The combined effects of noise and illumination on the performance efficiency of visual search and neuromotor task components

A battery of performance tests consisting of 'letter cancellation,' 'hand 'precision,' 'two-hand coordination,' and 'tweezer dexterity' were administered on 12 desk workers in an illumination chamber under six different combinations of noise and illumination made out of two levels of white noise (70 and 100 dB) and three levels of illuminations (50, 150, and 300 lx). The objective was to find out the combined effects of noise and illumination on the performance efficiency of the above tests. A 6 x 6 latin square design was followed. A three-way analysis of variance reflected significant combined effects of noise and illumination on the accuracy scores of the letter cancellation test and hand precision test and the efficiency score of the latter test. Significant separate effects of noise were, however, observable on the speed scores and efficiency scores of the letter cancellation test and that of illumination on the speed scores of this test as also the accuracy scores of the tweezer dexterity test. Studies ascertaining the effects of heat stress in combination with noise and illumination on human performance efficiency have been suggested.     

The effects of times of day on cognitive and visuo-motor performance efficiency

Twenty-four male graduate volunteers were administered a battery of psychological tests--critical flicker fusion (CFF; alternate and simultaneous), reaction time (simple and choice), memory (forward and backward), and associative recall--to ascertain their performance capability during the different times of day. Each subject performed the tests on two occasions, once in the morning (10:00 h) and on the second occasion in the evening (15:00 h), on two successive days, following a statistically balanced design. Analysis of variance reflected superior performance on reaction time (choice) and memory (backward) in the evening and on associative recall in the morning. While no such effects were noticeable on CFF, appreciable changes in performance with the decreasing brightness level of its light sources was observed. Further work in this direction on a variety of cognitive tests and sensory functions under various times (more than two times) throughout the day is suggested.     

Testosterone levels and cognitive functioning in women with polycystic ovary syndrome and in healthy young women

We investigated the possible influence of testosterone (T) on cognitive functioning in women with polycystic ovary syndrome (PCOS), an endocrine disorder associated with elevated levels of free testosterone (free T). Performance on a battery of neuropsychological tests in 29 women with elevated free T levels due to PCOS was compared to the performance of 22 age- and education-matched, healthy control women with free T levels in the normal female range. Women with PCOS had significantly higher levels of free T (estimated by the free androgen index) and demonstrated significantly worse performance on tests of verbal fluency, verbal memory, manual dexterity, and visuospatial working memory than the healthy control women. No differences between the groups were found on tests of mental rotation, spatial visualization, spatial perception, or perceptual speed. These results suggest that, in women, elevations in free T may be associated with poorer performance on cognitive tasks that tend to show a female advantage.     

Effects of the pharmacologic manipulation of testosterone on cognitive functioning in women with polycystic ovary syndrome: a randomized, placebo-controlled treatment study

In a previous study, we found that women with polycystic ovary syndrome (PCOS), an endocrine disorder characterized by chronic hyperandrogenism, performed more poorly than healthy, matched controls on a number of neuropsychological tests, in particular tests of verbal fluency, verbal memory, manual dexterity, and visuospatial working memory. This randomized, placebo-controlled trial was undertaken to investigate whether pharmacologic manipulation of free testosterone (free T) levels in women with PCOS might affect their performance on cognitive tests. Nineteen women with PCOS completed a battery of neuropsychological tests before and after 3 months of treatment with either an anti-androgen (cyproterone acetate) plus estrogen or with a placebo. Hormone treatment of women with PCOS caused a significant reduction in their free T levels but did not affect performance on tests visuospatial ability, verbal memory, manual dexterity, or perceptual speed. Women treated with hormone therapy did, however, demonstrate an improvement in their performance on a test of verbal fluency compared to their pre-treatment scores. These findings suggest that changes in free T levels do not have a significant impact on cognitive performance in women with PCOS, although reductions in free T may be beneficial for verbal fluency.     

