Virtual Morris water maze: opportunities and challenges.

The ability to accurately recall locations and navigate our environment relies on multiple cognitive mechanisms. The behavioural and neural correlates of spatial navigation have been repeatedly examined using different types of mazes and tasks with animals. Accurate performances of many of these tasks have proven to depend on specific circuits and brain structures and some have become the standard test of memory in many disease models. With the introduction of virtual reality (VR) to neuroscience research, VR tasks have become a popular method of examining human spatial memory and navigation. However, the types of VR tasks used to examine navigation across laboratories appears to greatly differ, from open arena mazes and virtual towns to driving simulators. Here, we examined over 200 VR navigation papers, and found that the most popular task used is the virtual analogue of the Morris water maze (VWM). Although we highlight the many advantages of using the VWM task, there are also some major difficulties related to the widespread use of this behavioural method. Despite the task's popularity, we demonstrate an inconsistency of use - particularly with respect to the environmental setup and procedures. Using different versions of the virtual water maze makes replication of findings and comparison of results across researchers very difficult. We suggest the need for protocol and design standardisation, alongside other difficulties that need to be addressed, if the virtual water maze is to become the 'gold standard' for human spatial research similar to its animal counterpart.

Differences in Spatial Memory Recognition Due to Cognitive Style.

Field independence refers to the ability to perceive details from the surrounding context as a whole and to represent the environment by relying on an internal reference frame. Conversely, field dependence individuals tend to focus their attention on single environmental features analysing them individually. This cognitive style affects several visuo-spatial abilities including spatial memory. This study assesses both the effect of field independence and field dependence on performance displayed on virtual environments of different complexity. Forty young healthy individuals took part in this study. Participants performed the Embedded Figures Test for field independence or dependence assessment and a new spatial memory recognition test. The spatial memory recognition test demanded to memorize a green box location in a virtual room picture. Thereafter, during ten trials participants had to decide if a green box was located in the same position as in the sample picture. Five of the pictures were correct. The information available in the virtual room was manipulated. Hence, two different experimental conditions were tested: a virtual room containing all landmarks and a virtual room with only two cues. Accuracy and reaction time were registered. Analyses demonstrated that higher field independent individuals were related to better spatial memory performance in two landmarks condition and were faster in all landmark condition. In addition, men and women did not differ in their performance. These results suggested that cognitive style affects spatial memory performance and this phenomenon is modulated by environment complexity. This does not affect accuracy but time spent. Moreover, field dependent individuals are unable to organize the navigational field by relying on internal reference frames when few landmarks are available, and this causes them to commit more errors.

Spatial learning in a virtual reality-based task is altered in very preterm children.

Very preterm births prevent a complete development of the nervous system. The hippocampus is especially vulnerable in this population since the perinatal period is critical for its growth and development. Learning and memory abilities, like spatial memory, depend on the hippocampal integrity. In this study we applied virtual-reality-based tasks to assess spatial memory in a sample of 20 very preterm children of 7 and 8 years of age. Two different conditions of difficulty were used. Very preterm children performed poorly in the task in comparison with the control group. They committed more errors than controls searching for the rewarded positions. However, no significant differences were observed in the mean speed, an index of the motor abilities and joystick handling. These results suggest that the hippocampal function is affected in this sample. Nevertheless, other variables to consider are discussed.

[Eslicarbazepine acetate in clinical practice. Efficacy and safety results]. / Acetato de eslicarbazepina en la practica clinica. Resultados de eficacia y seguridad.

