Division of the corpus callosum into subregions

Various attempts have been made to subdivide the corpus callosum (CC) into anatomically and functionally distinct subareas. A promising current approach is the use of factor analytic techniques in conjunction with traced MRI images. The traced images are divided into 99 percentile slices, where the widths of the percentile slices are used as variables that are entered into the analysis (Denenberg, Kertesz & Cowell, 1991). Studies that use this technique agree broadly between 6 and 7 factors, but available factor solutions contain inconsistencies and large gaps, which arise when many of the percentile slices do not load appreciably on any of the factors. The present study uses a larger number of brains (N = 184), all normalized, and some methodological refinements in the analysis of the traced MRI images of the CC. A stable 7 factor solution was found, and the factor structure for males and females was very similar.     

Purkinje cell activity in the cerebellar anterior lobe after rabbit eyeblink conditioning

The cerebellar anterior lobe may play a critical role in the execution and proper timing of learned responses. The current study was designed to monitor Purkinje cell activity in the rabbit cerebellar anterior lobe after eyeblink conditioning, and to assess whether Purkinje cells in recording locations may project to the interpositus nucleus. Rabbits were trained in an interstimulus interval discrimination procedure in which one tone signaled a 250-msec conditioned stimulus-unconditioned stimulus (CS-US) interval and a second tone signaled a 750-msec CS-US interval. All rabbits showed conditioned responses to each CS with mean onset and peak latencies that coincided with the CS-US interval. Many anterior lobe Purkinje cells showed significant learning-related activity after eyeblink conditioning to one or both of the CSs. More Purkinje cells responded with inhibition than with excitation to CS presentation. In addition, when the firing patterns of all conditioning-related Purkinje cells were pooled, it appeared that the population showed a pattern of excitation followed by inhibition during the CS-US interval. Using cholera toxin-conjugated horseradish peroxidase, Purkinje cells in recording areas were found to project to the interpositus nucleus. These data support previous studies that have suggested a role for the anterior cerebellar cortex in eyeblink conditioning as well as models of cerebellar-mediated CR timing that postulate that Purkinje cell activity inhibits conditioned response (CR) generation during the early portion of a trial by inhibiting the deep cerebellar nuclei and permits CR generation during the later portion of a trial through disinhibition of the cerebellar nuclei.     

My Disaster Recovery: a pilot randomized controlled trial of an Internet intervention

Abstract

This pilot study tested the efficacy of the My Disaster Recovery (MDR) website to decrease negative affect and increase coping self-efficacy. Fifty-six survivors of Hurricane Ike were recruited from a larger study being conducted at the University of Texas Medical Branch at the first anniversary of the storm. Restricted randomization was used to assign participants to the MDR website, an information-only website, or a usual care condition. Group×time interactions indicated that MDR reduced participant worry more than the other conditions. A similar trend was also identified for depression. Both websites were accessed a small to moderate amount and participants reported mixed satisfaction for both websites. Although the effect sizes for worry and depression were in the moderate to large range, small sample size and timing of the intervention qualify the findings. These preliminary findings encourage further evaluation of MDR with a larger, demographically diverse sample and indicate that the MDR website might be helpful in reducing worry and depression.     

The design and operation of an improved olfactometer for behavioral and physiological investigation1

An improved olfactometer is described, and its range of application for the study of the olfaction in man is discussed. The apparatus is based on air dilution; an odorant is diluted in a constant-flowing stream of air. The odor-containing air flows to S, who is seated in an enclosed partition with his head in a Plexiglas hood. A visual signal system allows communication between E and S. Precision flowmeters, solenoid valves, one-way floats, and an automated control system permit E to select rapidly a large range of stimuli, stimulus concentrations, and trial lengths. The apparatus has been used in a variety of situations ranging from absolute threshold detection to adaptation and recovery.     

