Intermanual differences on skilled and unskilled motor tasks in nonlateralized brain dysfunction

Descriptive Halstead-Reitan study of nonimpact mild traumatic brain injury

Patients subjected to severe acceleration forces in motor vehicle accidents that met criteria for uncomplicated mild traumatic brain injury (mTBI) in the absence of direct impact to the head were examined neuropsychologically using the Halstead-Reitan Neuropsychological Test Battery. The subjects were litigants and/or insurance claimants for whom there was psychometric evidence of acceptable test effort. The purpose of the study was to provide descriptive neuropsychological data for this particular clinical population. Individual test results were interpreted using inferential methods of level of performance, pathognomonic signs, score patterns, and right-left performance differences. These interpretive strategies yielded group data from which frequencies and percentages of atypical neuropsychological characteristics were calculated. The most salient clinical characteristics involved atypical right-left performance relationships on simple and more complex tests of motor function. Clinical data provided support for the possibility that a minority of nonimpact litigants or insurance claimants that sustain uncomplicated mTBI experience persistent diminishment in some neuropsychological abilities.

Enhancing Spatial Attention and Working Memory in Younger and Older Adults

Daily experiences demand both focused and broad allocation of attention for us to interact efficiently with our complex environments. Many types of attention have shown age-related decline, although there is also evidence that such deficits may be remediated with cognitive training. However, spatial attention abilities have shown inconsistent age-related differences, and the extent of potential enhancement of these abilities remains unknown. Here, we assessed spatial attention in both healthy younger and older adults and trained this ability in both age groups for 5 hr over the course of 2 weeks using a custom-made, computerized mobile training application. We compared training-related gains on a spatial attention assessment and spatial working memory task to age-matched controls who engaged in expectancy-matched, active placebo computerized training. Age-related declines in spatial attention abilities were observed regardless of task difficulty. Spatial attention training led to improved focused and distributed attention abilities as well as improved spatial working memory in both younger and older participants. No such improvements were observed in either of the age-matched control groups. Note that these findings were not a function of improvements in simple response time, as basic motoric function did not change after training. Furthermore, when using change in simple response time as a covariate, all findings remained significant. These results suggest that spatial attention training can lead to enhancements in spatial working memory regardless of age.

Age-related changes in expectation-based modulation of motion detectability

Expecting motion in some particular direction biases sensitivity to that direction, which speeds detection of motion. However, the neural processes underlying this effect remain underexplored, especially in the context of normal aging. To address this, we examined younger and older adults' performance in a motion detection task. In separate conditions, the probability was either 50% or 100% that a field of dots would move coherently in the direction a participant expected (either vertically or horizontally). Expectation and aging effects were assessed via response times (RT) to detect motion and electroencephalography (EEG). In both age groups, RTs were fastest when motion was similar to the expected direction of motion. RT tuning curves exhibited a characteristic U-shape such that detection time increased with an increasing deviation from the participant's expected direction. Strikingly, EEG results showed an analogous, hyperbolic curve for N1 amplitude, reflecting neural biasing. Though the form of behavioral and EEG curves did not vary with age, older adults displayed a clear decline in the speed of detection and a corresponding reduction in EEG N1 amplitude when horizontal (but not vertical) motion was expected. Our results suggest that expectation-based detection ability varies with age and, for older adults, also with axis of motion.

Regional grey matter shrinks in hypertensive individuals despite successful lowering of blood pressure

Objective

To determine whether reduction in brain grey matter volume associated with hypertension persisted or was remediated among hypertensive patients newly treated over the course of a year.

Methods

Forty-one hypertensive patients were assessed over the course of a one-year successful anti-hypertensive treatment. Brain areas identified previously in cross-sectional studies as differing in volume between hypertensive and normotensive individuals were examined with a semi-automated measurement technique (ALP, automated labeling pathway). Volumes of grey matter regions were computed at baseline and after a year of treatment and compared to archival data from normotensive individuals.

Results

Reductions in regional grey matter volume over the follow-up period were observed despite successful treatment of blood pressure. The comparison group of older, but normotensive individuals showed no significant changes over a year in the regions tested in the treated hypertensive group.

Conclusions

These novel results suggest that essential hypertension is associated with regional grey matter shrinkage and successful reduction of blood pressure may not completely counter that trend.

A new method of administering the Grooved Pegboard Test: Performance as a function of handedness and sex

The purpose of the present study was twofold: first to examine the influences of sex and handedness on manual performance on the Grooved Pegboard Test; and secondly to provide normative data for two versions (Place and Remove tasks) of the Grooved Pegboard Test, as previous work (Bryden & Roy, 1999) had suggested that the Remove task of the Grooved pegboard may provide a purer measure of motor speed of the two hands than the standard administration of the Grooved Pegboard Test. One hundred and fifty-three (47 males and 106 females) participants completed the Grooved Pegboard Test. Individuals performed the standard version of the Grooved Pegboard Test (Place task) and a novel version of the test (Remove task). In the standard version, participants were timed on their speed for placing the pegs, while in the novel version they were timed on their speed for removing the pegs. Results confirmed previously noted hand and sex differences in the Place task of the Grooved Pegboard Test, as well as the lack of effect of handedness on performance (Bornstein, 1995; Ruff & Parker, 1993). Significant performance differences between the hands were also noted for the Remove task. Findings also indicated that the Remove task was sensitive to sex and handedness effects.