Spatial Pattern of Eye Fixations and Evidence of Ultradian Rhythms in Aircraft Pilots.

INTRODUCTION: Eye fixations can be distributed in three ways: randomly, in clusters, and regularly. However, there is always a continuum among these types, because these spatial patterns are the result of a process evolving over time. The focus of the present work was to study the changes over time observed in the Nearest Neighbor Index (NNI), an index derived from the spatial distribution of eye fixations that has been reported to be sensitive to variations in mental workload. Of particular interest are periodic changes in the ultradian timescale (an ultradian rhythm is a recurrent period or cycle repeated throughout a 24-h circadian day). METHODS: Data from a previously reported experiment were further analyzed using temporal spectral analysis, which is one of the most commonly used techniques for studying measurements collected at regularly spaced intervals of time. RESULTS: An ultradian rhythm with a periodicity between 2 and 15 min was found, which is compatible with results obtained by analyzing reaction times in prolonged vigilance tasks. DISCUSSION: The identification of a periodicity in the allocation of mental resources should be considered in the design of automation support that is dynamically matched to mental workload.

A mathematical model of saccadic reaction time as a function of the fixation point brightness gain.

The gap effect refers to a reduction in saccadic reaction time (SRT) to an eccentric target, when the fixation point is removed before the target onset. Though it is known that the gap effect peaks when the fixation point is offset about 200 ms before the onset of the eccentric target, it is unknown how this effect is modulated by stimulus variations. In this paper, we propose and investigate a model of saccadic reaction time as a function of the fixation point brightness gain. The brightness gain is defined as the ratio of the final and initial intensities of the stimulus. We have conducted a typical gap effect experiment with 15 participants, where the brightness of the fixation point was manipulated under four conditions and two gap intervals, at the same time and 200 ms before the onset of the eccentric target. The conditions included removing the fixation point (offset), leaving it with constant brightness (overlap), reducing, and increasing its brightness (lower and higher brightness conditions). Experimental data showed a significant gap effect in the offset and lower brightness conditions when compared to the overlap condition. On the other hand, the SRT was significantly longer for the higher brightness condition than the SRT for the overlap condition. Linear regression analysis using ten values of brightness gain shows that our model fits the data well for the 0- and 200-ms gap, with a coefficient of determination of .89 and .94, respectively.

A developmental study of the effect of music training on timed movements.

When people clap to music, sing, play a musical instrument, or dance, they engage in temporal entrainment. We examined the effect of music training on the precision of temporal entrainment in 57 children aged 10-14 years (31 musicians, 26 non-musicians). Performance was examined for two tasks: self-paced finger tapping (discrete movements) and circle drawing (continuous movements). For each task, participants synchronized their movements with a steady pacing signal and then continued the movement at the same rate in the absence of the pacing signal. Analysis of movements during the continuation phase revealed that musicians were more accurate than non-musicians at finger tapping and, to a lesser extent, circle drawing. Performance on the finger-tapping task was positively associated with the number of years of formal music training, whereas performance on the circle-drawing task was positively associated with the age of participants. These results indicate that music training and maturation of the motor system reinforce distinct skills of timed movement.

Timing skills and expertise: discrete and continuous timed movements among musicians and athletes.

INTRODUCTION: Movement-based expertise relies on precise timing of movements and the capacity to predict the timing of events. Music performance involves discrete rhythmic actions that adhere to regular cycles of timed events, whereas many sports involve continuous movements that are not timed in a cyclical manner. It has been proposed that the precision of discrete movements relies on event timing (clock mechanism), whereas continuous movements are controlled by emergent timing. We examined whether movement-based expertise influences the timing mode adopted to maintain precise rhythmic actions. MATERIALS AND METHOD: Timing precision was evaluated in musicians, athletes and control participants. Discrete and continuous movements were assessed using finger-tapping and circle-drawing tasks, respectively, based on the synchronization-continuation paradigm. In Experiment 1, no auditory feedback was provided in the continuation phase of the trials, whereas in Experiment 2 every action triggered a feedback tone. RESULTS: Analysis of precision in the continuation phase indicated that athletes performed significantly better than musicians and controls in the circle-drawing task, whereas musicians were more precise than controls in the finger tapping task. Interestingly, musicians were also more precise than controls in the circle-drawing task. RESULTS also showed that the timing mode adopted was dependent on expertise and the presence of auditory feedback. DISCUSSION: RESULTS showed that movement-based expertise is associated with enhanced timing, but these effects depend on the nature of the training. Expertise was found to influence the timing strategy adopted to maintain precise rhythmic movements, suggesting that event and emergent timing mechanisms are not strictly tied to specific tasks, but can both be adopted to achieve precise timing.