Impression mismanagement: People as inept self‐presenters

People routinely manage the impressions they make on others, attempting to project a favorable self‐image. The bulk of the literature has portrayed people as savvy self‐presenters who typically succeed at conveying a desired impression. When people fail at making a favorable impression, such as when they come across as braggers, regulatory resource depletion is to blame. Recent research, however, has identified antecedents and strategies that foster systematic impression management failures (independently of regulatory resource depletion), suggesting that self‐presenters are far from savvy. In fact, they commonly mismanage their impressions without recognizing it. We review failed perspective taking and narcissism as two prominent antecedents of impression mismanagement. Further, we argue that failed perspective taking, exacerbated by narcissism, contributes to suboptimal impression management strategies, such as hubris, humblebragging, hypocrisy, and backhanded compliments. We conclude by discussing how self‐presenters might overcome some of the common traps of impression mismanagement.     

Effects of emotional valence and arousal manipulation on eyeblink classical conditioning and autonomic measures

Using a classical eyeblink conditioning paradigm, we have previously shown that the rate of acquisition of a conditioned response may be manipulated by engaging subjects in background tasks of varying complexity concurrent to conditioning. To further examine the influence of the background environment on conditioning, a picture set designed to elicit emotional responses, the International Affective Picture System (IAPS), was presented to subjects during classical eyeblink conditioning. The results suggest that eyeblink conditioning does appear to be sensitive to contextual manipulations of arousal. Pictures rated as very arousing were found to engage subjects enough to enhance learning, although not to the point that autonomic functions were significantly altered between picture groups. We suggest that group differences in learning may be a result of either novelty of, or vigilance to, interesting pictures rather than as a direct result of physiological arousal.     

Heart Rate Reactivity in HAD and LAD Rats during Pavlovian Fear Conditioning

Recently, we reported that High-Alcohol-Drinking (HAD) rats exhibited selective deficits in active avoidance learning under alcohol-naive conditions, and that administration of moderate doses of alcohol (0.5 and 1.0 g/kg) facilitated learning in these rats (Blankenship et al., 2000; Rorick et al., 2003b). We hypothesized that the deficits resulted from excessive fear in the aversive learning context and that the anxiolytic properties of alcohol may have contributed to the improved learning that was observed after alcohol administration. This hypothesis was supported by a recent study in which prolonged freezing in HAD rats was seen after a classical fear conditioning procedure (Rorick et al., 2003a). To provide additional evidence that HAD rats indeed exhibit behaviors consistent with the expression of increased fear in aversive learning contexts, we employed a Pavlovian fear conditioning task to measure heart rate in HAD and Low-Alcohol-Drinking (LAD) rats. In this study, HAD (HAD-1 and HAD-2) and LAD (LAD-1 and LAD-2) rats were assigned to one of three pre-exposure conditions: Context Only, Context/Tone, or Sequential (Context Only followed by Context/Tone) Pre-Exposure. Following pre-exposure, fear conditioning acquisition and extinction procedures were identical for all groups. Results indicated that although no baseline differences were observed between HAD and LAD rats, HAD rats receiving Context-Only pre-exposure exhibited excessive heart rate reactivity to the tone conditional stimulus during fear conditioning acquisition, compared to LAD rats receiving the same pre-exposure conditions. These findings support the hypothesis that HAD rats exhibit behaviors consistent with increased fear in aversive learning contexts, as measured by autonomic conditioning.     

Retention and extinction of delay eyeblink conditioning are modulated by central cannabinoids

Rats administered the cannabinoid agonist WIN55,212-2 or the antagonist SR141716A exhibit marked deficits during acquisition of delay eyeblink conditioning, as noted by Steinmetz and Freeman in an earlier study. However, the effects of these drugs on retention and extinction of eyeblink conditioning have not been assessed. The present study examined the effects of WIN55,212-2 and SR141716A on retention and extinction of delay eyeblink conditioning in rats. Rats were given acquisition training for five daily sessions followed by one session of retention training with subcutaneous administration of 3 mg/kg of WIN55,212-2 or 5 mg/kg of SR141716A and an additional session with the vehicle. Two sessions of extinction training were then given with WIN55,212-2, SR141716A, or vehicle. Retention and extinction were impaired by WIN55,212-2, whereas SR141716A produced no deficits. The extinction deficit in rats given WIN55,212-2 was observed only during the first session, suggesting a specific impairment in short-term plasticity mechanisms. The current results and previous findings indicate that the cannabinoid system modulates cerebellar contributions to acquisition, retention, and extinction of eyeblink conditioning.