RESUMEN
The relationship between stimulus intensity and the probability of detecting the presence of the stimulus is described by the psychometrical function.The probabilistic nature of this relationship is based on the stochastic behaviour of sensory neural channels and sensory networks involved in perceptual processing (Kiang 1968). This study tries to establish a continuum of variability across different levels of integration in the central nervous system. Once the opening and closing times of ionic channels was simulated, a threshold to the collective behaviour of voltage-gated ionic channels was imposed in order to generate the spike train of a single neuron. Afterwards,the trains of spikes of different neurons were added up,simulating the activity of a sensory nerve. By adding the activity due to the stimulus to the spontaneous neural behaviour,the psychometric function was simulated using a thresholding approach.The results can replicate the stochastic resonance phenomenon, but also open up the possibility that attentional phenomena can be mediated not only by increasing neural activity (bursting or oscillatory),but also by increasing noise at the neural level.