long-term depression in DG while inducing LTP in CA1. The mechanisms underlying the differential effect of TEA in CA1 and DG were investigated. It was observed that T-type voltage-dependent calcium channel (VDCC) blocker, Ni²⁺ (50 μM), partially blocked TEA-induced LTP in CA1. A complete blockade of the TEA-induced LTP occurred when Ni²⁺ was applied together with the NMDA receptor antagonist, D-APV. The L-type VDCC blocker, nifidipine (20 μM), had no effect on CA1 TEA-induced LTP. In DG of the same slice, TEA actually induced long-term depression (LTD) instead of LTP, an effect that was blocked by D-APV. Neither T-type nor L-type VDCC blockade could prevent this LTD. When the calcium concentration in the perfusion medium was increased, TEA induced a weak LTP in DG that was blocked by Ni²⁺. During exposure to TEA, the magnitude of field EPSPs was increased in both CA1 and DG, but the increase was substantially greater in CA1. Tetraethylammonium application also was associated with a large, late EPSP component in CA1 that persisted even after severing the connections between CA3 and CA1. All of the TEA effects in CA1, however, were dramatically reduced by Ni²⁺. The results of this study indicate that TEA indirectly acts via both T-type VDCCs and NMDA receptors in CA1 and, as a consequence, induces LTP. By contrast, TEA indirectly acts via only NMDA receptors in DG and results in LTD. The results raise the possibility of a major synaptic difference in the density and/or distribution of T-type VDCCs and NMDA receptors in CA1 and DG of the rat hippocampus.     

Reading in Colors: Highlighting for Active Reading in Religious Studies

This note from the classroom suggests that multicolor highlighting is a useful study technique for religious studies students. The note first reviews the literature regarding the effectiveness of traditional highlighting, then discusses advantages of the modified technique. Monochrome highlighting works only if readers select text through a discriminating reading process. Reading in colors fosters this sort of active reading. It prompts readers to ask how and why a given term, phrase or passage is important. This technique can help students grasp the basic categories and concepts of the discipline and it can embody course requirements or learning outcomes. The note concludes with practical suggestions for using the technique in the classroom.     

Quantitative depictions of threatening phenomena in news reports. The scary world of frequency data

Two experiments addressed the question of whether news reports depicting base‐rate data indicative of increasing population size over time would assuage the apprehension and victimization risk associated with another news story depicting frequency increases in a threatening phenomenon during the same time period. Men exposed to the population data manifested lower levels of apprehension and victimization risk than men not exposed to such data, but women showed no reduction in either apprehension and victimization risk than men not exposed to such data, but women showed no reduction in either apprehension or victimization risk after exposure to population data. This interaction was replicated in both experiments. Experiment 2 demonstrated that the same interaction can be produced using base‐rate data other than that depicting population increases over time and that the effects of the base‐rate stories are not merely a product of distraction from the threatening story. Differences in apprehension levels, information processing styles, mathematical problems solving skill, and sex role response sets were considered as alternative explanations for the interaction.     

The effect of guiding questions on students’ performance and attitude towards statistics

Background. In this study, the effect of guidance on students’ performance was investigated. This effect was hypothesized to be manifested through a reduction of cognitive load and enhancement of self‐explanations. Aim. The goal of this study was to investigate the effect of guiding questions on students’ understanding of statistics. Sample and Method. In an experimental setting, two randomly selected groups of students (N= 49) answered achievement and transfer questions on statistics as a measure of performance. Students in the intervention condition were given guiding questions to direct their way of reasoning before they answered the achievement questions. The students in the control condition were asked to write down their way of thinking before they answered the same achievement questions. In this way, both groups were stimulated to self‐explain, but only the reasoning processes of the students in the intervention condition were guided. Results and Conclusion. It was found that students in the intervention condition performed significantly better on achievement and transfer questions and that this effect of guidance was mediated by self‐explanations. Attitude towards statistics was positively related to performance.     

Radiation damage in TiOx at high current density

Abstract

Observations of beam damage under high-current-density irradiation in three forms of titanium oxide are presented. The three forms: TiO₂, Ti₂O₃ and TiO, have widely differing electrical conductivities but all appear to be damaged by the same mechanisms. The results are discussed in terms of a previously reported model which suggested that only ionic insulators should be susceptible to this type of damage.     

The Evil Eye: A Cautious Look

This article analyzes the superstition of the evil eye from a psychosocial perspective. The commonly employed antidotes to the evil eye are discussed. These include knock on wood, kenehora, and various other culturally prescribed protective measures. The sin of envy, the role of God, Scripture, and Satan are examined. The author concludes with a statement of his own way of dealing with the evil eye and its underlying essence.     

Repression versus sensitization in response to media violence as predictors of cognitive avoidance and vigilance

Repression and sensitization as situational modes of coping with anxiety were examined as predictors of trait measures of cognitive avoidance and vigilance. In this study, 303 undergraduates saw a violent film clip to elicit anxiety. Increases in skin conductance level (SCL) and state anxiety (STA) from baseline were measured to identify repressors (high SCL, low STA) and contrast them with sensitizers (low SCL, high STA) and genuinely low anxious individuals (low SCL, low STA). State anger was also recorded. Trait measures of vigilance and cognitive avoidance were collected 2 weeks earlier. Significant SCL × STA interactions indicated that repressors scored higher on cognitive avoidance and lower on vigilance compared to sensitizers and low anxious participants. Repressors were less likely than sensitizers to report gaze avoidance during the clip. The anger by SCL interaction was nonsignificant, suggesting that repressors and sensitizers differ specifically in the processing of anxiety rather than negative affect in general.     

Sub-centimeter language organization in the human temporal lobe

The human temporal lobe is well known to be critical for language comprehension. Previous physiological research has focused mainly on non-invasive neuroimaging and electrophysiological techniques with each approach requiring averaging across many trials and subjects. The results of these studies have implicated extended anatomical regions in peri-sylvian cortex in speech perception. These non-invasive studies typically report a spatially homogenous functional pattern of activity across several centimeters of cortex. We examined the spatiotemporal dynamics of word processing using electrophysiological signals acquired from high-density electrode arrays (4 mm spacing) placed directly on the human temporal lobe. Electrocorticographic (ECoG) activity revealed a rich mosaic of language activity, which was functionally distinct at four mm separation. Cortical sites responding specifically to word and not phoneme stimuli were surrounded by sites that responded to both words and phonemes. Other sub-regions of the temporal lobe responded robustly to self-produced speech and minimally to external stimuli while surrounding sites at 4 mm distance exhibited an inverse pattern of activation. These data provide evidence for temporal lobe specificity to words as well as self-produced speech. Furthermore, the results provide evidence that cortical processing in the temporal lobe is not spatially homogenous over centimeters of cortex. Rather, language processing is supported by independent and spatially distinct functional sub-regions of cortex at a resolution of at least 4 mm.