The mere presence of a goalkeeper affects the accuracy of penalty kicks.

The keeper-independent strategy, in which a football penalty kicker selects a target location in advance and ignores the goalkeeper's actions during the run-up, has been suggested to be the preferable strategy for taking a penalty kick. The current in-field experiment investigated the question of whether the goalkeeper can indeed be ignored. Ten intermediate-level football players were instructed to adopt a goalkeeper-independent strategy and to perform penalty kicks directed at one of two targets located in the upper corners of the goal under three conditions: without a goalkeeper, in the presence of a goalkeeper (who tried to save the ball), and in the presence of a goalkeeper who was informed by the penalty kickers where they intended to direct the ball. The mere presence of a goalkeeper impaired shot accuracy. The shots were more centralised, that is, biased toward the goalkeeper. The effects were enhanced for the condition in which the penalty kicker knew the goalkeeper was knowledgeable about ball direction. The findings were consistent with the response activation model that holds that aiming at a target can be biased toward salient visual non-targets. The implications for adopting and practising goalkeeper-independent strategies are discussed.

Olfactory impairment in familial ataxias.

The main clinical manifestations of the spinocerebellar ataxias (SCAs) result from the involvement of the cerebellum and its connections. Cerebellar activity has been consistently observed in functional imaging studies of olfaction, but the anatomical pathways responsible for this connection have not yet been elucidated. Previous studies have demonstrated olfactory deficit in SCA2, Friedreich's ataxia and in small groups of ataxia of diverse aetiology. The authors used a validated version of the 16-item smell identification test from Sniffin' Sticks (SS-16) was used to evaluate 37 patients with genetically determined autosomal dominant ataxia, and 31 with familial ataxia of unknown genetic basis. This data was also compared with results in 106 Parkinson's disease patients and 218 healthy controls. The SS-16 score was significantly lower in ataxia than in the control group (p<0.001, 95% CI for ß=0.55 to 1.90) and significantly higher in ataxia than in Parkinson's disease (p<0.001, 95% CI for ß=-4.58 to -3.00) when adjusted for age (p=0.001, 95% CI for ß=-0.05 to -0.01), gender (p=0.19) and history of tobacco use (p=0.41). When adjusted for general cognitive function, no significant difference was found between the ataxia and control groups. This study confirms previous findings of mild hyposmia in ataxia, and further suggests this may be due to general cognitive deficits rather than specific olfactory problems.

The effects of high pressure on the point of no return in simulated penalty kicks.

We investigated the effects of high pressure on the point of no return or the minimum time required for a kicker to respond to the goalkeeper's dive in a simulated penalty kick task. The goalkeeper moved to one side with different times available for the participants to direct the ball to the opposite side in low-pressure (acoustically isolated laboratory) and high-pressure situations (with a participative audience). One group of participants showed a significant lengthening of the point of no return under high pressure. With less time available, performance was at chance level. Unexpectedly, in a second group of participants, high pressure caused a qualitative change in which for short times available participants were inclined to aim in the direction of the goalkeeper's move. The distinct effects of high pressure are discussed within attentional control theory to reflect a decreasing efficiency of the goal-driven attentional system, slowing down performance, and a decreasing effectiveness in inhibiting stimulus-driven behavior.

Space and motion perception and discomfort in air travel.

INTRODUCTION: The perception of comfort during air trips is determined by several factors. External factors like cabin design and environmental parameters (temperature, humidity, air pressure, noise, and vibration) interact with individual characteristics (anxiety traits, fear of flying, and personality) from arrival at the airport to landing at the destination. In this study, we investigated the influence of space and motion discomfort (SMD), fear of heights, and anxiety on comfort perception during all phases of air travel. METHODS: We evaluated 51 frequent air travelers through a modified version of the Flight Anxiety Situations Questionnaire (FAS), in which new items were added and where the subjects were asked to report their level of discomfort or anxiety (not fear) for each phase of air travel (Chronbach's alpha = 0.974). Correlations were investigated among these scales: State-Trait Anxiety Inventory (STAI), Cohen's Acrophobia Questionnaire, and the Situational Characteristics Questionnaire (SitQ, designed to estimate SMD levels). RESULTS: Scores of SitQ correlated with discomfort in situations involving space and movement perception (Pearson's rho = 0.311), while discomfort was associated with cognitive mechanisms related to scores in the anxiety scales (Pearson's rho = 0.375). Anxiety traits were important determinants of comfort perception before and after flight, while the influence of SMD was more significant during the time spent in the aircraft cabin. DISCUSSION: SMD seems to be an important modulator of comfort perception in air travel. Its influence on physical well being and probably on cognitive performance, with possible effects on flight safety, deserves further investigation.

