Genetics of posttraumatic stress disorder

Posttraumatic stress disorder (PTSD) is a prevalent anxiety disorder marked by behavioral, physiologic, and hormonal alterations. PTSD is disabling and commonly follows a chronic course. The etiology of PTSD is unknown, although exposure to a traumatic event constitutes a necessary, but not sufficient, factor. A twin study of Vietnam veterans has shown significant genetic contribution to PTSD. The fact that PTSD's underlying genotypic vulnerability is only expressed following trauma exposure limits the usefulness of family-based linkage approaches. In contrast to the other major psychiatric disorders, large studies for the search of underlying genes have not been described in PTSD to date. Complementary approaches for locating involved genes include association-based studies employing case-control or parental genotypes for transmission dysequilibrium analysis and quantitative trait loci studies in animal models. Identification of susceptibility genes will increase our understanding of traumatic stress disorders and help to elucidate their molecular basis. The current review provides an up-to-date outline of progress in the field of PTSD.     

Regulation of glutamate synapses by nicotinic acetylcholine receptors in auditory cortex

Acetylcholine plays an important role in regulating the processing of sensory stimuli, and understanding its specific cellular actions is critical to understanding how sensory cortex develops and functions in different behavioral states. Here we review recent work on the cellular effects of nicotinic receptor activation in auditory cortex and describe how these actions could affect systems-level auditory function. In particular, we describe a novel function of nicotinic acetylcholine receptors to regulate glutamate synapses containing N-methyl-D-aspartate receptors during early postnatal development. The transient regulation of developing glutamate synapses also defines a window of vulnerability during which exposure to exogenous nicotine disrupts synapse development. Thus, it appears that nicotinic regulation of glutamate synapses is a critical feature of auditory cortex development.     

RETR_PWR: An SAS macro for retrospective statistical power analysis

In contrast to prospective power analysis, retrospective power analysis provides an estimate of the statistical power of a hypothesis test after an investigation has been conducted rather than before. In this article, three approaches to obtaining point estimates of power and an interval estimation algorithm are delineated. Previous research on the bias and sampling error of these estimates is briefly reviewed. Finally, an SAS macro that calculates the point and interval estimates is described. The macro was developed to estimate the power of anF test (obtained from analysis of variance, multiple regression analysis, or any of several multivariate analyses), but it may be easily adapted for use with other statistics, such as chi-square tests ort tests.     

Time scales in motor learning and development

A theoretical framework based on the concepts and tools of nonlinear dynamical systems is advanced to account for both the persistent and transitory changes traditionally shown for the learning and development of motor skills. The multiple time scales of change in task outcome over time are interpreted as originating from the system's trajectory on an evolving attractor landscape. Different bifurcations between attractor organizations and transient phenomena can lead to exponential, power law, or S-shaped learning curves. This unified dynamical account of the functions and time scales in motor learning and development offers several new hypotheses for future research on the nature of change in learning theory.     

Validation of the Japanese version of the NEO Five-Factor Inventory in a large community sample

The NEO Five-Factor Inventory is the shortened version of the Revised NEO Personality Inventory. The aim of this study was to examine the reliability and validity of the Japanese version of the shortened version in the general population of Japan. This version was translated into Japanese and then administered to 2,051 adults in a rural town in Akita Prefecture. A total of 1,664 (81.1%) individuals gave valid answers. Internal reliability, assessed by Cronbach alpha for subscales, ranged from .60 to .77. The scales were only weakly correlated both with each other and with age. In a multiple regression analysis, only the Neuroticism scale score was a significant predictor of scores on the General Health Questionnaire. Factor analysis supported the theoretical structure of personality. Overall, the Japanese version showed good reliability and validity in this sample of the general population of Japan.     

Temporal and spatial characteristics of attention to facilitate manual and eye-movement responses

Previous investigation found that the speed of saccadic eye movements is enhanced when a temporal interval (gap) is introduced between the disappearance of a foveal fixation mark and the appearance of a peripheral target (the gap paradigm). Attention was shown to be involved in the gap paradigm. Here, we investigated relevant temporal and spatial characteristics of attention, manipulating central fixation marks and peripheral targets. Results from three experiments indicate that (i) the speed of manual and eye-movement detection is accelerated when a fixation mark changes abruptly (in less than 100 ms) before its termination in the gap paradigm; (ii) the speed is further accelerated when a peripheral target location is pre-cued; (iii) sufficient time for fixation (1000 ms) is necessary for the facilitation. These results suggest that fast and transient attention at the fixation spot facilitates attentional disengagement process that urges a spatial-orienting mechanism. Sustained attention is required in the engagement process during the fixation.     

Probing memory with conceptual cues at multiple retention intervals: a comparison of forgetting rates on implicit and explicit tests

The time courses for implicit and explicit conceptual tests of memory were compared in two experiments. In Experiment 1, participants encoded target words by judging the apparent pleasantness of their meaning. Immediately thereafter or 48 h later, retrieval cues were presented to different groups of participants for either an implicit or an explicit free-association task. Whereas explicit test performance showed a decline over the 48-h delay, implicit test performance was statistically unaltered. In Experiment 2, memory was tested at five retention intervals, lasting up to 3 weeks. The forgetting functions of both implicit and explicit tests conformed to a logarithmic function. Despite the large conceptual priming effect, which resulted from relational encoding instructions, implicit memory performance still declined at a much slower rate than did performance on the cued-recall test. We argue that because nominal conceptual cues were held constant across the implicit and the explicit conditions, the observed dissociation in performance supports a memory systems approach.     

Retention of relative force in the scaling of a serial force pattern with an attenuated-force tap

The present study was designed to examine the retention of relative force in the scaling of a serial force pattern in a finger-tapping sequence using an attenuated tap. On practice trials, 12 undergraduate students tapped a force plate connected to strain gauges that gave them feedback about the force. On test trials, participants recalled the force pattern (200 gm-200 gm-200 gm-100 gm) and the intertap interval (400 msec.) practiced during the practice period without the feedback (recalled task). Then, they adaptively produced a halved (halved task) or doubled force profile (doubled task) at the fixed intertap interval. Analyses showed that mean peak forces at the first three tap positions of the tapping sequence undershot the expected forces across all tasks. Hence, the ratios of the forces in Serial Positions 1:4, 2:4, and 3:4 were considerably lower than 2.0. This is a contextual effect suggesting that the last attenuated tap affected the first three taps of the tapping sequence. Thus, because the relative force of movements appears to be a weaker invariant feature than sequencing and relative timing for generalized motor program theory of Schmidt and Lee, this finding does not support the relative force for a generalized motor program.     

Disorder in sequential speech perception: a case study on pure word deafness

We described disorders of a patient which were uniquely restricted to speech perception of syllable sequences after brain damage. The results of series of experiments using syllable sequences showed "negative recency effect," in which the subject's repetition performance at the latter syllable position was remarkably poor. Experimental analyses suggested that the "negative recency effect" could be due to dual factors: the lower rate of processing of speech sounds and the memory load of holding processes of preceding syllables imposed on the succeeding phonological processing. The results also suggested that the holding processes which imposed the memory load on the succeeding auditory phonological coding processing were modality nonspecific.