The study of sensory systems is an extraordinarily broad subject that includes everything from the analysis of the molecules that initially interact with the sensory stimulus to the intricate processing that takes place in the cerebral cortex. It is therefore virtually impossible to do justice to the breadth of this discipline in the limited number of pages that constitute this special issue. So, instead of trying to be exhaustive, we chose a few topics that epitomize the recent progress in the different fields — from the cortical mechanisms of colour vision (p. 563) to the molecular mechanisms of temperature perception (p. 529). We trust that this collection captures the essence of sensory neuroscience, and illustrates the depth of our understanding of the workings of our senses.
In this regard, it is rather humbling to remind ourselves that, despite such profound insights on how the nervous system processes sensory stimuli, we still lack any comprehension of how this processing leads to a sensory experience. For example, although we have a good idea of how our brain processes a painful stimulus or the colour red, we can only speculate on how we ultimately experience pain or redness. The subjective element that forms part of such an experience is still beyond our grasp, and some scholars doubt that it is a tractable problem at all.