INTRODUCTION. Eslicarbazepine acetate (ESL) is a new antiepileptic drug (AED) licensed in Spain in February 2011 as an adjunctive therapy in adults with partial seizures with or without secondary generalization. Clinical trials with ESL have demonstrated acceptable efficacy and safety. AIM. To evaluate the results of ESL in our epilepsy unit during its first year of clinical experience with this AED. PATIENTS AND METHODS. We included all patients who started treatment with ESL at our epilepsy unit from March 2011 to May 2012. We collected the following variables: gender, aetiology of epilepsy, epileptogenic area, reason for switch to ESL, clinical response after initiation of ESL, adverse effects of ESL, refractoriness criteria and treatment discontinuation. A bivariate factor-to-factor correlation study was carried out to establish associations between the independent variables and the clinical response. RESULTS. We recruited 105 patients (51.4% male). 20,7% of patients remained seizure-free and 58.4% showed > 50% improvement after introduction of ESL. At 6 months, 18.1% had experienced some type of side effect, with cognitive disorders being the most common, and 11.5% had discontinued treatment. Combination with lacosamide proved to be significantly less effective in the control of seizures. Combination of ESL with the rest of sodium channel inhibitors was similar in efficacy to others combinations. CONCLUSIONS. ESL is a well-tolerated and effective AED when is used as adjunctive treatment with most of other AED in clinical practice.

Acetato de eslicarbazepina en la práctica clínica. Resultados de eficacia y seguridad / Eslicarbazepine acetate in clinical practice. Efficacy and safety results

Introducción. El acetato de eslicarbazepina (ESL) es un nuevo fármaco antiepiléptico aprobado en España en febrero de 2011 como tratamiento adyuvante en adultos con crisis parciales, con o sin generalización secundaria. Los ensayos clínicos con ESL han demostrado una aceptable eficacia y seguridad. Objetivo. Evaluar los resultados de la ESL tras el primer año de experiencia en la práctica clínica. Pacientes y métodos. Incluimos a todos los pacientes que, habiendo iniciado tratamiento con ESL entre marzo de 2011 y mayo de 2012 en nuestra unidad, habían completado los seis meses de tratamiento continuado. Se recogieron siete variables independientes clínicas y demográficas. Se realizó un análisis de correlación bivariante factor a factor para establecer las posibles asociaciones entre las variables independientes recogidas y la respuesta clínica. Resultados. Incluimos un total de 105 pacientes (el 51,4%, hombres). El 58,4% mostró una mejoría superior al 50% en el número de crisis tras la introducción de la ESL (el 20,7% quedó libre de crisis). Al cabo de seis meses, un 18,1% experimentó algún tipo de efecto adverso, siendo los más frecuentes las quejas cognitivas, y un 11,5% abandonó el tratamiento. La combinación con lacosamida mostró menos eficacia estadística en el control de las crisis que el resto de las combinaciones. La combinación de ESL con el resto de los inhibidores de los canales del sodio no mostró diferencias significativas de eficacia. Conclusiones. La ESL constituye un fármaco antiepiléptico con buena tolerancia, y con una tasa de efectos adversos y de retención aceptables cuando se usa en combinación con la mayoría de los antiepilépticos disponibles (AU)

Introduction. Eslicarbazepine acetate (ESL) is a new antiepileptic drug (AED) licensed in Spain in February 2011 as an adjunctive therapy in adults with partial seizures with or without secondary generalization. Clinical trials with ESL have demonstrated acceptable efficacy and safety. Aim. To evaluate the results of ESL in our epilepsy unit during its first year of clinical experience with this AED. Patients and methods. We included all patients who started treatment with ESL at our epilepsy unit from March 2011 to May 2012. We collected the following variables: gender, aetiology of epilepsy, epileptogenic area, reason for switch to ESL, clinical response after initiation of ESL, adverse effects of ESL, refractoriness criteria and treatment discontinuation. A bivariate factor-to-factor correlation study was carried out to establish associations between the independent variables and the clinical response. Results. We recruited 105 patients (51.4% male). 20,7% of patients remained seizure-free and 58.4% showed > 50% improvement after introduction of ESL. At 6 months, 18.1% had experienced some type of side effect, with cognitive disorders being the most common, and 11.5% had discontinued treatment. Combination with lacosamide proved to be significantly less effective in the control of seizures. Combination of ESL with the rest of sodium channel inhibitors was similar in efficacy to others combinations. Conclusions. ESL is a well-tolerated and effective AED when is used as adjunctive treatment with most of other AED in clinical practice (AU)

Acute and chronic ethanol intake: effects on spatial and non-spatial memory in rats.

