Abstract
Neurons in macaque infero-temporal cortex (IT) are selectively sensitive to images of natural objects, and this sensitivity develops over the first months of life. We wanted to know whether IT neurons – like neurons in V2 and V4 but not V1 – were also sensitive to natural image statistics in texture images, and how that sensitivity might develop. We used the 2000 Portilla and Simoncelli model to generate two kinds of textures – all were matched in spatial frequency and orientation content – they differed only in the presence or absence of naturalistic image correlations. We recorded single- and multiple-unit neuronal responses to these textures in fixating macaque monkeys ranging from 6 to 24 months of age, using 96-channel “Utah” arrays. IT neurons responded better on average to the textures containing naturalistic image correlations at all ages; discriminability analysis supported this finding. We also measured latencies for the onset of the visual response and also for the onset of the differential response to naturalistic texture. Both measures of latency decreased and became less dispersed with age. In addition, we compared IT latencies with those from concurrent recordings in V1 and V2, and at each age we found the shortest latencies in V2. Our results demonstrate the sensitivity of IT neurons for naturalistic image content. Furthermore, they suggest that the likely origin of this sensitivity is in V2, across all ages tested.