Diurnal Variation in Oral Temperature, Sleepiness, and Performance of High School Girls

Evaluation of rhythmic fluctuations of physical and mental variables should be of special significance for the understanding of students' performance and setting the schedules of school activities. The present study investigated the pattern of diurnal variation in oral temperature, sleepiness and performance of a group of adolescents undergoing a daytime school schedule. Eighteen girls (mean age 16 years-old), who attended the same class from 0715h to 1645h, were tested on seven days. They measured their oral temperature, quantified their sleepiness level by means of a visual analogue scale, and completed the following tests: letter cancellation test, addition test, and a simple motor task. One-way ANOVA statistics for repeated measures was used in order to verify the effect of test time on oral temperature, sleepiness and performance. Possible correlations between the level of sleepiness and performance were investigated by means of Spearman rank correlation. The results revealed significant time of day effect on all variables, except for the number of addition errors. Oral temperature values showed an increase from morning to afternoon. Letter cancellation, motor task and addition scores increased from early morning to late afternoon, showing rapid fluctuations throughout the day. Sleepiness level was negatively correlated with letter cancellation scores during the first three tests of the day. In agreement with other work, the diurnal variation of oral temperature, letter cancellation and addition test showed an improvement as the day progressed. Sleepiness, on the other hand, decreased throughout the day, with the highest level associated with the first test of the day, suggesting a circadian pattern of variation rather than a cumulative effect due to school activities.     

Diurnal Variation in Oral Temperature,Sleepiness, and Performance of High School Girls

Evaluation of rhythmic fluctuations of physical and mental variables should be of special significance for the understanding of students' performance and setting the schedules of school activities. The present study investigated the pattern of diurnal variation in oral temperature, sleepiness and performance of a group of adolescents undergoing a daytime school schedule. Eighteen girls (mean age 16 years-old), who attended the same class from 0715h to 1645h, were tested on seven days. They measured their oral temperature, quantified their sleepiness level by means of a visual analogue scale, and completed the following tests: letter cancellation test, addition test, and a simple motor task. One-way ANOVA statistics for repeated measures was used in order to verify the effect of test time on oral temperature, sleepiness and performance. Possible correlations between the level of sleepiness and performance were investigated by means of Spearman rank correlation. The results revealed significant time of day effect on all variables, except for the number of addition errors. Oral temperature values showed an increase from morning to afternoon. Letter cancellation, motor task and addition scores increased from early morning to late afternoon, showing rapid fluctuations throughout the day. Sleepiness level was negatively correlated with letter cancellation scores during the first three tests of the day. In agreement with other work, the diurnal variation of oral temperature, letter cancellation and addition test showed an improvement as the day progressed. Sleepiness, on the other hand, decreased throughout the day, with the highest level associated with the first test of the day, suggesting a circadian pattern of variation rather than a cumulative effect due to school activities.     

Tactile perception and manual dexterity in computer users

Recent studies suggest that sensory input generated during highly repetitive tasks can degrade the sensory representation of the hand and eventually lead to sensory and motor problems. In this study, we investigated whether early changes in tactile perception and manual dexterity could be detected in persons exposed to computer tasks. Performance in tests designed to assess tactile perception (grating orientation task for spatial acuity and roughness discrimination) and manual dexterity (grooved pegboard test) was compared between two groups of healthy individuals, matched for age, gender, and experience, who differed in terms of computer habits. One group consisted of frequent users (FU, > 2 h/day, n = 36) and the other of non or occasional users (OU, < 2 h/day, n = 28). Comparison of performance between groups with subjects sorted by gender revealed significant differences (t-test, p < 0.05) in female, but not male, participants. Grating resolution thresholds at the tip on the second and fifth digits were, on average, 40% higher in female FU (n = 13) than in female OU (n = 10) and performance scores on the dexterity test were significantly higher for the left hand. The results of this study indicate that early signs of deterioration in hand function can be present in persons constantly exposed to computer tasks and that these signs are more readily apparent in women than in men. The loss of tactile spatial acuity found in female FU possibly reflect an early consequence of the degraded sensory representation of the hand resulting from constant repetitions of fine motor tasks.     