Abusive alcohol consumption produces neuronal damage and biochemical alterations in the mammal brain followed by cognitive disturbances. In this work rats receiving chronic and acute alcohol intake were evaluated in a spontaneous delayed non-matching to sample/position test. Chronic alcohol-treated rats had free access to an aqueous ethanol solution as the only available liquid source from the postnatal day 21 to the end of experiment (postnatal day 90). Acute alcoholic animals received an injection of 2 g/kg ethanol solution once per week. Subjects were evaluated in two tests (object recognition and spatial recognition) based on the spontaneous delayed non-matching to sample or to position paradigm using delays of 1 min, 15 min and 60 min. Results showed that chronic and acute alcohol intake impairs the rats' performance in both tests. Moreover, chronic alcohol-treated rats were more altered than acute treated animals in both tasks. Our results support the idea that chronic and acute alcohol administration during postnatal development caused widespread brain damage resulting in behavioral disturbances and learning disabilities.

A virtual-based task to assess place avoidance in humans.

Spatial memory can be assessed by virtual reality-based tasks, some of them similar to those previously used in rodents. In this study a virtual place avoidance task was developed based on a rodent labyrinth to evaluate human spatial memory. The task required subjects to avoid in a virtual room a prohibited zone defined solely by distal cues, while they collected rewards. The size of the to-be-avoided area was used as an independent variable as well as the gender of the participants. Subjects displayed an adequate performance after a single 5-min trial, entering the prohibited area on very few occasions. Our results showed that the size of the prohibited zone can be used to adapt task difficulty to different populations. Moreover, males were faster than females. They collected more rewards and spent less time in the prohibited area. Data collected supports the spatial component of the task and the validity of this procedure for spatial memory assessment in human beings.

Virtual reality tasks disclose spatial memory alterations in fibromyalgia.

OBJECTIVE: The objective is to assess performance on virtual reality spatial memory tasks as well as classical neuropsychological tests in patients with fibromyalgia (FM). METHODS: Fifteen FM patients and fifteen healthy age- and education-matched controls performed the virtual versions of the Morris water maze and the hole board (a virtual version called Boxes room). All participants also completed a comprehensive neuropsychological evaluation that included measures of general intelligence, attention/working memory and visuospatial memory. RESULTS: Both virtual reality tasks were demonstrated to be sensitive to spatial memory alterations. FM patients performed significantly worse than controls in the spatial navigation tasks, showing significantly more errors than their matched controls, while no significant differences were found between patients and controls regarding standard neuropsychological testing. In addition, those FM patients with longer chronicity had lower auditory memory span, visuospatial memory and general intelligence within their group. CONCLUSION: These results are the first to demonstrate that there is a spatial learning deficit in people with FM, which suggest that the hippocampal system can be disturbed in this syndrome.

Bilateral and unilateral hippocampal inactivation did not differ in their effect on consolidation processes in the Morris water maze.

Consolidation processes were studied in the rat by using functional inactivation techniques. Previous results showed that unilateral hippocampal inactivation alters consolidation. It is not clear if bilateral treatments increase the impairment. Wistar rats were trained in the Morris water maze during 4 consecutive days. Subjects received saline or tetrodotoxin in the dorsal hippocampus 1 min after training. Results showed that bilateral as well as unilateral treatments impair consolidation to the same degree, as shown by the mean latency to reach the platform. In both cases, the impairment is only visible in the first trial of the session following the blockade.

Partial unilateral inactivation of the dorsal hippocampus impairs spatial memory in the MWM.

The hippocampus is one of the more widely studied structures related with spatial memory. In this study, we assessed the effect of unilateral inactivation of the dorsal hippocampus with tetrodotoxin (TTX) on the performance displayed by Wistar rats in the spatial version of the Morris water maze. In experiment 1, we injected into the dorsal hippocampus in two different groups of rats 1 microl of saline solution or 5 ng of TTX in 1 microl of saline each day immediately after the training during four consecutive days. This procedure blocked consolidation and impaired spatial memory in the TTX group. In experiment 2, a new group of subjects was trained in the Morris water maze for 8 days and was administered 1 microl of saline on day 7 (saline session) and TTX on day 8 (TTX session) into the dorsal hippocampus 40 min before the training. Only the treatment with TTX altered the retrieval of memories. These experiments showed that unilateral interventions on the dorsal hippocampus can affect consolidation as well as retrieval of well-established spatial memories.