Dynamics of a Stroop matching task: effect of alcohol and reversal with training

Using a Stroop matching task, we evaluated how alcohol affects the time needed to overcome Stroop conflict and whether practice might reverse the effect of alcohol. Participants (n = 16) performed two sessions in which they had to compare the color of a color-word with the meaning of a color-word in neutral color. The two task stimuli were presented simultaneously or with a Stimulus Onset Asynchrony (SOA) of 200, 500, or 800 ms. For half of the subjects, alcohol was administered in the first session, and for the other half, alcohol was administered in the second session. The results showed that the Stroop effect was significant at the 0 and 200 ms intervals in the sober subjects. Moreover, in untrained intoxicated individuals, interference endured until the 500 ms interval, a result that was abolished in trained intoxicated subjects. In conclusion, alcohol increased the time needed for Stroop matching task conflict resolution. However, this deleterious effect was minimized by a previous practice session.

Dynamics of a Stroop matching task: effect of alcohol and reversal with training

Using a Stroop matching task, we evaluated how alcohol affects the time needed to overcome Stroop conflict and whether practice might reverse the effect of alcohol. Participants (n = 16) performed two sessions in which they had to compare the color of a color-word with the meaning of a color-word in neutral color. The two task stimuli were presented simultaneously or with a Stimulus Onset Asynchrony (SOA) of 200, 500, or 800 ms. For half of the subjects, alcohol was administered in the first session, and for the other half, alcohol was administered in the second session. The results showed that the Stroop effect was significant at the 0 and 200 ms intervals in the sober subjects. Moreover, in untrained intoxicated individuals, interference endured until the 500 ms interval, a result that was abolished in trained intoxicated subjects. In conclusion, alcohol increased the time needed for Stroop matching task conflict resolution. However, this deleterious effect was minimized by a previous practice session.(AU)

Applying a new version of the Brazilian-Portuguese UPSIT smell test in Brazil.

Standardized olfactory tests are now available to quantitatively assess disorders of olfaction. A Brazilian-Portuguese version of the University of Pennsylvania Smell Identification Test (UPSIT) is currently being developed specifically for the Brazilian population. The most recent Brazilian-Portuguese version of the UPSIT (UPSIT-Br2) was administered to 88 Brazilian subjects who had no history of neurological or otorhinolaryngological disease. UPSIT-Br2 scores decreased with age, were lower in men than in women, and were lower in subjects with lower income. The degree to which the poorer performance of subjects with lower socio-economic status reflects lack of familiarity with test items is not known. Although this version of the UPSIT provides a sensitive and useful test of smell function for the Brazilian population, a revision of some test items is needed to achieve comparable norms to those found using the North American UPSIT in the United States.

Applying a new version of the Brazilian-Portuguese UPSIT smell test in Brazil / Aplicando uma nova versão brasileira do UPSIT no Brasil

Standardized olfactory tests are now available to quantitatively assess disorders of olfaction. A Brazilian-Portuguese version of the University of Pennsylvania Smell Identification Test (UPSIT) is currently being developed specifically for the Brazilian population. The most recent Brazilian-Portuguese version of the UPSIT (UPSIT-Br2) was administered to 88 Brazilian subjects who had no history of neurological or otorhinolaryngological disease. UPSIT-Br2 scores decreased with age, were lower in men than in women, and were lower in subjects with lower income. The degree to which the poorer performance of subjects with lower socio-economic status reflects lack of familiarity with test items is not known. Although this version of the UPSIT provides a sensitive and useful test of smell function for the Brazilian population, a revision of some test items is needed to achieve comparable norms to those found using the North American UPSIT in the United States.

Testes padronizados já estão disponíveis para testagem do olfato e uma versão em Português esta sendo desenvolvida para o University of Pennsylvania Smell Identification Test (UPSIT), especificamente para a população brasileira. A versão mais recente deste teste (chamada UPSIT-Br2) foi aplicada a 88 sujeitos brasileiros que não tinham história de qualquer problema neurológico ou otorrinolaringológico. Compatível com dados prévios da literatura, a performance no UPSIT-Br2 decaiu com a idade e foi inferior no genero masculino. Os resultados foram mais baixos em participantes de menor nível sócio-econômico e a relação deste achado com a falta de familiaridade para com os itens do teste não é conhecida. Apesar desta versão do UPSIT poder ser útil para o teste da função olfativa da população brasileira, a revisão de alguns itens se faz necessária para alcançar valores comparáveis aos dados normativos norte-americanos.

