Neural correlates of categorization in monkeys

Perception is arguably the end product of a categorization process. We investigated the effects of categorization on the representation of stimulus features in combined psychophysical-electrophysiological experiments. We recorded from visual neurons in the anterior inferior temporal (IT) and the lateral prefrontal (PF) cortex of macaque monkeys, while they were performing a categorization task. We used parameterized line drawings of faces and fish as stimuli, and we varied the relevance of the different features for the task. Recently, we reported that the majority (>72) of the anterior IT feature selective neurons were tuned for features that were diagnostic for the categorization task (Sigala Logothetis, 2002, Nature). Moreover, we suggested that this fine-tuning of the neurons reflects the perceptual sensitization to the diagnostic features, which was revealed in a separate psychophysical study (Sigala et al., 2002, J Cogn Neurosci). In addition, the psychophysical and electrophysiological data support an exemplar-based framework for understanding visual object recognition. Finally, we studied the contribution of the anterior IT and lateral PF cortex in the context of a categorization task with natural images