[Retrospective study of 48 cases of primary central nervous system lymphoma]. / Estudio retrospectivo de 48 casos de linfoma primario del sistema nervioso central.

Primary central nervous system lymphoma (PCNSL) is an infrequent form of non-Hodgkin lymphoma restricted to the CNS. More than 90% are type B and mainly affect patients aged 50-70 years. Immunodeficiency is the most important risk factor. The aim of our study was to evaluate the immune status, clinical presentation and findings in complementary studies of PCNSL patients. A retrospective analysis of 48 cases treated in our center between January 1992 and May 2015 was performed. Median age at diagnosis was 61 years (range 25-84); with male predominance (2.1:1). Forty one cases (85%) were immunocompetent patients. Brain MRI findings showed parenchymal involvement in 45 cases (94%), 43% with frontal lobe and 35% basal ganglia, 4% had meningeal involvement and 2% had ophthalmic involvement at diagnosis. Fifty-five percent had restricted signal on diffusion weighted imaging and contrast enhancement was found in 89%. Pyramidal syndrome was the main initial clinical manifestation (56%). There were abnormal findings in 62% of CSF samples, but in only 11.1% positive cytology results were detected. The most frequent type was diffuse large B-cell lymphoma (83%), being B-cell type the most common form between them (96%). In our series PCNSL was more frequent in immunocompetent elderly male subjects. At initial evaluation, clinical manifestations and MRI findings were variable. The initial suspicion of this entity would allow an early diagnosis, avoiding empirical treatments that may confuse or delay diagnosis.

[Subcutaneous immunoglobulin. Treatment in chronic inflammatory demyelinating polyradiculo-neuropathy]. / Inmunoglobulina subcutánea. Tratamiento en polineuropatía desmielinizante inflamatoria crónica.

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is an acquired disease that may affect nerve roots and peripheral nerves. Despite its low incidence, diagnosis is particularly important because there are different effective treatments. Human immunoglobulin is one of the mainstays of the treatment. Although there are few studies up to date, subcutaneous immunoglobulin (IgSC) has been proposed as an alternative to intravenous administration with similar efficacy. We present three cases with definite CIDP, classified according to the European Federation of Neurological Societies / Peripheral Nerve, Society (EFNS /PNS) criteria in which was used SCIgG as a treatment after success with the intravenous route. The Overall Neuropathy Limitations Scale (ONLS) was used to estimate the changes in the muscular strength before and after treatment.

Neuromagnetic imaging of cortical oscillations accompanying tactile stimulation.

We applied a new method of imaging frequency-specific changes in brain activity in humans during a finger brushing task in order to measure changes in cortical rhythms during tactile stimulation. Neuromagnetic recordings were conducted in five subjects using a whole-head MEG system during tactile stimulation of the right index finger, with or without visual feedback, and while viewing another individual's index finger being stimulated. Volumetric images of changes in source power relative to pre-stimulus baseline levels were computed with 2 mm resolution over the entire brain using a minimum-variance beamforming algorithm (synthetic aperture magnetometry). Onset of tactile stimulation produced a brief (200-300 ms) suppression of mu band (8-15 Hz) and beta band (15-30 Hz) cortical activity in the primary somatosensory and primary motor cortex, respectively, followed by a bilateral increase in beta band activity ('beta rebound') in motor cortex. This pattern of suppression/rebound was absent when subjects observed finger brushing or brushing motions without receiving stimulation. In contrast, these conditions resulted in bilateral increases in beta band activity in sensorimotor areas and decreased power in the alpha (8-12 Hz) band in primary visual areas. These results show that spatially filtered MEG provides a useful method for directly imaging the temporal sequence of changes in cortical rhythms during transient tactile stimulation, and provide evidence that observation of tactile input to another individual's hand, or object motion itself, can influence independent rhythmic activity in visual and sensorimotor cortex.

Estimation of neural dynamics from MEG/EEG cortical current density maps: application to the reconstruction of large-scale cortical synchrony.

