Juan Santos

Recruitment of Occipital Cortex during Sensory Substitution Training Linked to Subjective Experience of Seeing in People with Blindness

Over three months of intensive training with a tactile stimulation device, 18 blind and 10 blindfolded seeing subjects improved in their ability to identify geometric figures by touch. Seven blind subjects spontaneously reported ‘visual qualia’, the subjective sensation of seeing flashes of light congruent with tactile stimuli. In the latter subjects tactile stimulation evoked activation of occipital cortex on electroencephalography (EEG). None of the blind subjects who failed to experience visual qualia, despite identical tactile stimulation training, showed EEG recruitment of occipital cortex. None of the blindfolded seeing humans reported visual-like sensations during tactile stimulation. These findings support the notion that the conscious experience of seeing is linked to the activation of occipital brain regions in people with blindness. Moreover, the findings indicate that provision of visual information can be achieved through non-visual sensory modalities which may help to minimize the disability of blind individuals, affording them some degree of object recognition and navigation aid.

How many fish need to be measured to effectively evaluate trawl selectivity

The aim of this study was to provide practitioners working with trawl selectivity with general and easily understandable guidelines regarding the fish sampling effort necessary during sea trials. In particular, we focused on how many fish would need to be caught and length measured in a trawl haul in order to assess the selectivity parameters of the trawl at a designated uncertainty level. We also investigated the dependency of this uncertainty level on the experimental method used to collect data and on the potential effects of factors such as the size structure in the catch relative to the size selection of the gear. We based this study on simulated data created from two different fisheries: the Barents Sea cod (Gadus morhua) trawl fishery and the Mediterranean Sea multispecies trawl fishery represented by red mullet (Mullus barbatus). We used these two completely different fisheries to obtain results that can be used as general guidelines for other fisheries. We found that the uncertainty in the selection parameters decreased with increasing number of fish measured and that this relationship could be described by a power model. The sampling effort needed to achieve a specific uncertainty level for the selection parameters was always lower for the covered codend method compared to the paired-gear method. In many cases, the number of fish that would need to be measured to maintain a specific uncertainty level was around 10 times higher for the paired-gear method than for the covered codend method. The trends observed for the effect of sampling effort in the two fishery cases investigated were similar; therefore the guidelines presented herein should be applicable to other fisheries.

Occipital cortex activation by long-term repetitive tactile stimulation is necessary for object recognition in blinds: A case report

Tactile vision has been approached from a variety of angles using different techniques. So far, a certain kind of object (and text) recognition has been shown, though seeing as such has not been achieved yet, and it remains unclear. Trough repetitive passive tactile stimulation perceptual processing is transferred from temporo-parietal to occipital areas, which affects object recognition. We report the results of passive tactile stimulation, as well as rTMS, applied to a 50 year old left handed blind male with over 97% loss of vision, who suffers from Peter’s anomaly and microphthalmia. After 15 weeks of passive tactile stimulation, the subject showed increased activity in occipital areas associated with the development of visual-like perception which remained unchanged after three months without passive tactile stimulation. Inhibitory rTMS over the visual cortex led to noticeable reduction of spatial recognition performance and visual sensations in this subject. Stable changes in occipital cortical activity can be associated with subjective sensations of seeing. Once occipital activation has been achieved, it is necessary for spatial object recognition. Both facts highlight the implication of occipital areas in tactile vision and the cortical plasticity of passive tactile long-term stimulation in people with blindness.

Brain cortical organization in entrepreneurs during a visual stroop decision task

Decision-making in entrepreneurs is a key aspect of their skills, but much about these processes remains unexplained. During a Stroop task, concomitant N200, P300, and N450 event- related potentials were measured in 25 founder entrepreneurs and in age-matched and gender- matched nonfounders/nonentrepreneurs (NFNE). Reaction times were shorter among founder entrepreneurs. The N200 was shorter and N450 larger in founder entrepreneurs. The personali- ties of both groups were measured using the Temperament and Character Inventory-Revised. Founder entrepreneurs scored significantly higher in novelty-seeking and self-directedness dimensions, as well as in exploratory excitability, impulsiveness, optimism, eagerness, and responsibility subdimensions. Possible interactions among candidate variables to differentiate between founder entrepreneurs versus NFNE were also addressed, and the model including impulsivity, N450 latency, and impulsivity*N450 interaction came up as the best model for discrimination between founder entrepreneurs and NFNE. A shorter N200, mostly associated with bilateral supplementary motor area activation, revealed a faster capability to make deci- sions when information was noncongruent or blurred. However, the larger N450 revealed a more intense post-evaluation cognitive process happening in founder entrepreneurs and was accompanied by a greater activation of anterior frontal regions. The whole decision-making process consumed more time and resources in founder entrepreneurs, even if its closure was faster. Attention, memory, and alertness, among other factors, have been invoked to explain some of these differences. Founder entrepreneurs may have cognitive and heuristic differences compared with the general population.

