Abstract
The occipital place area (OPA) – a cortical region supporting “visually-guided navigation” (i.e., finding our way through the immediately visible environment) in adulthood – has recently been found to be late developing, not fully functional until around 8 years old. But how is this prolonged development possible given that we move through our local environment long before 8 years old, often beginning with crawling followed by “toddler” walking? One possibility is that OPA represents only the visual information from an “adult-like” walking perspective, and not from the other perspectives encountered during early development. To directly test this hypothesis, using fMRI in 15 human adults, we measured the responses in OPA to videos depicting the actual first-person visual experience of navigating the immediate environment – from either a “walking” or “crawling” perspective, as well as two baseline perspectives (i.e., an aerial “flying” perspective and a “scrambled” version of the walking videos). Consistent with our hypothesis, we found that OPA responded significantly more to the walking videos compared to the crawling, flying, and scrambled ones. Critically, we also found that OPA responded similarly to the crawling, flying, and scrambled videos, indicating that OPA doesn't respond to crawling information any more than either a perspective by which humans don't navigate (“flying”) or a non-navigable perspective all together (“scrambled”). This pattern of results was unique to OPA, and was not found in other scene-selective regions, motion-selective cortex, or primary visual cortex – ruling out any general attentional, motion, or low-level visual information accounts. Collectively, these results reveal that OPA is “tuned” to visual information about adult-like walking, not crawling, consistent with its prolonged development hypothesis, and raise the intriguing question of whether crawling (and early walking) is a mode of visually-guided navigation at all, or is processed by a different neural system all together.