There is a growing interest in elucidating the role of specific patterns of neural dynamics--such as transient synchronization between distant cell assemblies--in brain functions. Magnetoencephalography (MEG)/electroencephalography (EEG) recordings consist in the spatial integration of the activity from large and multiple remotely located populations of neurons. Massive diffusive effects and poor signal-to-noise ratio (SNR) preclude the proper estimation of indices related to cortical dynamics from nonaveraged MEG/EEG surface recordings. Source localization from MEG/EEG surface recordings with its excellent time resolution could contribute to a better understanding of the working brain. We propose a robust and original approach to the MEG/EEG distributed inverse problem to better estimate neural dynamics of cortical sources. For this, the surrogate data method is introduced in the MEG/EEG inverse problem framework. We apply this approach on nonaveraged data with poor SNR using the minimum norm estimator and find source localization results weakly sensitive to noise. Surrogates allow the reduction of the source space in order to reconstruct MEG/EEG data with reduced biases in both source localization and time-series dynamics. Monte Carlo simulations and results obtained from real MEG data indicate it is possible to estimate non invasively an important part of cortical source locations and dynamic and, therefore, to reveal brain functional networks.

Estudio restrospectivo de 48 casos de linfoma primario del sistema nervioso central / Retrospective study of 48 cases of primary central nervous system lymphoma

Los linfomas primarios del sistema nervioso central (LPSNC) son neoplasias infrecuentes confinadas al SNC. Más del 90% son de tipo B y afectan principalmente a pacientes entre 50-70 años. La inmunodeficiencia es el factor de riesgo más importante. El objetivo de nuestro trabajo fue evaluar las características demográficas, estado inmunológico y los hallazgos en los estudios complementarios de pacientes con LPSNC. Se realizó el análisis retrospectivo de 48 casos estudiados en nuestro centro desde enero 1992 a mayo 2015. La edad mediana de presentación fue 61 años (25-84); la relación hombre:mujer 2.1:1. El 85% (41 casos) fueron inmunocompetentes al momento del diagnóstico. El 94% (45 casos) tuvo compromiso parenquimatoso, 4% (2 casos) meníngeo y 2% (1 caso) ocular. El lóbulo más afectado fue el frontal (43%) y 35% tuvieron compromiso ganglio basal. En RM, el 89% mostró realce con contraste y 55% restricción en difusión. El síndrome piramidal fue la manifestación inicial más frecuente (56%). El LCR fue inflamatorio en el 72%, aunque solo 11.1% presentó examen citológico positivo. El tipo más frecuente de LPSNC fue no-Hodgkin B (96%) y el subtipo difuso de células grandes el más habitual (83%). En nuestra serie la ausencia de inmunocompromiso fue una característica frecuente y la presentación clínico-radiológica fue muy pleomórfica. La sospecha inicial permitiría arribar a un diagnóstico temprano, evitando tratamientos empíricos que puedan confundir o retrasar el diagnóstico.

Primary central nervous system lymphoma (PCNSL) is an infrequent form of non-Hodgkin lymphoma restricted to the CNS. More than 90% are type B and mainly affect patients aged 50-70 years. Immunodeficiency is the most important risk factor. The aim of our study was to evaluate the immune status, clinical presentation and findings in complementary studies of PCNSL patients. A retrospective analysis of 48 cases treated in our center between January 1992 and May 2015 was performed. Median age at diagnosis was 61 years (range 25-84); with male predominance (2.1:1). Forty one cases (85%) were immunocompetent patients. Brain MRI findings showed parenchymal involvement in 45 cases (94%), 43% with frontal lobe and 35% basal ganglia, 4% had meningeal involvement and 2% had ophthalmic involvement at diagnosis. Fifty-five percent had restricted signal on diffusion weighted imaging and contrast enhancement was found in 89%. Pyramidal syndrome was the main initial clinical manifestation (56%). There were abnormal findings in 62% of CSF samples, but in only 11.1% positive cytology results were detected. The most frequent type was diffuse large B-cell lymphoma (83%), being B-cell type the most common form between them (96%). In our series PCNSL was more frequent in immunocompetent elderly male subjects. At initial evaluation, clinical manifestations and MRI findings were variable. The initial suspicion of this entity would allow an early diagnosis, avoiding empirical treatments that may confuse or delay diagnosis.

Inmunoglobulina subcutánea: Tratamiento en polineuropatía desmielinizante inflamatoria crónica / Subcutaneous immunoglobulin. Treatment in chronic inflammatory demyelinating polyradiculo-neuropathy

La polineuropatía desmielinizante inflamatoria crónica (CIDP) es una enfermedad adquirida que puede afectar a raíces, plexos y nervios periféricos. A pesar de su baja incidencia, su diagnóstico cobra especial relevancia dado que actualmente existen tratamientos efectivos para la misma. La gammaglobulina humana endovenosa (IVIgG) es, junto con los esteroides y la plasmaféresis, uno de los tratamientos de primera elección. La vía de administración subcutánea se ha propuesto como una alternativa novedosa frente a la administración endovenosa con una eficacia similar. Presentamos tres casos de CIDP definitiva, clasificados según los criterios de la European Federation of Neurological Societies/Peripheral Nerve Society (EFNS/PNS) en los cuales se utilizó tratamiento crónico con inmunoglobulina subcutánea (IgSC). Todos ellos habían recibido tratamiento previo con IVIgG. Se obtuvo mejoría de la fuerza evaluada por Overall Neuropathy Limitations Scale (ONLS) y los tres pacientes manifestaron una mejor adaptación a sus actividades de la vida diaria.

