Ictal unilateral eye blinking and contralateral blink inhibition — A video-EEG study and review of the literature

AbstractIntroductionThere is limited information on ictal unilateral eye blinking (UEB) as a lateralizing sign in focal seizures. We identified two patients with UEB and propose a novel mechanism of UEB based on a review of the literature.Materials and methodsWe report on two patients with intractable focal epilepsy showing UEB among 269 consecutive patients undergoing noninvasive video-EEG monitoring from October 2011 to May 2013.ResultsUnilateral eye blinking was observed in 0.7% (two of 269) of our patients. Patient one had four focal seizures. Semiological signs in all of her seizures were impaired consciousness, bilateral eye blinking (BEB), and UEB on the right. During one seizure, BEB recurred after UEB with a higher blink frequency on the right. Patient two had ten focal seizures. Among them were one electrographic seizure and nine focal seizures with BEB (in 3/10) and UEB on the left (in 1/10 seizures, respectively). Both patients did not display any clonic activity of the face. In seizures with UEB, ictal EEG onset was observed over the ipsilateral frontotemporal region in both of the patients (over F8 in 2/4, Fp2-F8 in 1/4, Sp2-T2 in 1/4, and F7 in 1/1 seizures, respectively). Ictal pattern during UEB showed bilateral ictal activity (in 4/4) and ictal discharges over the ipsilateral frontal region (maximum over F3 in 1/1 seizure). Interictal EEG showed sharp waves over the same regions.DiscussionUnilateral eye blinking was ipsilateral to the frontotemporal ictal EEG pattern in both patients. The asymmetric blink frequency during BEB in patient one leads to the hypothesis that ictal UEB is caused by contralateral blink inhibition due to activation in frontotemporal cortical areas and mediated by trigeminal fibers

Resistance to eye opening in patients with disorders of consciousness

Introduction: Resistance to eye opening (REO) is a commonly encountered phenomenon in clinical practice. We aim to investigate whether REO is a sign of consciousness or a reflex in severely brain-injured patients. Methods: We recorded REO in chronic patients with disorders of consciousness during a multimodal diagnostic assessment. REO evaluations were performed daily in each patient and clinical diagnosis of unresponsive wakefulness syndrome (UWS), minimally conscious state with (MCS+) or without (MCS−) preserved language processing was made using the Coma Recovery Scale-Revised (CRS-R). Results: Out of 150 consecutive patients, 79 patients fit inclusion criteria. REO was seen in 19 patients (24.1%). At the group level, there was a significant relationship between the presence of REO and the level of consciousness. We also observed a difference in the repeatability of REO between patients in UWS, MCS− and MCS+. Out of 23 patients in UWS, six showed REO, in whom five showed atypical brain patterns activation. Conclusion: Our findings suggest a voluntary basis for REO and stress the need for multiple serial assessments of REO in these patients, especially since most patients show fluctuating levels of consciousness. © 2018 Springer-Verlag GmbH Germany, part of Springer Natur

Developing a methodology for manipulating spontaneous blinks.

While blinking is necessary for ocular protection and lubrication, people blink much more than is necessary for routine ocular maintenance. These extra, spontaneous blinks are extremely difficult to manipulate and thus, have remained somewhat of a mystery. In order to determine the effects of spontaneous blinks, a methodology to manipulate them naturally must be created. The aim of this study was to develop such methodology using videos of animated speakers displaying high and low blink rates, and determine whether this influenced participant blink rates. It was expected that watching videos of a speaker's face would manipulate blink rate. It was also expected that participants would imitate the speaker's blink timing and blink immediately after the speaker blinks, called blink entrainment. Participants watched four videos, two featuring an animated speaker with a high blink rate, and two featuring the same animated speaker with a low blink rate. In between the speaker videos, participants completed ten trials of several variations of a lexical decision task. The speaker videos provided instructions on how to complete each of these tasks. A Wilcoxon signed-rank test showed that the differences between participant blink rates across the high blink rate and the low blink rate were significant (Z = -3.16, p = .002). Participants blinked more frequently while watching the high blink rate videos than when watching the low blink rate videos. A Wilcoxon signed-rank test also showed a significant difference between entrainment blinks and non-entrainment blinks in the high blink rate condition (Z = -3.65, p = .001), and the low blink rate condition (Z = -2.21, p = .027). These results indicate that a standardized methodology for manipulating spontaneous blinks is possible. With the use of the animated speaker videos, spontaneous blinks can be manipulated

