Abstract
V1 neurons in primates respond to binocular stimulation, but with various degrees of eye preferences. We used two-photon calcium imaging (GCaMP5) to study a) ocularity-contingent monocular and binocular responses of macaque V1 superficial neurons and their contributions to stable perception when the world is viewed with one or both eyes open; b) functional organization of ocularity and its relationships to orientation and SF maps. The stimulus was a high-contrast (0.9) drafting (2 cycles/sec) Gabor of 12 orientations (in 15° steps) and 6 SFs (0.25-8 cpd), and was presented binocularly or monocularly to each eye. Data analysis identified a total of 7335 neurons that were orientation selective with at least one eye. Most V1 superficial-layer neurons responded to stimulations from both eyes, and only a few were strictly monocular. When monocularly stimulated, the best responses of more monocular neurons were markedly stronger than those of more binocular neurons, approximately in the form of a quadratic function. However, stronger responses of monocular neurons were suppressed, and weaker responses of binocular neurons were enhanced by binocular stimulation. As a result, the net population responses remain little changed, which may be related to the homeostasis of perception under monocular and binocular viewing. The monocular and binocular response changes can be described with a binocular integration and gain control modal, which also predicts binocular summation at low stimulus contrasts. V1 neurons clustered with similar ocularity index within the same recording plane. The median clustering index was 1.87, significantly higher than permuted data. Neurons also formed ocular dominance columns across depth planes. Neuron-wise, ocularity, SF, and orientation functional maps intersected each other in a wide range of angles, with the median around 40°. The vector sums of individual angles were near 0°, but with large circular variances (>0.8), suggesting no reliable relationships among these functional maps.