Tactile perception and manual dexterity in computer users

Recent studies suggest that sensory input generated during highly repetitive tasks can degrade the sensory representation of the hand and eventually lead to sensory and motor problems. In this study, we investigated whether early changes in tactile perception and manual dexterity could be detected in persons exposed to computer tasks. Performance in tests designed to assess tactile perception (grating orientation task for spatial acuity and roughness discrimination) and manual dexterity (grooved pegboard test) was compared between two groups of healthy individuals, matched for age, gender, and experience, who differed in terms of computer habits. One group consisted of frequent users (FU, > 2 h/day, n = 36) and the other of non or occasional users (OU, < 2 h/day, n = 28). Comparison of performance between groups with subjects sorted by gender revealed significant differences ( t -test, p < 0.05) in female, but not male, participants. Grating resolution thresholds at the tip on the second and fifth digits were, on average, 40% higher in female FU ( n = 13) than in female OU ( n = 10) and performance scores on the dexterity test were significantly higher for the left hand. The results of this study indicate that early signs of deterioration in hand function can be present in persons constantly exposed to computer tasks and that these signs are more readily apparent in women than in men. The loss of tactile spatial acuity found in female FU possibly reflect an early consequence of the degraded sensory representation of the hand resulting from constant repetitions of fine motor tasks.     

Diurnal Variation in Mood and Performance in a Time-Isolated Environment

In order to document circadian rhythmicity in various psychological functions under the chronobiologically 'pure' condition of temporal isolation, a battery of mood and performance tests were administered about 6 times per day to a heterogeneous group of 18 subjects (ages 19-81, 5 female). Each subject spent about 5 days in temporal isolation, entrained to a routine equivalent to his/her own habitual sleep/wake cycle. Average time of day functions were obtained for the mood and performance variables, and compared to rectal temperature data subjected to exactly the same statistical analysis. Significant time of day effects were found in the mood variables of alertness, sleepiness, weariness, effort required, happiness and well-being. Times of 'best' mood were different from the time of peak temperature. Moreover, the minima of sleepiness, weariness and effort occurred earlier in the day than the maximum of alertness. Significant time of day effects were also found in the speed with which search and dexterity tasks were completed. Only the dexterity tasks showed a complete parallelism with the temperature rhythm.     

Increasing hand efficiency at cold temperatures by training hand vasodilation with a classical conditioning-biofeedback overlap design

The prolonged exposure of hands to cold environments leads to substantial cold pain and severe deterioration of manual dexterity, finger dexterity, hand strength, and tactile sensitivity. This study taught volunteers to warm their hands at –14 degrees Celsius and measured the hand efficiency effects. The subjects were six male and female nonsmoking volunteers. All research was conducted in a cold chamber during the warm summer months to eliminate seasonal factors. A combined multiple-baseline/ABA single-subject design with multiple replications was used. Each subject's hand performance was obtained for both hands in warm and in cold conditions. One hand was trained and both hands were retested in the cold. The second hand was trained and both hands were retested in the cold. Finally, the subject inhibited warming while in the cold (treatment removal) and both hands were tested again. The treatment itself used biofeedback instrumentation to extend and enlarge previously classically conditioned vasodilative episodes. The procedure was found to be effective for bringing about temperature changes in the cold. Large treatment effects were found on all hand efficiency measures. The results suggest wide implications for the workplace, for theory, and for future research.This research was supported by a grant from the Occupational Health and Safety division of the Alberta Department of Labor and by a Doctoral Fellowship from the Social Sciences and Humanities Research Council of Canada.     

