Cortical mechanisms specific to explicit visual object recognition

The cortical mechanisms associated with conscious object recognition were s tudied using functional magnetic resonance imaging (fMRI). Participants wer e required to recognize pictures of masked objects that were presented very briefly, randomly and repeatedly. This design yielded a gradual accomplish ment of successful recognition. Cortical activity in a ventrotemporal visua l region was linearly correlated with perception of object identity. Theref ore, although object recognition is rapid, awareness of an object's identit y is not a discrete phenomenon but rather associated with gradually increas ing cortical activity. Furthermore, the focus of the activity in the tempor al cortex shifted anteriorly as subjects reported an increased knowledge re garding identity. The results presented here provide new insights into the processes underlying explicit object recognition, as well as the analysis t hat takes place immediately before and after recognition is possible.