Predictive framework for codend size selection of brown shrimp (Crangon crangon) in the North Sea beam-trawl fishery

The brown shrimp (Crangon crangon) fishery is of great socio-economic importance to coastal communities on the North Sea. The fishery is exploited by beam trawlers often using codends with very small mesh sizes, leading to concerns about catch rates of undersized shrimp. However, little information is available on codend size selection, making it difficult to provide scientifically based advice on alternative codend designs. Therefore, this study establishes a predictive framework for codend size selection of brown shrimp, based on a large selectivity dataset from 33 different codend designs tested during four experimental fishing cruises, during which more than 350,000 brown shrimp were length measured. Predictions by the framework confirm concerns about the exploitation pattern in the fishery, because the retention probability of undersized shrimp reaches 95% with the currently applied designs. The framework predictions allow the exploration of obtainable exploitation patterns depending on codend design. For example, increasing codend mesh size to 25–29 mm would reduce the retention rate of undersized shrimp to a maximum of 50%, depending on codend mesh type.

MEG resting-state differences as a marker of clinical subtype in schizophrenia

A resting-state magnetoencephalography (MEG) can discriminate different subtypes of schizophrenia. We studied a sample of 45 male patients (age range was 27 to 55 years old) with schizophrenia diagnosis from San Juan de Dios Hospital (Ciempozuelos, Madrid, Spain) equally distributed among paranoid (n=15), residual (n=15) and disorganized (n=15) subtypes according to the Structured Clinical Interview for DSM-III-R Axis I Disorders (SCID-I). Healthy controls (N=20) are males, matched by age and sex at the Magnetoencefalografie Center “Dr. Perez-Modrego” (Madrid, Spain), without current or past neurological and/or psychiatric illness of any sort, including substance abuse. When we estimated the ability of the predominant symptom dimensions to segregate the resting MEG amplitude profiles using canonical discriminant analysis, three discriminant functions DF) were extracted, explaining 52% (χ2=584.291, p<0.000), 25% (χ2=323.354, p=0.115) and 22% (χ2=155.037, p=0.289) of the total variance respectively. Our findings are consistent with the idea that clinical dimensions of schizophrenia derived from the predominant clinical syndrome are an expression of specific dysfunction of the brain subsystems of the default network.

Desigualdades en mortalidad total y por causa de muerte según el nivel de estudios en Navarra: hallazgos de un estudio longitudinal 2001-2008

Fundamentos: Dada la ausencia de evidencia cientifica, el objetivo fue mostrar las desigualdades en mortalidad segun el nivel de estudios en Navarra y la contribucion de las principales causas de defuncion a la magnitud de desigualdades en la mortalidad por todas las causas de muerte. Metodos: Todos los ciudadanos de 25 anos y mayores residentes en Navarra en 2001 fueron seguidos durante 7 anos para conocer su estado vital. El indicador de posicion socioeconomica utilizado fue el nivel de estudios. Se estimaron las tasas de mortalidad general y por causa de muerte ajustadas por edad segun la educacion. Posteriormente, se calcularon la diferencia relativa (razon) y la diferencia absoluta de tasas entre las categorias mas baja y mas alta de nivel de estudios y la contribucion de las principales causas de muerte a la diferencia absoluta. Resultados: La razon de tasas por todas las causas de muerte fue 1,37 en hombres y 1,23 en mujeres. El virus de la inmunodeficiencia humana (VIH) (25,84) y los accidentes no intencionales (3,78) presentaron las razones de tasas mas altas en los hombres y la diabetes mellitus (4,92) y el VIH (4,38) en las mujeres. Las enfermedades cardiovasculares constituyeron la causa de muerte que mas contribuyo a la diferencia absoluta en mortalidad: 26% en hombres y 48% en mujeres. Conclusiones: La tasa de mortalidad en la poblacion navarra muestra un gradiente inverso con el nivel educativo, a excepcion de algunas localizaciones de cancer. Las enfermedades cardiovasculares son la causa de muerte que mas contribuye a las desigualdades absolutas en mortalidad, mientras que otras causas de muerte que muestran importantes desigualdades relativas contribuyen poco a las desigualdades absolutas.

Influencia de la mortalidad en las personas con bajo nivel educativo en la variación de las desigualdades de mortalidad en las comunidades autónomas

Background: Given the importance of mortality rates in each socioeconomic group, as explanation for the variation in mortality inequalities across populations, the objective of the present study is to evaluate whether regional variation in mortality inequalities in Spain is related to the mortality rates in different socioeconomic groups. Methods: The study included all persons aged 30-74 years living in Spain in 2001 and followed up for mortality over 7 years. In each of the 17 autonomous communities of Spain mortality rates were estimated for those with low and high education, as well as two measures of mortality inequality according to education: mortality rate difference and mortality rate ratio. Median value of mortality inequalities was calculated for the regions with the highest and lowest mortality rates and for those with intermediate mortality rates. And the Pearson correlation coefficient was used to estimate the relation between mortality rates and the measures of mortality inequality. Results: The correlation coefficients between mortality rate in low education and mortality rate difference and mortality rate ratio were 0.87 and 0.78 in women and 0.81 and 0.73 in men, respectively. The correlation coefficients between mortality rate in high education and mortality rate difference and mortality rate ratio were -0.07 and -0.24 in women and 0.10 and -0.06 in men, respectively. Conclusion: Regions with the lowest and highest mortality rates in low education people generally had the lowest and highest inequalities in mortality. The variation in the magnitude of inequalities in mortality from one place to another can be explained by the variation in mortality in low education people. No relation was observed between mortality rate in high education and mortality inequality