A CT-based study investigating the relationship between pedicle screw placement and stimulation threshold of compound muscle action potentials measured by intraoperative neurophysiological monitoring.

PURPOSE: Neurophysiological monitoring aims to improve the safety of pedicle screw placement, but few quantitative studies assess specificity and sensitivity. In this study, screw placement within the pedicle is measured (post-op CT scan, horizontal and vertical distance from the screw edge to the surface of the pedicle) and correlated with intraoperative neurophysiological stimulation thresholds. METHODS: A single surgeon placed 68 thoracic and 136 lumbar screws in 30 consecutive patients during instrumented fusion under EMG control. The female to male ratio was 1.6 and the average age was 61.3 years (SD 17.7). Radiological measurements, blinded to stimulation threshold, were done on reformatted CT reconstructions using OsiriX software. A standard deviation of the screw position of 2.8 mm was determined from pilot measurements, and a 1 mm of screw-pedicle edge distance was considered as a difference of interest (standardised difference of 0.35) leading to a power of the study of 75 % (significance level 0.05). RESULTS: Correct placement and stimulation thresholds above 10 mA were found in 71 % of screws. Twenty-two percent of screws caused cortical breach, 80 % of these had stimulation thresholds above 10 mA (sensitivity 20 %, specificity 90 %). True prediction of correct position of the screw was more frequent for lumbar than for thoracic screws. CONCLUSION: A screw stimulation threshold of >10 mA does not indicate correct pedicle screw placement. A hypothesised gradual decrease of screw stimulation thresholds was not observed as screw placement approaches the nerve root. Aside from a robust threshold of 2 mA indicating direct contact with nervous tissue, a secondary threshold appears to depend on patients' pathology and surgical conditions.

Soil Water Potentials and Capsicum annuum L. under Salinity

ABSTRACT Investigations into water potentials in the soil-plant system are of great relevance in environments with abiotic stresses, such as salinity and drought. An experiment was developed using bell pepper in a Neossolo Flúvico (Fluvent) irrigated with water of six levels of electrical conductivity (0, 1, 3, 5, 7 and 9 dS m-1) by using exclusively NaCl and by simulating the actual condition (using a mixture of salts). The treatments were arranged in a randomized block design, in a 6 × 2 factorial arrangement, with four replicates. Soil matric (Ψm) and osmotic (Ψo) potentials were determined 70 days after transplanting (DAT). Soil total potential was considered as the sum of Ψm and Ψo. Leaf water (obtained with the Scholander Chamber) and osmotic potentials were determined before sunrise (predawn) and at noon at 42 and 70 DAT. There were no significant differences between the salt sources used in the irrigation water for soil and plant water potentials. The supply of salts to the soil through irrigation water was the main factor responsible for the decrease in Ψo in the soil and in bell pepper leaves. The total potential of bell pepper at predawn reached values of -1.30 and -1.33 MPa at 42 and 70 DAT, respectively, when water of 9 dS m-1 was used in the irrigation. The total potential at noon reached -2.19 MPa. The soil subjected to the most saline treatment reached a water potential of -1.20 MPa at 70 DAT. There was no predawn equilibrium between the total water potentials of the soil and the plant, indicating that soil potential cannot be considered similar to that of the plant. The determination of the osmotic potential in the soil solution should not be neglected in saline soils, since it has strong influence on the calculation of the total potential.

The contributions of sensory dominance and attentional bias to cross-modal enhancement of visual cortex excitability.

Approaching or looming sounds (L-sounds) have been shown to selectively increase visual cortex excitability [Romei, V., Murray, M. M., Cappe, C., & Thut, G. Preperceptual and stimulus-selective enhancement of low-level human visual cortex excitability by sounds. Current Biology, 19, 1799-1805, 2009]. These cross-modal effects start at an early, preperceptual stage of sound processing and persist with increasing sound duration. Here, we identified individual factors contributing to cross-modal effects on visual cortex excitability and studied the persistence of effects after sound offset. To this end, we probed the impact of different L-sound velocities on phosphene perception postsound as a function of individual auditory versus visual preference/dominance using single-pulse TMS over the occipital pole. We found that the boosting of phosphene perception by L-sounds continued for several tens of milliseconds after the end of the L-sound and was temporally sensitive to different L-sound profiles (velocities). In addition, we found that this depended on an individual's preferred sensory modality (auditory vs. visual) as determined through a divided attention task (attentional preference), but not on their simple threshold detection level per sensory modality. Whereas individuals with "visual preference" showed enhanced phosphene perception irrespective of L-sound velocity, those with "auditory preference" showed differential peaks in phosphene perception whose delays after sound-offset followed the different L-sound velocity profiles. These novel findings suggest that looming signals modulate visual cortex excitability beyond sound duration possibly to support prompt identification and reaction to potentially dangerous approaching objects. The observed interindividual differences favor the idea that unlike early effects this late L-sound impact on visual cortex excitability is influenced by cross-modal attentional mechanisms rather than low-level sensory processes.

