Sohrab najafian¹, Vladimir K. Berezovskii¹, Michael J. Arcaro², Margaret S. Livingstone¹; ¹Department of Neurobiology, Harvard Medical School, Boston, MA, USA, ²Department of Psychology, University of Pennsylvania, Philadelphia, PA, USA

Inputs from the lateral geniculate nucleus segregate into ocular dominance columns in layer 4 of the macaque primary visual cortex (V1) via Hebbian mechanisms. Beyond V1 layer 4, most visual neurons are binocular. Research on developing frogs with transplanted third eyes revealed abnormal ocular dominance patterns despite lacking binocular overlap (Constantine-Paton et al., 1978). Inspired by this, we manipulated early visual experience in infant macaques to anti-correlate eye activity. Two macaques wore helmets with liquid crystal shutter lenses alternated at 0.1 Hz for the first postnatal year to test if anti-correlated activity induces ocular dominance columns beyond V1, providing insights into feature domain development in higher areas like the inferior temporal cortex. After rearing, one eye was injected with tetrodotoxin for 3 weeks, and ~500 sagittal sections (70 µm thick) were processed for cytochrome oxidase staining. We developed a pipeline to analyze ocular dominance columns in 2D slices and reconstruct 3D volumes of CO staining at different laminar depths (Oishi et al. 2024). Slices were co-registered and combined to construct a 3D histology volume, aligned to a reference MRI, revealing clear ocular dominance columns across the cortical surface extending beyond layer 4 of V1. To quantify column periodicity, visual areas in slices were segmented and flattened into 1D vectors, capturing staining intensity variations. Flattened 1D vectors were assembled into a cortical sheet, revealing the 2D column structure beyond V1. FFT analysis confirmed accurate reconstruction of columns in V1 and their presence beyond V1. The average column periodicity was 506.06±110µm in V1, 550.59±145µm in V2 ventral, and 554.98±137µm in V2 dorsal. The larger domains beyond V1 indicate that 1) Hebbian mechanisms act during development to segregate domains according to patterns of neuronal activity, even beyond primary sensory areas; and 2) hierarchical convergence creates larger domains (Nasr et al., 2016).