Validation of a posturographic approach to monitor sleepiness

Sleepiness is a major risk factor in traffic- and occupational accidents. While sleepiness is a persistent concern, there is no convenient test to monitor impending levels of sleepiness. We show that force platform posturographic balance testing addresses this need because it estimates time awake (TA) accurately and precisely. Testing the TA is appropriate because TA drives the sleep homeostatic process, a component in sleepiness. With 12 subjects we evaluated the accuracy and precision of repeated estimates of TA. Our extended study design that allows evaluating the accuracy and precision of posturographic TA-estimates is new. First, we tested the subjects’ balance every 2 h during 36 h of sustained wakefulness. This comprised the subjects’ reference curves (balance as a function of known and increasing TA). Then, we tested the subjects’ balance once a day over one week. We also tested the subjects’ balance once a week over one month. Finally, to estimate the subjects’ TA, we equated the balance scores with the scores in their reference curves. The accuracy of the estimates was 86%, and the precision was 97%. The high accuracy and precision of the estimates obtained with this one-month protocol validates the method of posturographic monitoring of sleepiness. So far, force platform posturographic balance testing has generally been used for clinical purposes, to quantify balance control and musculoskeletal performance. Our main result is that we now validated that balance testing provides accurate and precise estimates of TA, and hence, also provides an approach towards an automated monitor of sleepiness.     

What happened to VIM thalamotomy for Parkinson's disease?

A prospective review of 75 of 190 parkinsonian patients undergoing unilateral thalamotomy was displayed with a computer graphics technique examining three equal consecutive groups from the pre-, early, and late L-dopa eras. Histograms for average function and scattergrams of individual patient's performance preoperatively and up to 2 years postoperatively were prepared. No ipsilateral effects or consistent iatrogenic deterioration of any function were identified. 2 years after surgery, 82% had no tremor in the contralateral fingers or hand and 7% had almost no tremor; contralateral tremor elsewhere was infrequent. Rigidity and manual dexterity improved less strikingly, the latter only reflecting abolition of tremor; locomotion, speech, facial movement and handwriting did not improve. There was no mortality, but 8% had persistent significant complications. VIM thalamotomy remains the treatment of choice for severe drug-resistant parkinsonian tremor.     

Hand temperature norms for headache, hypertension, and irritable bowel syndrome

Hand temperature norms are presented for 221 headache patients (migraine, mixed, and tension), 105 hypertensives, 45 irritable bowel syndrome patients, and 56 normal controls under conditions of resting baseline, self-relaxation, volitional handwarming, mental arithmetic, and cold pressor. The two vascular headache groups (migraine and mixed) had significantly lower hand temperatures across conditions.     

Age and Grip Strength Predict Hand Dexterity in Adults

In the scientific literature, there is much evidence of a relationship between age and dexterity, where increased age is related to slower, less nimble and less smooth, less coordinated and less controlled performances. While some suggest that the relationship is a direct consequence of reduced muscle strength associated to increased age, there is a lack of research that has systematically investigated the relationships between age, strength and hand dexterity. Therefore, the aim of this study was to examine the associations between age, grip strength and dexterity. 107 adults (range 18-93 years) completed a series of hand dexterity tasks (i.e. steadiness, line tracking, aiming, and tapping) and a test of maximal grip strength. We performed three phases of analyses. Firstly, we evaluated the simple relationships between pairs of variables; replicating the existing literature; and found significant relationships of increased age and reduced strength; increased age and reduced dexterity, and; reduced strength and reduced dexterity. Secondly, we used standard Multiple Regression (MR) models to determine which of the age and strength factors accounted for the greater variance in dexterity. The results showed that both age and strength made significant contributions to the data variance, but that age explained more of the variance in steadiness and line tracking dexterity, whereas strength explained more of the variance in aiming and tapping dexterity. In a third phase of analysis, we used MR analyses to show an interaction between age and strength on steadiness hand dexterity. Simple Slopes post-hoc analyses showed that the interaction was explained by the middle to older aged adults showing a relationship between reduced strength and reduced hand steadiness, whereas younger aged adults showed no relationship between strength and steadiness hand dexterity. The results are discussed in terms of how age and grip strength predict different types of hand dexterity in adults.     

