Testosterone influences volitional, but not reflexive orienting of attention in human males.

The impact of testosterone (T) on the exogenous (Experiment 1) and endogenous (Experiment 2) orienting of visual attention in males was examined. Sixteen male participants completed both an exogenous and an endogenous cuing task on two separate days. About 2-3h prior to testing, either a placebo or a dose of T was administered. The inhibition of return (IOR) phenomenon was observed during the exogenous cuing task, but IOR was not influenced by T. During the endogenous task, participants demonstrated the expected cuing effects on both days. However, longer reaction time to invalid target locations was observed following T-administration. The manipulation of T-levels in males provides converging evidence of dissociation between reflexive and volitional orienting of attention.

Effect of Low Frequency Neuromuscular Electrical Stimulation on Glucose Profile of Persons with Type 2 Diabetes: A Pilot Study.

The purpose of this study was to examine the effect of low-frequency neuromuscular electrical stimulation (NMES) on glucose profile in persons with type 2 diabetes mellitus (T2DM). Eight persons with T2DM (41 to 65 years) completed a glucose tolerance test with and without NMES delivered to the knee extensors for a 1-hour period at 8 Hz. Three blood samples were collected: at rest, and then 60 and 120 minutes after consumption of a glucose load on the NMES and control days. In NMES groups glucose concentrations were significantly lower (P<0.01) than in the control conditions. Moreover, a significant positive correlation (r=0.9, P<0.01) was obtained between the intensity of stimulation and changes in blood glucose. Our results suggest that low-frequency stimulation seem suitable to induce enhance glucose uptake in persons with T2DM. Moreover, the intensity of stimulation reflecting the motor contraction should be considered during NMES procedure.

Evaluation of a 10-minute version of the Attention Network Test.

The widely used Java version of the Attention Network Test (ANT), which can be downloaded from https://www.sacklerinstitute.org/cornell/assays_and_tools/ , takes approximately 20 minutes to complete. A shorter version would be useful in clinical or applied research settings where many tests are administered. We assessed how well a new 10-minute version of the ANT agrees with the 20-minute version. Response time (RT) measures from the shorter version correlated very highly with the corresponding measures from the 20-minute version (Pearson correlations ranging from .88 to .92). Therefore RT measures from the shorter version can safely be used in place of those same measures from the 20-minute version. Correlations for the three network scores (alerting, orienting and conflict efficiency) were not as strong (range = .10 to .53). This is not surprising, given that the network scores are difference scores. Further research is needed to determine whether adequate reliability can be achieved for the network scores without unduly increasing the length of the task.

Body position differentially influences responses to exogenous and endogenous cues.

The influence of vestibular inputs on exogenous (Exp. 1) and endogenous (Exp. 2) orienting of visual attention was examined. The vestibular system was manipulated through a change in static body position. Participants engaged in an exogenous or endogenous response task while in a seated position, while lying in a prone position, and while in a prone position with their head down and neck flexed (HDNF). An attenuation of inhibition and facilitation effects during the exogenous task was observed in the HDNF position. However, responses to the cues remained similar in the endogenous task, irrespective of body position. The results reveal a potential dissociation between reflexive and volitional orienting of visual attention that is dependent on vestibular inputs.

Sports-related mild traumatic brain injury in female youths.

Sports-related concussion or mild-traumatic brain injury (mTBI) is common in children who participate in organised sports. We describe two case studies involving 14-year-old girls who each sustained a mTBI during ice hockey competition. Neurocognitive functioning post-injury is compared to baseline pre-injury assessment on the same measures. Results from Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT), Conners' Continuous Performance Test II (CPT-II) and the Attention Network Test (ANT) revealed decreased performance in attention, memory functioning and reaction time. Furthermore, some measures had not returned to baseline at midseason testing sessions approximately 30-40 days post-injury. The results are discussed with respect to the difference in recovery profiles and the need for thorough and ongoing evaluation following mTBI in the paediatric population, and for girls in particular.

Using the Attention Network Test to predict driving test scores.

Driving is a complex multi-factorial task that taps underlying mechanisms of cognition and attention. Not surprisingly, therefore, many tests of cognition and attention are significantly associated with driving outcomes. In this article, we introduce driving researchers and clinicians with an interest in driving to the Attention Network Test (ANT), which to our knowledge has not previously been used in driving research. It is a recently developed test that is based on a neural network model of the human attention system. It combines elements of Posner's cuing paradigm [Posner, M.I., 1980. Orienting of attention. Quarterly Journal of Experimental Psychology 32, 3-25.] with the Eriksen & Eriksen flanker task [Eriksen, B.A., Eriksen, C.W., 1974. Effects of noise letters upon the identification of a target letter in a nonsearch task. Perception & Psychophysics 16, 143-149.], and provides measures of three distinct functions of attention: alerting, orienting, and executive function. Our results demonstrate that the ANT has very good concurrent validity with the Useful Field of View (UFOV), and that it is comparable to UFOV in its ability to predict road test scores for a simulated drive. These findings suggest that further investigation of the usefulness of the ANT as a tool for driving researchers and clinicians is merited.

Paediatric sports-related mild traumatic brain injury.

Mild traumatic brain injury (mTBI) is a common but relatively understudied childhood injury that can impact cognitive functioning and development. The present report describes a case study of a 14-year-old boy who sustained two consecutive sports-related mTBIs within a 24 h period. Neurocognitive functioning at 2, 6, 8, 55 and 225 days after injury is compared to baseline prior to injury assessment on the same measures. Results from Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT), Conner Continuous Performance Test 2 (CPT-II) and the Attention Network Test (ANT) revealed decreased performance in attention, visual memory functioning and impulsivity, with some measures still not returning to baseline at 225 days post injury. The results are discussed with respect to return to normal activities at 4 days post injury. This case study highlights the need for increased research regarding the clinical management of mTBI in the paediatric population, particularly the potential deleterious effects of cumulative injuries.

