Neuroplasticidad en personas con baja visión: locus preferente retinal y su potencial para la rehabilitación visual / Neuroplasticity in people with low vision: Neuroplasticity in people with low vision: preferred retinal locus and its potential for visual rehabilitation and its potential for visual rehabilitation

Visual rehabilitation in people with irreversible Low Vision (LV) aims to optimize the use of remaining vision to execute visual tasks. Conventional rehabilitation exploits the visual potential through training using the remaining visual function, with or without visual aids, to improve performance on specific tasks. However, there is no consensus about the impact of this approach in the long term and on the quality of life of patients. On the other hand, visual neuro-rehabilitation has long-term advantages that can be complementary to conventional strategies and is based on the generation of scotoma awareness and training in the systematic use of extrafoveal regions for fixation and for use as oculomotor reference. These regions called preferred retinal loci (PRL) are established spontaneously in the peripheral retina that still retain visual function and constitute evidence of a high degree of plasticity of the visual system. There is wide evidence of the efficacy of visual neuro-rehabilitation strategies on performance in specific visual tasks, but their impact on the overall visual performance and quality of life of patients is still pending. (AU)

What we see is how we are: New paradigms in visual research

As most sensory modalities, the visual system needs to deal with very fast changes in the environment. Instead of processing all sensory stimuli, the brain is able to construct a perceptual experience by combining selected sensory input with an ongoing internal activity. Thus, the study of visual perception needs to be approached by examining not only the physical properties of stimuli, but also the brain's ongoing dynamical states onto which these perturbations are imposed. At least three different models account for this internal dynamics. One model is based on cardinal cells where the activity of few cells by itself constitutes the neuronal correlate of perception, while a second model is based on a population coding that states that the neuronal correlate of perception requires distributed activity throughout many areas of the brain. A third proposition, known as the temporal correlation hypothesis states that the distributed neuronal populations that correlate with perception, are also defined by synchronization of the activity on a millisecond time scale. This would serve to encode contextual information by defining relations between the features of visual objects. If temporal properties of neural activity are important to establish the neural mechanisms of perception, then the study of appropriate dynamical stimuli should be instrumental to determine how these systems operate. The use of natural stimuli and natural behaviors such as free viewing, which features fast changes of internal brain states as seen by motor markers, is proposed as a new experimental paradigm to study visual perception.

Computadores en investigación biomédica II: control experimental, adquisición y almacenaje de datos / Computers in biomedical research II: experimental control and data acquisition and storage

During the last decade, there has been a significant increase in the use of computers in biomedical research. In particular, the use of these instruments in experimental control, as well as in the acquisition and storage of experimental data, has become universal. The current capacity of these machines enables the precise manipulation of many experimental variables and allows for very fast acquisition of data. In this article, we discuss the fundamentals of small personal computers and its use in experimental control and data acquisition. Further, we discuss technical aspects related to the management of measurement instrument's control and their technical limitations. Electrical recordings from the cerebral cortex are used as examples to illustrate the different aspect included in this article

Computadores en investigación biomédica: I análisis de señales bioeléctricas / Computers in biomedical research: I analysis of bioelectrical signals

A personal computer equipped with an analog-to-digital conversion card is able to input, store and display signals of biomedical interest. These signals can additionally be submitted to ad-hoc software for analysis and diagnosis. Data acquisition is based on the sampling of a signal at a given rate and amplitude resolution. The automation of signal processing conveys syntactic aspects (data transduction, conditioning and reduction); and semantic aspects (feature extraction to describe and characterize the signal and diagnostic classification). The analytical approach that is at the basis of computer programming allows for the successful resolution of apparently complex tasks. Two basic principles involved are the definition of simple fundamental functions that are then iterated and the modular subdivision of tasks. These two principles are illustrated, respectively, by presenting the algorithm that detects relevant elements for the analysis of a polysomnogram, and the task flow in systems that automate electrocardiographic reports