Unveiling Unwritten Curricula: Enhancing Junior Faculty Development in Academic Emergency Medicine.

Recognition, i.e., reproducible discrimination, of signals from the sensory environment is a fundamental function of all central nervous systems (). Vision is considered the dominant sensory modality for most primates, who have high visual acuity and excellent binocular vision for recognizing their environment (). In the primate order, visual object recognition is supported by a wide bilateral network of brain regions, including subcortical structures and the occipital and temporal cortices (; ; ). Based primarily on non-human primates research, this network is generally conceived as being organized in a hierarchical manner, with definite processing stages increasing progressively in complexity of representation from posterior to anterior cortical regions, leading ultimately to rich invariant visual representations readily available for memory associations and behavior planning (; ; ; ; ; ; ; ; ; ; ; ). In this hierarchical network, the selective response properties of neural populations in a given brain region are thought to stem from the combination of simpler responses from lower levels. However, beyond the initial cascades of activities in early sensory brain structures (i.e. retina, lateral geniculate nucleus, primary visual cortices), whether visual object recognition is organized hierarchically remains largely unknown and disputed (; ; ; ; ; ). This is particularly the case within the temporal association cortex, which is disproportionately enlarged in humans compared to other primates (; ) and holds most category-selective ventral regions that are key for visual object recognition in our species (; ; ). Here, we provide important information to evaluate the hierarchical view of human visual object recognition through an extensive characterization of the time-course of category-selective brain activity along the human ventral occipito-temporal cortex (VOTC). To do so, we take advantage of the high spatial and temporal resolution provided by intracerebral electroencephalographic (iEEG) recordings in a particularly large sample of individual human brains (N=140) implanted from posterior to anterior regions of their VOTC (>11,000 intracerebral recording sites). With iEEG frequency-tagging, we isolate category-selective high frequency (‘high frequency broadband,’ 30–160 Hz) neural activity to natural images of faces – arguably the most familiar and ecologically valid stimulus in the human environment – to characterize its time-course across the whole VOTC. This allows testing two essential features of a hierarchical organization (; ): (1) an increase in representation complexity, or abstraction, along the VOTC and (2) a progressive increase in the onset time of the earliest neural response at each level of the hierarchy, its inputs being driven by the output from the previous level.