Seeking one's heading through eye movements

A study of eye movements during simulated travel toward a grove of four stationary trees revealed that observers looked most at pairs of trees that converged or decelerated apart. Such pairs specify that one's direction of travel, called heading, is to the outside of the near member of the pair. Observers looked at these trees more than those that accelerated apart; such pairs do not offer trustworthy heading information. Observers also looked at gaps between trees less often when they converged or diverged apart, and heading can never be between such pairs. Heading responses were in accord with eye movements. In general, if observers responded accurately, they had looked at trees that converged or decelerated apart; if they were inaccurate, they had not. Results support the notion that observers seek out their heading through eye movements, saccading to and fixating on the most informative locations in the field of view.

Effects of saccadic eye movements on postural control stabilization

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Saccadic and smooth pursuit eye movements attenuate postural sway similarly

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Effects of saccadic eye movements on postural control in older adults

Saccadic eye movements have been shown to affect posture by decreasing the magnitude of body sway in young adults. However, there is no evidence of how the search for visual information that occurs during eye movements affects postural control in older adults. The purpose of the present study was to determine the influence of saccadic eye movements on postural control in older adults while they stood on 2 different bases of support. Twelve older adults stood upright in 70-s trials under 2 stance conditions (wide and narrow) and 3 gaze conditions (fixation, saccadic eye movements at 0.5 Hz, and saccadic eye movements at 1.1 Hz). Head and trunk sway amplitude and mean sway frequency were measured in both the anterior/posterior (AP) and medial/lateral (ML) directions. The results showed that the amplitude of body sway was reduced during saccades compared with fixation, as previously observed in young adults. However, older adults exhibited similar sway amplitude and frequency in the AP direction under the wide and narrow stance conditions, which is different from observations in young adults, who display larger sway in a narrow stance compared with a wide stance while performing saccades. These results suggest that although older adults are affected by saccadic eye movements by a decrease in the amplitude of body sway, as observed in young adults, they present a more rigid postural control strategy that does not allow larger sway during a more challenging stance condition.

Monitorização vídeo-EEG prolongada em crises não epilépticas: semiologia clínica

O objetivo deste estudo foi mostrar a contribuição da monitorização vídeo-EEG prolongada (MVEP) no diagnóstico de crises não epilépticas (CNE) e estimar sua prevalência em um centro terciário de atendimento à Epilepsia (EP). Foram observados 47 pacientes com diagnóstico de CNE com crises espontâneas ou provocadas. Foram instituídos protocolos direcionados à história clínica e à semiologia das crises. A análise estatística baseou-se no teste de Fisher e na análise de cluster. Os resultados evidenciaram prevalência de 10% de CNE. Houve predominância do sexo feminino (63,8%); em 57% dos pacientes as crises foram espontâneas. A média de idade foi 32,5 ± 11anos. O sinal semiológico mais freqüente foi o sono aparente (87,2%). em 9% dos pacientes observaram-se tanto EP como CNE. Três agrupamentos resultaram da análise de cluster: CNE hipermotora das extremidades com alteração de tônus; CNE com automatismos e CNE axial com movimentos oculares. em conclusão, o estudo da semiologia clínica das CNE durante a MVEP contribui para o diagnóstico desta entidade nosológica e para o diagnóstico diferencial com EP; o teste provocativo auxilia na obtenção das crises.

Gaze pursuit and arm control of adolescent males diagnosed with attention deficit hyperactivity disorder (ADHD) and normal controls: evidence of a dissociation in processing visual information of short and long duration

Three-dimensional kinematic analysis of line of gaze, arm and ball was used to describe the visual and motor behaviour of male adolescents diagnosed with attention deficit hyperactivity disorder (ADHD). The ADHD participants were tested when both on (ADHD-On) and off (ADHD-Off) their medication and compared to age-matched normal controls in a modified table tennis task that required tracking the ball and hitting to cued right and left targets. Long-duration information was provided by a pre-cue, in which the target was illuminated approximately 2 s before the serve, and short-duration information by an early-cue illuminated about 350 ms after the serve, leaving -500 ms to select the target and perform the action. The ADHD groups differed significantly from the control group in both the pre-cue and early-cue conditions in being less accurate, in having a later onset and duration of pursuit tracking, and a higher frequency of gaze on and off the ball. The use of medication significantly reduced the gaze frequency of the ADHD participants, but surprisingly this did not lead to an increase in pursuit tracking, suggesting a barrier was reached beyond which ball flight information could not be processed. The control and ADHD groups did not differ in arm movement onset, duration and velocity in the short-duration early-cue condition; in the long-duration pre-cue condition, however, the ADHD group's movement time onset and arm velocity differed significantly from controls. The results show that the ADHD groups were able to process short-duration information without experiencing adverse effects on their motor behaviour; however, long-duration information contributed to irregular movement control.