Pure sensory neuropathy in patients with primary Sjogren's syndrome: clinical, immunological and electromyographic findings

A pure sensory neuropathy caused by lymphocytic infiltration of the dorsal root ganglia has been reported in a few patients with Sjögren's syndrome. The clinical, immunological, and electromyographic findings of five patients with this type of neuropathy and primary Sjögren's syndrome were reviewed. Typical clinical indications were the presence of a chronic asymmetrical sensory deficit, initial disease in the hands with a predominant loss of the vibratory and joint position senses, and an association with Adie's pupil syndrome or trigeminal sensory neuropathy. The simultaneous impairment of the central and peripheral evoked cortical potentials suggested that there was a lesion of the neuronal cell body. The neuropathy preceded the diagnosis of Sjögren's syndrome in four patients. Four patients were positive for Ro antibodies, but systemic vasculitis or malignancy was not found after a mean follow up of six years. These findings indicate that in patients with a sensory neuropathy the diagnosis of Sjögren's syndrome has to be considered, even if the patient denies the presence of sicca symptoms, and that appropriate tests must be carried out.

Bilateral Sequential NAION: A Comparison of Visual Outcomes in Fellow Eyes Using Quantitative Analysis of Goldmann Visual Fields

Purpose: Previous studies of the visual outcome in bilateral non-arteritic anterior ischemic optic neuropathy (NAION) have yielded conflicting results, specifically regarding congruity between fellow eyes. Prior studies have used measures of acuity and computerized perimetry but none has compared Goldmann visual field outcomes between fellow eyes. In order to better define the concordance of visual loss in this condition, we reviewed our cases of bilateral sequential NAION, including measures of visual acuity, pupillary function and both pattern and severity of visual field loss.Methods: We performed a retrospective chart review of 102 patients with a diagnosis of bilateral sequential NAION. Of the 102 patients, 86 were included in the study for analysis of final visual outcome between the affected eyes. Visual function was assessed using visual acuity, Goldmann visual fields, color vision and RAPD. A quantitative total visual field score and score per quadrant was analyzed for each eye using the numerical Goldmann visual field scoring method previously described by Esterman and colleagues. Based upon these scores, we calculated the total deviation and pattern deviation between fellow eyes and between eyes of different patients. Statistical significance was determined using nonparametric tests.Results: A statistically significant correlation was found between fellow eyes for multiple parameters, including logMAR visual acuity (P = 0.0101), global visual field (P = 0.0001), superior visual field (P = 0.0001), and inferior visual field (P = 0.0001). In addition, the mean deviation of both total (P = 0.0000000007) and pattern (P = 0.000000004) deviation analyses was significantly less between fellow eyes ("intra"-eyes) than between eyes of different patients ("inter"-eyes).Conclusions: Visual function between fellow eyes showed a fair to moderate correlation that was statistically significant. The pattern of vision loss was also more similar in fellow eyes than between eyes of different patients. These results may help allow better prediction of visual outcome for the second eye in patients with NAION. These findings may also be useful for evaluating efficacy of therapeutic interventions.

Leitura de imagens, cultura visual e prática educativa

Quase tudo do pouco que sabemos sobre o conhecimento produzido nos chega pelos meios de informação e comunicação. Estes, por sua vez, também constroem imagens do mundo. Imagens para deleitar, entreter, vender, sugerindo o que devemos vestir, comer, aparentar, pensar. Em nossa sociedade contemporânea discute-se a necessidade de uma alfabetização visual, que se expressa em várias designações, como leitura de imagens e compreensão crítica da cultura visual. Freqüentes mudanças de expressões e conceitos dificultam o entendimento dessas propostas para o currículo escolar, assim como a própria definição do professor ou professora que será responsável por esse conhecimento e seu referencial teórico. Este artigo apresenta os conceitos que fundamentam as propostas da leitura de imagens e cultura visual, sinalizando suas proximidades e distâncias. Contrasta alguns referenciais teóricos da antropologia, arte, educação, história, sociologia, e sugere linhas de trabalho em ambientes de aprendizagem para que se possa refletir a permanente formação docente.

How the visual brain encodes and keeps track of time.

Time is embedded in any sensory experience: the movements of a dance, the rhythm of a piece of music, the words of a speaker are all examples of temporally structured sensory events. In humans, if and how visual cortices perform temporal processing remains unclear. Here we show that both primary visual cortex (V1) and extrastriate area V5/MT are causally involved in encoding and keeping time in memory and that this involvement is independent from low-level visual processing. Most importantly we demonstrate that V1 and V5/MT come into play simultaneously and seem to be functionally linked during interval encoding, whereas they operate serially (V1 followed by V5/MT) and seem to be independent while maintaining temporal information in working memory. These data help to refine our knowledge of the functional properties of human visual cortex, highlighting the contribution and the temporal dynamics of V1 and V5/MT in the processing of the temporal aspects of visual information.