Finger dexterity, skin temperature, and blood flow during auxiliary heating in the cold.

The primary purpose of the present study was to compare the effectiveness of two forms of hand heating and to discuss specific trends that relate finger dexterity performance to variables such as finger skin temperature (T(fing)), finger blood flow (Q(fing)), forearm skin temperature (T(fsk)), forearm muscle temperature (Tfmus), mean weighted body skin temperature (Tsk), and change in body heat content (DeltaH(b)). These variables along with rate of body heat storage, toe skin temperature, and change in rectal temperature were measured during direct and indirect hand heating. Direct hand heating involved the use of electrically heated gloves to keep the fingers warm (heated gloves condition), whereas indirect hand heating involved warming the fingers indirectly by actively heating the torso with an electrically heated vest (heated vest condition). Seven men (age 35.6 +/- 5.6 yr) were subjected to each method of hand heating while they sat in a chair for 3 h during exposure to -25 degrees C air. Q(fing) was significantly (P < 0.05) higher during the heated vest condition compared with the heated gloves condition (234 +/- 28 and 33 +/- 4 perfusion units, respectively), despite a similar T(fing) (which ranged between 28 and 35 degrees C during the 3-h exposure). Despite the difference in Q(fing), there was no significant difference in finger dexterity performance. Therefore, finger dexterity can be maintained with direct hand heating despite a low Q(fing). DeltaH(b), Tsk, and T(fmus) reached a low of -472 +/- 18 kJ, 28.5 +/- 0.3 degrees C, and 29.8 +/- 0.5 degrees C, respectively, during the heated gloves condition, but the values were not low enough to affect finger dexterity.     

Behavioral Assessment of Manual Dexterity in Non-Human Primates

The corticospinal (CS) tract is the anatomical support of the exquisite motor ability to skillfully manipulate small objects, a prerogative mainly of primates¹. In case of lesion affecting the CS projection system at its origin (lesion of motor cortical areas) or along its trajectory (cervical cord lesion), there is a dramatic loss of manual dexterity (hand paralysis), as seen in some tetraplegic or hemiplegic patients. Although there is some spontaneous functional recovery after such lesion, it remains very limited in the adult. Various therapeutic strategies are presently proposed (e.g. cell therapy, neutralization of inhibitory axonal growth molecules, application of growth factors, etc), which are mostly developed in rodents. However, before clinical application, it is often recommended to test the feasibility, efficacy, and security of the treatment in non-human primates. This is especially true when the goal is to restore manual dexterity after a lesion of the central nervous system, as the organization of the motor system of rodents is different from that of primates^1,2. Macaque monkeys are illustrated here as a suitable behavioral model to quantify manual dexterity in primates, to reflect the deficits resulting from lesion of the motor cortex or cervical cord for instance, measure the extent of spontaneous functional recovery and, when a treatment is applied, evaluate how much it can enhance the functional recovery.The behavioral assessment of manual dexterity is based on four distinct, complementary, reach and grasp manual tasks (use of precision grip to grasp pellets), requiring an initial training of adult macaque monkeys. The preparation of the animals is demonstrated, as well as the positioning with respect to the behavioral set-up. The performance of a typical monkey is illustrated for each task. The collection and analysis of relevant parameters reflecting precise hand manipulation, as well as the control of force, are explained and demonstrated with representative results. These data are placed then in a broader context, showing how the behavioral data can be exploited to investigate the impact of a spinal cord lesion or of a lesion of the motor cortex and to what extent a treatment may enhance the spontaneous functional recovery, by comparing different groups of monkeys (treated versus sham treated for instance). Advantages and limitations of the behavioral tests are discussed. The present behavioral approach is in line with previous reports emphasizing the pertinence of the non-human primate model in the context of nervous system diseases^2,3.     