Sex differences in the Morris water maze in young rats: temporal dimensions / Diferencias sexuales en el laberinto acuático de Morris en ratas jóvenes: dimensiones temporales

There are many factors affecting our memory. The lapse of time between the acquisition and retrieval of information seems to be crucial because the intervening consolidation processes make a lasting engram. In this study, spatial memory was tested in 30day-old male and female Wistar rats by increasing delays between the acquisition phase and the probe test in the Morris water maze. Three groups of female rats were assessed with 1min, 6h and 12h delays as well as a male group tested with a result of a 12h delay. Results of the probe test revealed an adequate performance in males but a tendency in females to search for the missing platform in an incorrect place when long delays had occurred after acquisition (between 6 to 12h delays). These results suggest that females form a weaker representation of the environment than males, and such representation may be altered over time (AU)

Existen muchos factores que influyen en nuestra memoria. El lapso de tiempo entre la adquisición y la recuperación de información parece ser crucial. En este estudio se evaluó en el laberinto de Morris la memoria espacial en ratas macho y hembra a los 30 días postnatales, modificando el intervalo entre la fase de adquisición y recuperación. Se utilizaron tres grupos de ratas hembra evaluadas con intervalos de 1 minuto, 6 horas y 12 horas y un grupo de ratas macho evaluadas 12 horas tras la adquisición. La prueba de recuerdo revela una ejecución adecuada en el grupo de ratas macho y una tendencia en las hembras a buscar la plataforma en un cuadrante incorrecto cuando se utilizan intervalos de 6 y 12 horas. Estos resultados sugieren que las hembras forman una representación del entorno más débil, que podría verse alterada más fácilmente que en machos con el paso del tiempo (AU)

Diurnal locomotor activity and oxidative metabolism of the suprachiasmatic nucleus in two models of hepatic insufficiency.

Subjects with hepatic cirrhosis develop alterations of several rhythmic behavioural and biochemical patterns. Since most cirrhotic patients combine portal hypertension and hepatic impairment, our work aims to assess the extent to which rhythmical changes can be due to hepatic insufficiency or portal hypertension. This was done using two experimental models in rats, portacaval shunt model (PC) and portal hypertension by a triple stenosing ligature of the portal vein (PH). We assess diurnal locomotor activity and determine the oxidative metabolism of the suprachiasmatic nucleus (SCN) by histochemical determination of cytochrome oxidase (COX). The results show that animals with PC have altered diurnal locomotor rhythm compared to control and PH rats (p<0.001). They also present lower COX activity in the SCN (p<0.05). We conclude that rhythmic alterations are due to hepatic insufficiency and not to portal hypertension.

Quemodectomas de la región cervicofacial / Chemodectomas of the cervicofacial region

Los quemodectomas son tumores poco frecuentes que se originan a partir de los tejidos del paraganglio, son generalmente benignos y presentan un gran componente vascular en su estructura. En el período entre 1980 y 1998 fueron atendidos en el Instituto Nacional de Oncología y Radiobiología un total de 28 casos de localización cervicofacial. Sólo 17 casos cumplieron con los requisitos para su análisis estadístico. La cirugía fue el tratamiento inicial de elección en 9 pacientes, y la radioterapia fue usada como tratamiento de elección en 5 casos. Un paciente recibió terapéutica combinada y 2 casos no recibieron ningún tratamiento. El control local fue obtenido en 10 de los 15 casos tratados con un seguimiento promedio de 6,2 años. La cirugía fue capaz de controlar todos los tumores del seno carotídeo pero con una alta morbilidad y muerte posoperatoria. De forma general esta serie es comparable con la literatura revisada, no obstante se necesitan más casos para obtener resultados estadísticos significativos