El sistema de neuronas espejo y su activación en movimientos coordinados complejos

INTRODUCCIÓN Durante la observación de los movimientos realizados por los demás, la información visual se integra con las representaciones motoras, somatosensoriales y los recuerdos cinestésicos correspondientes, así como con las representaciones de los objetivos internos, instrucciones y la preferencia en la realización del movimiento. Los procesos corticales subyacentes han sido evaluados en monos y en humanos a través de la neuroimagen. En conjunto, estos estudios apuntan a una "equivalencia funcional" o "representaciones motoras compartidas" entre los procesos corticales de la observación del movimiento y la ejecución, en consonancia con el concepto de un sistema innato de procesamiento de la percepción con la producción motora desarrollado por especies sociales para la comprensión de las acciones y las intenciones de los miembros del grupo en el que se encuentran o al que pertenecen. Las neuronas espejo no son neuronas especiales, sino neuronas que tienen la capacidad de funcionar como un espejo. Se comprobó que el sistema se activaba en los seres humanos, comprobando que un individuo mirando un movimiento activa las áreas premotoras como si él lo estuviese realizando. Las áreas de Brodmann que pertenecen a este sistema de neuronas espejo son: AB 4, 6, 40, 44, 45 OBJETIVOS Evaluar la actividad cerebral y la participación del sistema de neuronas espejo ante estímulos de imaginación y observación de movimientos coordinados complejos, empleando el electroencefalograma como método de análisis. Como objetivos específicos nos propusimos: Analizar la activación cerebral empleando la tomografía electromagnética de baja resolución determinando las áreas de mayor intensidad. Analizar las bandas donde se produce una mayor actividad en los procedimientos de imaginación y observación de los tres movimientos coordinados complejos propuestos. Analizar la actividad de las áreas vinculadas con el sistema de neuronas espejo y comprobar si la metodología propuesta es una alternativa para su evaluación. DISEÑO Y METODOLOGÍA El diseño del trabajo fue de tipo transversal, observacional y descriptivo, al buscar obtener datos descriptores de la muestras, eligiendo una serie de casos. Cuando se determinó la significancia de las diferencias en las muestras dependientes se realizó un diseño analítico, al buscar evaluar una presunta relación causal entre dos factores, por lo que se analizaron las relaciones entre las variables. La muestra estuvo formada por 41 voluntarios (30 mujeres y 11 hombres), estudiantes de fisioterapia, terapia ocupacional o del master universitario en neuro-rehabilitación de la Universidad Católica San Antonio de Murcia, con edades comprendidas entre los 18 y los 40 años (media= 24 años). El EEG fue registrado con 32 canales Neuronic equipo Medicid (Neuronic, Cuba, La Habana) (Fig. 5.8.) utilizando un electrocap estándar (Fig. 5.7.) de 10 a 20. Se utilizaron 32 canales (Fz, pFz, Cz, pCZ, Pz, Oz, Fp1, Fp2, F3, F4, F7, F8, PF3, PF4, pC3, C4, PC4, T1, T2, T3, T4, T3A, T4A, T5, T6, P3, P4, O1 y O2), seleccionando las bandas en las siguientes amplitudes, aunque nuestro estudio se centrará en las amplitudes entre los 8,12 y los 19 Hz: Delta: 1Hz ¿ 4Hz; Theta: 4,12Hz ¿ 8Hz; Alpha1: 8,12Hz ¿ 10Hz; Alpha2: 10,12Hz ¿ 13Hz; Beta: 13,12 ¿ 19Hz. A todos los sujetos se le realizaron 11 registros de EEG, atendiendo a los siguientes estados: A: Permanecer con los ojos cerrados. B: Permanecer con los ojos abiertos (EB). C: Imaginar con los ojos abiertos que se está levantando de la silla y sentándose sucesivamente. D: Observar un video de una persona que está levantándose y sentándose de la silla sucesivamente. E: Imaginar con los ojos abiertos que se está levantando de la silla y sentándose sucesivamente tras haber visto el video. F: Imaginar con los ojos abiertos que está andando. G: Observar un video de una persona que está andando. H: Imaginar con los ojos abiertos que está andando tras haber visto el video. I: Imaginar con los ojos abiertos que está haciendo el pino (equilibrio sobre las manos). J: Observar un video de una persona haciendo el pino. K: Imaginar con los ojos abiertos que está haciendo el pino (equilibrio sobre las manos) tras haber visto el video. Se realizó el registro, la edición, el análisis cuantitativo, la localización de fuentes (método LORETA (del inglés Low-resolution Electromagnetic Tomography), la visualización tomográfica y el análisis estadístico (prueba T2 de Hotelling). RESULTADOS Cuando analizamos la banda alpha1los análisis realizados entre el estado basal con ojos abiertos y las condiciones C, D, E y H. Entre las condiciones EB y F se hallaron unas diferencias significativas extremadamente concretas en las áreas de Brodmann (AB) 18. Las diferencias significativas de las soluciones LORETA entre EB y G muestran que el AB 9 y 11. Observamos en el análisis que aparece una proyección en las condiciones EB e I en el AB 19. Si la condición que comparamos con el EB la condición J se activa AB 9 y 46. También se compararon EB y K, obteniendo diferencias significativas en AB 18 y 19. Cuando analizamos la banda alpha 2 en las condiciones EB y A la actividad se produce en AB 17, 18 y 19. Cuando analizamos las condiciones EB y H se pudo comprobar como las diferencias significativas las encontramos en el lóbulo frontal del hemisferio derecho de AB 10, 38, 44, 45, 46. Cuando valoramos las diferencias significativas entre EB y K, y observamos la actividad de áreas como el AB 18 y el AB 19. En los análisis realizados en la banda beta aparecen diferencias significativas en las condiciones A, F, G, H, I, J y K. Comenzando con el análisis de las diferencias significativas de las condiciones EB y A, destacamos como en las bandas alpha el predominio de las actividades en el lóbulo occipital tiene un carácter unilateral dado que la actividad se concentra en el hemisferio derecho del AB 39 y de AB 11, 20, 27 y 40. Cuando valoramos las diferencias significativas entre EB y F observamos que aparece un solo área, el AB 40. Mayor cantidad de diferencias significativas encontramos cuando comparamos EB y G, donde las áreas AB 1, 3, 4, 21, 22,40, 42, 44 y 48 son las que más activación presentan. Las diferencias significativas entre EB y H se presentan en AB 1, 2, 3, 4, 5, 6, 7, 20, 22, 28, 35, 36, 43 y 44. Las diferencias significativas de las condiciones EB y J nos enseñan una actividad unilateral de AB 7, 18, 19, 39. En último lugar dentro de las diferencias significativas dependientes en la banda beta observamos que cuando comparamos las condiciones EB y K obtenemos todos los valores en un margen muy pequeño en AB 2, 3, 4, 6, 48. Si valoramos las diferencias significativas entre las condiciones C y E se observa que las diferencias se proyectan de modo bilateral, aunque el mapa de activación proyecta áreas de máximas intensidades en mayor cantidad en el hemisferio izquierdo en AB 2, 3, 4, 6, 8, 11, 22, 23, 36, 37, 40 y 48. Si comparamos las condiciones F y H se activan AB 6, 7, 8, 17, 18, 19, 23 y 44. Observamos, al analizar I y K que en las tres bandas se observan diferencias significativas en las AB 18 y AB 48, así como en las AB 2, 5, 8, 17, 21, 40, 43 y 46. CONCLUSIONES El uso del electroencefalograma, empleando la tomografía electromagnética de baja resolución es útil para detectar las áreas de máxima actividad en la corteza cerebral ante los procedimientos de imaginación y observación de dos de los tres movimientos coordinados complejos propuestos. La banda más activa en la descripción de las áreas que presentan máximas intensidades en las condiciones estudiadas es la beta El uso del electroencefalograma, empleando la tomografía electromagnética de baja resolución es útil para detectar la actividad en las áreas vinculadas con el sistema de neuronas espejo, en los tres movimientos coordinados complejos propuestos. El uso del video es útil para la activación del sistema de neuronas espejo, con actividad principal en las áreas motoras de las bandas alpha.MedicinaTerapia y Rehabilitació

