This research started with simulations of large arrays of coupled neurons in order to investigate under which conditions synchronous firing activity is obtained. Our results showed that the occurrence of firing synchrony can be triggered by changes in the excitability of the neurons in the visual cortex. Investigations of this transition from asynchronous to synchronous firing showed that the onset of firing synchrony is always accompanied by a marked increase of the firing frequency. Therefore, we have proposed that achieving firing synchrony between neurons processing the same object might be a mechanism to increase the contrast between the object and its background. The notion that excitable neurons can synchronize their firing activity rapidly is important for understanding its role in visual processing, especially in such tasks as visual tracking.
Visual tracking requires fast responses to constantly changing visual inputs.
The figure shows a typical simulation of neuronal firing activity. The neurons initially fire at a moderate frequency. At about one third through the simulation, the excitability of the neurons is increased. The neurons thereupon start to fire synchronously. The uppermost trace shows a measure for the firing correlation among the neurons.