Friday, March 21, 2025
3/21/2025
The standard model for development assumes that areas develop sequentially, in a feedforward manner starting with primary visual cortex (V1). However, there is a notable exception: Primate motion area MT, and its homolog PSS in the ferret, develop as early as V1. Early phases of development should therefore not be seen as being under the control of V1 only, but will be jointly influenced by V1 and MT/PSS. To appropriately incorporate this idea into developmental models, however, a precise understanding of how the areas interact during develop is required. Should MT/PSS largely be seen as a secondary stage that filters developmental drive received from V1, or are the areas interacting in a more complex way, which ultimately would result in more flexibility for how development could propagate through the visual hierarchy? Here, we will investigate the interactions between ferret PSS and V1, during an early phase of visual development in which selectivity for motion direction develops, to address this question. Our experiments will use retrograde tracers, extracellular recordings, and manipulations of neural activity (inactivation and stimulation) to test two questions: First, whether PSS can function in a V1-independent manner, almost like a primary area, during this developmental phase. Second, whether feedback from PSS plays a role in V1 development, a reversal of the standard assumptions that would also mean that V1-PSS interactions will impact even the most fundamental level of visual processing. The overarching goal of this proposal is to expand developmental models from focusing on a single area at a time, to a network-wide view, a necessary step to capture the complexity of a process that ultimately occurs at the network level.
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