What is transmitted in "synaptic transmission"?

Even students that obtain a high grade in neurophysiology often carry away a serious misconception concerning the final result of the complex set of events that follows the arrival of an action potential at the presynaptic terminal. The misconception consists in considering that "at a synapse, information is passed on from one neuron to the next" is equivalent to (and often expressed explicitly as) "the action potential passes from one neuron to the next." More than half of four groups of students who were asked to comment on an excerpt from a recent physiology textbook that openly stated the misconception had no clear objection to the text presented. We propose that the first culprit in generating this misconception is the term "synaptic transmission," which promotes the notion of transferring something or passing something along (implicitly unchanged). To avoid establishing this misconception, the first simple suggestion is to use words like "synaptic integration" rather than "synaptic transmission" right from the start. More generally, it would be important to focus on the function of synaptic events rather than on rote listing of all the numerous steps that are known to occur, which are so complex as to saturate the mind of the student.

The use of smell identification tests in the diagnosis of Parkinson's disease in Brazil.

Smell identification tests may be of routine clinical value in the differential diagnosis of PD but are subject to cultural variation and have not been systematically evaluated in the Brazilian population. We have applied culturally adapted translations of the University of Pennsylvania 40-item smell identification test (UPSIT-40) and the 16-item identification test from Sniffin' Sticks (SS-16) to nondemented Brazilian PD patients and controls. Pearson's correlation coefficient between the test scores was 0.76 (95% CI 0.70-0.81, n = 204, P < 0.001). To calculate reliability measures for each test we used the diagnosis (either PD or control) as outcome variable for separate logistic regression analyses using the score in the UPSIT-40 or the SS-16 as a covariate. The SS-16 specificity was 89.0% with a sensitivity of 81.1% (106 PD and 118 controls). The UPSIT-40 specificity was 83.5% and its sensitivity 82.1% (95 PD and 109 controls). Regression curves were used to associate an individual's smell test score with the probability of belonging to the PD, as opposed to the control group. Our data provide support for the use of the UPSIT-40 and SS-16 to help distinguish early PD from controls.

A spiderless arachnophobia therapy: comparison between placebo and treatment groups and six-month follow-up study.

We describe a new arachnophobia therapy that is specially suited for those individuals with severe arachnophobia who are reluctant to undergo direct or even virtual exposure treatments. In this therapy, patients attend a computer presentation of images that, while not being spiders, have a subset of the characteristics of spiders. The Atomium of Brussels is an example of such an image. The treatment group (n = 13) exhibited a significant improvement (time x group interaction: P = .0026) when compared to the placebo group (n = 12) in a repeated measures multivariate ANOVA. A k-means clustering algorithm revealed that, after 4 weeks of treatment, 42% of the patients moved from the arachnophobic to the nonarachnophobic cluster. Six months after concluding the treatment, a follow-up study showed a substantial consolidation of the recovery process where 92% of the arachnophobic patients moved to the nonarachnophobic cluster.

Effects of acute alcohol intoxication on visuospatial attention.

The aim of the present study was to examine the effects of acute alcohol intoxication on the spatial distribution of visual attention measured with simple reaction times (RTs) to targets presented over an extended region of the visual field. Control (n=10) and alcohol groups (n=14) were tested with the same protocol. Participants were tested in two different conditions; in Experiment I, participants were instructed to direct their visual attention to the centre, while in Experiment II they were asked to orient their attention covertly to both right and left, but not to the centre. Throughout participants were required to fixate a small cross in the centre of the computer screen. In the alcohol group, participants received an alcohol dose of 0.4 g/kg so as to produce a blood alcohol concentration (BAC) in the range of 0.08% during the experiments. The spatial distribution of RTs was analysed graphically with geostatistical methods and statistically through analysis of variance of particular regions of the visual field. Results showed that controls were able to direct their attention tightly towards the centre (Expt I) and also to divide attention (Expt II) to the right and left. Participants in the alcohol group fixed their attention more diffusely in the centre (Expt I) and were unable to disengage attention from the centre in Experiment II. We conclude that acute alcohol intoxication impairs the ability to dissociate attention from gaze.