Blinking and the Brain: Pathways and Pathology

A blink is a rapid bilateral eyelid closure and co-occurring eye movement. The eyes rotate down towards the tip of the nose and back up again. Seemingly, this generally unnoticed often repeated action is not very spectacular. However, if not for the occasional blink we would all be blind. A blink is an interesting phenomenon worth investigating. Through its role as a protective barrier for the eye and as a distributor of the eye’s tearfi lm, blinking is a necessity for our well-being but is also an important tool for neuroscience research and physicians. It is an extremely useful model to study motor performance, motor control, synaptic plasticity and is an excellent physiological instrument for the assessment of internal networks and nuclei [Nishimura, T. and Mori, K, 1996]. The blink rate, refl ex blink characteristics and learned blinks are the three main parameters that can be studied to this end. The blink rate is the frequency with which spontaneous blinks occur and can give information about the dopaminergic system [Karson 1988] and might even be usable as a measure of fatigue [Stern et al. 1994]. The refl ex blink is a rapid involuntary response evoked by external stimulation of the eye or eyelid. It has a protective function and is for instance used in research and physiological tests that use the blink to provide important information on the integrity of afferent and efferent pathways. However, important gaps remain in the knowledge of pathways underlying blinking, and aberrations in pathways or compensatory mechanisms are not fully understood. The learned blink is acquired during eyeblink or eyelid conditioning in which an involuntary blink-evoking stimulus is repeatedly combined with a neutral stimulus. After training the neutral stimulus can evoke the learned blink

Monitoring and predicting actions and their consequences in the human brain.

There is substantial evidence that our ability to monitor our actions is based on the use of an internal forward model that uses an efference copy of the motor command to predict the sensory consequences of an action. This prediction is used to attenuate the sensory consequences of our actions. There is accumulating evidence that our ability to understand and predict the actions of others and their consequences is based on the same systems that are involved in monitoring our own actions. This thesis describes a series of experiments investigating the neural mechanisms underlying our ability to monitor our actions and predict their sensory consequences, and our ability to understand and predict the actions of others. I describe two fMRI experiments investigating the neural mechanism underlying sensorimotor attenuation during eye-blinks. I find that the neural response to visual stimulation is actively suppressed during eye-blinks. Another two studies provide evidence that our ability to monitor the actions of others and their consequences is based on the same neural mechanisms that are involved in monitoring our own actions and predicting their sensory consequences. They also suggest that the mirror system acts in a predictive manner, anticipating the actions of others, rather than merely responding to sensory input. I also examine the possibility that, in addition to using our motor systems to understand the actions of others, we understand the sensations experienced by others by representing these sensations in our own sensory cortices. I find evidence of a touch mirror system, which responds to both the observation and experience of touch. Finally, I describe two electroencephalography experiments that shed light on the development of our ability to understand other people's actions, providing evidence for the early development and involvement of the mirror system in action observation and in predicting the sensory consequences of actions

An Investigation of Computer Vision Syndrome with Smart Devices

The overarching theme of the thesis was to investigate the association between smart device use and computer vision syndrome. The initial study designed and developed the Open Field Tear film Analyser (OFTA) enabling a continuous, real-time assessment of the tear film and blink characteristics during smart device use. The monocular OFTA prototype was validated and showed good intra- and inter-observer repeatability relative to the Oculus Keratograph 5M and Bausch and Lomb one position keratometer. Subsequently, tear osmolarity following engagement with reading and gaming tasks on smart device and paper platforms was investigated. Discrete measures of osmolarity pre- and post-engagement with the tasks were obtained with the TearLab osmometer; osmolarity values differed between platforms when participants were engaged in a gaming task but no such difference was observed with the reading task. In addition, the influence of repeated measurements on tear osmolarity was also explored. To simulate the habitual binocular viewing conditions normally associated with smart device use, the binocular OFTA was developed. The device was used to assess the tear film and blink characteristics whilst engaging with reading and gaming tasks on smart device and paper platforms. The results revealed differences in blink characteristics and non-invasive tear break up time between the different platforms and tasks assessed. In addition, the thesis also reports on an investigation examining the real-time accommodative response to various targets displayed on smart devices using an open-field autorefractor with a Badal lens system adaptation. The results showed that accommodative latency, accommodative lag, mean velocity of accommodation, speed of disaccommodation and mean velocity of disaccommodation varied across the different platforms. Through the use of validated subjective questionnaires and smartphone apps, the relationship between duration of smartphone use and symptoms of dry eye were examined. The findings of this study demonstrated that longer duration of smartphone and personal computer use were associated with higher risk of dry eyes as indicated by subjective questionnaire outcomes.Ministry of Higher Education, MalaysiaInternational Islamic University Malaysi