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is an acquired disease that may affect nerve roots and peripheral nerves. Despite its low incidence, diagnosis is particularly important because there are different effective treatments. Human immunoglobulin is one of the mainstays of the treatment. Although there are few studies up to date, subcutaneous immunoglobulin (IgSC) has been proposed as an alternative to intravenous administration with similar efficacy. We present three cases with definite CIDP, classified according to the European Federation of Neurological Societies / Peripheral Nerve, Society (EFNS /PNS) criteria in which was used SCIgG as a treatment after success with the intravenous route. The Overall Neuropathy Limitations Scale (ONLS) was used to estimate the changes in the muscular strength before and after treatment.

Color vision in the comb frequency domain.

In 1982, Horace Barlow considered the question of human trichromacy in the context of information theory: according to the Sampling Theorem, three types of receptors covering the visible spectrum (400-700 nm) might be sufficient to reconstruct the color signal. Although Barlow was led to reject the direct application of the Sampling Theorem to explain color dimensionality, the theoretical framework offers a fresh point of view for analyzing the color system in conjunction with the physical characteristics of natural color signals. This review aims to illustrate that if the strict mathematical reconstruction (as implied by the Sampling Theorem) is replaced by a pragmatic approximation of color signals, then trichromacy, with its subsequent opponent-color process, could be regarded as an optimization of color constancy abilities in the spectral environment of primates. Higher dimension systems (tetrachromacy) found in other species can also serve the purpose of color constancy optimization in environments where color signals exhibit a finer spectral structure.

Radical embodiment: neural dynamics and consciousness.

We propose a new approach to the neuroscience of consciousness, growing out of the 'enactive' viewpoint in cognitive science. This approach aims to map the neural substrates of consciousness at the level of large-scale, emergent and transient dynamical patterns of brain activity (rather than at the level of particular circuits or classes of neurons), and it suggests that the processes crucial for consciousness cut across the brain-body-world divisions, rather than being brain-bound neural events. Whereas standard approaches to the neural correlates of consciousness have assumed a one-way causal-explanatory relationship between internal neural representational systems and the contents of consciousness, our approach allows for theories and hypotheses about the two-way or reciprocal relationship between embodied conscious states and local neuronal activity.

Toward a neurodynamical understanding of ictogenesis.

Although considerable information on cellular and network mechanisms of epilepsy exists, it is still not understood why, how, and when the transition from interictal to ictal state takes place. The authors review their work on nonlinear EEG analysis and provide consistent evidences that dynamical changes in the neural activity allows the characterization of a preictal state several minutes before seizure onset. This new neurodynamical approach of ictogenesis opens new perspectives for studying the basic mechanisms in epilepsy as well as for possible therapeutic interventions.

Guiding the study of brain dynamics by using first-person data: synchrony patterns correlate with ongoing conscious states during a simple visual task.

Even during well-calibrated cognitive tasks, successive brain responses to repeated identical stimulations are highly variable. The source of this variability is believed to reside mainly in fluctuations of the subject's cognitive "context" defined by his/her attentive state, spontaneous thought process, strategy to carry out the task, and so on... As these factors are hard to manipulate precisely, they are usually not controlled, and the variability is discarded by averaging techniques. We combined first-person data and the analysis of neural processes to reduce such noise. We presented the subjects with a three-dimensional illusion and recorded their electrical brain activity and their own report about their cognitive context. Trials were clustered according to these first-person data, and separate dynamical analyses were conducted for each cluster. We found that (i) characteristic patterns of endogenous synchrony appeared in frontal electrodes before stimulation. These patterns depended on the degree of preparation and the immediacy of perception as verbally reported. (ii) These patterns were stable for several recordings. (iii) Preparatory states modulate both the behavioral performance and the evoked and induced synchronous patterns that follow. (iv) These results indicated that first-person data can be used to detect and interpret neural processes.