The ‘when’ parietal pathway explored by lesion studies

The perception of events in space and time is at the root of our interactions with the environment. The precision with which we perceive visual events in time enables us to act upon objects with great accuracy and the loss of such functions due to brain lesions can be catastrophic. We outline a visual timing mechanism that deals with the trajectory of an object's existence across time, a crucial function when keeping track of multiple objects that temporally overlap or occur sequentially. Recent evidence suggests these functions are served by an extended network of areas, which we call the ‘when’ pathway. Here we show that the when pathway is distinct from and interacts with the well-established ‘where’ and ‘what’ pathways.