Quemodectomas de la región cervicofacial / Chemodectomas of the cervicofacial region

Los quemodectomas son tumores poco frecuentes que se originan a partir de los tejidos del paraganglio, son generalmente benignos y presentan un gran componente vascular en su estructura. En el período entre 1980 y 1998 fueron atendidos en el Instituto Nacional de Oncología y Radiobiología un total de 28 casos de localización cervicofacial. Sólo 17 casos cumplieron con los requisitos para su análisis estadístico. La cirugía fue el tratamiento inicial de elección en 9 pacientes, y la radioterapia fue usada como tratamiento de elección en 5 casos. Un paciente recibió terapéutica combinada y 2 casos no recibieron ningún tratamiento. El control local fue obtenido en 10 de los 15 casos tratados con un seguimiento promedio de 6,2 años. La cirugía fue capaz de controlar todos los tumores del seno carotídeo pero con una alta morbilidad y muerte posoperatoria. De forma general esta serie es comparable con la literatura revisada, no obstante se necesitan más casos para obtener resultados estadísticos significativos(AU)

Vaciamiento selectivo lateral para tratamiento electivo del cuello en cáncer laríngeo / Selective lateral dumping for elective treatment of the neck in laryngeal cancer

El vaciamiento selectivo lateral es una técnica quirúrgica diseñada para resecar los ganglios linfáticos en riesgo de metástasis subclínicas en el carcinoma de laringe e hipofaringe con ganglios clínicamente negativos donde la cirugía es el tratamiento de elección. Consiste en la exéresis de los niveles ganglionares II, III y IV homolaterales o bilaterales en dependencia de la localización tumoral. Las diferentes técnicas de vaciamientos selectivos se vienen popularizando desde hace algo más de una década y su aplicación está basada en trabajos clásicos que pusieron en evidencia los patrones de diseminación cervical de los carcinomas de vías aerodigestivas superiores en los años 70 y 80, con el objetivo de mantener buenos resultados oncológicos con mejores resultados estéticos y funcionales. Actualmente existen controversias sobre este tema en lo concerniente a sus indicaciones y resultados oncológicos. Con el avance de la investigación clínica los vaciamientos selectivos encontraran su papel en el tratamiento de los tumores de cabeza y cuello. En el manejo del cáncer laríngeo el vaciamiento selectivo lateral ha logrado reducir los índices de recurrencia regional pero no la supervivencia en la mayoría de las series. Nuestro trabajo es una revisión y análisis del estado actual de esta controversia. Se realiza además un breve bosquejo de la técnica quirúrgica

Vaciamiento selectivo lateral para tratamiento electivo del cuello en cáncer laríngeo / Selective lateral dumping for elective treatment of the neck in laryngeal cancer

El vaciamiento selectivo lateral es una técnica quirúrgica diseñada para resecar los ganglios linfáticos en riesgo de metástasis subclínicas en el carcinoma de laringe e hipofaringe con ganglios clínicamente negativos donde la cirugía es el tratamiento de elección. Consiste en la exéresis de los niveles ganglionares II, III y IV homolaterales o bilaterales en dependencia de la localización tumoral. Las diferentes técnicas de vaciamientos selectivos se vienen popularizando desde hace algo más de una década y su aplicación está basada en trabajos clásicos que pusieron en evidencia los patrones de diseminación cervical de los carcinomas de vías aerodigestivas superiores en los años 70 y 80, con el objetivo de mantener buenos resultados oncológicos con mejores resultados estéticos y funcionales. Actualmente existen controversias sobre este tema en lo concerniente a sus indicaciones y resultados oncológicos. Con el avance de la investigación clínica los vaciamientos selectivos encontraran su papel en el tratamiento de los tumores de cabeza y cuello. En el manejo del cáncer laríngeo el vaciamiento selectivo lateral ha logrado reducir los índices de recurrencia regional pero no la supervivencia en la mayoría de las series. Nuestro trabajo es una revisión y análisis del estado actual de esta controversia. Se realiza además un breve bosquejo de la técnica quirúrgica