Inhibition or facilitation of return: Does chromatic component count?

Inhibitory effects have been reported when a target is preceded by a cue of the same color and location. Color-based inhibition was found using red and blue nonisoluminant stimuli (Law et al., 1995). Here we investigate whether this phenomenon depends on the chromatic subsystem involved by employing isoluminant colors varying along either the violet-yellow or purple-turquoise cardinal axis. Experiment 1 replicated Law et al.'s study: After fixating magenta, either a red or blue cue was presented, followed by a magenta "neutral attractor," and, finally, by a red or blue target. In Experiment 2, violet and yellow, cue or target, varied along a tritan confusion line in the CIE 1976 chromaticity diagram. In Experiment 3, purple and turquoise, cue or target, varied along a deutan confusion line in the CIE 1976 chromaticity diagram. Normal trichromats (n = 19) participated in all three experiments. In Experiment 1, color repetition indeed resulted in longer reaction times (RTs) (4.7 ms, P = 0.038). In Experiment 2, however, no significant color repetition effect was found; RTs to violet and yellow were not significantly different, though tending toward slower responses (2 ms) for violet repetition but faster (5 ms) for yellow. Experiment 3 also showed no color repetition effect (P = 0.58); notably, RTs were overall faster for purple than for turquoise (22 ms, P 0.05), but faster for turquoise (7 ms, P > 0.05). These findings demonstrate that color repetition is not always inhibitory but may turn facilitatory depending on the colors employed. The results indicate that disengagement of attention is an unlikely mechanism to be the sole explanation of previously reported color-based inhibition of return. We suggest a complementary, perceptual explanation: response (dis)advantage depends on whether the stimuli are isoluminant and on the opponent chromatic subsystem involved. The choice of the colors employed and the cue-attractor-target constellation also may be of significance.

Olfaction and the homing ability of pigeons raised in a tropical area in Brazil.

Several workers have investigated the effect of anosmia on pigeon navigation in different geographical locations because it has been suggested that homing behavior is based on different cues, such as olfactory cues, the Earth's magnetic field or infrasound, and that in the absence of one cue another would be used. In this situation, no cue is universally indispensable, including olfactory ones. In order to extend such observations to a novel biome, we observed the behaviour of 192 young inexperienced birds raised in southeastern Brazil, a tropical area where olfactory tests had never been run before. The birds were released from eight symmetrically distributed sites 17 to 44 km from the loft. Half of these birds (experimentals) had been made temporarily anosmic by washing their olfactory mucosae with 4% solution of ZnSO4 the day before release, while controls were treated with Ringer solution. The results of release tests showed that anosmia totally impaired the navigational performance of experimental birds, which were unable to home from sites at relatively short distances from home (34-44 km) and whose pooled initial bearings produced a (negative) homeward component not significantly different from 0. Homing performance of controls was significantly better, and their pooled vanishing bearings had a significant homeward component, in spite of much scatter in individual releases. We conclude that pigeon homing in the study area depends on olfactory information, even though local environmental conditions in the interior of the State of Sao Paulo, as in several other parts of the world, do not appear to be as favorable as Italy for the development of efficient olfactory navigation.

Chediak-Higashi syndrome with parkinsonism.

Chediak-Higashi syndrome (CHS), typically presents with partial albinism and severe hematological abnormalities. About 10% of the patients have a mild adult form associated with various neurological manifestations. We describe the case of a 24-year-old woman with parkinsonism that responded well to antiparkinsonian drugs.

Dynamics of visual feedback in a laboratory simulation of a penalty kick.

Sport scientists have devoted relatively little attention to soccer penalty kicks, despite their decisive role in important competitions such as the World Cup. Two possible kicker strategies have been described: ignoring the goalkeeper action (open loop) or trying to react to the goalkeeper action (closed loop). We used a paradigm simulating a penalty kick in the laboratory to investigate the dynamics of the closed-loop strategy in these controlled conditions. The probability of correctly responding to the simulated goalkeeper motion as a function of time available followed a logistic curve. Kickers on average reached perfect performance only if the goalkeeper committed him or herself to one side about 400 ms before ball contact and showed chance performance if the goalkeeper motion occurred less than 150 ms before ball contact. Interestingly, coincidence judgement--another aspect of the laboratory responses--appeared to be affected for a much longer time (> 500 ms) than was needed to correctly determine laterality. The present study is meant as groundwork for experiments in more ecological conditions applicable to kickers and goalkeepers.