Paranasal sinus infection causing orbital subperiosteal abscess: Surgical management of this devastating entity

Background: Orbital infection is an uncommon devastating infection and is usually a complication of paranasal sinus infection. Without appropriate treatment, orbital infection may lead to serious complications, even death. Prompt treatment is mandatory to avoid visual loss or intracranial complications. The literature shows that initially, intravenous antibiotics should be administered, and after 48 h, if no improvement appears, the affected orbit and the sinuses must be surgically drained. The authors describe two cases of orbital cellulitis with a brief literature review. Case report: The authors describe two cases of orbital abscess caused by paranasal sinus infection. In case 1, the patient presented a decreased visual acuity associated with ophthalmoplegia of the right eye. In case 2, the patient presented a decreased visual acuity. Thus, administration of intravenous antibiotic combined with surgical drainage was performed. After surgical procedure, eye movements were normalized in case 1, and in both patients, the visual acuity returned to normal parameters. Discussion: The authors recommend early surgical drainage with parenteral antibiotic administration and careful postoperative observations by monitoring the signs and symptoms of the orbital complaint. © 2012 Springer-Verlag.

Movimento dos olhos e controle postural

The control of stances such as the upright stance seems not to have a purpose in itself; this control could facilitate the execution of other simultaneous tasks, the so-called suprapostural tasks. The goal of this study was to determine the effects of saccadic eye movements on the control of posture. Twelve adult participants had their body oscillations analyzed while standing upright, for 70 s, in the postural conditions of feet apart and feet together, performing fixation in the central target or horizontal saccadic movements, in the conditions slow (0,5 Hz) and fast (1,1 Hz). The results showed that saccadic movements, independently of their frequency, strongly reduced trunk and head oscillations in the anterior-posterior (AP) axis. In this axis, there was an effect of feet position only in head oscillation. In the medio-lateral (ML) axis, the results showed a strong effect of feet position with body oscillation decreased in the condition of feet apart. The effect of the visual task in the ML axis occurred only for trunk oscillation, not reaching significance level in the pairewise comparisons. In the AP axis, the data corroborate a facilitatory explanation of the control of posture: the reduction in body oscillation limited the variations of the stimulus image projected on the retina, facilitating the execution of saccadic movements as compared to fixation. In the ML axis, the effect of reducing the basis of support was more evident than the effect of saccadic movements, suggesting that the available resources were used primarily for the postural task in detriment of the visual task. Additionally, aspects like attentional focus and sensory information pick up are discussed as mechanisms involved in this task

Aquisição da informação visual: controle da postura e do olhar

Postural control is needed to perform various daily activities, from staying in one posture, standing, to sports situations. Many studies have shown that sensory systems help to maintain posture stable; acquisition of perceptual information, particularly through head and eye movements, allows static and dynamic equilibrium. Research related to both motor behavior and physical activities such as gymnastics have contributed to a better understanding of complexities involved in human postural control. The purpose of this study was to review the related literature, searching for possible answers on how everyday and sports actions are performed, with respect to the control and maintenance of posture. Its focus was on how the human body acquires information from the sensory systems, vision in special, and how this information acts to support the control of posture and gaze

Influência de movimentos oculares sacádicos no equilíbrio postural de idosos praticantes de vôlei adaptado e idosos sedentários

Pós-graduação em Desenvolvimento Humano e Tecnologias - IBRC

Eye blink in newborn and preschool-age children

Purpose: To investigate the dynamics of ocular eyelid movements in newborn infants and preschool-age children.Methods: Fifty newborn infants and 200 preschool children aged 4-6 years were examined. Images of each child, with his or her eyes in the primary eye position looking at an object placed at the child's height, were recorded with a digital videocamera for 3 mins. Complete and incomplete blink rates, opening, closing and complete blink times were calculated.Results: Newborn infants presented a lower number of incomplete movements than preschool children. The complete blink rate was lower in newborn infants (6.2 blinks/min) than in preschool children (8.0 blinks/minute). Eyelid closing, opening and compete blink times were longer in newborn infants than in preschool children at all observation times.Conclusions: Newborn infants had a different pattern of eyelid movement compared with preschool children. Specific characteristics that are found in this group of children particularly, such as immaturity of the neural system and more resistant tear film, may explain these findings in part.

Head, eye and arm coordination in table tennis

The aim of this study was to determine the role of head, eye and arm movements during the execution of a table tennis forehand stroke. Three-dimensional kinematic analysis of line-of-gaze, arm and ball was used to describe visual and motor behaviour. Skilled and less skilled participants returned the ball to cued right or left target areas under three levels of temporal constraint: pre-, early- and late-cue conditions. In the pre- and early-cue conditions, both high and low skill participants tracked the ball early in flight and kept gaze stable on a location in advance of the ball before ball-bat contact. Skilled participants demonstrated an earlier onset of ball tracking and recorded higher performance accuracy than less skilled counterparts. The manipulation of cue condition showed the limits of adaptation to maintain accuracy on the target. Participants were able to accommodate the constraints imposed by the early-cue condition by using a shorter quiet eye duration, earlier quiet eye offset and reduced arm velocity at contact. In the late-cue condition, modifications to gaze, head and arm movements were not sufficient to preserve accuracy. The findings highlight the functional coupling between perception and action during time-constrained, goal-directed actions.