Muscle dimensions in the Japanese macaque hand

Macaques have been used as an important paradigm for understanding the neural control mechanisms of human precision grip capabilities. Therefore, we dissected the forearms and hands of two male Japanese macaques to systematically record the muscle mass, fascicle length and physiological cross-sectional area (PCSA). Comparisons of the mass fractions and PCSA fractions of the hand musculature among the Japanese macaque, chimpanzee, and human demonstrated that the sizes of the thenar and hypothenar eminence muscle groups are more balanced in the macaque and chimpanzee, but those of the thenar eminence group are much larger in the human, indicating that the capacity to generate force at the tip of the thumb is more restricted in macaques, despite their high manual dexterity. In the macaque, however, the extrinsic flexor muscles are much larger, possibly to facilitate weight bearing by the forelimbs in pronograde quadrupedal locomotion and forceful grasping of arboreal supports in gap-crossing movements such as leaping. Taking such anatomical differences imposed on the hand musculoskeletal system into consideration seems to be an important method of clarifying the mechanisms of precision grip in macaques.     

Specific features of regulatory and information-related components of cognitive processes in 7-10-year-old children with local EEG abnormalities in the right hemisphere

Two groups of 7-10-year-old children were formed on the basis of the results of visual analysis of their EEG. The first group included 15 children with local EEG deviations in the right hemisphere, and the second group included 21 children without EEG deviations from the age norm (control group). In both groups, verbal and nonverbal higher mental functions and the ability to voluntary control of activity were assessed by means of neuropsychological methods. As compared to children of the control group, children with local EEG deviations in the right hemisphere demonstrated some difficulties in strategy formation, reduced ability to maintain already formed programs, increased fatigue, changes in affective behavior (anxiety and behavioral excitability), deficit of visual and somatosensory perceptual synthesis, reduction in object recognition efficiency, and visual memory deficit.     

Hand temperature norms for headache,hypertension, and irritable bowel syndrome

Hand temperature norms are presented for 221 headache patients (migraine, mixed, and tension), 105 hypertensives, 45 irritable bowel syndrome patients, and 56 normal controls under conditions of resting baseline, self-relaxation, volitional handwarming, mental arithmetic, and cold pressor. The two vascular headache groups (migraine and mixed) had significantly lower hand temperatures across conditions.This research was supported in part by grants from NINCDS (NS-15235 and NS-23440), from NHLBI (HL-27622 and HL-31189), and from NIDDK (DK-38614).     

CD‐sensitive Zn‐porphyrin tweezer host‐guest complexes,part 1: MC/OPLS‐2005 computational approach for predicting preferred interporphyrin helicity

This article describes a computational study on dimeric zinc porphyrin tweezer complexes with primary/secondary amines and secondary alcohols that validates the use of Optimized Potential for Liquid Simulations (OPLS‐2005) as the lead computational choice for assisting the tweezer methodology in the absolute configurational assignment of organic compounds. A supramolecular, microscale approach known as the tweezer method has been widely applied in the past decade for determining the absolute configuration of chiral substrates that are difficult to study by other readily available methods. The method relies on a host/guest complexation mechanism between a porphyrin tweezer moiety and a substrate, after its conversion into a bidentate conjugate. The formation of 1:1 complexes is a stereodifferentiating process: upon complexation, the originally achiral tweezer adopts a preferential interporphyrin helicity, dictated by the absolute configuration of the chiral substrate. By correctly predicting the sign of the interporphyrin helicity in the complex, OPLS‐2005 provides a correlation between the observed circular dichroism (CD) signal and the absolute configuration of the substrate. It also offers a great degree of insight into the structural factors responsible for chiral recognition and the amplitude of exciton couplets. Moreover, the preferential binding sites between the Zn‐tweezer and secondary amine conjugates were revealed by using the new computational approach. Chirality, 2010. © 2009 Wiley‐Liss, Inc.