Starting with the "right" foot minimizes sprint start time.

Although asymmetries in hand and foot performance have been examined using a variety of movement tasks that require the fine control of the timing and amplitude of force generation, foot asymmetries in a functional gross motor movement task, such as the track and field sprint start, have yet to be examined. Twenty individuals (10 experienced, 10 inexperienced) were assessed for pedal asymmetries using the track and field sprint start. Each participant performed 48 starts (24 right foot starts and 24 left foot starts). The pattern of pedal asymmetries was consistent with that of manual asymmetries in that a left foot (i.e., left foot in rear position) reaction time advantage was found while there was a right foot (i.e., right foot in rear position) advantage for movement time and total response time (time from stimulus presentation until the end of the movement). These results are consistent with a right hemisphere specialization for spatio-temporal and attentional processes, and a left hemisphere specialization for movement execution.

Object- and location-based inhibition of return in younger and older adults.

When a cued object moves to new spatial coordinates, inhibition of return (IOR) with younger adults is found at the original cued location (location-based IOR) and at the current location of the object (object-based IOR). Older adults, however, show only location-based IOR. To determine whether this pattern of results represents a general age-related deficit in object-based IOR, the authors used static displays in which the placeholders (i.e., objects) were either present (location-based IOR+object-based IOR) or absent (location-based IOR only). Both age groups showed location-based IOR, but the older adults failed to show object-based IOR, consistent with age-related differences in visual pathways.

Visual attention and older drivers: the contribution of inhibition of return to safe driving.

Increasing data suggest that visual attention may be impaired in some older drivers, and that such impairment may be related to poorer driving abilities and a higher crash risk. Because effective scanning of the environment is important for safe driving, the authors sought to examine the relationship between a reflexive visual attention mechanism and driving. To examine this issue the authors conducted a preliminary study using the inhibition of return (IOR) paradigm, which has been labeled as a fundamental search mechanism. Forty-one drivers aged 55 and over completed two on-road driving evaluations and IOR testing. After accounting for the contribution of age, IOR statistically predicted overall driving evaluation scores (p = .045), and the number of errors in scanning the environment (p = .031). To the authors' knowledge these findings represent the first documentation of a relationship between IOR and driving. The results are informative regarding the importance of reflexive visual attention mechanisms towards safe driving.

The role of temporal and spatial factors in the covert orienting of visual attention tasks.

There is a biphasic pattern in response times to peripheral uninformative cues, with faster responses to targets in cued locations when the stimulus onset asynchrony (SOA) is under 300 ms and slower responses when it is over 300 ms. The effect has typically been attributed entirely to the SOA while ignoring other aspects of the cues (duration, spatial configuration). To examine these other factors, along with SOA, the present experiments included manipulations of SOA (50, 100, 200, 400, 800 ms), inter-stimulus interval (ISI; 0, 50, 100, 150, 200, 300, 350, 400, 500, 600, 700, and 750 ms), and whether or not the cue and target overlap in the same space. The results indicate that cueing effects depend on the combination of cue duration, ISI, SOA, and the spatial configuration of the cues and targets. Three factors are used to explain these time course results.

Differences in attentional set between athletes and nonathletes.

The purpose of this study was to determine if the ability to set attention is different between athletes and nonathletes. University volleyball players were compared with nonathletes on a spatial cuing task similar to that of C. L. Folk, R. W. Remington, and J. C. Johnston (1992). As expected, both groups showed evidence of entering into a specific attentional set because attentional cuing effects were found only when cues and targets shared a task-relevant feature (onset or color). In addition, the cuing effects when the cues matched the targets were greater for the athletes than for the nonathletes. The results are discussed in terms of the orienting of attention and athletic performance.

Variability within individuals of plasma ionic magnesium concentrations.

BACKGROUND: With the invention of the ion-selective electrode (ISE), ionic magnesium (iMg) is a common blood assay. This could be advantageous, as iMg is the biologically active form of Mg. There is some evidence that iMg has considerable within subject variability. RESULTS: Individual ranges averaged.08 mmol/L (range.05 to.14). Coefficients of variation (CV) ranged from 3% to 7% (mean 4%) while analytical variation was determined to be 2.3%. Biological variability thus accounts for almost half of the variability, which is clinically significant, as 9 of the 13 subjects recorded at least one value below a reference range of.46 -.60 mmol/L. A significant within-day variation (p <.001) was noted, with differences between 7:00 and 10:00 as well as 10:00 and 22:00. Between day variations were not significant (p =.56). CONCLUSIONS: A plausible explanation of this data is that iMg has a circadian rhythm. Thus, cautious interpretation of single iMg values is warranted until future research determines the nature of iMg variability.

Determining whether attentional control settings are inclusive or exclusive.

The aim of the present study was to determine whether attentional control settings operate with an inclusive rule (orient attention to stimuli that share a task-relevant feature with the target) or an exclusive rule (do not orient attention to stimuli that do not share a task-relevant feature with the target). All three experiments used a variation of the Folk and Remington (e.g., Folk, Remington, & Johnston, 1992) paradigm. In Experiment 1, cuing effects were found for combination cues (cues containing an onset feature and a color feature) with both onset and color targets. Experiment 2, using a delay between cue and target, revealed inhibition of return (IOR) for combination cues with onset and color targets. Unexpectedly, IOR was also found for onset cues with color targets, and this finding was confirmed in Experiment 3. These findings indicate that attentional control settings use an inclusive rule. Moreover, the presence of IOR with onset cues and color targets suggests that onset cues may automatically capture attention, but attention control settings allow for rapid disengagement when the onset cue does not contain a task-relevant feature.