Changes in volume, surface estimate, three-dimensional shape and total number of neurons of the human primary visual cortex from midgestation until old age.

Macroscopic features such as volume, surface estimate, thickness and caudorostral length of the human primary visual cortex (Brodman's area 17) of 46 human brains between midgestation and 93 years were studied by means of camera lucida drawings from serial frontal sections. Individual values were best fitted by a logistic function from midgestation to adulthood and by a regression line between adulthood and old age. Allometric functions were calculated to study developmental relationships between all the features. The three-dimensional shape of area 17 was also reconstructed from the serial sections in 15 cases and correlated with the sequence of morphological events. The sulcal pattern of area 17 begins to develop around 21 weeks of gestation but remains rather simple until birth, while it becomes more convoluted, particularly in the caudal part, during the postnatal period. Until birth, a large increase in cortical thickness (about 83% of its mean adult value) and caudorostral length (69%) produces a moderate increase in cortical volume (31%) and surface estimate (40%) of area 17. After birth, the cortical volume and surface undergo their maximum growth rate, in spite of a rather small increase in cortical thickness and caudorostral length. This is due to the development of the pattern of gyrification within and around the calcarine fissure. All macroscopic features have reached the mean adult value by the end of the first postnatal year. With aging, the only features to undergo significant regression are the cortical surface estimate and the caudorostral length. The total number of neurons in area 17 shows great interindividual variability at all ages. No decrease in the postnatal period or in aging could be demonstrated.

Us explico un conte? Ús de llibres il·lustrats per a la didàctica de l'educació visual i plàstica

L'objectiu d'aquest article és promoure la incorporació de llibres il-lustrats a l'espai docent, tot defensant la interacció entre escola i entorn. Amb aquesta intenció es presenta una experiència docent que es du a terme a les classes de Didàctica de l'Educació Visual i Plàstica (UB), en la formació inicial del professorat d'educació primària, que empra el llibre il-lustrat com a eina docent. Es tracta d'un corpus d'obres de gran qualitat, la temàtica dels quals està relacionada amb el fet artístic i la seva didàctica. Amb l'ús a les aules universitàries d'aquest tipus de llibres es volen aconseguir principalment tres objectius: donar-los a conèixer als futurs mestres per a la seva formació i perquè els puguin compartir amb els seus futurs alumnes a les aules d'Educació Primària; tractar temes específics de l'àrea de plàstica, i fomentar la reflexió sobre la pràctica docent o altres temes específics.

La didàctica de l'educació visual i plàstica, entre el discurs visual i el discurs estètic. La perversió del model

El presente trabajo es el resultado de un año de investigación de campo y de estudio bibliográfico, que se formalizó en un proyecto educativo dirigido a alumnos de 3 de secundaria en la área de educación visual y plástica. " Las manos" , título del proyecto, se presentó como una alternativa en la didáctica de la educación visual y plástica cuando se plantea desde un aprendizaje lineal, desde un modelo. El planteamiento consistió en potenciar la comprensión y expresión artísticas a partir de la interrelación de otras áreas de conocimiento con la visual y plástica para sensibilizar al alumno en la importancia que tiene el proceso en el acto creativo. Valorar el proceso facilitó la asimilación de conceptos como figuración, abstracción y síntesis tan importantes para entender el hecho artístico. La valoración positiva del proyecto no pretende contraponer dos metodologías diferentes: la lineal con modelos y la que se presenta en espiral, inductiva, con referentes que no tienen que ser necesariamente visuales. Las dos opciones pueden actuar en simbiosis siempre que el alumno sepa percibir el significado que quiere dar a su obra y que todo no quede en una pura representación decorativa.

Dins el bosc de la cultura visual. Apunts per a una actualització pedagògica

L'era de la comunicació acara la comunitat educativa davant de nous reptes, especialment en l'àmbit de la cultura visual. La cultura visual es manifesta avui arreu i no hi ha àmbit ni familiar ni social ni educatiu que no en participi. Més enllà de la visualització i experimentació d'alguns procediments artístics canònics, l'ensenyament de les arts visuals i plàstiques observa la necessitat d'ampliar el seu radi d'acció, reflexió i anàlisi de manera coparticipada. Un repàs a la trajectòria històrica de l'aprenentatge artístic dóna peu a algunes preguntes rellevants com ara, quins aprenentatges per a quines competències? Per a quina societat i amb quins instruments cal educar els infants? Quines inèrcies i teories s¿hereten del passat i quin lloc cal que tinguin en el futur? Quines aportacions cognitives o empíriques permetrien una renovació positiva en l'àmbit de l¿educació visual i plàstica? Són preguntes difícils però peremptòries si no es vol girar l'esquena a l'evidència dels canvis comunicatius i socials del nostre temps.