Reflections on the past two decades of neuroscience

| The first issue of Nature Reviews Neuroscience was published 20 years ago, in 2000. To mark this anniversary, in this Viewpoint article we asked a selection of researchers from across the field who have authored pieces published in the journal in recent years for their thoughts on notable and interesting developments in neuroscience, and particularly in their areas of the field, over the past two decades. They also provide some thoughts on current lines of research and questions that excite them. ViewpoinT Nature reviews | NEURoSCiENCE sensory pathways (for example, visual, somatosensory and auditory) have shown suppression of reafferent sensory information by motor-related inputs at higher levels of sensory processing, including in the cortex. Indeed, much of the sensory input that we experience in our everyday lives is reafferent as it is generated by our own behaviour. The brain’s ability to predict the sensory consequences of our actions and cognitive processing that is central to our subjective awareness of initiating and controlling our own volitional actions in the world (that is, our sense of agency). In this context, a fundamental question logically arises: how exactly does the brain actually predict the sensory consequences of our actions in a dynamically changing world? Two particularly exciting lines of research are currently addressing this question. First, emerging technologies including based on motor-related inputs is vital for both perceptual stability and accurate motor control. This computational strategy also provides the flexibility required for fine-tuning and updating relationships between motor signals and resultant sensory feedback in order to compensate for changes to our body or the environment. Furthermore, the ability to distinguish between sensory exafference and reafference is a hallmark of higher-level perceptual