Fig. 1.

Brain regions involved in the perceptual tasks considered in this paper. Incoming stimuli are represented as neural firing in areas such as V1, S1 and SC. Areas MT, S2 and A1, which we analyse here, are the first areas where firing rate provides information allowing a decision on the presence of a percept of visual movement, altered skin vibration (“flutter”) frequency or the grouping of sounds (“tone stream segregation”). Subsequent areas may make the perceptual decision and generate motor output (note that although we show a pure feed-forward flow of information, in reality there are also reverse interactions between different areas which probably contribute to the perceptual decision). V1, primary visual cortex; S1, primary somatosensory cortex; SC, superior colliculus; MT, middle temporal area; S2, secondary somatosensory cortex; A1, primary auditory cortex; PFC, prefrontal cortex; LIP, lateral intraparietal area; PMv, ventral premotor area; IPS, intraparietal sulcus; STG, superior temporal gyrus; M1, primary motor cortex.